Manual Work & Worker-Machine Systems

Manual Work & Worker-Machine Systems
Sections: Manual Work Systems Worker-Machine Systems Automated Work Systems Determining Worker and Machine Requirements Machine Clusters Chapter 2

Three Categories of Work Systems
Manual work system Worker performing one or more tasks without the aid of powered tools Worker-machine system Human worker operates powered equipment Automated work system Process performed without the direct participation of a human worker

Manual Work System

Worker-Machine System

Automated System

Some Definitions Workpiece being machined (production work)
Work unit – the object that is processed by the work system Workpiece being machined (production work) Material being moved (logistics work) Customer in a store (service work) Product being designed (knowledge work) Unit operations – tasks and processes that are treated as being independent of other work activities

Manual Work Systems Human body accomplishing some physical task without an external source of power With or without hand tools When hand tools are used, the power to operate them is derived from the strength of a human worker Other human faculties are required, such as hand-eye coordination and mental effort

Pure Manual Work Involves the physical and mental capabilities of the human worker, and no machines, tools, or other implements are employed in performing the task. Material handler moving cartons in a warehouse Workers loading furniture into a moving van without the use of dollies Dealer at a casino table dealing cards Office worker filing documents Assembly worker snap-fitting two parts together

Manual Work with Hand Tools
Manual tasks are commonly improved by the use of hand tools. A tool is a device or implement for making changes to some object (e.g., the work unit), such as cutting, grinding, striking, squeezing, or other process. A hand tool is a small tool that is operated by the strength and skill of the human user. Examples of manual tasks involving the use of hand tools include the following: Machinist filing a part Assembly worker using screwdriver Painter using paintbrush to paint door trim QC inspector using micrometer to measure a shaft diameter

Repetitive vs. Nonrepetitive Tasks
Relatively short duration (usually a few minutes or less) High degree of similarity from one cycle to the next Nonrepetitive Task Takes a long time Work cycles are not similar

Cycle Time Variations A main objective in work design is to determine the one best method for a task, and then to standardize its use Once the method has been standardized, the actual time to perform the task is a variable because of: Differences in worker performance differences in hand and body motions Mistakes by worker Variations in starting work units The learning curve phenomenon Differences in the physical and cognitive attributes among workers performing the task Variations in the methods used by different workers to perform the task

Worker Performance Defined as the pace or relative speed of working
As worker performance increases, cycle time decreases From the employer’s viewpoint, it is desirable for worker performance to be high What is a reasonable pace to expect from a worker?

Normal Performance A pace of working that can be maintained by a properly trained average worker throughout an entire work shift without injurious effect on the worker’s health or physical well-being The work shift is usually 8 hours, during which periodic rest breaks are allowed Normal performance = 100% performance Common benchmark of normal performance: Walking at 3 miles/hr

Normal Time The time to complete a task when working at normal performance Actual time to perform the cycle depends on worker performance Tc = Tn / Pw where Tc = cycle time, Tn = normal time, and Pw = worker performance or pace

Example: Normal Performance
Given: A man walks in the early morning for health and fitness. His usual route is 1.85 miles. A typical time is 30 min. The benchmark of normal performance = 3 miles/hr. Determine: (a) how long the route would take at normal performance and (b) the man’s performance when he completes the route in 30 min.

Example: Solution (a) At 3 miles/hr, time = 1.85 miles / 3 miles/hr
= hr = 37 min (b) Rearranging equation, Pw = Tn / Tc Pw = 37 min / 30 min = = % Alternative approach in (b): Using velocity = 1.85 miles / 0.5 hr = 3.7 miles/hr Pw = 3.7 miles/hr / 3.0 miles/hr = %

Standard Performance Same as normal performance, but acknowledges that periodic rest breaks must be taken by the worker Periodic rest breaks are allowed during the work shift Federal law requires employer to pay the worker during these breaks Other interruptions and delays also occur during the shift

PFD Allowance Bathroom breaks, personal phone calls
To account for the delays due to: Personal time (P) Bathroom breaks, personal phone calls Fatigue (F) Rest breaks are intended to deal with fatigue Delays (D) Interruptions, equipment breakdowns

Standard Time Defined as the normal time but with an allowance added in to account for losses due to personal time, fatigue, and delays Tstd = Tn (1 + Apfd) where Tstd = standard time, Tn = normal time, and Apfd = PFD allowance factor Also called the allowed time

Irregular Work Elements
Elements that are performed with a frequency of less than once per cycle Examples: periodic changing of tools (e.g., changing a knife blade) Irregular elements are prorated into the regular cycle according to their frequency

Example: Determining Standard Time
Given: The normal time to perform the regular work cycle is 3.23 min. In addition, an irregular work element with a normal time = 1.25 min is performed every 5 cycles. The PFD allowance factor is 15%. Determine (a) the standard time and (b) the number of work units produced during an 8-hr shift if the worker's pace is consistent with standard performance.

Standard Hours and Worker Efficiency
Two common measures of worker productivity used in industry to assess a worker’s productivity are standard hours and worker efficiency Standard hours – represents the amount of work actually accomplished Hstd = Q Tstd Hstd = standard hours accomplished; Q = quantity of work units completed; Tstd = standard time per work unit Worker efficiency – work accomplished as a proportion of shift hours Ew = Hstd / Hsh Ew = worker efficiency; Hstd = # of standard hours of work accomplished; Hsh = # of shift hours (8 hr)

Worker efficiency Worker efficiency is commonly used to evaluate workers in industry. In many incentive wage payment plans, the worker’s earnings are based on his or her efficiency or the number of standard hours accomplished. Worker efficiency and standard hours are easily computed, because the number of hours in the shift and the standard time are known, and the number of work units produced can be readily counted.

