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Predetermined Time Systems

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Presentation on theme: "Predetermined Time Systems"— Presentation transcript:

1 Predetermined Time Systems
INSY 3021 Auburn University Spring 2007

2 History Fredrick Taylor Frank and Lillian Gilbreth
Time Study Frank and Lillian Gilbreth Motion Studies Predetermined Time Systems (PDTS) Combination of time and motion studies Fredrick Taylor – looked at work as something that could be controlled. Tasks were broken down into elements which were studied to determine if they were productive or unproductive. A stopwatch was used to determine the time for each. Taylor used the concept of performance rating to adapt the numbers to the average skilled worker working under average conditions. Frank and Lillian Gilbreth discovered all manual operations were combinations of basic elements. The Gilbreths isolated and identified these elements to improve methods…to reduce the motion content, the effort and time to perform the task could be reduced. Followers of Taylor practiced time study, but followers of the Gilbreths practiced motion study...from a third party came predetermined time systems which is a combination of time and motion studies.

3 Therbligs! Work can be described by these 17.
Effective/Productive: Reach, Move, Grasp, Release, Pre-Position, Use, Assemble & Disassemble. Ineffective/Non-Productive: Search, Select, Position, Inspect, Plan, Unavoidable Delay, Avoidable Delay, Hold, Rest to overcome fatigue.



6 Uses To predict standard times for new or modified jobs
Used to improve method analysis Can identify ergonomic risk factors and risk of repetitive strain indices (RSI)

7 Composition Sets of motion-time tables with rules and instructions
Specialized training is essential to the practical application of these techniques Times are at 100% - which eliminates performance rating May be slight variability among different people using the same tool TRAINING – many companies require certification before you can set standards using systems such as MTM or MOST

8 Types of Systems Acceleration-deceleration Systems
Different body motions move at different velocities 40% of total time is used during acceleration, 20% for constant velocity, and 40% for deceleration Not widely used today Very important in fields of Biomechanics and Kinematics Average-motion Systems Represents average motion difficulties for industrial operations Additive Systems Basic time values are used with a correction factor for difficult motions

9 Methods-Time Measurement (MTM)
A procedure that analyses manual operations or methods into basic motions needed to perform it, and assigns each a pre-determined time based on the motion and environmental conditions MTM is the pioneer in the average motion system MOST is derived from MTM MTM-2 and MOST are used frequently

10 MTM-1 Fundamental Motions Procedure
Reach, turn, position, release, move, grasp, disengage Procedure Summarize all right-hand and left-hand motions Determine time measurement unit (TMU) Remove non-limiting motion values Non limiting motions are simultaneous motions * higher value is the limiting value No allowances given because the time values are based on a work rate that can be sustained at steady-state MTM-2 is a system of synthesized MTM data, using single basic MTM motions and combinations of MTM motions MTM-3 – saving time at the expense of accuracy, MTM-V (metal cutting operations), MTM-C (banking and insurance), MTM-M (operator work using a microscope) plus others

11 Time Measurement Units (TMU)
1 TMU = hour 1 TMU = min 1 TMU = sec 1 hour = 100,000 TMU 1 min = 1667 TMU 1 sec = 27.8 TMU

12 Maynard Operation Sequence Technique (MOST)
Developed in 1980 by Zjell Zandin Establishes standards at least 5 times faster than MTM-1, w/little if any sacrifice in accuracy Concentrates on the movements of objects MOST is 95% confidence with ± 5% accuracy

13 MOST Procedure Watch job/task Determine sequence(s) to use
Determine index values Add index values to determine TMU Multiply TMU by 10 Convert TMU to seconds, minutes, hours

14 Concept of MOST Definition of work
Work is the displacement of a mass or object Work = Force X Distance f = 10 lbs. d = 4 in. f = 10 lbs. d = 0 in.

15 Concept of MOST In Work, an object is moved GET and PUT
For example, you can lift a box and place it down three feet away. Basic body motions used to perform work occur in repeating patterns or sequences. This is the foundation of BasicMOST and the sequence models that make up MOST.

16 Concept of MOST MOST Analysis Index Values (1, 3, 6…) Sequence Model
Method Description Parameters (A, B, G…) Phases

17 Concept of MOST Method Description Documents the action performed
Clear, concise and easily understood Comprised of recommended words Example: Grasp marker located three steps away on the floor and put in holder.

18 Sequence Models Sequence models represent the sequence of events that occurs when an object is moved or a tool is used. Predefined sequence models represent different types of activities. Three sequence models can be used to analyze all types of manual work: General Move (moved freely through space) Controlled Move (movement restricted; attached or in contact) Tool Use (using common hand tools)

19 Phases Sequence models are structured into phases used to describe the action performed. Each of the predefined sequence models has a different set of phases. From Method Description Example: Grasp marker located three steps away on the floor and put in holder. Phase: Get Put Return How did I GET the marker? How did I PUT the marker? Did I RETURN?

