about motion economy

1. Principles of Motion Economy
Methods & Movements at the workplace

2. Introduction
We will look at one worker working at a workplace, bench or table and to apply
to him or her the principles which have been laid down.
Before embarking on a detailed study of an operative doing a job at a single
workplace, it is important to make certain that the job is in fact necessary and is
being done as it should be done.
The questioning technique must be applied as regards:
 PURPOSE: To ensure that the job is necessary.
 PLACE: To ensure that it is being done where it should be done.
 SEQUENCE: To ensure that it is in its right place in the sequence of operations.
 PERSON: To ensure that it is being done by the right person.
 MEANS: By which the job is being done and to simplify them as much as is
economically justified.

3. Principles of Motion Economy
The basis for the development of improved methods at the workplace can be
classified as below:
1. Use of the human body
2. Arrangement of the workplace
3. Design of tools and equipment

4. Use of the Human Body
Below points should be considered:
1. The two hands should begin and complete their movements at the same time.
2. The two hands should not be idle at the same time except during periods of
rest.
3. Motions of the arms should be symmetrical and in opposite directions and
should be made simultaneously.
4. Hand and body motions should be made at the lowest classification at which it
is possible to do the work satisfactorily.
5. Momentum should be employed to help the worker, but should be reduced to
a minimum whenever it has to be overcome by muscular effort.

5. Use of the Human Body
6. Continuous curved movements are to be preferred to straight-line motions
involving sudden and sharp changes in direction.
7. "Ballistic" (i.e. free-swinging) movements are faster, easier and more accurate
than restricted or controlled movements.
8. Rhythm is essential to the smooth and automatic performance of a repetitive
operation. The work should be arranged to permit easy and natural rhythm
whenever possible.
9. Work should be arranged so that eye movements are confined to a comfortable
area, without the need for frequent changes of focus.

6. Arrangement of the Workplace
1. Definite and fixed stations should be provided for all tools and materials to
permit habit formation.
2. Tools and materials should be pre-positioned to reduce searching.
3. Gravity feed, bins and containers should be used to deliver the materials as close
to the point of use as possible.
4. Tools, materials and controls should be located within the maximum working
area and as near to the worker as possible.

7. Arrangement of the Workplace
5. Materials and tools should be arranged to permit the best sequence of motions.
6. "Drop deliveries" or ejectors should be used wherever possible, so that the
operative does not have to use his or her hands to dispose of the finished work.
7. Provision should be made for adequate lighting, and a chair of the type and
height to permit good posture should be provided. The height of the workplace
and seat should be arranged to allow alternate standing and sitting.
8. The colour of the workplace should contrast with that of the work and thus
reduce eye fatigue.

8. Design of Tools and Equipment
1. The hands should be relieved of all work of "holding" the workpiece where this
can be done by a jig, fixture or foot-operated device.
2. Two or more tools should be combined wherever possible.
3. Where each finger performs some specific movement, as in typewriting, the
load should be distributed in accordance with the inherent capacities of the
fingers.
4. Handles such as those on cranks and large screwdrivers should be so designed
that as much of the surface of the hand as possible can come into contact with
the handle. This is especially necessary when considerable force has to be used
on the handle.
5. Levers, crossbars and handwheels should be so placed that the operative can
use them with the least change in body position and the greatest "mechanical
advantage".

9. Normal and maximum working areas
Normal working area
(finger, wrist and
elbow movements)
Maximum
working area
(shoulder
movements)

10. Normal and maximum working areas
Figure (b) has better
arrangement than figure (a)

11. Classification of Movements
The motion economy in the use of the human body calls for movements to be of
the lowest classification possible. This classification is built up on the pivots around
which the body members must move:
It is obvious that each movement above Class 1 will involve movements of all classes below
it. Thus the saving in effort resulting from using the lowest class possible is obvious.

12. Workplace Layout and Simplification of Movements
A few general notes on laying out the workplace may be useful:
1. If similar work is being done by each hand, there should be a separate supply of
materials or parts for each hand.
2. If the eyes are used to select material, as far as possible the material should be
kept in an area where the eyes can locate it without there being any need to
turn the head.
3. Use semi-circular arrangements in preference to circular arrangements.
4. Design the workplace using ergonomic principles.
5. The nature and the shape of the material influence its position in the layout.

13. Workplace Layout and Simplification of Movements
A few general notes on laying out the workplace may be useful:
6. Hand tools should be picked up with the least possible disturbance to the rhythm
and symmetry of movements. As far as possible the operator should be able to
pick up or put down a tool as the hand moves from one part of the work to the
next, without making a special journey. Natural movements are curved, not
straight; tools should be placed on the arc of movements.
7. Tools should be easy to pick up and replace; as far as possible they should have an
automatic return, or the location of the next piece of material to be moved should
allow the tool to be returned as the hand travels to pick it up.

