abhinavergonomics in hand tools designs

7/30/2019 Abhinavergonomics in Hand Tools Designs

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ERGONOMICS IN HAND TO

DESIGN

ABHINA

DEPT. OF IND

NIT


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ERGONOMICS IN HAND TOOLS DESIG

An ergonomically designed tool- Enhances operator performance thus productivity

quality of work.

Reduces operator discomfort, fatigue or physical st

Prevents injury or accidents.

Is usable to maximum population.


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SOME EXAMPLES OF HAND TO


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How an Ergonomic tool ca

achieved?

Ergonomic factors to be considered ar

Handles and Grip design- Biomechanical consideration

Tool weight , center of gravity

Tool shape

Static forces and loads

Dynamic reaction force such as vibrations and torques

Operator- gender, position etc.

Work location

Tool orientation


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HANDLES AND GRIP DESIG

IMPORTANT ASPECTS

Location of the handles

Handles should be located at or above the center of gload.

Some tools can have two handles also one for support

control.


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Some examples of handles


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TYPES OF GRIPS

Precision grip - provides control for precision and accutool is gripped between the thumb and the fingertips.

Power grip - provides maximum hand power for high fothe fingers wrap around the handle.


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Handles sizes

For a Power grip - diameter should be large for better gripdelivering greater required force and torque. The recommdiameter for a power grip is 40-45mm.Ex- hammer .

For a Precision grip diameter should be smaller so as to paccuracy in work or job. The recommended diameter for grip is 8-16mm.Ex- nut drivers

For tools needing both Precision and Power grip - The idea

diameter is a compromise between 25 and 40mm.ex-scre

For maximum power in an adult male, it should be 3 or 4 diameter (Drury, 1980).

Length at least 10 to 15 centimetres, to fit the width of thefor large-handed population, shorter if the butt end of thefit into the palm, when it should be rounded. Allow for theworking gloves.


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ANTHROPOMETRY FOR TOOL DE

All these anthropometry should be considered while designing a tool wh

By maximum people.


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HANDLES SHAPES

Cylindrical, if the grip is to twist round the handle.Ex-one piece rolling pin.

Uniform diameter and smooth surface along the length, to aexample on the back of an axe handle.

Thickened centrally, if there is a need to secure against slidingis a sheep-shearing hand-piece.

Bent to keep the wrist in straight position. The crucial ergonomtool use and design -- bend the tool, not the wrists.

Pommel - an enlargement of the butt end, for security againwould occur with momentary relaxation of grip.


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HANDLES SHAPES

Axe handleBent handles


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SOME BAD DESIGN

Handles get smaller,but hand does not

Smaller handles are difficult to use by normal-sized


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HANDLES SURFACE

Handles surface are designed such that they have maximum gripshould be able to deliver maximum power with accuracy.

Handles should be designed for bare or gloved hand operation. Smoothness for sliding or rotating the handle within the hand.


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Roughness may be deliberate, to have a better grip.

Grips should be contoured to the curve of the palm of the han

Some handles have a textured rubber handles for safety and against heat, vibration, and electricity, against sudden jolts.

Some screwdrivers have 'fluted' handles (deep ridges along th

and others are smooth.


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Biomechanical consideratio

and

Musculoskeletal Disorders

Forceful grip exertions of hand rely on muscle contractions inmuscle forces are transferred to fingers via tendons.

Grip Configuration - determines level of muscle exertion andtension, and there is some effect of hand and wrist anthropo

Wrist Angle - during grip-type exertions it directly affects the intra-wrist supporting forces acting normal to the direction ofsynovia (the lubricating sheaths around tendons).


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Musculoskeletal Disorders (MSDs

Along with common injuries such as cuts, lacerations, and brufrequent and prolonged use of hand tools can cause sorenepains, and fatigue, which, when ignored, can lead to chronicmusculoskeletal injuries (MSIs) of various kinds.

MSDs are the major work place injury. There are many differethese injuries:

CTD - Cumulative Trauma DisordersOOD - Occupational Overuse DisorderRMI - Repetitive Motion InjuryRMD - Repetitive Motion DisorderRSI - Repetitive Strain InjuryUECTD - Upper Extremity Cumulative Trauma Disorder


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CAUSES OF MSDs

Four risk factors increase the likelihood of an MSD:

Posture of hand and body - Posture deviated from "neutral posincreases the likelihood of injury. This can include hand deviatioextensions, or poor seated posture.

Number of Repetitions - High frequency of performing a motionincrease the likelihood of injury. Insufficient micro breaks betwe(such as keystrokes) and the resulting muscle fatigue contribute

process. Amount of Force - A higher force with which the motion is perfo

increase the likelihood of injury. A common problem is that keykeyboard are hit with excessive force.

Level of Stress - Stress increases muscle tension which in turn incforces on the tendons.


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AWKWARD BODY POSITION


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CONCLUSION

Keeping in mind of ergonomics factors for a hand tools we ca

happening to a user at the same time we can increase productresults to more profit.

abhinavergonomics in hand tools designs

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