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CNC automatic lathes
News Release from: Citizen Machinery UK | Subject: Citizen M16 III CNC sliding head turn/mill centre
Edited by the Manufacturingtalk Editorial
Team on 05 November 2007
CNC sliding head automatic machines
specials
Use of a CNC sliding head automatic lathe is being used by a medical instrumentation firm to develop components as well as machine special tooling and cutting accessories for surgeons.
Stryker Instruments (Ireland) is using a Citizen M16 III CNC sliding head turn/mill centre in production and development Stryker normally uses the machine to produce batches of titanium pins of 0.027in diameter by 11in long
This article was originally published on Manufacturingtalk on 27 Apr 2004 at 8.00am (UK)
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These are used as part of a special tool assembly for working close to the spinal area of the body and other surgical tooling.
The M16 also provides a significant advantage to develop products.
At its Carrigtwohill facility in County Cork, Ireland, Aaron Glavey, senior manufacturing engineer, said: "The Citizen has brought R and D and pre-production completely under our control, dramatically reduced development lead time and enabled us to experiment and perfect new ideas".
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As part of the Stryker Instruments organisation headquartered in Kalemazoo, USA, all components produced at Carrigtwohill are shipped to the US for distribution worldwide.
The company also develops customised special tools to meet surgeons' needs, involving batches as small as three- or five-off.
The Citizen sliding head mill/turn centre was bought to support development of the process for producing the pins.
Glavey said: "We needed a difficult product to prove the technology before adding more simple components and then expand its use into development once we knew and understood the capability of the machine.
This involved some three months' validation before it was handed over to production".
The selection of the Citizen resulted from NC Engineering's understanding and ability to develop the Stryker processes, said NC Engineering to manufacturingtalk.com.
The machine was also Stryker Instruments (Ireland)'s first venture into the realms of mill/turning and the company chose sliding head rather than fixed head machine design.
The reason was for long parts, which are supported by the guide bush.
* Titanium machining complexity - machining of the titanium pin component proved very complex, particularly due to its length to diameter ratio and the machinability of the material.
The part had to be straight within +0.001in and have no visible marks or surface blemishes.
The Citizen M16 had to produce two threaded portions one at its centre, the other at one end, plus several notches that had to be milled at one end.
The company now tends to split the Citizen's availability between production and new product development.
The facility runs 24h/5 day week utilising lean manufacturing techniques.
Pat O'Donoghue, R and D prototype technician has been largely involved with the Citizen machine, developing processes that include turning, milling, polar milling, drilling, slotting, balanced turning and threading.
He said that the balanced turning cycles were important to achieve the requirements for the titanium pin, which uses the M16's 3-axis gang tool slide and 2-axis turret to simultaneously rough and finish the outside diameter while supporting the material in the sub-spindle of the machine.
Some components are also machined from stainless steel and copper.
O'Donoghue said: "Here the patented CoolBlaster 2,000 lb/in2 high pressure coolant system was invaluable.
It enables us to run faster, without swarf problems, and it clears any chips from the subspindle and around the gantry unload.
We have also found it increases tool life and particularly for the roughing tool on the titanium pin.
This tool is also able to perform a deeper cut - thus helping to ensure the surface finish is maintained with the finish insert".
The Citizen M16 III has a capacity of 80 tools of which 20 can be driven by 0.75kW motors.
It has the capability to machine with three tools simultaneously from the 10-station turret, the nine-station gangtool slide and a separate triple tool fixed unit.
The main and subspindles have 10,000 rev/min motors powered by 2.2kW and 0.75kW respectively.
Within the medical device industry, a capable and repeatable machining process is essential to establish and maintain process control, said NC Engineering to manufacturingtalk.com.
Stryker is also open to inspection by the American Food and Drug Administration which inspects the process from validation to production through inspection control and documentation, so it is essential that the company has a very stable production process that is well proven.
Such has been the acceptance of the Citizen M16 III at Stryker Instruments (Ireland) that O'Donoghue will also program prototype parts at the machine while production is running.
"This saves valuable time," he said.
"Also, due to the ability of the machine to carry so many tools, we leave core tooling on the machine and tend to work to rationalised bar sizes.
For some parts, we even remove the complete tool block with tools and replace it with a preset block to maximise the use of the machine because it is such a key part of our operation now".
* About Stryker - established in the 1940s by Dr Homer Stryker, an orthopaedic surgeon who was determined to develop new tooling in order to improve operating techniques and patient recovery, the company began life in the basement of a hospital in Michigan, USA.
There, Dr Stryker set the 'ground rules' that are still maintained to this day in a business that has sales of US$5.4 billion and employs some 16,000 people around the world.
Stryker Instruments (Ireland) was set up on the greenfield site at Carrigtwohill in 1998 to produce surgical saw blades, burs and drills for the medical sector.
Since then it has grown at an impressive year-on-year rate of 20% with its employee number expanding from 25 to 180.
A research, development and test capability was added in 2001, and the business has invested heavily in CNC machining technologies. Request a free brochure from Citizen Machinery UK ...
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