20 Index Values A B G A B P A 6 6 1 6 0 1 0 Get Put Return
A B G A B P A Get Put Return Each parameter is assigned an index value based on the motion needed to perform the activity. Index values are then used to generate the total time required to perform a task.

21 How is Work Measurement Done?
Method Description from video: Grasp heavy box located within reach, walk eight steps, position on pallet and return to initial location. A B G A B P A Get Put Return 300 TMU x .036 sec/TMU = 10.8 seconds

22 How is Work Measurement Done?
TMU 300 250 330 A B G A B P A Top Row Get Put Return A B G A B P A Middle Row Get Put Return A B G A B P A Bottom Row Get Put Return

23 Sources of error & variance
Hard to classify some motions Difference in opinion between team members Variation in distance measurements Repeatability and variation of worker Very time-consuming to break up job Repetitive to enter in data May not match actual times

24 Pro’s & Con’s Advantages: Disadvantages:
Efficiently estimates the time to perform a task Accurate results Methods are easily understood Sequence models result in minimal paperwork Encourages method development and continuous improvement Disadvantages: Requires exact job description and layout Chance of omitting elements when estimating new jobs Not always applicable to non-repetitive operations

25 Basic Sequence Models General Move Controlled Move Tool Use
The spatial movement of an object freely through the air Controlled Move The movement of an object when it either remains in contact with a surface or remains attached to another object during movement Tool Use Tool use is for common hand tools

26 Basic Sequence Models Activity Sequence Model Parameter General Move
ABG ABP A A – action distance B – body motion G – gain control P – placement Controlled Move ABG MXI A M – move controlled X – process time I – alignment Tool Use ABG ABP * ABP A F/L – fasten/loosen C – cut S – surface treat M – measure R – record T – think

27 General Move Parameters ABG | ABP | A Get | Put | Return
Action Distance (A) – horizontal distance Body Motion (B) – vertical distance Gain Control (G) Placement (P) ABG | ABP | A Get | Put | Return Assign an index value based on complexity Accounts for 50-60% of most industrial work A – analyze all spatial movements or actions of the fingers, hands and/or feet, loaded or unloaded B – vertical motions of the body or the actions necessary to overcome an obstruction or impairment to body movement G – obtain complete manual control of an object and release the object after placement P – final stage of an object’s displacement to align, orient and/or engage the object Final A – used for return to original workstation or move hands from machine for safety purposes Talk about what affects the index values --- within reach, number of steps, collect,

28 General Move

29 MOST (PTS) When determining the normal time that it takes to obtain an object, Action Distance is accounted for in the calculation

30 MOST (PTS) As you can see, Body Movement is taken into account for the calculation

31 Controlled Move Parameters: ABG | MXI | A
Action Distance (A) – horizontal distance Body Motion (B) – vertical distance Gain Control (G) Move Controlled (M) Process Time (X) – machine time Alignment (I) ABG | MXI | A Get | Move or Actuate | Return M – manually guided movements or actions of objects over a controlled path X – account for the time for work controlled by electronic or mechanical devices or machines, not by manual actions I – analyze manual actions following the Move Controlled or at the conclusion of Process Time to achieve the alignment of objects Examples: push a button, pulling a lever, turning a steering wheel

32 Tool Use Parameters: ABG | ABP | * | ABP | A
Fasten (F) Loosen (L) Cut (C) Surface Treat (S) Measure (M) Record (R) Think (T) ABG | ABP | * | ABP | A Get | Put | Tool Action | Put | Return F/L – assembling/disassembling one object to another using fingers, hand, or hand tool C – separate, divide or remove part of an object using a sharp edge S – removing unwanted material or particles from, or applying a substance to the surface of an object M – determine a certain physical characteristic of an object R – manual actions performed with a pencil, pen, marker for the purpose of recording information T – eye actions and mental activity employed to obtain information or to inspect an object

33 Examples Example: Get a handful of washers and put them onto 3 bolts located 5 inches apart. A1 B0 G3 (A1 B0 P1) A0 (3) = 100 TMU Example: A worker slides a ruler within reach and pushes it 6 inches (15 cm) to measure two points that are 8 inches apart. A1 B0 G1 M1 X0 I6 A0 = 90 TMU Example: Grasp wrench and fasten bolt with 3 wrist strokes and aside. A1 B0 G1 A1 B0 P3 F10 A1 B0 P1 A0 = 180 TMU


35 Other MOST Systems MiniMOST MaxiMOST AdminMOST
MOST® Work Measurement Systems: Third Edition, Revised and Expanded, Kjell B. Zandin

36 Special Issues Work Factors  For instance, allows the incorporation of stairs & gates into PDTS models.

37 Questions & Comments

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