Product category:
CNC lathes
News Release from: Yuasa Warwick Machinery | Subject: Takamaz XD-8 twin-spindle CNC lathe
Edited by the Manufacturingtalk Editorial
Team on 25 October 2002
Twin-spindle CNC lathe automates drill
and tap
Acquisition of a twin-spindle CNC lathe has allowed Barton Coldform to automate a drilling and tapping operation on cold headed assembly studs.
Acquisition of a Takamaz XD-8 twin-spindle CNC lathe from Yuasa Warwick Machinery has allowed Droitwich-based Barton Coldform to automate a drilling and tapping operation on cold headed assembly studs The components, destined for an automotive application, are required in volumes of 15,000 per week and would formerly have been drilled and tapped on a manually operated production drilling machine
This article was originally published on Manufacturingtalk on 9 Dec 2002 at 8.00am (UK)
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By using the Takamaz machine, however, presence of the tapped hole on the finished component is guaranteed, as is concentricity of the hole to the stud.
Furthermore, tool life of taps has quadrupled to circa 8,000 components.
Moreover the manual alternative would have required six operators working a two-shift pattern whereas the CNC machine is minimally manned.
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Paul Denning, managing director of Barton Coldform, commented, "Automation of this type allows us to compete successfully with low wage economies in Asia and the Far East.
We are experiencing record sales at the moment and have grown by 37 per cent at a time when manufacturing is meant to be in recession.
We are confidently forecasting over 15 per cent growth in 2003." The secret of Barton Coldform's success is due to a high level of basic expertise - its three owner/directors formed a management buy-out consortium in 1999 - combined with continuity of improvement and investment.
The company also undertakes design and development for customers, utilising CNC machining facilities for rapid pre-production prototyping in parallel with development of production cold forming tooling.
This has allowed it to dominate the market for high precision, high volume components.
Around 35 per cent of output is exported including 100 million components per annum to China.
Said Denning, "Cold forming processes have been around for many years but there is a general lack of appreciation for what the process can offer.
We produce quite complicated parts using coiled wire from 3mm to 20mm diameter, up to 120 mm maximum length in a wide variety of materials.
Production rates are such that even multi-spindle auto turning machines cannot hope to compete while the mechanical strength of a cold formed component is normally much higher than a machined equivalent." Many of these parts are ready to use but a proportion require second operation machining.
There are two problems here.
Firstly the metallurgical properties of an ideal cold forming material, which needs to be malleable and ductile, are at odds with free machining.
Secondly, the volumes are very high.
Barton Coldform's fastest single-die cold forming machine operates at up to 470 hits per minute, and the smallest batch run that the company normally considers is 50,000-off.
On its latest multi-station machine, minimum quantity is 250,000-off, which can be produced in a matter of hours.
Denning explained, "Around 15 per cent of our output - around 30 million components per annum - needs subsequent machining to generate tapped holes, cross holes or undercuts.
This explains why we need a comparatively large second operation department.
In addition, we use outside subcontract machinists.
However our aim is always to improve the quality of the end product and the competitiveness of our service.
To that end we have been looking for suitable CNC equipment for some time with the aim of automating what are currently manual tasks." The cold forming process results in a net shape blank, normally requiring a minimal amount of machining to complete.
This has fostered a belief in some circles that a satisfactory solution can be arrived at using rudimentary equipment.
Barton Coldform does not subscribe to this view.
Ongoing contracts are serviced using cam controlled rotary transfer machines, which can cope with high volumes.
However for volumes in the region of 20,000 per week this type of equipment is unsuitable.
"Cam machines are fiddly to set up," Denning stated.
"However, most CNC machines need a lot of customising for this type of work, which is why many second operation applications use manually operated equipment.
This has the disadvantage of being a compromise process, lacking proper controls combined with ongoing direct labour costs.
When we came across the Takamaz XD-8, we were immediately excited as the machine addresses all of those issues." The Takamaz lathe is a horizontally-opposed, twin-spindle turning machine.
Each spindle is loaded and unloaded by its own dedicated, high speed gantry servo loader (75m/min) from/to parallel input/output conveyors.
Tooling is platen-mounted between the spindles, with up to six tools available for machining on each spindle.
Depending on customer requirements, the machine can be set up for identical operations on each spindle, as is the case at Barton Coldform.
Alternatively a transfer facility can be incorporated for sequential front- and back-end working.
"The lathe's design lends itself to second operation machining and appeared ideal for our requirements, so we had trials conducted at Yuasa Warwick Machinery," Mr Denning recalled.
"While these were on-going, we gained a contract for a stud-type component required at the rate of 15,000 per week and it is this, rather than the components originally designated, that have run on the machine." The component is a top-hat shaped stud with a rebate on the 'brim' and two lugs, produced from BS3111 type 9/2 heat treatable medium carbon steel.
The second operation requirement is drilling and M6 tapping to a depth of 42 mm.
Ultimate use of the component is as an assembly feature, which is welded into a sheet metal pressing for motor industry use.
Production of the base component is carried out on a cold heading machine.
In a single shift this is capable of producing 60,000 components which fulfils four weeks' production requirements at the end user.
The Takamaz XD-8 is capable of drilling and tapping at a rate of just over 15,000 per week, in line with customer requirements.
Denning commented, "In the cold forming industry, second operation machining is all about balance and guaranteeing quality at a competitive price.
The Takamaz lathe is not a low cost machine but in this application it has proved highly cost effective.
Because the component is located in the chuck and rotated for drilling and tapping, concentricity of the hole is assured: likewise the process automatically ensures correct depth.
Moreover, every component that passes through the machine is drilled and tapped to the same specification.
In addition, the machine needs no operator.
We are installing vibratory bowl feeders for prolonged periods of unmanned running, but even without them it is a simple matter for one of our personnel to keep the infeed side topped up with components." Denning is well aware that, on a component that requires a small undercut or other turning operation in addition to drilling or tapping, the benefit of the lathe would be even greater.
He concluded, "On medium volume parts, a machine like the XD-8 is virtually ideal.
It offers the process reliability of a rotary transfer machine combined with high levels of flexibility and we will certainly be considering additional, similar machines for our second operation shop.".
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