14. Workplace Layout and Simplification of Movements
A few general notes on laying out the workplace may be useful:
8. Finished work should be:
 dropped down a hole.
 dropped through a hole when the hand is starting the first motion of the next
cycle.
 put in a container placed so that hand movements are kept to minimum;
 if the operation is an intermediate one, placed in a container in such a way
that the next operative can pick it up easily.
9. Always look into the possibility of using pedals or knee-operated levers for locking
or indexing devices on fixtures or devices for disposing of finished work.

15. Semi-circular working arrangement
This is a correct and better arrangement than a circular arrangement

16. Circular working arrangement

17. Therblig (Therbligs)
The Keys to Simplifying Work.
The system of symbols that represent every elementary of hand / arm and
eye movements – a system for analyzing the motions involved in performing
a task.
How this word came?
Gilbreth = Th er bl ig = Therblig
Any manual task is composed of work elements, and the work elements can be
further subdivided into basic motion elements.

18. History of Therblig (Therbligs)
 Any manual task is composed of work elements, and the work elements can be
further subdivided into basic motion elements.
 Frank Gilbreth was the first to catalog (list) the basic motion elements between
1908 and 1924.
 The identification of individual motions, as well as moments of delay in the
process, was designed to find unnecessary or inefficient motions and to utilize or
eliminate even split-seconds of wasted time.
 Therbligs are the basic building blocks of virtually all manual work performed at a
single workplace and consisting primarily of hand motions.

20. Symbolic Representation

21. Symbolic Representation

22. Micro Motions used in picking up a button to be attached

23. Basic Motions
1. Transport empty (TE) – reach for an object
2. Grasp (G) – grasp an object
3. Transport loaded (TL) – move an object with hand and arm
4. Hold (H) – hold an object
5. Release load (RL) – release control of an object
6. Use (U) – manipulate a tool
7. Pre-position (PP) – position object for next operation
8. Position (P) – position object in defined location
9. Assemble (A) – join two parts
10. Disassemble (DA) – separate multiple parts that were previously joined
11. Search (Sh) – attempt to find an object using eyes or hand

24. Basic Motions
12. Select (St) – choose among several objects in a group
13. Plan (Pn) – decide on an action
14. Inspect (I) – determine quality of object
15. Unavoidable delay (UD) – waiting due to factors beyond worker control
16. Avoidable delay (AD) – worker waiting
17. Rest (R) – resting to overcome fatigue

25. Types of Therblig
There are basically three types of Therblig motion:
1. Motions required for performing an operation
2. Motions that tend to slow down type 1 motion
3. Motions that do not perform an operation

26. TYPE-1- Motions required for performing an operation
 Transport empty
 Grasp
 Transport loaded (carry)
 Position
 Use
 Assemble
 Disassemble
 Release load
 Inspect

27. TYPE-2- Motions that tend to slow down type 1 motion
 Search
 Find*
 Select
 Plan (person thinking)
 Pre-position (set up)

28. TYPE-3- Motions that do not perform an operation
 Hold
 Unavoidable delay
 Avoidable delay (standby)
 Rest

29. Classification of Therbligs
Effective Therbligs:
 Reach
 Move
 Grasp
 Release
 Pre-position
 Use
 Assemble
 Disassemble
Ineffective Therbligs:
 Search
 Select
 Position
 Inspect
 Plan
 Unavoidable Delay
 Avoidable Delay
 Rest to Overcome Fatigue
 Hold

32. Therbligs Analysis Steps
 Take time to carefully observe the overall operation
 Try to picture the operation in your mind
 Write down the steps in the operation, starting with just one hand’s motion
 Re-observe the operation and correct the written description
 Describe the motions in more detail and fill out the therblig symbols

33. Use of Therbligs
Each therblig represents time and energy spent by a worker to perform a task.
If the task is repetitive, of relatively short duration, and will be performed many
times, it may be appropriate to analyze the therbligs that make up the work cycle as
part of the work design process.
The term micromotion analysis is sometimes used for this type of analysis.
Objectives:
 Eliminate ineffective therbligs if possible
 Avoid holding objects with hand – Use workholder
 Combine therbligs – Perform right-hand and left-hand motions
simultaneously
 Simplify overall method
 Reduce time for a motion, e.g., shorten distance

34. Recommended Dimensions for Seated Tasks

35. Workplace Layout and Simplification of Movements

36. Workplace Layout and Simplification of Movements

37. Workplace Layout and Simplification of Movements

38. An Example of Workstation Layout

39. Thank You