My company produces biologic medical devices derived from porcine intestine. One of our product lines is cylindrical or tubular devices made by covering mandrels with the material, drying, and then removing. We continue to experience difficulty removing the tubes from the mandrels. The mandrels are hardened SS that have been electropolished. The electopolishing provides a smooth surface, but not necessarily a "slick" one. Diameters 1.5mm to 7mm. Since the devices are permanently implanted in the human body, any process materials such as lubricants must be biocompatible. So far, we have tried PTFE spray lubricant and Dow Chemical 360 medical silicone lubricant. We have also tried bead blasting the mandrels to provide an overall reduced surface area in contact with our material. What experience or suggestions do you have? Thanks in advance for any information you can provide.
Have you looked at specialized coatings? There are thousands of options out there for all kinds of applications and lots of companies that specialize in certain types, applications, or **********. In my career I have solved numeorus operational problems related to friction, wear, corrosion, and other problems with specialized coatings or plating on either or aluminum.
Thanks for the reply. I left off one important step in the process: prior to removing the tube from the mandrel, we cut the tube to section lengths. So, using coatings is an issue because they will be damaged by the cutting process. We have used PTFE coated mandrels and the tube can be removed in one piece, but then a post-operation is required to cut the tube, without support, into sections. This process presents its own problems. It is still a potential option, but we would prefer to cut the tubes while still on the mandrel.
Having said that, suggestions for cutting tough, thin-walled tube (like a drinking straw) are welcome. Thanks.
Could blowing a puff of air in the mandrel at some point help lift the dried tube off of the mandrel? Are the cut pieces always in the same spot or same length? Maybe slight grooves in the mandrel at the cut line and the tube might bridge the gap and then also provide a place for a razor or cut wheel etc. to run without marking the mandrel?
How about cam method? I don't know..just a suggestion..
The above ideas are very creative and helpful in making us aware about the engineering products. Thanks.
This is very nice post about teh removal of materials from mandrels. Here we can also use the concept off Austempering. This is a great post and very useful ideas. ,
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