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News Release from: Mike Page - editor's feature articles | Subject: Twin spindle machining centres
Edited by the Manufacturingtalk Editorial
Team on 30 August 2007
Twin-spindle machining centres cut
downtime
If you are regularly machining small to medium batches of relatively complex prismatic parts it may be time to look at twin-spindle machining centres, says Mike Page.
Why have two spindles on a machining centre? If you spoke to Starrag Heckert, the company might suggest three or four spindles That company builds multi-spindle machining centres for machining medium batches of high precision parts - particularly for the aerospace, turbo-charger and hydraulics industries
Continuous path 5-axis machining with each separate spindle/workpiece manipulator set-up is done too.
For many of the less complex workpieces, wanted in medium batches, a twin-spindle machining centre may be the answer.
Which machine tool company first thought of an 'off-the-shelf' twin-spindle machining centre, I am not sure.
Certainly Honsberg Lamb (Honsberg and Lamb are now part of the USA's MAG Group) built twin-spindle, horizontal machining centres (HMC) from the early 1990s.
I understand too, that the Schwaebische Werkzeugmaschinen (Swabian Machine Tools) factory in Germany was already producing twin spindle vertical machining centres (VMC) at about the same time.
Honsberg's machine had two independently working spindles.
It meant that while one spindle was cutting, you could be automatically tool changing (ATC) at the other.
Essentially, you could either reduce ATC time to virtually zero (second spindle 'kicks in' as soon as the first has finished) or machine two parts simultaneously.
As the Honsberg HMC's spindles operate independently, you could do two different jobs at the same time.
A lot depended upon how you set up the machining program, understanding that the distance between the two spindles is constant.
As far as I know, no one has come up with a machining centre, in which one can vary the distance between the two spindles.
Maybe it is possible to have each direct drive spindle cartridge offset in a drum inside a combined machining head.
Each drum might rotate through 360 deg, varying the distance between the spindles - just a thought! Maybe someone has built one? The other European machine tool builder that pursued the twin-spindle idea is Alfing Kessler Sondermaschinen (AKS), also in Germany.
Honsberg, AKS and the Schwaebische Werkzeugmaschinen (SW) have continued to offer twin-spindle machining centres.
The latest news, published in Manufacturingtalk this week, came from SW.
The company will offer you a twin-spindle, continuous path 5-axis, machining centre.
The company has aerospace component manufacturers particularly in mind.
* Rotary transfer machines - the twin-spindle machining centre - or machining unit - idea has also been taken up by the builders of rotary transfer (or dial-type) machines.
Yes, rotary transfer is still the best way to produce thousands of precision prismatic components - some will turn and grind them too.
Perhaps the German special machines builder Ketterer Maschinenbau (KM) was the first to build such a 3-axis, twin-spindle machining unit.
In 2002, KM was offering its 'Duo-Flex' unit option with other 1-, 2- and 3-axis unit heads, when specifying rotary transfer machines.
AKS - and Honsberg too - has often incorporated twin-spindle units in linear transfer machines.
I think Mikron Agno in Switzerland and Witzig und Frank (MAG group) offers such an option.
Twin spindles - working independently - can offer a lot of potential for either virtually removing ATC down time from the production machining cycle or increasing throughput using one machine.
There is also the consideration that for the project work in hand, two spindles might be more economical than linking up two separate single-spindle machining centres.
Yet another thing to think about when wearing shoe leather out at the EMO 2007 exhibition in Hannover next month! The show in Germany runs during September 17-22.
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