Graphite has been used in mold production for more than 50 years. The development of existing materials has created options for making graphite available for a variety of applications. Ingot graphite moulds are commonly used for aluminum, gold and silver casting. By combining the low cost of processing graphite with the high strength of graphite materials, the advantages of graphite permanent molds can be realized, providing an economical choice for other molds in the zinc-aluminum casting industry.
The correct choice of graphite grade is crucial to the performance of the die. In general, the use of extruded graphite grades is not recommended in the manufacture of graphite moulds requiring fine detail due to the relatively large porosity. When budget constraints or small volumes dictate economic solutions, some high-density extrusion may be the solution. In most cases, applications using fine graphite moulds use moulded or isostatic graphite grades. Both series show high density and small particle size, which are very suitable for very high strength, excellent finish and excellent service life. Isostatic graphite has the best quality and can be used in complex die design and mass production.
No matter which grade is chosen, graphite is very stable. When molten metal is introduced, it does not warp, twist, or inspect. The casting precision of parts is higher than that of sand or iron. Graphite can also be stored indefinitely without changing shape, rusting, oxidizing, or deteriorating in any way.
Graphite mold manufacturers need to provide customers with the best product for the application, while also performing another important function of informing customers of any potential pitfalls.
Finally, we will discuss various misunderstandings about graphite. A common misconception is that graphite is weak and easily damaged. Graphite is a crystalline structure. Therefore, it is very rigid and keeps its size very well. Graphite is very strong and can withstand considerable stress. When used in an incorrectly designed process, it may damage or even break, but from a production point of view, this is a better result than other die material warping under tight tolerances. Before the problem is discovered, the deformed material may produce an entire nonconforming part.
In addition, the expected life of graphite molds is generally considered to be relatively short. This is a complete misunderstanding. In terms of overall performance, graphite is close to the performance of metal materials. If we take into account the reduced production cost of graphite molds, the relationship between the cost per run and the cost of other materials will be better.
In short, graphite molds can and do represent a viable, cost-effective solution. Engineering, design, and manufacturing processes, coupled with following the correct operating procedures, can enable parts to meet or exceed customer expectations in terms of performance and service time.