Permanent Mold Castings : Manufacturing Processes

Manufacturing Process Foundry:

The casting profile is machined into a specialty mould material (two or more depending on the complexity of the part), along with the gating system. The machined molds are then assembled along with required cores into a die assembly. The metal is poured into a die which then flows under gravity while being skillfully tilted to fill the mould appropriately.  After the casting is removed from the cavity the moulds and cores are cooled in a proprietary solution which readies it for the next cycle.


Unlike sand molds, these metallic molds are re-usable and are cost effective for bulk production. Also, due to the nature of cooling profile that can be achieved in these molds, they result in producing better surface finish, better mechanical properties and also can achieve close dimensional tolerances that are not achievable through sand castings. It also produces very high density castings that are pressure tight and have excellent structural characteristics.


However, manufacturing though permanent mold process require special design capability, including selection of die/core materials, choosing parting line, providing efficient gating systems, and tilting angles. Rapsri has proven design capability for permanent mold design and manufacturing, developed by a strong in-house R&D department.


Rapsri can manufacture permanent mold castings ranging from a few grams to up to about 20 kilograms. While the smaller sizes are manufactured by manual process, the bigger sizes are manufactured on machine with automated PLC controlled tilting and mold coating facility.


Permanent mold casting is often referred to as Gravity Die Casting – since the flow of metal into the mold is only assisted by gravity alone.

Manufacturing Process Machining:

  • Turning (CNC Turning Centers, Conventional Lathes)
  • Milling (CNC Milling, Conventional Milling Machines)
  • Drilling (Radial Drilling Machine, Drill Tap Center)
  • Vertical Machining Centers

The process of machining castings is mainly by poka-yoke (mistake proofing) fixturing that ensures the quality of the part as it moves through the production chain. Critical to quality dimensions that are either customer defined or internally defined are calibrated to CpK of 1.33 or better.

Surface plating in Silver, Tin or Nickel is outsourced with Rapsri designed process.