INTRODUCTION
1. A key is a inserted between the shaft and hub or boss of the pulley
and gears to connect these together in order to prevent relative motion
between them.
2. It is always inserted parallel to the axis of the shaft.
3. It is temporary fastenings.
4. A keyway is a slot or recess in a shaft and hub of the pulley to
accommodate a key. 5. It is made of mild steel
What are the Different Types of Keys in Machine Design?
Keys and various Types of Keys in Machine Design are used to join the Mechanical
components. There are elements like nut and bolt, screw, keys, and couplings, joints like
cotter joints, and knuckle joints that are used for non-permanent joining and non-
permanent fastening of mechanical components. As we focus on the simplest
elements used for joining the mechanical components, types of keys in Machine Design
are one of them.
In the list of machine design elements, the Key is one of the most important elements.
One of the best features of the Key joint is it is detachable, so the key can be used as a
temporary fastening. In this article, we will see about the keys, the design of keys, key
joints, the function of key joints, and the types of keys in Machine Design in detail.
What are Keys in Machine Design?
Key is one of the machine element parts, used to connect transmission shaft
to rotating machine elements like gear, flywheel, sprockets, or pulleys. So
based on the uses and function of keys Generally, keys are made up of ductile
materials like mild steel and plain carbon steel by hardening and tempering. In
the case of corrosive environment brass and stainless steel material are used
to design a key. For safety purposes, 3-4 factors of safety should be provided.
The design of the key joint consists of a shaft, hub, and key as shown below
fig. The slot is provided in the rotating shaft or in the hub or both of them to
insert the key known as keyways. The keyway is usually manufactured by a
vertical or horizontal milling cutter. The key is inserted inside the keyway
parallel to the axis of the rotation.
Design Consideration of key :
1) Power to be transmitted.
2) Tightness of fit
3) Stability of connection
4) Cost
5) Crushing failure of key:
6) shearing failure of key
7) The material of key, shaft should be the same but the key should be
weaker than the shaft.
Application Of Mechanical Keys :
1) Sunk Key: used for heavy-duty application
a) Rectangular sunk key: for preventing rotation of gears and pulleys on the
shaft
b) Gib headed key: used where the key to be removed frequently.
c) feather key: Machine tool
2) Saddle key: for light-duty or low power transmission
3) Round key: Used for low Power drive
4) Splines: Where providing axial movement between the shaft and mounted
member
References:-
• Collins, J. A., Busby, H., & Staab, G. (n.d.). Mechanical Design of Machine Elements and
Machines.John Wiley & Sons.
•
• Hamrock, B. J., Schmid, S. R., & Jacobson, B. O. (2006). Fundamentals of machine elements:
Bernard J. Hamrock, Steven R. Schmid, Bo O. Jacobson. Boston: McGraw-Hill Higher
Education.
• Kurt M. Marshek, Robert C. Juvinall (2021). Fundamentals of machine component design.
John Wiley & Sons.
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