Nesting Creates a Milling Challenge

This job shop uses remaining steel stock to hold a mated pair of aircraft parts.


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Alpha Machining & Manufacturing is a small, nimble job shop in Tulsa, Oklahoma that specializes in quickly delivering CNC machining work in various materials and lot sizes. Much of the work the shop sees is overflow from manufacturers in either aircraft or oilfield industries, two fields accounting for much of the production in this region. Just like any job shop, Alpha’s hold on many jobs is unpredictable—it can’t always know whether it will see a particular part number again. General Manager Dale Killion says this uncertainty rules out custom fixturing for many parts. Instead, the shop finds low-cost alternatives for holding parts.
An example is the part seen here, a detention arm for an aircraft wing. This part is made from 15-5 stainless steel, and comes in right- and left-hand mated pairs. To produce a mated set in a single cycle, and also to hold the parts securely, Alpha mills the parts complete out of a solid steel block.
Mr. Killion says one particular challenge of this machining is the channel that the nesting creates between the separate pieces. The metal has a hardness of 42 Rc. An end mill from Gorilla Mill has proven effective at taking this cut, he says. The tool has a carbide substrate that was developed for hard materials such as titanium, but seems to also work well in this deep channel.

Here is side one of the nested set of parts, with a little of the shape of the parts becoming visible.



Here is side two, with the two parts rising up out of the steel block. The channel between these two parts is a difficult feature to machine efficiently.