ISSUE #07

Support Cylinders

Supporting the Part
The previous two chapters discussed cylinders for positioning and clamping-two of the three steps in workholding. In this chapter we look at cylinders used to implement the third step: supporting the part. Supports add rigidity to fixtured parts to minimize part deflection and machining vibration. Proper support is necessary for high quality, repeatable machining results..
It’s important not to confuse work supports with the support points and planes inherent in the workpiece positioning step. As explained in Chapter 2, rigid support points or surfaces additional to those used in the 3-2-1 locating process must not be introduced.

Hydraulic work supports are just what the name implies: hydraulic devices used to support a workpiece during a machining process. These cylinders can be set up so that they are normally retracted out of the way and engage the part only when needed. After a part has been positioned, the work support advances to contact the part with slight pressure, then locks in place.
Production runs can be limited by the labor-intensive
Care must be taken to ensure that points of application of clamping pressure are aligned with support points. An offset of the centerlines will cause bending of the workpiece.

Additionally, the direction of the clamping force must be axial to the centerline of the work support plunger. Side loading of the work support must be avoided in order to obtain safe, reliable, repeatable results.