Five-axis Machining Gives Shop a Cutting Edge in Medical Work

Matt Dahms isn’t a doctor, but he attends several orthopedic shows every year, often conducts consultations with surgeons and is sometimes asked to be on-hand during orthopedic surgeries. Dahms is an engineer, machinist and the president of Oak View Tool Company LLC that designs, prototypes and manufactures special surgical cutting devices and orthopedic carbide tools. Keeping in close contact with its medical device OEM customers and surgeons is what allows the shop to set itself apart from the competition by continuously creating new and improved tools and devices that work more efficiently and are easier on the orthopedic surgeons that use them and, most critical, on the patients they treat.

Oak View Tool, located in Columbia City, Indiana, concentrates heavily on surgical rasps, reamers and broaches, tools all used to cut or remove human bone as part of the preparation for installing orthopedic implants. The shop will develop a new tool or enhance an existing design, then produce a couple hundred for testing. However, more customers are having Oak View Tool also run production, which means the shop is now averaging about 110 to 120 jobs per month that can entail one to 5,000 pieces per order.

With approximately 15 CNC machine tools and 25 employees, the ISO 9000 and 13485:2003-certified shop does all the machining, in-house, necessary to produce its surgical tools. Processes include 5-axis milling, turning, drilling, 5-axis grinding and inspection. And while no machining work is outsourced these days, that wasn’t always the case at Oak View Tool.

In 1996, Oak View Tool started as a re-grind shop specializing in carbide cutting tools and eventually took on the challenging task of also grinding stainless steel. These two materials are now the only two the shop currently works with. Eventually, many medical OEM customers requested that the shop also do the machining work, which Oak View Tool would then outsource to local shops, keeping only the grinding work in house.

As business rapidly increased, Dahms considered bringing all outsourced machining work back in house. Not only would doing so improve the shop’s profitability, but most importantly, also help maintain and further improve upon the high quality and integrity of the surgical tools and devices the shop produces. In 2010, the decision was definite when Dahms saw the capabilities of the 5-axis INTEGREX 200-IV S Multi-Tasking Machine from Mazak Corp.

He instantly realized that this one machine would accommodate all the returning outsourced work, effectively perform the shop’s hard machining operations – all stainless steel and carbide parts are cut in a 40-45 Rc hardened state – and allow the shop to generate tool and device designs that otherwise couldn’t be done cost-effectively.

“We considered a Swiss-style lathe, but that type of machine would have limited us in terms of part processing,” said Dahms. “We knew the complex geometries of our surgical tools and devices required a machine with 5-axis capability, specifically the B-axis milling spindle movement the Mazak INTEGREX 200-IV S provides.”

Additionally, he said the Mazak machine provides the speed, torque, rigidity, accuracy and significant machine mass for hard machining that is often lacking in basic level machines on the market. The INTEGREX 200-IV S easily maintains the shop’s required tolerances of +/- 0.0005” and accommodates its part sizes that can range from 1” to 24” long and from 0.187” to 4’ in diameter.

Oak View Tools’ multi-tasking INTEGREX 200-IV S is a twin turning spindle machine with a milling spindle and 20-tool capacity automatic tool changer. The milling spindle delivers 12,000-rpm cutting speed, 25 hp and 88 ft-lbs of torque for the shop’s hard machining operations. The spindle provides 225 degrees of B axis travel, indexing at 0.0001-degree increments.

According to Dahms, the twin turning spindles on the INTEGREX 200-IV S, unlike other machines, both generate the same speed and precision. They both provide 5,000 rpm spindle speeds and index at increments of 0.001 degrees for high-precision C-axis part positioning and synchronized part transfers. The shop has the turning spindles configured for both 6” and 8” chucks.

“Actually, my experience with Mazak machines started way back when I was working in the automotive industry. While doing so, I used to hard mill on Mazaks all the time, and even back then Mazak’s mills and lathes had the rigidity and torque to handle the tough task,” explained Dahms. “We were doing hard machining way before it was as common as it is today.”

Dahms added that for many machine tools on the market today, hard machining simply over powers them. They are unable to generate the speed, torque and accuracy needed to run the tooling used in hard machining. For these machines, the operation creates pressure that taxes tooling and machine spindles, but Dahms said, “those issues with hard machining are non-existent with the Mazak machine, and its control runs great with our CAM software for quick and easy programming and for generating superior surface finishes.”

