It is recommended to heat the shaft above the softening temperature of the resin and push it in with a jig.
The shaft insert machine manufactured in-house by Sanko Gosei is designed with the following operating conditions as a guide
① Press-in load and shaft temperature
②Press-fit allowance (gap between shaft diameter and prepared hole diameter)
0.2 to 0.4 mm in diameter (aim for about 0.3 mm)
However, in the case of oil-impregnated metal, preheating is difficult, so the press-fit allowance should be reduced by an order of magnitude to about 0.02 mm
③Knurling
Common twill (Dianal)
It was difficult to meet the standards for coaxiality and perpendicularity when inserting the shaft metal fittings at a temperature that melts the resin, so there was a time when cold press-fitting was performed. However, it is difficult to achieve accuracy in cold work, and if the press-fitting allowance is increased, cracks will occur due to residual stress over time, causing a serious problem.
Therefore, the shaft must be heated above the softening temperature of the resin before being press-fitted.
*The metal insert (female thread side) for receiving M3 screws, etc. must be press-fit after melting the interface resin to a temperature above its melting point.
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