Worker-Machine Systems
When worker operates a powered equipment we refer to the arrangement as a worker-machine system. Examples: Machinist operating a milling machine Factory worker loading and unloading parts at a machine tool. Truck driver driving an 18-wheel tractor-trailer Worker crew operating a rolling mill that converts hot steel blocks into flat plates. Clerical worker entering data into a PC

Types of Powered Equipment
Distinguished from hand tools by the fact that a source of power other than human strength is used to operate it. Common power sources are electric, pneumatic, hydraulic, and fossil fuel motors Portable power tools are light enough in weight portable power drills, rotary saws, chain saws, and electric hedge trimmers. Mobile powered equipment are generally heavy pieces of equipment Transportation equipment, agricultural and lawn-keeping, forklift trucks, electric power generator at construction site Stationary powered machines stand on the floor or ground and cannot be moved while they are operating Machine tools (e.g., turning, drilling, milling); office equipment (personal computers, photocopiers, telephones, fax machines); cash registers, heat treatment furnaces

Classification of Powered Machinery

Numbers of Workers and Machines Means of classifying worker-machine systems is according to whether there are one or more workers and one or more machines One worker and One machine Taxicab driver and taxi One worker & Multiple machines A worker tending several production machines Multiple workers and One machine Ship's crew Multiple workers and Multiple machines Emergency repair crew responding to machine breakdowns in a factory

One Worker and One Machine
Good work design attempts to achieve the following objectives: Design the controls of the machine to be logical and easy to operate for the worker. Design the work sequence so that as much of the worker’s task as possible can be accomplished while the machine is operating, thereby minimizing worker idle time. Minimize the idle times of both the worker and the machine. Design the task and the machine to be safe for the worker.

Level of Operator Attention
Full-time attention Welders performing arc welding Part-time attention during each work cycle Worker loading and unloading a production machine on semi-automatic cycle Periodic attention with regular servicing Crane operator in steel mill Periodic attention with random servicing Firefighters responding to alarms

Two welders performing arc welding on pipe - requires full-time attention of workers (photo courtesy of Lincoln Electric Co.)

Cycle Time Analysis in Worker Machine System
In terms of cycle time analysis, worker-machine systems fall into two categories: systems in which the machine time depends on operator control, the task can be either repetitive or nonrepetitive systems in which the machine time is constant and independent of operator control, and the work cycle is repetitive.

Cycle Time with no Overlap between Worker and Machine
If there is no overlap in work elements between the worker and the machine, then the normal time for the cycle is simply the sum of their respective normal times: Normal time for cycle Tn = Tnw + Tm Where Tnw = normal time for the worker-controlled portion of the cycle, min: and Tm = machine cycle time (assumed constant). Standard time for cycle Tstd = Tnw (1 + Apfd) + Tm (1 + Am) where Tnw = normal time of the worker, min; Tm = constant time for the machine cycle, min; Am = machine allowance factor, used in the equation as a decimal fraction

Worker-Machine Systems with Internal Work Elements
In the operation of a worker-machine system, it is important to distinguish between the operator’s work elements that are performed in succession with the machine’s work elements and those that are performed simultaneously with the machine elements. Operator elements that are performed sequentially are called external work elements while those that are performed simultaneously with the machine cycle are called internal work elements.

Example 2.10 Internal Versus External Work Elements in Cycle Time Analysis
The work cycle in a worker-machine system consists of the elements and associated times given in the table below. All of the operator’s work elements are external to the machine time. Can some of the worker’s elements be made internal to the machine cycle, and if so, what is the expected cycle time for the operation?

Comment Although the total times for the worker and the machine are the same as before, element 4 in the revised cycle (which Consists of elements 1, 2, and 6 from the original work cycle) is performed simultaneously with the machine time, resulting in the following new cycle time: Tc = = 0.97 min This represents a 34% reduction in cycle time, which translates into a 53% increase in production rate. When internal elements are present in the work cycle, it must then be determined whether the machine cycle time or the sum of the worker’s internal elements take longer.

Automated Work Systems
Automation is the technology by which a process or procedure is accomplished without human assistance Implemented using a program of instructions combined with a control system that executes the instructions Power is required to drive the process and operate the control system

Levels of Automated Systems
Semiautomated machine Performs a portion of the work cycle under some form of program control Human worker tends the machine for the remainder of the cycle, by loading and unloading it Operator must be present every cycle Fully automated machine Operates for extended periods of time with no human attention

Automated robotic spot welding cell (photo courtesy of Ford Motor Company)

Service Operations and Office Work
Sections: Service Operations Office Work Chapter 6 Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Service Operations Service operations provide a service to a client or customer By contrast, production operations provide a product Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Service Industries: Typical Companies
Banking – Citigroup, Bank of America Communications – Verizon, Comcast Education – Lehigh, Penn State Entertainment – Walt Disney, Viacom, MGM Health Care – Aetna, Health Net, hospitals Hotel – Hilton, Holiday Inn, Ritz Carlton Insurance – New York Life, State Farm Retail Trade – Wal-Mart, Sears, Home Depot Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