Oak View Tools’ INTEGREX 200-IV S not only hard machines all the shop’s surgical tools and devices, it does so in significantly less operations while also eliminating the need for multiple machines and set ups. Work pieces that would require as many as four Ops on a lathe and 4 Ops on a milling machine are completely machined on the multi-tasking Mazak in two Ops. And for a specific hip broach currently done on other machines, the shop plans to move it to the INTEGREX 200-IV S, which will reduce the broach machining from 10 Ops down to only one Op.

The INTEGREX 200-IV S at Oak View Tool is situated in a cell along with a 5-axis grinder. Having the two machines in close proximity allows one machinist to operate both machines. All tools and devices the shop produces are ground, so once the Mazak machine completes machining operations, parts are quickly transferred to the grinder for finishing.

In part processing, Oak View Tool machinists often use the twin turning spindles on the INTEGREX 200-IV S for work support when machining the shop’s longer tools and devices, some of which are up to 24” long. The equal speed and synchronized C-axis motion of both spindles allow the machinists to chuck one end of the part in one spindle and the opposite part end in the second spindle as the machine’s milling spindle works on the part. Or the twin spindles are used for sequential operations – first Op/front side work in one spindle, then a coordinated part transfer to the second spindle for the second Op/back side work.

Dahms’ observations of orthopedic surgical tools and devices in action and his many consultations with surgeons and OEMs has led to several improvements and enhancements of how existing tools and devices are used and how they perform. For instance, an engineering goal at Oak View Tool is to lessen the need for surgeons to have to use a hammer on surgical tools or devices.

To remove bone material in preparation for implants, many existing surgical tools and devices require surgeons to use hammers, which provide the force necessary for these tools and devices to work properly. Such tools and devices are typically designed to accept strike plates strictly for this purpose. However, having to use hammers on tools and devices is hard on surgeons and equally hard on patients.

“We are now helping develop surgical tools and devices that make a difference because they lessen the need for having to use a hammer on them. Many designs of today’s existing surgical tools are such that they could be improved in regards to ergonomics ,” said Dahms. “Their geometries are often insufficient and could be better. With our extensive surgical tool background and the machining capabilities of our Mazak machine, we are able to improve the geometries of these tools and, along with that, their performance. For instance, we recently improved an existing tool that previously removed bone material in only one direction. By simply optimizing its teeth geometries, we were able to produce the same tool that now removes bone material in both forward and back directions – more efficient and less stress on both surgeon and patient.”

Dahms went on to say that the machining capabilities of the INTEGREX 200-IV S allow the shop to quickly produce prototypes of new and improved surgical tool and device designs that couldn’t otherwise be made in the past. With every new job, he said the shop first considers how the part will be processed with the Mazak machine’s capabilities in mind, then it is determined if the component can be ground. And according to Dahms, there is basically nothing the shop can’t make thanks to the Mazak’s 5-axis machining.

In addition to completely eliminating the need for outsourcing machining virtually overnight and allowing it to produce new and improved surgical tools and devices, the INTEGREX 200-IV S, according to Dahms, gives the shop a high-level of credibility with its customers. He added that many of his customers are not yet utilizing the kind of machining capability the Mazak machine provides.

As a result, production run jobs have increased at Oak View Tool, so has business. The shop grew 21% in 2011, and Dahms expects growth to climb to 30% in 2012. But, he said that the shop will always be one that focuses, first and foremost, on R&D and prototyping for the medical industry.

“Our R&D, prototyping and production capabilities give us a significant competitive advantage,” said Dahms. “We will continue to stay on the cutting edge by incorporating the latest innovative machine tool technology such as that from Mazak. For the very near future, we are moving into ultra high-speed machining and already have another Mazak machine in mind for that.”


About Mazak Corporation

Mazak Corporation is a leader in the design and manufacture of productive machine tool solutions. Committed to being a partner to customers with innovative technology, its world-class facility in Florence, Kentucky, produces over 100 models of turning centers, Multi-Tasking machines and vertical machining centers, including 5- axis models. Continuously investing in manufacturing technology allows the Kentucky Mazak iSMART Factory™ to be the most advanced and efficient in the industry, providing high-quality and reliable products through its “Production-On-Demand” practice. Mazak maintains eight Technology Centers across North America to provide local hands-on applications, service and sales support to customers. For more information on Mazak's products and solutions, visit www.mazakusa.com or follow us on Twitter and Facebook.