Presentation on theme: "Predetermined Time Systems"— Presentation transcript:
1Predetermined Time Systems INSY 3021Auburn UniversitySpring 2007
2History Fredrick Taylor Frank and Lillian Gilbreth Time StudyFrank and Lillian GilbrethMotion StudiesPredetermined Time Systems (PDTS)Combination of time and motion studiesFredrick 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.
3Therbligs! 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.
6Uses To predict standard times for new or modified jobs Used to improve method analysisCan identify ergonomic risk factors and risk of repetitive strain indices (RSI)
7Composition Sets of motion-time tables with rules and instructions Specialized training is essential to the practical application of these techniquesTimes are at 100% - which eliminates performance ratingMay be slight variability among different people using the same toolTRAINING – many companies require certification before you can set standards using systems such as MTM or MOST
8Types of Systems Acceleration-deceleration Systems Different body motions move at different velocities40% of total time is used during acceleration, 20% for constant velocity, and 40% for decelerationNot widely used todayVery important in fields of Biomechanics and KinematicsAverage-motion SystemsRepresents average motion difficulties for industrial operationsAdditive SystemsBasic time values are used with a correction factor for difficult motions
9Methods-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 conditionsMTM is the pioneer in the average motion systemMOST is derived from MTMMTM-2 and MOST are used frequently
10MTM-1 Fundamental Motions Procedure Reach, turn, position, release, move, grasp, disengageProcedureSummarize all right-hand and left-hand motionsDetermine time measurement unit (TMU)Remove non-limiting motion valuesNon limiting motions are simultaneous motions* higher value is the limiting valueNo allowances given because the time values are based on a work rate that can be sustained at steady-stateMTM-2 is a system of synthesized MTM data, using single basic MTM motions and combinations of MTM motionsMTM-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
12Maynard Operation Sequence Technique (MOST) Developed in 1980 by Zjell ZandinEstablishes standards at least 5 times faster than MTM-1, w/little if any sacrifice in accuracyConcentrates on the movements of objectsMOST is 95% confidence with ± 5% accuracy
13MOST Procedure Watch job/task Determine sequence(s) to use Determine index valuesAdd index values to determine TMUMultiply TMU by 10Convert TMU to seconds, minutes, hours
14Concept of MOST Definition of work Work is the displacement of a mass or objectWork = Force X Distancef = 10 lbs.d = 4 in.f = 10 lbs.d = 0 in.
15Concept 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.
16Concept of MOST MOST Analysis Index Values (1, 3, 6…) Sequence Model Method DescriptionParameters (A, B, G…)Phases
17Concept of MOST Method Description Documents the action performed Clear, concise and easily understoodComprised of recommended wordsExample:Grasp marker located three steps away on the floor and put in holder.
18Sequence ModelsSequence 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)
19PhasesSequence 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 ReturnHow did I GET the marker?How did I PUT the marker?Did I RETURN?
20Index Values A B G A B P A 6 6 1 6 0 1 0 Get Put Return A B G A B P AGet Put ReturnEach 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.
21How 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 AGet Put Return300 TMU x .036 sec/TMU = 10.8 seconds
22How is Work Measurement Done? TMU300250330A B G A B P ATop RowGet Put ReturnA B G A B P AMiddle RowGet Put ReturnA B G A B P ABottom RowGet Put Return
23Sources of error & variance Hard to classify some motionsDifference in opinion between team membersVariation in distance measurementsRepeatability and variation of workerVery time-consuming to break up jobRepetitive to enter in dataMay not match actual times
24Pro’s & Con’s Advantages: Disadvantages: Efficiently estimates the time to perform a taskAccurate resultsMethods are easily understoodSequence models result in minimal paperworkEncourages method development and continuous improvementDisadvantages:Requires exact job description and layoutChance of omitting elements when estimating new jobsNot always applicable to non-repetitive operations
25Basic Sequence Models General Move Controlled Move Tool Use The spatial movement of an object freely through the airControlled MoveThe movement of an object when it either remains in contact with a surface or remains attached to another object during movementTool UseTool use is for common hand tools
26Basic Sequence Models Activity Sequence Model Parameter General Move ABG ABP AA – action distanceB – body motionG – gain controlP – placementControlled MoveABG MXI AM – move controlledX – process timeI – alignmentTool UseABG ABP * ABP AF/L – fasten/loosenC – cutS – surface treatM – measureR – recordT – think
27General Move Parameters ABG | ABP | A Get | Put | Return Action Distance (A) – horizontal distanceBody Motion (B) – vertical distanceGain Control (G)Placement (P)ABG | ABP | AGet | Put | ReturnAssign an index value based on complexityAccounts for 50-60% of most industrial workA – analyze all spatial movements or actions of the fingers, hands and/or feet, loaded or unloadedB – vertical motions of the body or the actions necessary to overcome an obstruction or impairment to body movementG – obtain complete manual control of an object and release the object after placementP – final stage of an object’s displacement to align, orient and/or engage the objectFinal A – used for return to original workstation or move hands from machine for safety purposesTalk about what affects the index values --- within reach, number of steps, collect,
29MOST (PTS)When determining the normal time that it takes to obtain an object, Action Distance is accounted for in the calculation
30MOST (PTS)As you can see, Body Movement is taken into account for the calculation
31Controlled Move Parameters: ABG | MXI | A Action Distance (A) – horizontal distanceBody Motion (B) – vertical distanceGain Control (G)Move Controlled (M)Process Time (X) – machine timeAlignment (I)ABG | MXI | AGet | Move or Actuate | ReturnM – manually guided movements or actions of objects over a controlled pathX – account for the time for work controlled by electronic or mechanical devices or machines, not by manual actionsI – analyze manual actions following the Move Controlled or at the conclusion of Process Time to achieve the alignment of objectsExamples: push a button, pulling a lever, turning a steering wheel
32Tool Use Parameters: ABG | ABP | * | ABP | A Fasten (F)Loosen (L)Cut (C)Surface Treat (S)Measure (M)Record (R)Think (T)ABG | ABP | * | ABP | AGet | Put | Tool Action | Put | ReturnF/L – assembling/disassembling one object to another using fingers, hand, or hand toolC – separate, divide or remove part of an object using a sharp edgeS – removing unwanted material or particles from, or applying a substance to the surface of an objectM – determine a certain physical characteristic of an objectR – manual actions performed with a pencil, pen, marker for the purpose of recording informationT – eye actions and mental activity employed to obtain information or to inspect an object
33ExamplesExample: Get a handful of washers and put them onto 3 bolts located 5 inches apart.A1 B0 G3 (A1 B0 P1) A0 (3) = 100 TMUExample: 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 TMUExample: Grasp wrench and fasten bolt with 3 wrist strokes and aside.A1 B0 G1 A1 B0 P3 F10 A1 B0 P1 A0 = 180 TMU