Tiny tools make a big difference for medical manufacturing

Micro endmills are making all the difference in the medical manufacturing industry, but not just for subtractive manufacturing. Jeff Boyd of Sutton Tools sheds some light on his company’s work in this area.

One of the greatest advantages of my role with Sutton Tools has been to gain a perspective of the global manufacturing industry. Over the years, I’ve been able to observe technological trends and advancements across the industrial sector, and in different market segments.

One of these changes has been the way additive manufacturing is replacing subtractive manufacturing in some areas, beginning with the aerospace and medical sectors. Subtractive manufacturing is the process of machining the purchased raw material to precisely required dimensions by removing the excess material. Across the medical industry, where unique low-volume components need to be produced from expensive and difficult-to-machine materials such as Titanium, additive manufacturing is proving to be more effective in both cost and effort.

One of the tools particularly important and useful for the medical-mould and die industry undertaking additive manufacturing is the micro endmill. This tiny cutting tool precisely cuts away material for medical device moulds in the orthodontic, orthopaedic and respiratory fields.

At Sutton Tools, we’ve used these tools to help our customers build a range of medical aids. Though smaller than most of our tools, they come in a range of sizes and diameters to suit any number of mould and die projects.

Available in three profiles – Square End, Corner Rad and Ball Nose – from 0.2mm to 3mm, as well as multiple neck lengths per diameter for materials needing a deeper cut, the Sutton Tools micro endmill can machine hardened materials up to 62HRC with exceptional tool life and surface quality.

What often occurs in depth machining is that rate of vibration increases the deeper the tool cuts because the sound waves become greater. This can cause serious damage to your micro endmill, reducing tool life and ruining the surface finish of the material. These problems are usually corrected by changing the cutting conditions to match the material group, as well as improving machining conditions through tool holding, work clamping or machine spindles.

Our micro endmills have been designed with the consequences of tool vibration in mind, so we’ve made a few changes to a traditional micro endmill to provide a solution. Rather than the traditional rake angle, which can cause the tool to scrape through the material – causing more vibrations and poor surface quality – the positive rake angle of the Sutton Tools micro endmill – available from 10-12 degrees – allows the tool to slice through the material. This makes penetrating the work piece easier, and reduces power needed, also cutting operational costs.

When compared to a competitor’s product, we found that stress concentration in our micro endmill was reduced by more than 20%, leading to reduced tool wear and a finer finished product.

The unique micro geometry of our micro endmills also helps to minimise vibrations and create a smoother surface finish. Each micro endmill has what we call a wiper edge due to a hairline margin that yields 60-70% better smoothness than tools without the wiper edge. Within the medical industry, where moulds require extreme precision for a product to work properly, this aspect of the micro endmill is imperative.

All our micro endmills are coated in a TiSiN PVD coating to increase wear resistance, performance and efficiency in minimum to zero lubrication. As I mentioned above, for medical device manufacturers making high quantities of unique low-volume components, the coating extends the tool life to ensure more components can be cut at less of a cost in replacing tools and downtime.

Case Study – Side Milling Comparison – Sutton Tools v Competitors
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While tool replacement is an inevitable outcome, the medical industry can benefit significantly from using a trusted cutting tool that is durable and long-lasting, and able to perform under stressful conditions at the lowest cost.

In an industry where efficiency and quality are of the utmost importance, especially for medical components like dentures that require extremely precise moulds, we’re proud to be a part of it and look forward to new innovative means of mould cutting with micro endmills.

This transcript was previously published in Australian Manufacturing Technology Oct-Nov’18 Magazine.

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