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HEXKEY REDESIGN

DD 311 – Applied ErgonomicsGUIDE – Prof. Dr. Sougata Karmakar

120205023 | 120205044

Lolla Sruzan Vishram Meena

Hex key/Allen key

The hex socket screw drive has a hexagonal recess

and may be driven by a hex wrench, also known as

an Allen Wrench, Allen key, hex key or inbus as well

as by a hex screwdriver (also known as a hex driver)

or bit.

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Hex Socket

Nomenclature

The term "hex key" has various synonyms. Some are explained by the

geographical and commercial history of the drive type's development:

Allen, Hex, Unbrako, Zeta and Inbus key or wrench.

Allen – Named after publisher Allen Manufacturing Company

Hex - Geometrical shape(Hexagonal)

Zeta - refers to the sixth letter of the Greek alphabet

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Hex key standard sizes

Hex keys are measured across-flats (AF), which is the distance between

two opposite (parallel) flat sides of the key.

Standard metric sizes measured in millimetres(mm) are

0.7, 0.9, 1.0, 1.25, 1.3, 1.5

2 to 6 in 0.5 mm increments

7 to 22 in 1 mm increments

24, 25, 27, 30, 32, 36, 42 and 46 mm.

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Features

The tool is simple, small and light

The contact surfaces of the screw or bolt are protected from external damage

The tool can be used with a headless screw

The screw can be inserted into its hole using the key

Torque is constrained by the length and thickness of the key

The tool can be manufactured very cheaply

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Types

L-shaped Hexkey

T-shaped Hexkey

The L-shaped are formed from hexagonal wire stock, while the T-handles are the same hex

wire stock with a metal or plastic handle attached to the end.

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Manufacturing

Hex socket screw heads are usually made by stamping the head with a

die, plasticly deforming the metal.

Other ways – Linear Broaching and Rotary Broaching

Broaching - a hole is drilled and then the corners are broached out.

Hex keys are made by imparting the hexagon cross-section to steel wire

(for example, with a die), then bending and shearing.

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Applications – Present Scenario

Hex keys are used with automotive, plumbing and electrical applications. They’re

designed to provide 360° rotation at angles up to 35°.

Hex keys with T-shaped handles can provide increased turning power and more

comfortable grips.

Non-sparking, non-magnetic Allen wrenches can be useful in hazardous environments.

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Existing products

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Aim and Objectives

The use of hand tools frequently leads to feelings of discomfort during work.

These feelings of discomfort can reduce efficiency and job satisfaction of

workers.

Thus, our research is concentrated on the areas of improving grip, safety and

comfort to the selected hand tool.

Ease of repetition

Grip

Space

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User Survey

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User Survey

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User survey findings

The existing hex keys are mainly focused on efficiency.

Repetitive motion leads to wrist pain/discomfort.

Grip of the tool is also not much comfortable.

Also the existing hex keys have only single uses (to open hexagonal socket screws).

To maintain equilibrium of the handle within the hand, the gripping force must be

sufficient to counteract the reactive moments or forces.

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Redesign ideas

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Final Design

Hollow hexkeys are designed to open both socket screws and

screws with hexagonal head.

These hollow hexkeys can be joined together to attain grip and

provide ease of repeated motion.

Combinations can be varied depending on the space that is

available.

Combinations : Short – Short

Long – Long

Short – Long

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Final Design

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Final Design (various combinations)

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Prototype

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Discussion

Joining of hexkeys is completely user’s choice. Since by default they are not joined, this feature is in doubt.

Instruction is needed while using the product for the first time

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Evaluation

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Existing

Redesign

0

0.5

1

1.5

2

2.5

3

3.5

4

Grip Usability

(ease)

Space

Effective

Efficiency

(Time)

2

1

4

3

4

2 2

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Conclusion

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References

1. Fraser, T.M. 1980 Ergonomics principles in the design of handtools. Occupational Safety and Health Series, No 44 Geneva, Switzerland International Labour Office.

2. Aghazadeh, F., Mital, A., 1987. Injuries due to hand tools; results of a questionnaire. Appl. Ergon. 18 (4), 273–278.

3. Fellows, G.L., Freivalds, A., 1991. Ergonomics evaluation of a foam rubber grip for tool handles. Appl. Ergon. 22 (4), 225–230.

4. Kadefors, R., Areskoug, A., Dahlman, S., Kilbom, A., Sperling, L., Wikstrom, L., Oster, J., 1993. An approach to ergonomics evaluation of hand tools. Appl. Ergon. 24 (3), 203}211.

5. Freivalds, A., 1996. Tool evaluation and design. In: Bhattacharya, A., McGlothlin, J.D. (Eds.), Occupational Ergonomics: Theory and Applications. Marcel Dekker, New York, pp. 311}317.

6. Westling, G., Johansson, R.S., 1984. Factors infuencing the force control during precision grip. Exp. Brain. Res. 53 (2), 277}284.

7. Lowe, B.D., Freivalds, A., 1999. E!ect of carpal tunnel syndrome on grip force coordination on hand tools. Ergonomics 42 (4), 550}564.

8. Wikipedia, Wikimedia foundation - Available from: http://en.wikipedia.org/wiki/Hex_key [Accessed 2 January 2015]

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Thank you