The Nature Of Services A service is intangible; it is experienced
The time to deliver a service is variable and usually unpredictable How long will it take for an auto mechanic to diagnose an engine problem? How long will it take for an obstetrician to deliver a baby? How long will it take for a mechanical engineer to design a new part? Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Comparisons: Products vs. Services
Tangible Products are consumed Minimum variations, one unit to the next Time to complete is generally predictable No customer contact with manufacturer Services Intangible Services are experienced Variations between one service and the next Time to complete often unpredictable Customer contact with service provider Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Service Quality Factors
Customer interaction How well did the customer get along with the car salesman? Quality of workmanship Did the customer get a good haircut? Waiting time How long did the customer have to wait before being served? Service time How long did the service take once it began Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Types of Service Providers
Service Organizations – service is the main business of the company or organization Internal Services – department provides a service within the larger company Example: Accounting Department Product Companies that also provide a service Example: Dell Corp. sells PCs but they maintain a service call center for customers with problems Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Scheduled vs. Random Services
Scheduled Service Operation – customer arrival times are scheduled Examples: doctor and dentist appointments, airline passenger service, college courses Random Service Operation – customers arrive randomly Examples: hospital emergency rooms, retail stores, fast food restaurants Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Facilities- vs. Field-Based Services
Facilities-based services – customers must be at the service provider’s facility for the service to be rendered Examples: banks, barber shops, hotels, movie theaters, retail trade Field-based services – service is rendered at customer’s location Examples: custodial services, household appliance repairs, garbage collection Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Level Of Customer Contact
High-contact services – customer is involved a high proportion of the service time Each service tends to be different Examples: hairdressers, dental offices, restaurants Generally associated with facilities-based services Low-contact services – little direct contact between customer and service provider Examples: postal delivery, tax collectors Generally associated with field-based services Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Implications of Level of Contact
High contact services: More difficult to plan staffing requirements in random service operations Good interpersonal skills required of service providers Low-contact services: Possible to analyze the work process and make methods improvements Technical and analytical skills are more important Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Manual Work vs. Service Work
Manual repetitive work Processing of material Worker attributes are physical Blue collar worker Work is performed in factories, warehouses, construction sites Associated with primary and secondary industries Service work Information processing Worker attributes are mental, communication White collar worker Work is performed in banks, offices, stores, restaurants, hospitals Associated with tertiary industries Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Standards & Staffing for Service Work
Setting standards and determining staffing levels is more difficult for service operations than for repetitive work because Services are variable, so service times vary Random arrivals - difficult to predict workloads Customer contact affects service time Intangible work units Details of the service are not known in advance Creative work cannot be measured directly Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Standards Used In Service Work
Hospital staff nurse – standard = number of patients for which nurse is responsible Salesperson – sales quota Dental hygienist – 45 minutes per patient Dentist – different appointment times for different categories of dental work Caseworker – standard = number of cases College faculty – standard = three courses per semester Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Office Work An office is a place where the business-oriented activities of an organization are transacted and/or its services are rendered Office work is concerned with business processes and functions Design Sales Accounting Scheduling Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Office Activities Physical and mental actions performed by office worker while performing an assigned task Examples: Answering and making telephone calls Calculating Decision-making Participating in meetings Photocopying Reading Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Office Applications Related to the business processes of the organization and oriented toward end results Examples: Accounts payable Engineering drawing preparation Payroll Preparing and making presentations Production scheduling Sales forecasting Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Routine vs. Creative Office Work
Characteristics of routine office work: Tends to be easy Less education required Repetitive Predictable Defined procedures Characteristics of creative office work: Tends to be difficult More education required Non-repetitive Problem solving Problems are unique Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Routine Office Work Activities
Filing papers Carrying things Collating and sorting Mail handling Photocopying Typing and keying Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Creative Office Work Activities
Analysis Calculating Decision-making Drawing conclusions or inferences Drawing or sketching Proofreading or checking Thinking Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Routine Plus Creative Work Activities
Answering telephone calls Making telephone calls Participating in meetings Reading Writing Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Knowledge Workers and Support Staff
Knowledge workers – office workers who accomplish the creative information-processing activities and applications in offices Two types: Managerial Non-managerial Support workers – provide administrative and staff assistance for the office Perform routine office tasks Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Job Titles of Knowledge Workers
Managerial: Chief executive officer Vice president Manager Superintendent Principal (school) Dean (college) General (army) Admiral (navy) Non-managerial: Engineer Lawyer Medical doctor Research scientist Editor Chemist Marketing analyst Professor Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Job Titles of Support Personnel
Administrative assistant Administrative associate Bookkeeper Clerical worker Data entry operator Editorial assistant Equipment technician Receptionist Secretary Stenographer Telephone operator Typist Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Knowledge Work Routine office work can be subjected to analysis, mechanization, and automation Knowledge work depends on uniquely human traits that cannot be automated Creative abilities – required for creative work Discretion – knowledge worker must decide how to approach a given problem or task Self-pacing – knowledge worker works at own pace No machine pacing Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Allocation of Workloads
Ideal allocation of workloads between knowledge workers and support staff Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Allocation Reported in Research Study
Actual allocation of workloads between knowledge workers and support staff as indicated in a 1988 study of office work Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Why Professionals Do Routine Work
The work is easier Results measured more readily Can predict the time required Support personnel are assigned to managers, not professional staff Support personnel are not available Support personnel do not do their jobs adequately Support personnel are not trained properly Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Office Automation Modern implementation of computers and other business machines to automate much of the routine and repetitive information-processing work accomplished in offices Mainframe computers introduced into business in 1950s PCs introduce into offices in 1980s Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Characteristics of Office Automation
Its purpose is to assist workers in accomplishing their information-processing activities and applications It consists of hardware (PCs, telephones, photocopiers) and software (word processors, spreadsheets) It is a networked environment It represents the convergence and integration of three traditional office technologies Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Three Traditional Office Technologies
Office machine technology Typewriters, adding machines, dictation machines, and photocopiers Data processing technology Computers, data storage devices, printers and other output devices Communication technologies Telephones and teletype machines. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computer Augmentation of Office Work
Use of computer systems to enhance worker capabilities in low-volume creative work Concerned with increasing and improving Effectiveness of the process Convenience of the worker Quality of the result Access to needed information Communication with colleagues and co-workers Procedures for performing creative work Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Office Automation vs. Augmentation
Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Examples of Computer Augmentation
Design engineer - CAD workstation Writer – PC word processor software College professor – PC slide preparation software Commercial artist - computer graphics terminal Lawyer - legal documents on a word processor Process planner - process planning software Time study engineer - specialized work measurement software Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Methods Engineering Part II Chapters:
Introduction to Methods Engineering and Operations Analysis Charting Techniques Motion Study and Work Design Part II Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Introduction to Methods Engineering and Operations Analysis
Sections: Evolution and Scope of Methods Engineering How to Apply Methods Engineering Basic Data Collection and Analysis Techniques Automation and Methods Engineering Chapter 8 Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Methods Engineering Analysis and design of work methods and systems, including the tooling, equipment, technologies, workplace layout, plant layout, and work environment Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Other names for methods engineering:
Work study Work simplification Methods study Process re-engineering Business process re-engineering Methods Engineering is often associated with work measurement. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Objectives in Methods Engineering
Increase productivity and efficiency Reduce cycle time Reduce product cost Reduce labor content Improve motivation and morale Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Other Objectives Improve customer satisfaction
Improve product and/or service quality Reduce lead times and improve work flow Increase flexibility of work system Improve worker safety Apply more ergonomic work methods Enhance the environment (both inside and outside the facility) Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Operations Analysis Study of an operation or group of related operations for the purpose of analyzing their efficiency and effectiveness so that improvements can be developed Objectives in operations analysis Increase productivity Reduce time and cost Improve safety and quality Same basic objectives as methods engineering Methods engineering places more emphasis on design. It is broader than operations analysis. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Evolution and Scope of Methods Engineering
Initial research (late 19th century) - Frank Gilbreth: Motion study Scientific management (late 19th century-early 20th century)- Frederick W. Taylor: Motion and time study (first principle of the five principles) Primary concern: manual physical labor Today: methods engineering is applied to areas such as indirect labor, logistics, service operations, office work, and plant layout. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Methods Engineering Can be divided into two areas: Methods analysis
Methods design Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Methods Analysis Concerned with the study of an existing method or process break the method (process) down into work elements or basic operations examine the details of the elements: a systematic (= purposefully regular, methodical) search to improve the process This involved checklists of questions and suggestions for improvements Objectives : Eliminate unnecessary and non-value-adding work elements Combine elements and operations Rearrange elements into more logical sequence Simplify remaining elements and operations In your project Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Methods Design Concerned with either of the following situations:
Design of a new method or process Required for new product or service and there is no existing precedent Method must be designed from scratch, using best existing practice for similar operations Redesign of an existing method or process based on a preceding methods analysis Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Systematic Approach in Methods Engineering
Define the problem and objectives Analyze the problem Formulate alternatives Evaluate alternatives and select the best solution Implement the best method Audit the study (follow-ups) IE 407-IE 408 A systematic approach is more likely to yield operational improvements than an undisciplined approach Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Step 1: Define the problem and objectives
Problem: the reason for needing a systematic approach to determine its solution low productivity, high cost, inefficient methods, the need for a new method/operation Objective: the desired improvement or new methods design that would result from the project. Increase productivity, reduce labor content, improve safety, develop a new method The problem definition and the objectives must be specific to the problem under investigation. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Step 2: Analyze the problem
Data collection and analysis. Kind of activities involved Identify the basic function of the operation Gather background information Observe existing/similar processes Collect data Construct experiments on the process Develop/utilize a mathematical model of the process Perform a computer simulation of the process Use charting techniques Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Step 3: Formulate Alternatives
There are multiple ways to perform a task or accomplish a process. Some of them are more efficient and effective than others Formulate all feasible alternatives Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Step 4: Evaluate alternatives and select the best
Methodical assessment of the alternatives with respect to the original problem definition and the objectives. Selecting the best one with respect to the objective (but this is not a simple task) Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Step 5: Implement the best method
Install the selected solution Introduce/institute changes proposed in the existing method Pilot studies and trials of the new (revised) method Documentation of the revised method Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Step 6: Audit the study Continuous improvement (follow-ups)
Fine-tune the organization’s problem solving and decision making skills How successful was the project in terms of the original problem definition and the objectives? What were the implementation issues? What should be done differently in the next study? Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

