The document discusses the redesign of hex keys to improve grip, safety, and comfort. It begins by describing hex keys and their standard sizes. User surveys found the existing hex keys focus on efficiency but cause wrist pain from repetitive motion. The final redesign features hollow hex keys that can join together in various combinations to provide a better grip and ease of repeated use while maintaining work space. Prototypes were created and evaluations showed improvements in grip usability, space effectiveness, and efficiency compared to existing hex keys.

1. 1
HEXKEY REDESIGN
DD 311 – Applied Ergonomics
GUIDE – Prof. Dr. Sougata Karmakar
120205023 | 120205044
Lolla Sruzan Vishram Meena

2. 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

3. 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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4. 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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5. 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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6. 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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7. 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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8. 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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9. Existing products
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10. 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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11. User Survey
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12. User Survey
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13. 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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14. Redesign ideas
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15. 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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16. Final Design
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17. Final Design (various combinations)
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18. Prototype
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19. 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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20. 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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21. Conclusion
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22. 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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23. Thank you