Machining’s Involvement in Lightweighting the World

By Kip Hanson

Lightweighting is a big piece of sustainability. Fuel costs have been fairly low the past couple of years, but everyone knows they’re going to rebound at some point, probably with a vengeance. Add to that concerns over global warming, air pollution, and the environmental impacts of fracking and offshore drilling, and it means one thing: Planes, trains, and automobiles must become lighter and more fuel-efficient.

Machine shops don’t as a rule directly contribute to the lightweighting movement, although they definitely feel its effects, and often not in a good way. True, lighter cars use more parts made of easy-to-machine aluminum (yeah!), but they also use plenty of parts made of nasty-to-machine steel and iron.

But wait. How does a relatively heavy metal like dual-phase steel or compacted graphite iron (CGI) make cars lighter? Since these materials are stronger by volume than their traditional counterparts, less material can be used. A similar effect is felt on the aerospace side, where an increasing amount of abrasive carbon fiber–based composite materials is used, as well as the usual aerospace suspects, titanium and Inconel. All are challenging to machine. Add to this the growing number of three-dimensional-printed metal aerospace parts, the majority of which require secondary machining operations but are generally difficult to hold due to their complex shapes and sometimes delicate (but strong) structures. The result? Machining will only continue to get harder as cars and planes become lighter.

If you’ve ever attempted to surprise your father-in-law on his birthday by mounting a Big Jon universal rod holder to the gunwale of his fiberglass fishing boat, only to find that the holes you drilled soon splintered and cracked, leaving him visibly upset and you wondering about future invitations to the lake during bass season, you’ve experienced delamination. It’s one of the primary failure modes faced by aerospace workers machining carbon fiber reinforced plastic (CFRP) aircraft fuselage material, which is similar in composition to fiberglass. The moral to this sad story is that anyone making holes in fishing boats or commercial aircraft should use a special type of tool designed specifically for this abrasive but — thanks to lightweighting — ever more widely used material.