TI 2111 Work System Design and Ergonomics 5. Predetermined Time System

TI 2111 Work System Design and Ergonomics

5. Predetermined Time System

2TI 2111 Work System Design and Ergonomics

Classifications

Work measurement techniques

Direct timestudy

Worksampling

Standarddata

Performanceevaluation

Predeterminedtimes

Generalapproaches

MTMMOST

Funcional approaches(for specific activities)

MTM-M, MTM-C, MTM-V


Advantages of predetermined times Setting standards for a very short motions (very

hard to evaluate using other measures) Standard “language” of documenting sequences of

elements which define operations Enable to determine standard times for new

operations for whom we don’t have past data Enable to compare different methods of performing

a new task (before applying the preferred method) Usable for workers training


Methods Time Measurements (MTM) The data for the development of MTM was obtained from

motion pictures (using mechanical cameras) of skilled workers performing a wide range of motions

Influence factors were identified and isolated in the motion analysis

The influence factors became the motion characteristics which are used for determining the standard times

Each motion was separately defined and tabulated for setting the standard times

MTM was accepted as a standard method in many countries all over the world


MTM-1 – the basic MTM module Basic time unit: TMU = time Measurement Unit

1 TMU = 0.00001 hour

= 0.0006 min

= 0.036 sec

This time unit was a result of the picture technology

This time unit enable investigating much shorter motions (around 3-4 hundredth of a second) than using a stopwatch


MTM-1 (1948) – definition & characteristics A procedure which analyses manual work

into a basic motions required to perform it The procedure assigns to each motion a pre-

determined time standard which is influenced by the environmental conditions

Based on 23 basic motions and consists of approximately 5,000 time values (4,988)


Basic Elements

Reach (R): move the hand or finger to a destination – affected by the length of the motion and the type of reach

Move (M): transport an object to a destination – affected by length of a motion, the weight of the object and the type of move

Grasp (G): secure sufficient control on one or more objects with the fingers or hand in order to permit the performance of the next required motion – affected by the size shape and location of the object

Position (P): align, orient, and engage object with another object (when only minor motions required) – affected by the ease of handling, symmetry and the amount of pressure required for insertion

Release (RL): relinquish control of an object by the fingers or hand


Basic Elements (cont.) Disengage (D): break contact between one object to another –

affected by the amount of effort required Turn (T): the motion employed to turn the hand, either empty or

loaded, by a movement that rotates the hand, wrist, and forearm about the long axis of the forearm – affected by the degree of rotation and by the weight of the object

Apply pressure (AP) Eye Travel (ET): considered only when the eyes must direct the

hand or the body movements (includes eye focus and eye travel time) – affected by the distance between the travel points and the distance between the eye to the line of travel

Body leg and foot motion (BMF): other motions which are associated with the body and legs (walking, standing, bending etc.)


Other MTM Based Methods

MTM-2 (1965): Used for setting standard time for longer tasks Based on 9 basic motions and consists of 39 time values

MTM-3 (1970): Consists of 4 categories of manual motions (10 time

values): Handle, Transport, Step & foot motion, and Bend & arise

MTM-V : Metal cutting operations MTM-C : Clerical work


MOST – Maynard Operation Sequence Technique In MTM:

the elements are stand alone and do not relate to the sequence of the operation

In MOST: The compete sequence of the operation, which

consists of smaller elements, is addressed


What is MOST ?

Maynard Operation Sequence Technique Developed by Zandin (1980) Utilizes larger blocks of fundamental motions than

MTM-1 General Move

A B G A B P A Controlled Move

A B G M X I A Tool Use

A B G A B P _ A B P A


Three activity sequences in MOST The General Move Sequence (for a free movement

through air)

The Controlled Move Sequence (for a movement in which the object remains in contact with a surface or is attached to another object during the movement)

The Tool Use Sequence (for the use of common hand tools)


Why MOST?

It is much faster than traditional time study technique (e.g. Basic MOST is 40 times faster than MTM-1)

Accuracy of up to 95% can be obtained It requires less documentation


Remember TMU ?

Time for therbligs is measured in Time Measurement Unit (TMU)

1 TMU = 0.00001 hour

= 0.0006 minute

= 0.036 second 1 hour = 100,000 TMU 1 minute = 1,667 TMU 1 second = 27.8 TMU


Sequence ModelsBasic MOST WORK MEASUREMENT TECHNIQUE

ACTIVITY SEQUENCE MODEL SUB – ACTIVITIES

General Move A B G A B P A A – Action Distance

B – Body Motion

G – Gain Control

P – Placement

Controlled Move A B G M X I A M – Move Controlled

X – Process Time

I – Alignment

Tool Use A B G A B P _ A B P A F – Fasten

L – Loosen

C – Cut

S – Surface Treat

M – Measure

R – Record

T - Think


MOST Study Form

MOST - CalculationCode:

Date:

Area: Sign:

Page: /

Activity:

Conditions:

No.

Method Sequence Model Fr. TMU

1 Describe activity 1 Ax Bx Gx Ax Bx Px Ax

2　 Describe activity 2 Ax Bx Gx Ax Bx Px Ax 　　

3　 Describe activity 3 Ax Bx Gx Mx Xx Ix Ax 　　

　　　 Ax Bx Gx Ax Bx Px _ Ax Bx Px Ax 　　

TIME = minutes (min.) 　


MOST Study Form


Example Get cover, and place in front.

Reach 24”, grasp, move 24” in front. Open cover.

Reach the cover with other hand by 30”, grasp the flap of cover, disengage the flap with normal effort, turn flap by 120 degree.

Remove spec from the cover, and place aside on table. Grasp the spec inside the cover, move it out of the frame

by 4”, move it on the table by 30” Close the cover.

Reach for the cover flap in other hand, turn the cover to close, apply slight pressure

Put the cover aside. Move it back to previous position in 30”


Example Get cover, and place in front.

Reach 24”, grasp, move 24” in front. A1 B0 G1 A1 B0 P1 A0

Open cover. Reach the cover with other hand by 30”, grasp the flap

of cover, disengage the flap with normal effort, turn flap by 120 degree.

A1 B0 G3 M1 X0 I0 A0 Remove spec from the cover, and place aside on table.

Grasp the spec inside the cover, move it out of the frame by 4”, move it on the table by 30”

A1 B0 G3 A1 B0 P1 A0


Example

Close the cover. Reach for the cover flap in other hand, turn the cover to

close, apply slight pressure A1 B0 G1 M3 X0 I0 A0

Put the cover aside. Move it back to previous position in 30” A0 B0 G0 A1 B0 P1 A1

Documents

TI 2111 Work System Design and Ergonomics 5. Predetermined Time System