The Techniques of Methods Engineering
The following techniques are mostly accociated with the analysis step in the methods engineering. Charting and diagramming techniques Motion Study and Work Design Facility Layout Planning Work Measurement Techniques New approaches Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Charting & Diagramming Techniques
They are available mainly for collecting, displaying and analyzing data Network diagrams Traditional industrial engineering charting techniques Operation charts Process charts Flow diagrams Other (alternative) diagrams Block diagrams Process maps Next week Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Motion Study and Work Design
Concerned with basic motions of a human worker while performing a given task 17 basic motion elements, like reach, grasp, move, release “Principles of motion economy”- guidelines for work design Use of human body in developing the standard method (e.g., design the work so that both hands are fully utilized) Workplace layout Design of tooling used in the task Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Motion Study and Work Design -Objective
Unnecessary motions can be eliminated. Some of the motion elements can be combined. The method can be simplified. In your project 2 weeks later Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Facility Layout Planning
Facility layout refers to: Size and shape of a facility Arrangement of the different departments and equipment within the facility The layout plays an important role in determining the overall efficiency of the operations Problem area includes: Design of a new facility Installing new equipment, retiring old equipment Expanding (or contracting) an existing facility IE 302 and IE 407 Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Work Measurement Techniques
Four basic work measurement techniques: Direct time study Predetermined motion time systems (PMTS) Standard data systems Work sampling They can be used in methods engineering to make improvements in the work methods 3 weeks later Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

