END USER: ulrich medical, +49-731-9654-0, www.ulrichmedical.com.
CHALLENGE: Extend tool life when machining titanium vertebrae implants and supports.
SOLUTION: A shrink-fit collet and collet chuck system.
SOLUTION PROVIDER: Bilz Tool Co. Inc., (847) 734-9390, www.bilzusa.com.

Implants and supports in the vertebrae are helping more patients overcome a common disorder: back pain. In many cases, the prosthesis eliminates the need for surgically induced stiffening of the vertebrae in the affected area, allowing the the body to retain its flexibility.

Because they are corrosion-resistant and the human body tolerates them, titanium alloys are common materials for prosthetic components. In addition, titanium alloys withstand the high stresses exerted on the components, enabling them to continue to function faultlessly for extended periods.

After switching to the TER shrink-fit collet and collet chuck system from Bilz, ulrich medical increased tool life 300 percent.

After a surgery, an oxide layer develops on the surface of an implant, a "passivating effect." This prevents titanium from passing into the body.

One manufacturer of these vertebrae implants and supports is ulrich medical, Ulm, Germany, which also has a facility in Chesterfield, Mo. The company produces vertebral supports made of Ti6Al4V. Machining the difficult-to-cut workpiece material was limiting tool life to 500 pieces, after which the tools imparted an unacceptable surface finish.

Applied on an INDEX G 200 horizontal lathe, the cutting tools were held in a 10mm ER25 collet for roughing and a 6mm ER25 collet for finishing. Roughing was performed at a cutting speed of 50.24 m/min. (164.8 sfm) and a feed rate of 0.08 mm/min. (0.003 ipm). Cutting time when roughing consumed 75 seconds. Finishing took 20 seconds at a speed of 75.36 m/min. (247.2 sfm) and a feed of 0.05 mm/min. (0.002 ipm).

Seeking to extend tool life, the medical parts manufacturer turned to toolholder manufacturer Bilz Werkzeugfabrik GmbH & Co. KG, Ostifildern, Germany, the parent company of Lombard, Ill.-based Bilz Tool Co. Inc. Bilz recommended its TER1000/25 shrink-fit collet and collet chuck system for roughing and its TER0600/25 for finishing.

Although the cutting speed when roughing remained the same, the medical parts manufacturer increased the feed rate when roughing to 0.2 mm/min. (0.008 ipm) and the finishing speed and feed to 84.78 m/min. (278.1 sfm) and 0.06 mm/min. (0.002 ipm), respectively, after switching to the TER shrink-fit system. In addition, cutting time dropped to 30 seconds when roughing and 17 seconds when finishing—a 50.5 percent decrease—and tool life increased 300 percent, enabling one tool to produce 1,500 parts.

Based on a machine cost of just under $4/min., ulrich medical saves more than $4,750 on each 1,500-part run of the titanium vertebral supports.