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An Ounce of Extrusion, A Pound of Cure

Aluminum extrusions help leading medical equipment manufacturer save money, time and lives.

Oncologists rely on sophisticated radiotherapy medical equipment that precisely delivers radiation to cancerous cells, while preserving the surrounding healthy cells. Similarly, leading radiation oncology equipment company, Accuray, relies on tightly orchestrated relationships with its component suppliers to help design, develop, and integrate components for its TomoTherapy® System. When a failing steel coupling threatened to derail the system's industry-leading reliability, the company looked to aluminum extrusions to provide an immediate solution.

The TomoTherapy System boasts one of the most reliable uptime rates in the industry at approximately 99 percent, and each component contributes to equipment accuracy and uptime performance. Coupled to a pneumatic actuator, 64 mechanical "leaves" shutter open and closed to deliver the system's prescribed dosage of radiation to diseased cells. But the couplings (machined from stock steel using electrical discharge machining) used to connect the leaves with the actuator, would break and prompt a system error causing the machine to safely shut down.

When Bradley Brunker, a senior sustaining engineer from Accuray's Madison, WI campus examined solutions for failing couplings, his criteria were both technical and economical. Industry-leading performance was mandatory, but he also wanted to reduce the full assembly part count, the part cost, and, ultimately, the assembly labor cost. And he needed to do it fast.

Brunker turned to AEC member Alexandria Industries in Minnesota to help design, engineer and manufacture a reliable component. Design engineers with medical market expertise from Alexandria worked closely with Brunker to create the part's die and ensure the extruded pieces were made to exact specifications using Finite Element Analysis (FEA) studies to prove part performance.

They identified slight variations from the original design that would improve the part's overall strength and durability and assure repeatability from the tooling.

 As Extruded  After Machining

Enhancing the mechanical properties to prevent breakage, the new aluminum couplings were extruded, machined and hard-coat anodized, increasing wear resistance and simplifying mating assembly for an intended snap-fit design.

Because the coupling was extruded, the design could be shaped to snap-fit to mating components. The leaf, coupling and another redesigned component easily snapped together and cut the assembly labor by 30 to 60 minutes for each completed assembly.

Using an aluminum-extruded part also cut component manufacturing costs by nearly 90 percent and took only a quarter of the time to produce. And because of the couplings' snap-fit geometry, Accuray also was able to eliminate a tool previously used for assembly.

As a final manufacturing step, an identification tag was laser etched on each component. This tag is recorded so Accuray and Alexandria Industries can track and monitor each component for quality assurance purposes.

Also read:
Medical device OEMs can cure their supply-chain ills with suppliers that do more than supply.

TomoTherapy photos courtesy of Accuray.