New Approaches Lean production Based on the Toyota production system
Embraced by U.S. companies due to its success at Toyota Six Sigma and other quality-focused programs Widely adopted in industry for improving quality of work processes 5S: The 5-step work organization: Seiri (Sort), Seiton (Set in order), Seiso(Shine), Seiketsu (Standardize), Shitsuke (Sustain) Most of the tools used are adaptations of the old IE principles. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Selecting Among Alternative Proposals
Need for a systematic procedure to decide among alternative proposals To begin, list the technical features and functional specifications for the application Must features Some features and specifications that should be guaranteed at the minimum level. Desirable features Not must features Criteria matrix to evaluate alternatives Proposals are evaluated against the features and specifications Eliminate candidates that do not satisfy “must features” Develop scores for desirable features Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Evaluation of Robots for Welding

Evaluation of Robots for Welding
Eliminate C because, it doesn’t satisfy one of the must features Select D because, it has the highest score among desirable features. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Basic Data Collection & Analysis Tools
Histograms Pareto charts Pie charts Check sheets Defect concentration diagrams Scatter diagrams Cause and effect diagrams Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Histogram A statistical graph consisting of bars representing different values, in which the length of each bar indicates the frequency or relative frequency of each member A useful tool because the analyst can quickly visualize the features of the data, such as: Shape of the distribution (theoretical form, Normal, Gama etc.) Any central tendency in the distribution (single or multimodal) Approximations of the mean and mode (numerical value of the centre) Amount of scatter in the data (variance or risk) Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Number of individual parts

Histogram for Data Display
Normal distribution Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Pareto Chart Special form of histogram in which attribute data are arranged according to some criterion such as cost or value Based on Pareto’s (XIXth century economist who was trying to analyze the distribution of wealth in Italy) Law: “the vital few and the trivial many” also known as 80%-20% rule 80% of a nation’s wealth is owned by 20% of the population 80% of sales are accounted for by 20% of the SKUs (stock keeping unit or items in stock) Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Pareto chart as a cumulative frequency distribution

Pareto cumulative distribution
Can be modeled by where y=cumulative fraction of the value variable (e.g., wealth, inventory value, revenue), x=cumulative fraction of the item variable (e.g., population, inventory items, customers) A is a constant determines the shape of the distribution (shape parameter). Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Example: Pareto Cumulative Distribution
Given: 20% of the total inventory items in a company’s warehouse accounts for 80% of the value of the inventory. Determine: (a) The parameter A in the Pareto cumulative distribution equation. (b) Given that the relationship is valid for the remaining inventory, how much of the inventory value is accounted for by 50% of the items? Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Example: Solution a) x=0.2, y=0.8 A=(0.20(1-0.8))/(0.80-0.20)=0.06667
50% items in inventory account for 94.1% of the value of the inventory Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Pareto Principle in Turkey
80% of the academic publications are affiliated to 20% of the universities. 78% of the earnings are derived from 96 export items, which makes the 20% of all export items. In 2007 elections, three parties (20% of the political parties) won the 84% of the votes. Three highest grossing movies in last November, i.e., Harry Potter, New York’ta Beş Minare, Saw 3D (only 20% of the movies) makes 80% of the total gross revenues. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Pie Charts Example: Annual sales revenues and customer distributions for two years Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Check Sheet Not check lists
Data collection tool generally used in the preliminary stages of a study of a quality problem To recogize the trends Diagnose the problem Identify areas of further study Data often entered by worker as check marks in a given category Examples: Process distribution check sheet - data on process variability Defective item check sheet – types and frequencies of defects on the product Defect location check sheet - where defects occur on the product Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Make an investigation to determine the causes of this variability
It is clear from the check sheet that the third shift is reponsible for much of the variability in the data. Make an investigation to determine the causes of this variability Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

The average daily production rate for the third shift is below the daily rate for the other two shifts. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Defect Concentration Diagram
A drawing of the product (all relevant views), onto which the locations and frequencies of various defect types are added Useful for analyzing the causes of product or part defects By analyzing the defect types and corresponding locations, the underlying causes of the defects can possibly be identified Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Case study involving final assembly of refrigerators Four views of refrigerator showing locations of surface defects Defects here Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

