1. Appearance inspection

 
The first mold parts of each working shift in the vulcanization process shall be inspected for appearance, while 100% of the parts in the finished product acceptance shall be inspected for appearance.
 
Visual inspection is generally used for appearance inspection.
 
When checking the smoothness of the working surface of the part, the smoothness specified on the mold drawing is generally the standard.
 
2. Dimensional inspection
 
First mold inspection is carried out in vulcanization process; random inspection is generally carried out for finished product acceptance, but for parts with strict size requirements or parts requiring mechanical processing and parts requiring stable treatment in the working medium, in principle, 100 of the main dimensions shall be inspected.
 
After vulcanization and removal of burrs, the parts shall be parked for 6 hours before dimensional inspection. The elastic deformation of rubber parts is large. If the measurement method or measuring tool is not selected properly, the accuracy of the measurement will be affected. General test mold identification and trial production should use general measuring tools and instruments, while batch production should use special measuring tools.
 
3. Performance test
 
a) For Sauer type A hardness test, the thickness of the sample shall not be less than 6mm, the width shall not be less than 15mm, and the length shall not be less than 40mm. If the thickness does not meet the requirements, the same sample can be overlapped for measurement, but it is not allowed to exceed four layers, and the upper and lower surfaces shall be parallel.
 
B) Oil swelling resistance test: immerse the sample in oil, acid, alkali or other liquid medium, and measure the change of size, volume or weight after a certain period of time at the specified temperature.
 
c) For the test of rubber-metal bonding strength, the cross-sectional method is generally used to pick up the rubber on the metal parts with the steel needle of "3". If there are uniform rubber bonding marks on the surface of the broken metal parts after being picked up by the rubber, the bonding strength is considered to be qualified. For the parts of each working class, 1-3 pieces shall be selected for bonding strength inspection during the first mold inspection and finished product acceptance.