TABLE OF CONTENTS Sanding and Benching and Vibratory Finishing.
Achieving the final specified surface finish on titanium alloy parts is time consuming because of material hardness and specifications that are more demanding than for most other materials. Chapter 11: Sanding and Benching covers hand sanding and mechanically-assisted sanding. Chapter 12: Vibratory Finishing deals with mass media finishing that while commonly used for materials other than titanium alloys and on small parts, is just starting to be employed for large titanium alloy air-frame parts.
Sanding is a major cost element of the machining process. Sanding and benching are both terms for the same process and are used interchangeably. I define both terms as getting rid of burrs and improving surface finish to the drawing specifications. This sanding or benching also includes the blending of steps between cutter passes and the removal of material that milling missed. There are some hard to get at areas from a milling standpoint and it is sometimes more efficient to sand and blend at the bench than to spend the extra time trying to mill certain features. Benching costs less per hour because the employees are usually paid less than machine operators and because expensive capital equipment is not being tied up. The cost tradeoffs for this decision vary between shops.
The basic message of this chapter is that sanding is a potential area for large savings because it typically adds 10-20% to the cost...