The defects were clearly shown to be concentrated around the middle section of the refrigerator. Upon investigations, it was learned that a belt was wrapped around each unit for material handling purposes. The defects were caused by the belt. The necessary correction action was taken. Defects here Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Scatter Diagrams An x-y plot of data collected on two variables, where a correlation between the variables is suspected It is useful to identify a possible relationship that exists between two processes. The data are plotted as pairs; for each xi value, there is a corresponding yi value The shape of the collection of data points often reveals a pattern or relationship between the two variables Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Scatter Diagram Effect of cobalt content on wear resistance for a cemented carbide cutting tool Negative correlation: As cobalt increases wear resistance decreases. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Cause and Effect Diagram
A graphical-tabular chart used to list and analyze the potential causes of a given problem Can be used to identify which causes are most consequential (related) and how to take corrective action against them Also known as a “fishbone diagram” or “spray diagram” Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Six general categories of causes 5M + 1P Machines Equipment, tools etc. Materials Mother nature Enviromental factor such as air temperature, humadity etc. Methods Procedures, sequence of activities etc. Measurement Validity and accuracy of the data collection procedure People Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Time Study and Work Measurement
Chapters: Introduction to Work Measurement Direct Time Study Predetermined Motion Time Systems Standard Data Systems Work Sampling Computerized Work Measurement and Standard Maintenance Economic Justification and Applications of Time Standards Learning Curves Part III

Introduction to Work Measurement
Sections: Time Standards and How They Are Determined Prerequisites for Valid Time Standards Allowances in Time Standards Accuracy, Precision, and Speed of Application in Work Measurement Chapter 12

Time Is Important Most workers are paid for their time on the job
The labor content (cost of labor time) is often a major factor in the total cost of a product or service For any organization, it is important to know how much time will be required to accomplish a given amount of work

Some Definitions Work measurement – evaluation of a task in terms of the time that should be allowed by an average worker to perform the task 4 techniques Focus on human work

Some Definitions Standard time (allowed time) – amount of time that should be allowed for an average worker to process one work unit using the standard method and working at normal pace Includes allowance

Some Definitions Time study – all the ways in which time is analyzed in work situations How much time it should take to accomplish a given task Both terms (work measurement and time study) can be used interchangeably

When Are Time Standards Beneficial?
Characteristics of industrial situations in which time standards would be beneficial Low productivity: significant opportunities for improvement Repeat orders: once the time standard is set for the first, it can be used for successive ones Long production runs: reduced average cost of work measurement Repetitive work cycles: work measurement can be justified more readily Short cycle times: requires less time to set standards

Functions of Time Standards
They define a “fair day’s work” They provide a means to convert workload into staffing and equipment needs They allow alternative methods to be compared objectively They provide a basis for wage incentives and evaluation of worker performance They provide time data for: Production planning and scheduling Cost estimating Material requirements planning

Methods to Determine Time Standards
Vary in terms of accuracy and reliability of the values derived from the method amount of time required to apply the corresponding method

Methods to Determine Time Standards
Estimation Judgment of a person who is familiar with the job Subjective Least accurate method Historical records Records on the actual times and production quantities for previous identical or similar job orders - “Time card”s Average time per part Improvement over estimates Limitation: No indication of efficiency measures Work measurement techniques Time consuming More accurate than estimation and historical records

Work Measurement Techniques
Direct time study (DTS) Predetermined motion time system (PMTS) Standard data systems (SDS) Work sampling

Task Hierarchy & Work Measurement
Pyramidal Structure of Work Work measurement techniques measure work at different levels of this hierarchy

1. Direct Time Study Direct observation of a task using a stopwatch to record the time taken to accomplish a task. The task is usually divided into work elements and each work element is timed seperately. During the observation, the analyst evaluates the worker’s pace - performance rating Normal time Tn=Tobs(PR) where Tn = normal time, min; Tobs= observed time, min; PR = performance rating of the worker’s pace Standard time Tstd =Tn(1+Apfd)

2. Predetermined Motion Time Systems
A database of normal times of basic motion elements (therbligs) such as reach, grasp, move etc. Conditions under which the motion elements (work variables) are performed are important. Example: normal time for TL Distance moved Weight of the object being moved The analyst list all of the basic motion elements that comprise the task; then normal times for basic motion elements are summed up to obtain the normal time for the task Advantages: No need for performance rating Can be applied before production starts

3. Standard Data Systems A compilation of normal time values for work elements used in the tasks performed in facility Used to establish time standards for tasks composed of work elements similar to those in the database Source of data: direct time study, PMTS, work sampling, historical data Effect of work variables should be included Tables Charts Mathematical equations

4. Work Sampling A random sampling technique to estimate the proportions of time spent in different activities Identify activities clearly. Example: machine setup, production, idleness Multiple subjects (entities) can be included Observations Random: minimize bias Large in number: to achieve statistical accuracy Objectives: Setting time standards Estimating resource utilization Determining an allowance factors

5. Computerized Work Measurement
Facilitates collection of data Performs routine computations Organizes time standards files and databases Retrieves data in predetermined motion time systems and standard data systems Assists in the preparation of the documentation Methods descriptions Reports

12.2 Prerequisites for Valid Time Standards
Time to perform a task depends on worker (gender, strength etc.), worker’s pace, method used, work unit Factors that must be standardized before a time standard can be set (except for the worker)

Average Worker A worker who
is representative of the persons who usually perform tasks similar to the task being measured. if the work is performed mostly by men (women), then the average worker is male (female) have learned the task, practiced and proficient at it is capable of performing the task consistently throughout the shift

Standard (Normal) Performance
A pace of working that can be maintained by an average worker throughout an entire work shift without harmful effects on the worker’s health or physical well-being Benchmarks of standard performance: Walking at 3 miles/hr on level flat ground Dealing four hands of cards from a 52 card deck in exactly 30 sec

