There are a wide variety of specifications for coin and medallion. ranging from small to large, with plum blossoms and different sizes. Available in pure gold sterling silver, gold plated and silver plated. The custom-made medallion molds are more complicated to make than the currency.
Prepare coin mold material
The steel material for making the stamp of the medallion is provided by the material department according to the requirements of the mould making workshop. The ordinary lathe is used to form a pointed top and a flat bottom surface, and the obtained blank is also called a pointed top. The tip surface should be as smooth and flat as possible.
The apex is polished on the cloth wheel. Generally, there will be traces of the turning tool on the top surface, which will affect the pattern and the bottom surface of the flip stamp and the clarity and flatness of the stamp. Therefore, it should be polished. When polishing, it is necessary to slowly rotate in a certain direction on the cloth throwing wheel until there are no defects such as turning marks and pits on the top surface.
Roll over the impression
The hydraulic equipment used in the turning equipment is generally open-turning. Firstly, the center is pointed out. After the surface of the tip is cleaned, the surface of the hydraulic press is placed on the surface of the hydraulic press. The tip is upward. The auxiliary tool can be used to clamp the tip and the original mold is placed on the top. . After the hydraulic press is pressurized, the Hough block is removed and the pressurization process is continued. Repeat the steps of pressing, depressurizing, and checking the pattern until the edges of the pattern are pressed out.
During the turning process, the impression will produce a processing hardness, which is not conducive to the pattern extrusion. Generally, annealing treatment is required, and the stamp is heated and then cooled to eliminate the processing hardness and then continue to be pressed.
Semi-finished product overhaul
A full inspection is required, and common defects are checked against the mold card and trimmed.
Quenching can be carried out using an atmosphere furnace, and the surface is protected with nitrogen; tempering is performed by an iron plate heating method.
Grinding is the last step in the production of stamps. It mainly processes the surface of the stamp to eliminate defects (small holes, junk marks or bumps) and curvatures on the mold surface in each process. The next article will detail the steps required before and after grinding.
After the grinding process, the stamp can be delivered to the coin production workshop after the inspection is passed.
Usually it will take 2-4 days to finish a custom coin mold.