Machine Parts

Strap Clamp: The simpliest and probably most commonly used clamp is the strap clamp.All strap clamps employ the principles of levers.The most important feature is that the clamping bar can be slid onto and off of the workpiece for easy workpiece removal.A compression spring between the base clamping bar holds the bar in position when the clamp bar is loosened. The pillar and heel pin, rests in a groove on the under side of the bar to prevent it from turning when the clamping bar is loosen .                                             Advantages of Strap Clamp: The talked of topics of the merits of this type of clamp are stated below- Ø The design of the strap clamp is the simpliest one. Ø If the height of the workpiece varies, strap clamp can hold it without any problem. Ø Strap clamping may be actuated by hand knob. Ø There is no effect of vibration like other type of clamp. Ø It is easy to load and unload within the clamp.

The clamps on mill fixtures must be extremely rigid. Because   cutting forces exerted by a milling cutter may change as the cutter enters or leaves the work and throw an extra load on clamps as shown in the following figure. Clamps must not loosen by vibration caused by interrupted cutting of the mill cutter. Interrupted cutting occurs especially   at the beginning and end of the cut.                                                                                                                     Figure:  Work is lifted up at the beginning of cut                                                                                                                                   Figure:  Work is forced down at one end but lifted up at the other