How to use manual metal mold to produce casting grinding balls

The manual metal mold is widely used in foundries to produce casting chromium grinding media ball, including low, medium and high chrome contents. Balls size from dia30mm to 150mm. This kind of metal mould is easy to operate and investment costs are low. Metal mould adopts the chilling process to get refined microstructure.

But how to use them so that can lengthen the lifetime of the metal mold? 

Here is the detailed using instruction.

  • Heating: The metal mould should be heated before using .when its temperature ups around 200-300degrees, then can start to pour. Or the metal mould will be easily hurt. 
  • Sand Molding: After heating, the top and bottom metal mould should be filled with common sand.  A hole is needed in the middle of the top mould  so that the molten iron can be filled inside.  
  • Mould Ball Core Painting: After the sand molding,  the ball core of the metal mould should be protected with acetylene through spay smoke or using high-temperature painting. In this way, can lengthen the mould’s life and enhance balls quality. 
  • Casting: The top mould and the bottom mould should be closed after protecting. Then with the help of pouring ladle, pouring the molten iron into the mould
  • Open mould:  After several minutes , we should open the mould with the help of two round bars to respectively insert the holes on the surface of mould, and then get the balls out. Then re-mould and re-cast .
  • Sand ratio: 100kg common sand equipped with 20kg clay and 8-12kg water glass, and the put them into sand mixer machine to crush down.

The key points for the whole process :

First the cold metal mould should be heated before fully pouring. This is very important. So clients made the mistakes and damaged the mould at the first time using. So if heating the moulds is a little bit difficult, then you can do like following: after sand molding finishing and closed the top and the bottom mold, first time pouring, please ONLY  Pouring HALF FULL  of the molten iron into the metal mold. Let the molten iron’s temperature heated the metal mold. Then get the half balls out, and for the second time pouring, fill fully.

Second, protecting process is very important. You can choose acetylene or special painting to coated on the surface of ball cores. It’s better to do this protection every day.

Third, after finishing the works every day, the operators should fill the sand inside of the mold and when next day coming, directly pouring the molten iron in and no need to heat the metal molds again.

Fourth, If the molds long time no use and the environment is wet, then when reusing, even already fill the sand inside of the molds, still need to heat again, Or you will hear little noise like small fireworks. And the ball’s quality is bad.

If you still met some other problems or matters, welcome you contact us. 

  • metal mould for grinding ball