Friction Heating.....Thermal Seizure Question
Friction Heating.....Thermal Seizure Question
(OP)
I have a question concerning the potential for frictional heat generation to cause the seizure of a shaft within a bore?
My issue involves a punch becoming stuck within a bore during a compression punching operation. I believe the issue is a lubrication issue where the frictional coefficient becomes high thus creating a frictional force in excess of the applied load causing mechanical seizure, or, perhaps the frictional heat generates enough thermal expansion in the punch, eliminating the clearance.
I have been trying to relate the thermal expansion of the punch with the "flash" temperature created during the frictional sliding (proposed by Blok, etc). I am having a hard time gaining confidence in my results. Ultimately I am looking for some general guidance in regards to this issue and whether it is commonly experienced. In addition, I would like to determine a "minimum" frictional coefficient needed to cause the seizure of the punch. Thanks for the help.
My issue involves a punch becoming stuck within a bore during a compression punching operation. I believe the issue is a lubrication issue where the frictional coefficient becomes high thus creating a frictional force in excess of the applied load causing mechanical seizure, or, perhaps the frictional heat generates enough thermal expansion in the punch, eliminating the clearance.
I have been trying to relate the thermal expansion of the punch with the "flash" temperature created during the frictional sliding (proposed by Blok, etc). I am having a hard time gaining confidence in my results. Ultimately I am looking for some general guidance in regards to this issue and whether it is commonly experienced. In addition, I would like to determine a "minimum" frictional coefficient needed to cause the seizure of the punch. Thanks for the help.





RE: Friction Heating.....Thermal Seizure Question
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RE: Friction Heating.....Thermal Seizure Question
I guess my question boils down to whether this frictional heat generation has the potential to alter the frictional coefficient enough in the localized contact area to prevent the motion of the punch.
FYI...the operation in question is a rotary pharma tablet punch. The punch diameters appear to have some "burnished" areas indicating a temperature change. In addition there are some apparant wear issues, although their origin can't be confirmed due to the removal process. Thanks again.
RE: Friction Heating.....Thermal Seizure Question
RE: Friction Heating.....Thermal Seizure Question
You can have this read further to different types of seizure. A visual inspection of the damaged surface could give you valid inputs of sources/causes which may have led to seizure.
http://www.groupk.com/tec-seizures.htm
RE: Friction Heating.....Thermal Seizure Question