Predetermined Time Systems INSY 3021 Auburn University Spring 2007.
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Transcript of Predetermined Time Systems INSY 3021 Auburn University Spring 2007.
Predetermined Time Systems
INSY 3021
Auburn UniversitySpring 2007
History Fredrick Taylor
Time Study Frank and Lillian Gilbreth
Motion Studies Predetermined Time Systems (PDTS)
Combination of time and motion studies
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.
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)
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
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
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-1 Fundamental Motions
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
Time Measurement Units (TMU) 1 TMU = 0.00001 hour 1 TMU = 0.0006 min 1 TMU = 0.036 sec 1 hour = 100,000 TMU 1 min = 1667 TMU 1 sec = 27.8 TMU
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 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
Concept of MOST
f = 10 lbs.d = 4 in.
f = 10 lbs.d = 0 in.
Definition of work Work is the displacement of a mass or
object Work = Force X Distance
In Work, an object is movedGET 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.
Concept of MOST
Concept of MOST
MOST Analysis
Index Values(1, 3, 6…)
Sequence ModelMethod Description
Parameters (A, B, G…)
Phases
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.
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)
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 ReturnHow did I GET the marker?
How did I PUT the marker?
Did I RETURN?
Index Values
A B G A B P A 6 6 1 6 0 1 0
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.
Get Put Return
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 1 0 3 10 0 6 10 Get Put Return
300 TMU x .036 sec/TMU = 10.8 seconds
How is Work Measurement Done?
A B G A B P A 1 0 3 10 6 3 10 Get Put Return
A B G A B P A 1 0 3 10 0 6 10 Get Put Return
A B G A B P A 1 0 3 10 0 1 10 Get Put Return
Top Row
Middle Row
Bottom Row
TMU
300
250
330
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
Pro’s & Con’sDisadvantages: Requires exact job
description and layout Chance of omitting
elements when estimating new jobs
Not always applicable to non-repetitive operations
Advantages: 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
Basic Sequence Models General Move
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
Basic Sequence ModelsActivity Sequence Model Parameter
General Move
ABG ABP A A – action distanceB – body motionG – gain controlP – placement
Controlled Move
ABG MXI A M – move controlledX – process timeI – alignment
Tool Use ABG ABP * ABP A F/L – fasten/loosenC – cutS – surface treatM – measureR – recordT – think
General Move Parameters
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
General Move
MOST (PTS) When determining
the normal time that it takes to obtain an object, Action Distance is accounted for in the calculation
MOST (PTS) As you can see,
Body Movement is taken into account for the calculation
Controlled Move Parameters:
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
Tool Use Parameters:
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
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
Other MOST Systems MiniMOST MaxiMOST AdminMOST
MOST® Work Measurement Systems: Third Edition, Revised and Expanded, Kjell B. Zandin
Special Issues Work Factors For instance, allows
the incorporation of stairs & gates into PDTS models.
Questions & Comments