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Inside Dental Technology
September 2023
Volume 14, Issue 9

Get the Most Out of Your Mill

Support, software, and more to maximize performance

Greg Everett

As much as 3D printing technology has advanced in recent years, milling is likely to remain a critical part of dental laboratory workflows for at least two more decades. Zirconia discs are affordable and getting even more so. The milling process is proven and well known, as the market is mature. The mill is still a better extension of the artist than a 3D printer is at this point, and the mechanical properties of milled restorations are superior because there is no layer adhesion boundary. Beyond all of that, even if a beautiful, durable, insurance-billable 3D printed restoration were available today, it typically takes 5 to 8 years for new technology to be fully adopted. As we have not even reached that point yet, milling will remain the dominant fabrication method for years to come.

What considerations are important when purchasing a mill?

By far, the most important consideration is after-purchase support. Your relationship with the dealer is paramount—you can go through an amazing sales process, and then never hear from the company again. Put the time in to find a dealer who does not have a "fire and forget" mentality. It's best to ask around; find a few colleagues who are milling the same materials you want to mill and ask what their experiences have been. When you get closer to a decision, require the dealer to provide at least three referrals of happy customers who have had the machines for 6 months or more and can speak to you. I also weigh the company's time in the industry heavily because if your manufacturer disappears 2 years after you buy the machine, you are not in a good position. Serviceability is important as well; when the machine breaks, how is that handled? Also, what is the cost of standard preventive maintenance? What does a spindle cost? Every machine will need multiple spindles in its lifetime, and they can range from $1,500 to $13,000.

What new developments are most exciting?

The general trajectory of the market has been exciting. Not long ago, these machines were much more expensive. The accessibility of the technology in recent years has made digital dentistry grow to where it is now. A desktop machine is inherently not industrial, but we are starting to see more industrial features added to desktop machines. Specifically, the mechanical designs are improving. We are seeing more rigidity, which any machinist in an aerospace shop would tell you is critical. We are seeing better construction—cast aluminum frames, some machines built up on granite, etc. We are also seeing some machines that use closed-loop servo control, which is an important differentiation. Closed-loop control means the machine has internal feedback regarding its position, which greatly improves its accuracy and repeatability. We are also seeing better spindles with more horsepower and higher RPMs, which allows for more efficient machining strategies.

How can milling performance be maximized?

Maintenance is the key; do not try to push the envelope with your mill unless it is in perfect condition. Next, you need to define what type of performance you want. For most laboratories, the keys are process time and/or quality. Usually, there is a tradeoff whereby faster production yields subpar quality, and higher quality requires a slower process. However, there are some scenarios in which you can achieve both, primarily through the use of open CAM software. I can run an amazing machine poorly or a poor machine amazingly, depending on the software. If you make an adjustment in an open CAM software that allows that, then you can balance your design and machining processes, your tooling, etc. If all of those variables are controlled and designed for each other, you actually can have both speed and precision. The right software and strategies can increase production by 10% to 25%, which can be like adding another mill.

Key Takeaway

Every mill on the market right now is good; some feature minor differences that may cater to certain laboratories' preferences, but the keys are support, maintenance, and software.

About the Author

Greg Everett is President of Denteon LLC, a milling machine support and service provider based in Murrieta, California.

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