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News Release from: Mike Page - editor's feature articles | Subject: Multi-spindles
Edited by the Manufacturingtalk Editorial
Team on 17 October 2007
Multi-spindle automatic lathes advance
As the operational flexibility of CNC multi-spindle lathes increases and the changeover times dramatically reduce, is it time for large batch production to use more of them, asks Mike Page.
Some years ago, a UK bearing manufacturer had begun to replace its cam-driven multi-spindle automatic lathes with batteries of CNC single-spindle automatics The changeover programme stopped in 'mid flight' so as to speak, as the company simply was not maintaining high output rates with single-spindle CNC lathes
The initial attraction of single-spindle, CNC lathes had been the drastically reduced changeover times when compared with replacing and setting up cams.
Also the factory had to machine, or buy in, the cams.
CNC single-spindle lathes, since then, have become very much faster, but then, so have CNC multi-spindle lathes.
Initially the price asked for a CNC six-spindle automatic lathe was regarded by many machine shops as astronomical - maybe EUR 500,000 for one machine - but those involved in machining high value components, and valued single set-up machining in high volumes, bought them.
During the subsequent 20 years or so, CNC multi-spindle lathe prices have come down, while their flexibility in machining terms has escalated.
They have also become remarkably fast operators.
For example, I saw one machine at the recent EMO 2007 machine tool show in Hannover, Germany, that had linear motor operated slides and offered to accelerate each slide at up to 4G to reach perhaps 50m/min fast traverse speed to get that turning tool into its next position.
Apparently you can now have a slide with a tool turret or too instead of one cutting tool.
The fact that you can even broach a difficult hole shape on a multi-spindle lathe (and yes, on some single-spindle machines too), let alone perform a host of other machining operations including spline-hobbing can only be impressive.
Another CNC multi-spindle lathe builder offered to do what previously was the job of front-loading twin spindle automatics.
Rather than machine from large diameter bar, the company offered to load partly pre-machined or raw, sawn billets into an eight-spindle machine.
Typically, the machine can be set up to machine two parts at once, each being chucked onto each of four spindles.
To do this, the company had developed a 'whizzy' parts loading/unloading system, which would also reverse the job for back-end working.
On the control systems side, to make setting up easier and quicker, the latest CNC multi-spindle automatics offer process simulation software.
It means that while the 'multi' is processing its current job, an operator can 'virtually' set up the next job and 'virtually' prove it out, so that the actual setting-up, when it comes to it, is made significantly easier.
The latest in-cycle dimensional probing systems and a host of sensors on these complex machine tools provide much more confidence in feeding up the magazine and walking away to let the machine produce unattended for a shift or more.
If a factory has a shop full of single-spindle automatics and, to raise output, the owner is rather baulking at the costs of introducing extensive part handling automation, maybe it is time to talk about multi-spindle machining.
Typically one CNC multi-spindle automatic can do the work of five to six single-spindle, 2/3-axis CNC lathes.
Among the companies who will be very pleased to talk to you are, to name a few: Gital (Gildemeister Italiana - DMG group), Italy; Index-Werke, Germany; Nakamura, Japan; Schuette, Germany and Tornos in Switzerland.
Most of these companies are registered on Manufacturingtalk.
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