Product category:
Chucks and collets for rotational work
News Release from: Leader Chuck Systems | Subject: Hainbuch front access collet system
Edited by the Manufacturingtalk Editorial
Team on 04 September 2001
Standardising collets reduces set-up
times
By standardising on the Hainbuch front access collet system for four CNC turning machines, Luneside Engineering has significantly increased its production flexibility and cut set-up times.
By standardising on the Hainbuch front access collet system for four CNC turning machines, precision engineering specialist Luneside Engineering has significantly increased its production flexibility, reduced set-up and machining times, and cut costs at its Halton (Lancs) site In one case, the improved access to the job - which is a direct result of the collets - has reduced the number of machining tasks needed to complete the component from three operations on separate machines to two operations carried out in a single set-up on a mill-turning centre
This article was originally published on Manufacturingtalk on 23 Jun 2008 at 8.00am (UK)
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Capable of fast changeovers, a collet chuck has a runout accuracy of only five microns and is a replacement for other styles of collet chucks in bar-fed turning applications.
As a result, the machining time required for a typical batch of 100 components has shrivelled from 42 hours to ten hours, moving the job from loss into profit.
The component concerned is an aerospace retaining sleeve, which is machined from 1m lengths of bar.
The operational sequence is to turn the outside diameter, bore through the middle, rough thread internally and externally, mill a slot on one end, then turn the component round and, gripping on the rough cut thread, finish the back end.
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A turning centre fitted with precision collet chucks on its main- and sub-spindles is central to a subcontractor's successful policy of machining small batches of precise, complex parts.
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Capable of fast changeovers, a collet chuck design has a runout accuracy of five microns and is as an economical replacement for multi-bore and other styles of collet chucks in bar-fed applications.
Once the back end work is completed, the part is mounted on a mandrel then the external thread is finish cut.
Previously, the main turning operations were completed on a CNC lathe and the slot was produced on a milling machine, then a manual centre lathe finish cut the thread.
However, Luneside's acquisition of the mill-turning machine has provided all the necessary capabilities in one machine - including the ability to reference the thread start position to the milled slots for repeatable, accurate CNC thread cutting.
Nevertheless, were it not for the compactness of the Hainbuch collet chuck, supplied by Leader Chuck Systems, turret access to the job would be restricted by clearance problems and it would be impossible to finish cut the thread.
David Taylor, Luneside's chief manufacturing engineer, comments: "For many years we had used a collet system which mounted directly into the machine spindle.
However, we recognise the importance of flexibility in the way we tool our machines, and a collet system that could be adapted to various different machines had to be a part of that.
"With Hainbuch we now have the capability to use the system on all three of our most modern turning machines, and this pays considerable dividends in terms of both allocating work and ease of set up." Luneside is an established supplier of complex components and sub-assemblies to the aerospace, nuclear, defence and specialised machine tool sectors.
Founded over 50 years ago, the company offers a wide range of in-house manufacturing facilities including turning, milling, grinding and jig boring, complemented by in-house tool and cutter grinding facilities and CAD/CAM.
In addition, it has extensive project management experience and is able to source specialised services such as hard chrome plating.
Batch quantities are relatively small; 100-off constitutes a large batch and the median figure is closer to 20.
The company therefore needs to employ manufacturing processes which are themselves highly repeatable, but which are also quick to set up.
"The Hainbuch system was recommended to us by the supplier of one of our lathes," David Taylor recounts.
"Compared to the in-spindle system that we had been used to, Hainbuch offers a number of advantages.
"The capability to change collets from the front of the chuck in a matter of seconds is very useful and has been very well received by our setter/operators.
Likewise, the quality is very good and new collets always fit first time.
"From a machining point of view, it is also very much more rigid and this obviously helps us to maintain accuracy and finish.
A further operational advantage is the much improved clearance it provides for turret-mounted tooling, making collisions much less likely." Capable of handling parts up to 1,000mm diameter, Hainbuch collet chucks offer high-accuracy clamping of up to 0.004mm TIR and higher clamping forces - up to 50 per cent more, with the same drawbar pull - than a conventional jaw or collet chuck.
Luneside seeks to retain the chucks on its machines for as long as possible and has invested in developing specialised collet-mounted fixtures for certain jobs.
All three of the machines are equipped to take the same size collet chuck; this includes a machine which is nominally a ten inch chucker for which a special A2-8 adapter was commissioned from Leader Chuck Systems.
This provides the company with the high level of flexibility required.
"On appropriate jobs, the collet chucks provide valuable rigidity, concentricity and tool access advantages," David Taylor confirms.
"Provided that we have the correct collets available and the work will fit, the ease of collet exchange makes the Hainbuch system preferable to conventional jaw-type chucks in the majority of situations.".
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