As digital dentistry continues to evolve, laboratories face increasingly complex decisions when integrating new technologies. Milling machines, in particular, represent a significant investment—one that can either streamline workflows and expand capabilities or introduce costly inefficiencies if not chosen with careful consideration.
Chris Brown, BSEE, the manager of Aclivi Consulting in Ann Arbor, Michigan, explains how to go about choosing the right mill for each lab by focusing on their immediate needs, the mill’s material compatibility, workflow efficiencies, and reliable product support to ensure the greatest long-term value from the machine.
Q: What are the most common mistakes labs make when purchasing their first mill?
The natural inclination is to focus on price. Obviously, it is a very important consideration, but it shouldn't be the primary factor. A lower-priced mill that struggles with material compatibility, integration, reliability, or support can end up costing significantly more in the long run.
Another key consideration is usage. Labs should clearly define what materials they intend to mill and choose a machine that delivers consistent, high-quality results for those specific applications. While it might be enticing to invest in a mill that handles every material, it’s important to consider if that mill really does do a great job for every material or not. Some machines may be better suited to only zirconia work, for example. And, perhaps, a mill dedicated to specific materials may be a better choice in the long run, offering superior performance for that material. On the other hand, if you’re considering a high-quality mill capable of processing zirconia, glass ceramic, titanium, and chrome-cobalt, think carefully about how your lab intends to prioritize production. Otherwise, it may lead to challenging production decisions about when to switch materials. Do you tie up your high-quality mill for 45 minutes milling a five-unit PMMA temporary, or use it for three customized abutments in the same time period? Which job should be prioritized?
When purchasing that first (or even next) mill, ultimately, you should strongly consider what products and material you need to start milling to pay for that investment. Master the equipment and processes involved. Once mastered, then move onto additional products and materials if time and capacity are available to expand what you can do with that mill. Or, buy another mill to focus on those additional products and materials, leaving the original mill focused on the first products.
Q: What should a lab consider when investing in a new milling machine?
Start by evaluating material capability and your product mix. The new milling machine should be able to handle the output you need now, not just the products you hope to deliver a year from now. Once those needs are defined, you can start comparing factors like milling speed, tool life, reliability, and system support.
Speed is always an attractive metric, but it must be weighed against quality. If one machine mills a crown in half the time of another, will the lab owner still be happy with the detail and margin quality of the faster mill? Tooling is an ongoing cost; find out how often tooling needs to be replaced and at what cost. Some tools have coatings that significantly extend their life cycle, but they come at a significant cost. It may make sense to use coated tools for the roughing steps in the milling process and use uncoated tools for finishing.
I would recommend focusing on mills that consistently deliver high-quality, reliable outputs—and come with vendor support that can be counted on when needed.
Q: How can labs optimize their CAD/CAM workflow to get the most out of their milling machine investment?
Optimizing workflow means eliminating unnecessary steps and reducing errors that lead to remakes. This process is highly lab specific and requires a holistic review of the entire production process. Labs need to identify where there are bottlenecks that slow things down and areas where quality or reliability issues arise. Then, refine those steps to improve consistency and efficiency. The operators of the equipment—whether working with scanners, CAD, CAM, or mills—will often have great insight into where problems tend to occur and why. But it’s also essential to have someone who can look at all the puzzle pieces from the operator’s point of view and find the best way to fit them all together in a way that works best for your lab.
Q: How can a lab calculate the return on investment of bringing milling fully in-house vs continuing to outsource?
Labs often overlook the added costs of in-house milling. Beyond the initial equipment and supporting CAM software costs, there are ongoing expenses—such as maintenance and electricity, as well as labor for setup, operation, and finishing. While the per-unit material cost will go down out of the mill, the laboratory will spend more per unit in labor to support the in-house process. Thus, there may or may not be an actual cost advantage to keeping milling in-house, especially if you have internal remakes. But, the intangible benefit here is control. Owning a mill gives labs far more control over when projects are sent to the mill and when they will be ready for delivery.
The real value often lies in the intangibles—expanded product offerings, faster delivery times, and improved customer satisfaction. Those factors don't fit into a simple calculator. Once a lab purchases and masters the use of a mill, they can always find ways to improve their products and services. This, in turn, generates more business and revenue, and that can go beyond what a return-on-investment calculation can measure.
Q: Are there any exciting new developments in milling machines or features that labs should be watching for?
Some new milling machines are designed to refine 3D-printed bars and bridges, which I find interesting. However, these mills target a very niche market and there are regulatory implications that still need to be sorted out. Overall, I'm a fan of affordable, reliable, and quality output. My advice is to scale up with additional machines to address demand as required.
Speed sintering of zirconia is a bigger game-changer right now. Sintering is the primary bottleneck in zirconia crown production. If labs can speed that step up, then they can increase productivity and improve turnaround time, expanding their capacity.