Distribution of Worker Performance
Variations among workers →performance variations Worker performance is expressed in terms of daily output

More on Standard Performance
Standard performance is commonly defined to be a pace that can be readily attained by the majority of workers Companies want most workers to be able to achieve the standard performance easily. A typical policy is to define standard performance so that an average worker is able to work at a pace that is 130% of that pace Thus, most workers are able to easily achieve standard performance

How a Standard Time is Defined
Distribution of worker performance, indicating how standard time is defined so that it can be readily achieved by most workers 100/ 1.3 8 * 60 / 100

Standard Method Determining the optimum method for processing a work unit “One best method”: the safest, quickest, most productive, and least stressful to the worker Must include all of the details on how the task is performed, including: Procedure - hand and body motions Tools Equipment Workplace layout (what are the locations of the parts, tools) Irregular work Working conditions (is the work performed outside or inside) Setup

Standard Work Units The time needed to process the work unit depends on its starting condition Therefore this condition must be specified by engineering documents If the actual condition deviates from the specification, then extra time may be required to accomplish the task Exactly what changes are made in the work unit by the task? What is the final state of the completed work unit?

12.3 Allowances in Time Standards
Normal time is adjusted by an allowance factor Apfd to obtain the standard time Purpose of allowance factor is to compensate for lost time due to work interruptions and other reasons Standard time: Tstd = Tn(1 + Apfd) where pfd = personal time, fatigue, and delays

Reasons for Lost Time at Work
Work-related interruptions Machine breakdowns Waiting for materials or parts Receiving instructions from foreman Talking to co-workers about work-related matters Rest breaks for fatigue Cleaning up at end of shift Non-work-related interruptions Personal needs (e.g., restroom breaks) Talking to co-workers about matters unrelated to work Lunch break (not included in Apfd) Smoke break Beverage break إستراحة شرابِ Personal telephone call

How to Allow for Lost Time
Two approaches used by companies: Scheduled rest breaks during the shift Typical - one 15-minute break in mid-morning and another in mid-afternoon A PFD allowance is added to the normal time This allows the worker to take a break on his/her own time

PFD Allowance Personal time Fatigue Delays
Rest room breaks, phone calls, water fountain stops, cigarette breaks (5% typical) For example: A larger value will be approporiate if the work environment is hot Fatigue Rest allowance to overcome fatigue due to work-related stresses and conditions (5% or more) For example: If the work is physiologically very demanding, then relaxation time should be allowed periodically for the body to recover (in this case use 20% allowance) Delays Random, unavoidable interruptions Machine breakdowns, foreman instructions (5% typical) Usually management is responsible for these delays. Sudden urge for a cigarette break? Is it personal or delay?

Other Types of Allowances
There are other reasons for adding allowances, which are not as common as PFD allowances. They are applied in addition to Apfd Contingency طوارئِ allowance Additional allowance due to a problem with the task (e.g., raw material problem ) - not greater than 5% Temporary basis – after solving the underlying problem, it will disappear Policy allowance: They are based on company policy Machine allowance (set by company policy as a part of the wage incentive s.) Training allowance – for teaching new workers Learning allowance – learning a new task

Tstd = Tnw (1 + Apfd) + Tm (1 + Am)
Policy Allowances To cover special work situations that are usually associated with a wage incentive system. Example: Machine allowance – provides an opportunity of the worker to maintain a high rate of earnings even though (s)he has control over only a portion of the cycle. Tstd = Tnw (1 + Apfd) + Tm (1 + Am)

Example: Use of machine allowance in a wage incentive plan
Given: A wage incentive plan pays workers a daily wage at a rate of $15/hr multiplied by the number of standard hours accomplished during the shift. Tnw =1 min, Tm =3 min, Apfd =15%. Workers’ work elements are external. Determine the standard time for Am=0, Am=30%. What does a worker earn for the day under each Am (policy!) if (s)he produces 115 parts a day?

Example Solution Tstd = 1 (1 + .15) + 3 (1 + 0)=4.15 min
Hstd under Hstd=115(4.15)/60=7.95 hr Hstd=115(5.05)/60=9.68 hr The worker is paid under 15(7.95)=$119.25 15(119.25)=$145.19

12.4 Measurement A procedure in which an unknown quantity is compared to a known standard, using an accepted and consistent system of units Important attributes of a measurement system: Accuracy Precision Speed of response Work measurement is a measurement process

Accuracy and Precision
Degree to which the measured value agrees with the true value of the quality of interest Freedom from systematic errors, which are positive or negative deviations from the true value that are consistent from measurement to measurement Precision Repeatability of the measurement system High precision means random errors are small, where errors are assumed to follow a normal distribution Plus or minus three standard deviations often used as a benchmark: [m-3s,m-3s]

Measurement Accuracy vs. Precision
High accuracy Low precision Low accuracy High precision High accuracy High precision

Measurement Accuracy vs. Precision
High precision, but low accuracy High accuracy, but low precision Accuracy indicates proximity of measurement results to the true value, precision to the repeatability or reproducibility of the measurement

Relative Accuracy of Time Standards

Application Speed Ratio
Speed of response – the lag فارق الزمن between the time when the measuring device is applied and when the measured value is available to the user how much time is required to determine the time standard for a given task Varies for different work measurement techniques In work measurement speed of response is application speed ratio. Application speed ratio = ratio of the time required to set the standard divided by the value of the time standard itself Typical values = 100 to 250 Application speed ratio=100: It takes 100 min of analyst time to determine a 1 min-time standard.

