Advantages of Using Graphite Molds

Graphite has been used in mold production for over 50 years. The development of available materials has created options to make graphite available for a variety of applications. Ingot graphite molds are commonly used for casting aluminum, gold and silver. By combining the low cost of graphite processing with the high strength of graphite materials, the advantages of graphite permanent molds can be exploited to provide an economical alternative to other molds in the zinc and aluminum casting industry.

The correct choice of graphite grade is critical to the performance of the mold.

In general, the use of extruded graphite grades is not recommended for the manufacture of graphite dies requiring fine detail due to the relatively large porosity. When budget constraints or small lot sizes dictate an economical solution, some high density extrusion may be the solution. In most cases, applications using fine graphite dies use either molded or isostatically pressed graphite grades. Both families exhibit high densities and small grain sizes that are well suited for very high strengths, excellent finishes and excellent service life. Isostatic graphite is the best quality and can be used for complex mold designs and mass production.

600mm UHP Graphite Electrode

Choosing the right grade

Regardless of the grade chosen, graphite is very stable. It will not warp, twist or check when introduced into molten metal. Parts are cast more accurately than sand or iron. Graphite can also be stored indefinitely without changing shape, rusting, oxidizing or deteriorating in any way.

Graphite mold makers need to provide their customers with the most suitable product for the application, while also performing another important function of informing the customer of any potential pitfalls.

Finally, we will discuss various misconceptions about graphite.

A common misconception is that graphite is fragile and can be easily damaged. Graphite is a crystalline structure. As such, it is very strong and holds its dimensions very well. Graphite is very strong and can withstand considerable pressure. It can be damaged or even fractured when used in incorrectly designed processes, but from a production standpoint, this is a better result than other mold materials that warp under tight tolerances. The warped material may produce a complete non-conforming part before the problem is detected.

Also, it is generally believed that graphite molds have a relatively short life expectancy. This is a complete misconception. In terms of overall performance, graphite approaches the performance of metallic materials. The cost per run in relation to the cost of other materials is better when the reduced cost of producing graphite tooling is taken into account.

In short, graphite tooling can and does represent a viable and cost effective solution. The engineering, design and manufacturing process, along with following proper operating procedures, can result in parts that meet or exceed customer expectations in terms of performance and service time.