Where 2-axis CNC lathes were once top dog in most turning departments, mill/turn centers now lead the pack.
With the ability to drill cross-holes, mill complex shapes and sculpt multidimensional surfaces on turned workpieces, CNC lathes with driven, or live, tools are making a big impact on the bottom line of many machine shops, with a commensurate improvement in part quality and delivery time. Despite this obvious benefit, however, driven tools carry the burden of additional tooling costs and a commitment to preventive maintenance of toolholders. This makes it critical for shops to do their homework before embarking on the road to driven tools.
David Fischer, product specialist for Okuma America Corp., Charlotte, N.C., explained that the majority of CNC lathes sold today come with some form of driven-tool capability. Many of these machines offer spindle speeds of 6,000 rpm or higher, with horsepower and torque ratings comparable to small machining centers.
“Compared to 10 years ago, mill/turn centers today have enough power to do some really decent work,” Fischer said. “There’s also an increased focus on shops looking to avoid moving parts from machine to machine, getting things done in one operation wherever possible. Multifunction, [driven tools] on a standard lathe are a big improvement for them.”
Adding that multifunction capability to the purchase of a conventional CNC lathe might be as easy as spending $30,000 for a C-axis spindle option and a live tool-equipped turret. It could also mean investing 10 times that amount or more in a twin-spindle, multiturret monster with more axis letters than a bowl of alphabet soup.
Regardless of how much machine a shop can afford, it’s important to remember the additional cash outlay needed to tool that machine. Where a shop might get away with spending a few thousand bucks on some stick tools and ER collet chucks to tool a 2-axis CNC lathe, properly equipping a mill/turn center will cost far more than that.
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