IE 419 1

IE 419 Work Design:

Productivity and Safety

Dr. Andris Freivalds

Class #13

IE 419 2

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)

• 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

Time to analyze 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

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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 - 1Only three activity sequences:

1) General Move• Movement of object freely through space• ½ of all work sequences

2) Controlled Move• Movement of object attached to another or

in contact with a surface• ⅓ of all work sequences

3) Tool/Equipment Use• 1/6 of all work sequences

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General Move - Basics• Has 4 subactivities:

1) A = Action distance (horizontal)2) B = Body motion (vertical)3) G = Gain control (i.e. GET cases A, B, C)4) P = Placement (i.e. PUT cases A, B, C)

• Grouped into 3 phases:1) Get – reach and gain control of object2) Put – move object to new location3) 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 motionG = 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

Get Put Return

A6 B6 G1 A1 B0 P3 A0

A6 = Walk 3 steps to object B6 = Bend and ariseG1 = Gain control of light objectA1 = Move object a distance within reachB0 = No body motionP3 = Place and adjust objectA0 = No return

Walk 3 steps to pick up a bolt from the floor, arise, place bolt in a bolt hole.

∑IV = 6+6+1+1+3 = 17

17x10 = 170 TMUs

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General Move - Parameter IndexingAction Distance (A)

• 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 IndexingBody Motion (B)

• 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 IndexingBody 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 IndexingGain Control (G)

• G0 no gain control, hold

• G1 light object (simo)

• G3 variety– Light objects (non simo)– Heavy or bulky– Blind or obstructed– Disengage (force)– Interlocked– Collect several

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General Move - Parameter IndexingPlacement (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