Lathe fixture :
(1) To avoid vibrations while revolving, the fixtures should be accurately balanced.
(2) There should be no projection on the fixture which may cause injury to the operator.
(3) The fixture should be rigid and overhang should be kept minimum possible so that there is no bending action.
(4) Clamps used to fix the fixture to the lathe should be designed properly so that they don’t get loosened by centrifugal force.
(5) The fixture should be as light weight as possible since it is rotating.
1.7 Grinding Fixtures
The workholding devices for grinding operations will depend upon the type of grinding operation and the machine used. We shall take each one by one, as below.
(1) Fixtures for external grinding. A mandrel is the most common fixture used for grinding external surface of a workpiece. As written earlier, a mandrel is hardened and is held between centres of a machine. The mandrel is used for internal chucking of round workpiece with bores. The workpiece is located and held on the mandrel with the help of the bore so that external surface may be machined truly concentric to the bore. The various types of mandrel are :
(i) Taper mandrel. In this type of mandrel, the outer chucking surface is given a slender taper of about 0.5 mm per metre, Fix. 1.55. The diameter of the bore of the workpiece must be smaller