Predetermined Time
Systems
INSY 3021
Auburn University
Spring 2007
History
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Fredrick Taylor
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Frank and Lillian Gilbreth
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Time Study
Motion Studies
Predetermined Time Systems
(PDTS)
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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.
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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)
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Composition
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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
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Acceleration-deceleration Systems
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Average-motion Systems
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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
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)
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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
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Fundamental Motions
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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
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Time Measurement Units
(TMU)
1
1
1
1
1
1
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TMU = 0.00001 hour
TMU = 0.0006 min
TMU = 0.036 sec
hour = 100,000 TMU
min = 1667 TMU
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
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Concept of MOST
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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.
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.
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Concept of MOST
MOST Analysis
Method Description
Sequence Model
Phases
Parameters (A, B, G…)
Index Values
(1, 3, 6…)
Concept of MOST
Method Description
 Documents the action performed
Clear, concise and easily understood
 Comprised of recommended words
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Example:
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Grasp marker located three steps
away on the floor and put in holder.
Sequence Models
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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
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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
How did I GET
the marker?
Put
How did I PUT the
marker?
Return
Did I
RETURN?
Index Values
A 6B 6 G1
Get
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A 6B 0 P 1
Put
A0
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.
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 1B 0 G3
Get
A 10B 0P
Put
6
A 10
Return
300 TMU x .036 sec/TMU = 10.8 seconds
How is Work Measurement
Done?
Top Row
Middle Row
Bottom Row
A 1B 0 G3
Get
A 1B 0 G3
Get
A 1B 0 G3
Get
A 10B 0P
Put
A 10B 0P
Put
A 10B 6P
Put
A 10
Return
6
1
3
A 10
Return
A 10
Return
TMU
300
250
330
Sources of error & variance
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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’s
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
Disadvantages:
 Requires exact job
description and layout
 Chance of omitting
elements when
estimating new jobs
 Not always applicable
to non-repetitive
operations
Basic Sequence Models
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General Move
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Controlled Move
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The spatial movement of an object
freely through the air
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 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
General Move
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Parameters
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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)
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When determining
the normal time
that it takes to
obtain an object,
Action Distance is
accounted for in
the calculation
MOST (PTS)
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As you can see,
Body Movement is
taken into account
for the calculation
Controlled Move
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Parameters:
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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
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Parameters:
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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
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Example: Get a handful of washers and put
them onto 3 bolts located 5 inches apart.
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Example: A worker slides a ruler within reach
and pushes it 6 inches (15 cm) to measure two
points that are 8 inches apart.
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A1 B0 G3 (A1 B0 P1) A0 (3) = 100 TMU
A1 B0 G1 M1 X0 I6 A0 = 90 TMU
Example: Grasp wrench and fasten bolt with 3
wrist strokes and aside.
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A1 B0 G1 A1 B0 P3 F10 A1 B0 P1 A0 = 180 TMU
Other MOST Systems
MiniMOST
 MaxiMOST
 AdminMOST
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MOST® Work Measurement Systems:
Third Edition, Revised and
Expanded, Kjell B. Zandin
Special Issues
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Work Factors  For instance, allows
the incorporation of stairs & gates
into PDTS models.
Questions & Comments