Better workholding improves machining

Ever since CNC machining became the dominant method to cut and grind metal, a perception has existed that machining can be manipulated and easily simplified. With computers crunching the numbers, how hard can machining be?

That perception couldn’t be further from the truth. Whether you are looking at 4 weeks or 4 days of lead time, cutting metal still takes time and a lot of preparation.

But while the basics of cutting and grinding remain the same, part manufacturers have an opportunity to improve processes to better match the requirements of the information age we live in.

In this column, which focuses on workholding, or fixturing, I hope to bring an awareness of this potential “added value.” I’ll start with the basics, or “Fixturing 101,” and work my way up in future columns.

Every part is made of geometrical elements designed to work in concert with other parts. For example, a rack-and-pinion steering system, or any gearing really, contains housings to hold the gearing, shafts driven from the gearing, support structures to hold the shafts, braking systems to control the speed, wheels bolted to the shafts, bearings to keep the shafts rotating … you get the idea.

But all those parts fit in two categories: round and non-round.

A nonround part usually has six datum points.