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Whilst the bulk of Croom Precision Medical’s work is 3-axis and to a lesser degree, 5-axis, the company does make effective use of a Citizen Cincom M32 9-axis Swiss type turning centre when there is a requirement to machine small parts accurately in short cycle times.
As most of the parts manufactured by Croom are implanted into the human body, it is critical that they are dimensionally accurate with excellent surface finishes. With many implants being exported US where they are strictly regulated by the Food and Drug Administration, Croom’s managing director Patrick Byrnes says everything has to be absolutely perfect. “From the design through to the finished part there’s simply no room for error,” he advises.
To help achieve the required standard, Croom uses Alphacam software as its primary CAD/CAM system. Their main product ranges are knee replacements, hip systems and shoulder prosthesis, and Alphacam is instrumental in the production of them all.
The majority of parts are manufactured from cobalt chrome and medical grade titanium, through 3D milling on Fanuc Robodrills, a range of Bridgeports and Hitachi Seiki machining centres along with Citizen and Star lathes. Mr Byrnes says the ability to quickly produce CNC code that can be post-processed simply and rapidly to any machine on the shopfloor is critical to the entire manufacturing process.
A patella base plate as part of a knee system is a typical example of how Alphacam has saved significant amounts of programming time. The part involves milling, drilling and tapping, and with its various sized slots is relatively complex. “The first finished product came off the mill about 12 hours after starting the project,” Mr Byrnes explains. “Without Alphacam the process would take much longer and it’s this speed which gives us a definite edge over our competitors that don’t use the software. Also, its ease of use is a crucial factor – it’s very intuitive.”
As Alphacam is used extensively in the Republic of Ireland where Croom is located (the company is named after the village it is based in) it is taught in a number of colleges and at the Irish Training Agency, FÁS. “It’s important to us that our apprentices have a good working knowledge of Alphacam because we don’t have time to train them from scratch. We expect it as the norm now that a first year apprentice will have a basic grounding in Alphacam up to 3-axis.”
More than 50 highly skilled employees work in a 20,000ft² purpose-built facility on a two acre site offering plenty of scope for expansion. And ironically, it is the current financial difficulties facing the Republic of Ireland that is driving Croom’s changing approach to the marketplace. With Alphacam providing the ability to manage increasingly more complex geometries efficiently, switching from 2D to mainly 3D work means the company can focus on high value business in a niche market, instead of trying to compete with overseas competition. “Alphacam really comes into its own by ensuring we can produce high precision, complex parts quickly and competitively,” Mr Byrnes affirms.
And with geometries getting evermore complex, the day may well be not too far into the future when 5-axis and even 9-axis machining becomes the norm. But Croom is well prepared – its Bridgeport mills provide full 5-axis machining capability and the 9-axis Citizen achieves simultaneous machining and parallel machining using two spindles and three tool posts – gang, turret and back – with significantly reduced cycle times.
Mr Byrnes says that while Alphacam is the bread and butter of the 3-axis and 5-axis machines, it also works perfectly on the 9-axis variant. “Without Alphacam, the Citizen would take much longer to program,” he concludes.