Motion Economy and Analysis ( IEM )

Topic includes

- The Principles of Motion Economy

- Use of human body

- Arrangement of work place

- Design of tools

- Micro motion study

- It's purpose

- Advantage 

- SIMO CHART

- Ergonomics
- Purpose

The Principles of Motion Economy

The principles of motion economy form a set of rules and suggestions to improve the manual work in manufacturing and reduce fatigue and unnecessary movements by the worker, which can lead to the reduction in the work.

The principles of motion economy can be classified into four groups:

Principles related to the use of human body,

Principles related to the arrangement of the work

Principles related to the design of tools and equipment.

Principles related to time conservation.

Use of Human Body

The two hands should begin motions at the same time.

The two hands should not be idle at the same time except during rest periods.

Motions of the arms should be made in opposite and symmetrical directions and should be made simultaneously

Hand motions should be confined to the lowest classification with which it is possible to perform the work satisfactorily:

Finger motions

Wrist motions

Forearm motions

Upper arm motions

Shoulder motions

Momentum should be employed to assist the worker whenever possible, and it should be reduced to a minimum if it must be overcome by muscular effort.

Smooth continuous motions of the hands are preferable to zigzag motions or straight-line motions involving sudden and sharp changes in direction.

Ballistic (i.e. free swinging) movements are faster, easier and more accurate than restricted or controlled movements.

Arrangement of the Work Place

There should be a definite and fixed place for all tools and materials.

Tools, materials, and controls should be located close in and directly in front of the operator.

Drop delivers should be used whenever possible.

Materials and tools should be located to permit the best sequence of motions.

Arrange the height of the workplace and chair for alternate sitting and standing, when possible.

Provide a chair of the type and height to permit good posture.

Design of Tools and Equipment

Combine tools whenever possible.

Preposition tools and materials.

Where each finger performs some specific movement, the load should be distributed in accordance with the inherent capacities of the fingers.

For light assembly, a screwdriver handle should be smaller at the bottom.

Micro Motion study

Micro motion study is one of the most accurate techniques of work analysis used for work improvement. It makes use of motion pictures of the different activities or movement, so with the help of camera. ... The motion time data from the film is transferred to simo chart.

Purpose of Micro Motion Study:

It can be used for following purposes:

1. To study the nature and path of movements for obtaining the elements of an operation.

2. To study the activities of the machine and the operator.
3. To impart training to the workers or operators regarding motion; economy so that unnecessary movement by the workers may be avoided.

4. To study the relationship between the activities of operator and the machine.

5. To keep permanent record of the most efficient way of performing a task for future reference.

6. To obtain motion time data for developing synthetic time standards for various elements.

 Advantages of Micro Motion Study:

It has the following important advantages:

1. It provides a permanent record of motion study on films.

2. A large number of operators can see the procedure at any time even after the completion of motion study work.

 3. Films can easily reveal the difference between the present and the proposed technique.

4. Films can be demonstrated to large work force at any desired speed.

5. It provides very accurate time for each operation or motion in comparison to stop watch time study.

6. It helps in making detailed and accurate analysis of the prevailing technique.

SIMO CHART

SIMO is an acronym for Simultaneous-Motion Cycle.

The chart is used in conjunction with Therbligs to study the detailed activity of a worker, to capture how long the operation takes, and what activities are being performed by each hand.

Therbligs in the SIMO chart are critically examined to explore the possibility of:

(i) Removing or eliminating the unproductive Therbligs such as find, select and avoidable delay etc.

(ii) Resequencing of the productive therbligs such as assemble and disassemble etc.

Operation: Finish hand filing copper work piece.

Time for searching, lifting and holding work piece to the vice.

Table by left hand = 0.2 min

Time for opening the vice by right hand = 0.2 min

Holding the work piece in the vice with both hands = 0.4 min

Time taken for lifting and holding file by right hand = 0.2 min

Time taken for hand filing with both hands = 1.00 min

Time for bringing the micrometer by right hand = 0.2 min

Time taken in checking dimension with both hands = 0.8 min

Time for opening the vice by right hand = 0.2 min

Time taken in removing work piece with left hand = 0.2 min

ERGONOMICS

The term ergonomics is derived from the Greek word ergos meaning “work” and nomos meaning “natural laws of” or “study of.” The profession has two major branches with considerable overlap. One discipline, the focus of this article, and sometimes referred to as “industrial ergonomics, or “physical ergonomics,” concentrates on the physical aspects of work and human capabilities such as force, posture, and repetition.

The purpose/goals of workplace ergonomics applications include:

Occupational injury and illness reduction
Workers’ compensation cost containment
Productivity improvement
Work quality improvement
Turnover, absentee and presentee reduction
Government regulation compliance

These goals are often reached through:

Evaluation and control of work site risk factors
Worker and stakeholder interviews identifying issues and potential improvements (qualitative information)
Identification and quantification of existing work site risk conditions (quantitative information)
Recommendation of engineering and administrative controls to reduce the identified risks
Education of management and workers to risk conditions and improvement opportunities

Work Risk Factors

Certain workplace characteristics are associated with injury and impaired performance. These work characteristics are called risk factors and include: Task Physical Characteristics (primarily interaction between the worker and the work setting)
Posture
Force
Velocity/acceleration
Repetition
Duration
Recovery time
Heavy dynamic exertion
Segmental vibration

Other Workplace Risks

The risk factors addressed by industrial ergonomics are a partial list of hazards present in the work setting. Others include:
Job stress
Job invariability
Cognitive demands
Work organization
Workload
Working hours (shift work, overtime)
Displays and control panels
Slip and falls
Fire
Electrical exposures
Chemical exposures
Biological exposures
Ionizing radiation
Radio frequency/microwave radiation.