November 2007 Edition

MEDICAL MANUFACTURING

Internal Job Shops Get a Leg – or Maybe a Hip – Up

Using milling machines with the right operating system allows a medical manufacturer to avoid bottlenecks and expenses

If I knew I was going to live this long I'd have taken better care of myself, is a mantra of the Baby Boom generation. As that generation reaches its 60th anniversary, its members are facing the need for replacement joints that have either been damaged by age or abuse. Even Olympic athletes are making commercials for knee and hip replacements.

As the Boomers age, demand for joint replacements is rising. Meeting that need is DePuy Orthopaedics, Warsaw, IN. The company has been in the orthopedic device industry for more than a century, producing such products as the Preservation Uni-Compartmental Knee implant and the S-ROM hip.

Although DePuy is part of Johnson & Johnson, the model shop and tool room operate as job shops, where Lean production is a way of life. The tool room focuses on fixtures while the model shop concentrates on conventional prototyping.

Jon Heckman, DePuy tool room supervisor, has been with the company for 31 years. He leads a team of 12 machinists.

"We're a cost-efficiency center," Heckman said. "People don't want to put money into fixtures. It's imperative that we be effective from the top down."

Only the Right Touch

Although making fixtures isn't a glamorous part of the orthopedic device industry, it's critical to the company. Unlike machined parts that are components of other machines, DePuy's products go into human bodies, so it's imperative the implant isn't touched improperly as it is moved from one point to another during the manufacturing process.

User's don't need to be wizards in math or geometry to quickly produce a part.

"The fixturing has to replicate the product, which means the tolerances are tight and prints don't exist," Heckman said.

His concern for producing a quality product isn't just theoretical. There's a practical example in the company. A co-worker had joint-replacement surgery in her hand.

"She was like a different person," Heckman said. "She was excited to show me how she could bend and move her finger."

It's that kind of result that inspires both of the "shops" within DePuy.

The model shop and tool room both have Hurco VMX series vertical machining centers, and use them differently based on the requirements of each job and the skills of the operator.

According to Heckman, the machines offer the flexibility, usability, and efficiency to run a lean operation. The machines' offer capabilities that assist the talents of the users. User's don't need to be wizards in math or geometry to quickly produce a part, according to Heckman.

Bill Sellers' group uses NC programming and the Hurco control's DXF transfer software feature. He leads eight people in the Prototyping Services department.

"We just send the DXF file straight to the machine," Sellers said.

"We have one shift and about 800 projects run through this shop each year," he said.

Manufacturing Considerations

The prototyping group receives a plastic form and a CAD file from the Rapid Prototyping department and must determine how to manufacture the part.

"We focus on conventional prototyping," Sellers said. "Our goal is manufacturability of the part."

The prototyping group machines 17-4, 300 series stainless, titanium, and cobalt in its model shop. The shop needs equipment that is adaptable and offers easy revision. Parts from the shop are taken to the cadaver lab for first-round tests.

In the tool room, Heckman said the Hurco Conversational Programming on his machines, a VMX24 and VMX30, held down costs at least two ways: they eliminated the bottleneck of going back and forth with CAD/CAM programmers and the investment in CAD/CAM seats.

The simplicity of the conversational programming makes it productive, according to Heckman.

His group uses the lines and arcs part of the control's programming software. The AutoCalculation feature eliminates time-consuming data entry and the bother of trigging out the part. Hurco

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