VTLs turned upside down.

Author:Davisson, John F.
Position:Vertical turning lathe

An innovative approach to automatic self-loading CNC vertical lathe technology created and developed in Germany is building a growing presence in the North American market.

Three German manufacturers with strong US operations are each marketing CNC overhead vertical turning machines which feature a moving spindle that holds the part upside down. A "motor-spindle" can then move on an X- and Z-axis aiding both machining movements and automatic self-loading. The machines are designed for small and medium size parts held in the chuck for machining and needing auto-loading. Basic turning, drilling and milling is performed.

Machines include the VSC from EMAG Corp, Troy, MI; from Gildemeister/American Pfauter, Loves Park, IL, the Hessapp; and from Index Corp, Shelton, CT, the V200.

"The technology was developed by EMAG," explains Robert Cramer, EMAG president. "The original concept was born in 1991 and the company was so enthusiastic it built a prototype within a few months. Later that year in September it was introduced at a machine exposition in Dusseldorf." An incubation period for introduction and marketing was carried out in Germany by all three manufacturers because the concept was labeled so "futuristic."

View from the top

"If you look at a traditional vertical or horizontal turning lathe you get either a two-axis or four-axis, but there's only so many configurations of those arrangements," explains American/Pfauter's Robert Dunlap. "This technology created a new motor spindle placing it on top, upside down. If the new spindle hadn't been developed there would be no way we could put it on top. This also affords excellent chip control because all chips, through gravity, simply fall straight down and out."

This chip control method for the new machines has drawn strong interest according to Mr Dunlap because, "there's a real trend in US industry, driven by the automotive boys, that we must control chips. The desire is to run dry because of coolant complications and mounting pressure from the EPA."

Coolant, of course, does two things, it controls the amount of wear on a cutter and it controls the direction in the flow of the chip. Ordinarily chips must be separated from the coolant before disposing of the fluid. "If you don't have coolant to control the chip flow," reasons Mr Dunlap, "then the best alternative is to put the spindle on top and let gravity do it for you."

As the chips fall down, they don't have anywhere else to fall except the...

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