Relative Application Speed

Computerized Work Measurement
and Standards Maintenance Sections: Computer Systems for Direct Time Study and Work Sampling Computerized Systems Based on Predetermined Motion Times and Standard Data Work Measurement Based on Expert Systems Maintenance of Time Standards Chapter 17 Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computerized Work Measurement
Applications: Direct time study Predetermined motion time systems Standard data systems Work sampling Objective in computerizing the techniques: Reduce the manual and clerical content by performing the tedious and time-consuming computational chores The creative problem-solving and design steps still require the expertise of an analyst or engineer Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computerized Direct Time Study
Steps in conventional direct time study: Define and document standard method Divide the task into work elements Time the work elements to obtain observed time Rate the worker’s performance to determine normal time Apply allowances to compute standard time PDA and PC can be applied in steps 3, 4, 5 Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computerized Direct Time Study
Block diagram shows how PCs and PDAs can be used in direct time study Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Functions Performed by PDA and PC
Collecting and recording the data: Timing the work elements (step 3) Maintains statistical record of time data, computes mean and standard deviation Computes number of cycles required to achieve a specified confidence interval Rating the worker’s performance (step 4) Performed simultaneously with step 3 Rating to nearest 5% Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

More PDA and PC Functions
Analysis and computations: Statistical analysis and charting Elimination of outliers from computations Standard time computation Generation of work instructions based on methods description Interface to other programs (e.g., MRP, CAPP, scheduling) Standards maintenance Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computerized Work Sampling
Computations during work sampling design Number of observations required to achieve a specified confidence interval Schedule of randomized times Making the observations Using a random beeper to alert when to make observation tours Recording the observation data Uploading the data to a PC Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computerized Work Sampling
Block diagram shows how PCs and PDAs can be used in work sampling Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computerized PMTS and SDS
Ideal work measurement technique would include a means of setting the standard time in advance of each job Predetermined motion time systems and standard data systems have this capability Two principal functions of the ideal computerized PMTS/SDS: Work measurement - setting the standard before the job is running Standards database - for standards that have been set, and for maintenance of the standards Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Work Measurement Function
Responsibilities of Analyst: Define standard method Decide what special tools, fixtures, and gauges might be required Define and evaluate what work variables might affect element times Retrieve data from database of element times Interact with computer system to develop time standard and associated documentation Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Work Measurement Function
Responsibilities of the PC: Perform routine calculations Facilitate retrieval of data needed by analyst Facilitate generation of methods description Library of generic work element descriptions that can be used to develop task methods description Easy entry of new descriptions Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Computerized PMTS and SDS
Block diagram shows how PCs can be used in predetermined motion-time systems and standard data systems Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Application Speed Ratio
A computerized work measurement system must have a lower application speed ratio to justify its investment and operating costs Application speed ratio is lower for a computerized PMTS/SDS because of: Automatic computations Fast retrieval of work elements and times from database Other features of user-friendly PC software (e.g., icons, help menus, drag-and-drop functions) Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Standards Database Function
Storage and retrieval capabilities Centralized database Access by qualified users at all locations Mass updating features - to update all standards affected by a change (e.g., a change in allowance factor) Data export features - to product cost estimating, computer-aided process planning, MRP, production scheduling, etc. Standards maintenance - periodic review of all standards to maintain their validity Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Expert Systems A computer program that is capable of solving complex problems that normally require a human with years of education and experience A good time study analyst must have training and years of experience Components of computer work measurement system based on expert system technology: Knowledge base of expert TS analyst Computer-compatible description of task Inference engine - capability to apply knowledge base to task description to set time standard Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Knowledge Base What is in the knowledge base?
Technical knowledge about tasks to be studied Logic used by a successful TS analyst to set a standard The knowledge and logic constitute a set of rules used by the analyst to solve a work measurement problem The rules must be coded into a computer program Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Task Description Requirement - to describe the task so that it can be understood by the computer system This computer-compatible description must contain all of the pertinent information needed to determine the time standard Sequence of motion elements Distances and other work variables Tooling Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Inference Engine Problem-solving procedure to apply knowledge base to a given task description to determine the time standard for the task Expert system uses its knowledge and logic to solve a specific work measurement problem In a manner analogous to the way a human analyst would solve the problem Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Maintenance of Time Standards
Purpose - to protect the validity of the time standards by Periodically review the tasks and their associated time standards Update the standards for those tasks that have been affected by methods improvements or other changes Maintaining the standards is accomplished by: Conducting periodic audits of the existing standards to determine whether they are still valid Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Why Standards Lose Validity
Surreptitious improvements by worker Worker improvises a special tool that shaves time from the task Worker revises workplace layout to reduce time to move things Manual elements that are external to the machine cycle are made internal elements Worker changes machine settings to speed cycle time Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Why Standards Lose Validity
Legitimate and official changes that may be overlooked in the standards updating process: Engineering changes in the design of the product Installation of a new production machine to replace the machine used when the standard was set Improved workholding fixture with fast-acting clamp Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

How Frequently to Audit Standards
Recommended frequency for auditing time standards* Standard hours/year Frequency of audit More than 700 hr 6 months Between 100 and 700 hr 1 year Between 50 and 100 hr 2 years Less than 50 hr 3 years * Niebel, B. W., “Time Study” Handbook of Industrial Engineering, G. Salvendy (ed.) Wiley and IIE, 1992 Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN ©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Manual Work & Worker-Machine Systems

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