Questions with Mike Huggett and Ross Kenyon

1. How has INDEX achieved machining bone screws on a CNC multi-spindle?

It’s been a challenge. The process takes advantage of nearly every technological advantage of our CNC multi-spindles, and the creativity and expertise of our application engineers.

Having two tool slides per spindle station is key, as it accommodates the tools needed and enables use of specially designed steady rests to maintain precision and surface finish. Because we’re machining titanium, we need extreme rigidity and the ability to cut at a lower rpm with high torque, consistently achieved on our latest generation of multi-spindles.

Additionally, to maximize the effectiveness of a multi-spindle, a part’s total cycle time must be as evenly divided across spindle stations as possible. We’ve implemented multiple strategies to achieve this, such as double synchronous spindles to spread the Torx machining across two stations.

2. Why did INDEX invest in R&D to make this option a reality?

With a population that’s living longer and maintaining a more active lifestyle later in life, there’s been dramatic growth in the demand for implants and their related components. Our customers have been asking us for the ability to machine bone screws on a multi-spindle for a long time, but now we’ve reached the point where technology has advanced enough to make it possible.

3. Will it be difficult for manufacturers to implement this process?

While the development of the process was extremely difficult, implementation will be easy for manufacturers. We’ll effectively deliver a turnkey solution that’s no more difficult to run than their existing process. We also provide the training and knowledge transfer needed to optimize it.

4. Are changeover times prohibitively long?

In general, changeover times on our multi-spindles have seen dramatic reductions through our modular toolholding system and patented W-serration interface. For many medical manufacturers, though, those advancements won’t come into play. The tooling capacity of our machines combined with using carefully selected tools ensures a wide variety of leads, threads, and features can be machined with no physical changes to the setup. A diverse range of bone screws can be machined with software-only changeovers taking less than a minute to perform.

5. Which manufacturers will receive the greatest benefit from using a CNC multi-spindle to produce bone screws?

First and foremost, shops facing labor or space constraints will see the most immediate impact. By cutting cycle times up to 80%, they can replace four or five Swiss-type machines with a single multi-spindle, providing a tremendous boost to output per operator and much more efficient use of floor space. We’ve seen many of our medical customers expand or relocate facilities to accommodate growth. These huge investments can be reduced or postponed by migrating part production to multi-spindles.

This new process also helps shops easily reach quality requirements. Maintaining Cpk across five machines is significantly more difficult than maintaining it across a single machine, especially when that single machine is a multi-spindle that, by the nature of its design, ensures incredibly stable, predictable, and precise output.

If a manufacturer is interested in estimating the degree of impact on their operations, they can contact us at sales@index-usa.com. Our engineering team will be happy to work with them to evaluate their current processes and create a realistic cost-benefit analysis.

INDEX Corp.
https://www.index-group.com