Dust protectors

Although there are many standard parts for dust and dirt protection (bellows, curtains, etc.) these standard parts are not always applicable. Size and shape of mating parts puzzles designers. By providing a fixture or a jig with a chip protector secures that chips and dirt will not interfere between mating parts and surfaces. Keeping the tooling equipment clean secures the correct machining of workpieces and the protection of machining equipment (machine tools, fixtures) and the health of production personnel. In precision machinery the dust is an invisible enemy, we hear the expression “clean room” very often even in less advantageous technological manufacturing processes.
The solutions presented in this article are very simple. Five types of dust protector for a moving shaft are described. At the above figure you can see the sharp-edged bushings. Sharp-edge bushings are custom bushings with an extra feature: one sharp edge that keeps out dirt. A very sharp edge is usually machined but due to lower strength of the sharp edge a flat about 0.15mm is specified.
The dust protector of the above figure is a simple cap  which is secure by means of hex set screw directly one the shaft and reciprocates with it. It’s a chip version of a below and can be manufactured for many sizes where a standard one is not applicable. Aluminum alloys and structural steel are the usual materials for this part.

The two last protectors are compression spring shields. In the above figure you can see how the shield encloses the spring. The shield can be single or double. Single shield requires an extra concentric mounting hole and the double one a second shield larger in diameter reversed in order to mate one in other. Which type is better depends from standard parts availability (standard deep drawing caps) and in shop manufacturing capabilities. These spring shields prevent chips and dirt from interfering with the compression of the spring.
Using o-ring seals with the dust protectors we increase their resistance to the dirt penetration.