I recently had the opportunity to spend a day with a couple of engineers that design and manufacture mills, for both industrial applications and the dental industry. We got on the topic of the environment in the average dental lab and how it relates to continued accuracy of dental mills. Interestingly, a room temperature change of just 10-15 degrees can result in a change in the consistent accuracy of mills. The reason for this is related to the thermal expansion of all the components in the mill. As the mill becomes warmer the components in the mill expand resulting in a dimensional change in the parts we mill. With a 10 degree increase in room and mill temperature, we could have a 40 micron change in our milled parts. An 18 degree change can create errors of over 100 microns.
Here are a couple of general practices: If you come into a cool environment in the morning it would be recommended to put the mill through a warm-up cycle before milling any cases. In addition, only calibrate your mill once it has warmed up. Calibrating a cold mill will almost insure some degree of inaccurate production. For the best continuous reproducible results, do whatever is necessary to maintain a fairly constant mill room temperature as close to 70 degrees as possible. Adding heat and or cooling as needed in your mill space to maintain a constant temperature should be seriously considered.
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Thanks for reading,
Bob Cohen, CDTBack to All Posts