Diamond turning machines are fairly complex pieces of machinery. Each one has been designed by engineers to produce repeatable results. Repeatability, is exactly what it sounds like. It describes a diamond turning machine’s (or DTM) ability to repeat the same exact cut more than once. This is not limited to simply ‘looking’ like the same cut. When looking for repeatable results DTM users are looking for the same exact cuts with the same exact errors down to the nanometer. To accomplish this, engineers must have a solid understanding of what influences temperature variation can have on a turned part.
Temperature variations are the single greatest source of error in diamond turning industry. In fact, thermal error can be found all over the precision manufacturing and engineering industry. Temperature sneaks its way in from various heat sources, many of which are outside of the DTM. This includes sunlight, room lighting, humans (yes, humans standing next to a DTM can have an effect on the outcome), and HVAC.
Here is the catch about temperature variation… It’s complex… Even though changes in temperature are deterministic and measurable, correcting each change throughout an enclosure can be challenging.
During a cut, thermal variation errors may be taken into account by certain diamond turning manufacturers, but generally if temperature has varied at all, the damage is already done… Thanks temperature change…
Let’s not be mistaken, thermal variation is not inevitable in precision engineering. There are things that can be done to control it accurately.
Want the solution? Come back for Part II next week!
Please visit the library at http://www.praecis.com/research-papers/ to learn more about how thermal effects can cause errors in diamond turning part cuts.