Heat Treat Today’s Medical and Heat Treating December 2019 issue featured an article on medical alloys. Heat Treat Today asked Roger Jones, CEO Emeritus of Solar Atmospheres, Inc., to comment on how specialty medical metals are heat treated. These include titanium, niobium, tantalum, nitinol, and copper, to name a few, which in turn are used to create such standard medical devices and equipment as diagnostic guide wires, miniscule screws for implants, complex surgical tools that are operated robotically, and more. Read to see how Roger describes the hot zone and conditions under which medical device alloys are heat treated.
To read the full article to which Roger Jones’ comments pertain, go to Medical Alloys Their Uses and Heat Treatments
Vacuum furnace chambers processing titanium, niobium, chrome cobalt, and other medical device alloys are typically constructed from stainless steel. The hot zones are comprised entirely of metal (moly); graphite materials are never used in the construction of the hot zone or in fixturing parts. These furnaces process medical device alloys exclusively to avoid cross-contamination of the hot zone or the medical parts being treated.
Ultimate vacuum levels should be 1 X 10-6 Torr or better, with leak rates no greater than 2 microns Hg per hour. Gas system isolation valves aid in achieving tight vacuum, as they eliminate constant pumping on the quench system. Vacuum furnace leak up procedures are performed weekly, as well as a bake out at 2400 °F for one hour.
Because of the alloys processed, cooling gases are mainly high purity argon from a liquid source. Very seldom is nitrogen used for cooling. Either type K or type N Inconel clad work thermocouples are imbedded in the loads for precise temperature readouts at +/- 10 °F or better. Processes include vacuum annealing, aging, stress relieving, solution treating, hardening, tempering, and other special processing. All furnaces are approved to the MedAccred quality standard, are surveyed to AMS 2750E, and comply with AS9100D in their processing parameters. Because the alloys are thermally treated, the vacuum furnaces operate in an air conditioned clean room with controlled temperatures and humidity levels.
To read the full article to which Roger Jones’ comments pertain, go to Medical Alloys Their Uses and Heat Treatments
