For the control of forging quality, there is a special set of marking method for searching during the production and use.The marking of raw materials should be noted from the beginning.The content of calibration includes material number, batch number of furnace, date of receipt and delivery, code number of supplier, etc.This helps to distinguish whether variation in materials is due to factors in the manufacturing process itself or to factors that are not.The marking of raw materials also provides a reliable basis for evaluating the quality of products from the supplier.
The marking of important forgings, including part number, batch number, forging date and manufacturer's mark, should be recorded in the production one by one, so that in case of problems in the process of use, it can be used to help find the cause and identify the responsible person.Mark the part printed on the forging where the forging is easily found.If the mark on the forging is cut off during machining, a metal label should be put on the forging when it is assembled or re-marked by other methods such as printing die in the workshop production process to avoid confusion.
The amount of metal set aside on a forging for cutting.The aim of forgings cutting is to meet the requirement of dimension precision and surface roughness.In the forging process due to underpressure, die wear, wrong movement of upper and lower die, forging oxidation and decarburization, cooling shrinkage and other reasons, forging size is difficult to be accurate, shape may be warped crooked, surface roughness can not meet the requirements and other defects.
Therefore, when producing forgings, an extra layer of metal should be left on the surface of the forging blank, which should be cut off later when machining to ensure the processing quality of forgings.For some important bearing parts that require a sampling test of 100%, or for the purpose of inspection and machining positioning, an excess metal shall be left. This excess metal is called a margin.