IE 419
Work Design:
Productivity and Safety
Dr. Andris Freivalds
Class #13
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Other Special Cases
2) Principle of limiting motion
– For two different motions for each hand
– Use the longer time
3) Principle of combined motion
– For two combined motion in one hand
– Use longer time
4) R is included in C-type motions
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Examples
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Sources of Error
• Discreteness – tabular data
– No interpolation
– Hopefully, this averages out
• Synthesis assumes correct process
• Need correct application - practice
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Comparison of
MTM and Time Study
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Summary of MTM-2 Data
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Ex #1: U-bolt (Cable
clamp) assembly
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Ex #2: Flashlight assembly
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Maynard Operation Sequence
Technique (MOST, pp. 508-513)
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Developed by Zandin in 1967
At SAAB-Scania in Sweden
Published in 1980 through H.B. Maynard
Basically simplified MTM (same TMU)
Faster than MTM-1 and MTM-2
Has many diverse tool applications
Has computer program!!
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MOST – Comparison with MTM
Factor
MTM-1
MTM-2
MOST
250x
100x
10x
Speed wrt MTM-1
1
2.5
25
Speed wrt MTM-2
-
1
10
Min. cycle time for
5% accuracy (min)
0.36
1.0
2.0
Time to analyze
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Versions of MOST
• Maxi MOST
– For rare operations (<150/week)
– For long cycles (minutes to hours)
– Very quick, but less accurate
• Basic MOST
– Between 150 and 1,500 operations/week
– Typical cycle times: 0.5 – 3 minutes
• Mini MOST
– More than 1,500 operations/week
– Cycle times < 0.5 min
– Most detailed and time consuming
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Basics of Basic MOST - 1
Only three activity sequences:
1) General Move
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Movement of object freely through space
½ of all work sequences
2) Controlled Move
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Movement of object attached to another or
in contact with a surface
⅓ of all work sequences
3) Tool/Equipment Use
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1/6 of all work sequences
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General Move - Basics
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Has 4 subactivities:
1)
2)
3)
4)
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A = Action distance (horizontal)
B = Body motion (vertical)
G = Gain control (i.e. GET cases A, B, C)
P = Placement (i.e. PUT cases A, B, C)
Grouped into 3 phases:
1) Get – reach and gain control of object
2) Put – move object to new location
3) Return – distance walked back to
workstation, not for hands
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General Move – Typical Steps
1) Reach some distance with hands for
object, perhaps with body motion or steps
2) Gain manual control of object
3) Move object some distance, perhaps with
body motion or steps
4) Place the object at specified location
5) Return to workplace (if needed)
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General Move
Get
Put
Return
A B G
A B P
A
A = Action distance
B = Body motion
G = Gain control
P = Placement
• Obtain Index Values based on characteristics
• Sum Index Values, multiply by 10 → TMUs
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MOST - General Move
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Ex #1 - General Move
Walk 3 steps to pick up a bolt from the floor, arise,
place bolt in a bolt hole.
Get
A6 B6 G1
Put
A1 B0 P3
Return
A0
A6 = Walk 3 steps to object
B6 = Bend and arise
G1 = Gain control of light object
A1 = Move object a distance within reach
B0 = No body motion
∑IV = 6+6+1+1+3 = 17
P3 = Place and adjust object
A0 = No return
17x10 = 170 TMUs
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General Move - Parameter Indexing
Action Distance (A)
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A0 ≤ 2 in
A1 within reach
A3 1 - 2 steps
A6 3 - 4 steps
A10 5 - 7 steps
A16 8 -10 steps
Extended values
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General Move - Parameter Indexing
Body Motion (B)
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B0 no body motion
B3 sit/stand no adj.
B3 bend/arise – 50%
B6 bend and arise
B10 sit/stand with adj.
B16 variety
– Bend and sit
– Stand and bend
– Climb on or off
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General Move - Parameter Indexing
Body Motion (B) con’t
• B16 passing through door (steps before and after
are included in value)
• A16 B16 G1 A1 B6 P1 A0 = 410 TMU
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General Move - Parameter Indexing
Gain Control (G)
• G0 no gain control, hold
• G1 light object (simo)
• G3 variety
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Light objects (non simo)
Heavy or bulky
Blind or obstructed
Disengage (force)
Interlocked
Collect several
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General Move - Parameter Indexing
Placement (P)
• P0 no placement, toss
• P1 lay aside, loose fit
• P3 loose fit blind
– Place with adjustment
– Double placement
– Place with light pressure
• P6 heavy pressure
– With care or precision
– Blind or obstructed
– Intermediate moves
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General Move - Parameter Indexing
• Return – last A for time for operator to walk
back to normal workstation
• Return – not meant for returning hands
• Placement with insertion – two lines
• Repeat cycles - handful of washers on 6 bolts
A1 B0 G3
(A1 B0 P1)
A0 (6)
(1+3) + 6(1+1) + 0 x 10 = 160 TMU
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