Machine Technology: No-hands tool changing

When CNC milling machines were conceived, some in the metalworking industry weren’t satisfied. These people asked why a computer couldn’t also manage tool changes so a person wouldn’t be needed to make them.

This was the impetus behind the development of the automatic toolchanger, according to Kevin Holdmann, operations manager for TAC Rockford (Ill.), which sells ATCs. Holdmann said almost all CNC machines come equipped with an ATC.

He explained that automated tool-changing processes work two ways. Either the spindle moves to exchange its current tool with another in a magazine, or a mechanical arm makes the change.

Tormach’s 10-tool automatic toolchanger is mounted on the company’s PCNC 770 milling machine. Image courtesy of Tormach.

Machining centers are typically equipped with drum-style ATCs, Holdmann said. These disc-shaped devices have tools arranged around their perimeters. There are also rack-style ATCs capable of holding numerous lined-up tools. These ATCs include a mechanism that shuttles tools between the machine and their pockets on the rack.

Another option for holding and exchanging multiple tools is a chain-type ATC. To picture these, Holdmann said to think of a large circulating bicycle chain with toolholding linkages. The chain is set in motion to retrieve a particular tool for placement in the spindle.

Long chains and sprockets are replaced by cams in CTM-series toolchangers from the Italian firm Colombo Filippetti Spa. The result is a simpler system that requires less maintenance, according to Chris Salamone, sales manager for Indexing Technologies Inc., Ramsey, N.J., which sells them. Priced from about $15,000 to $40,000, CTMs clamp, extract and exchange tools, simultaneously inserting the new one in the spindle and the old one into its magazine.