Dies, moulds and forming tools

The tools and dies used in processes like forming (stamping, forging, extrusion, etc.) punching and blanking, as well as the injection moulds, have to be tough and very resistance to wear and fatigue.

Therefore, they are usually made of specific tool steels particularly designed for for cold or hot working or, when higher performance is required, with HSS or powder-metallurgical steels, which can be very expensive.

troqueles2Anyway, one should not forget that the final properties of the steel are determined by the heat treatment. Dies and moulds can become really expensive, with a significant part of their cost coming from the raw material. However, it is useless to choose a premium steel if it is not properly treated to achieve its optimum performance. That is, an inexpensive operation (heat treatment) can ruin the expectations placed on a tool, no matter its very high cost.

The multistage cryogenic treatment is a simple and inexpensive operation that improves the performance of tool steels and may even help to minimize the consequences of a poor or inadequate heat treatment. generally, it increases wear resistance and fatigue strength, but also toughness and conductivity. And, very important in these applications, it improves dimensional stability and enables to achieve better surface finish. Therefore, it is a process that should be applied to any tool in which durability and accuracy are a must.

The fact that cryogenic treatments are not just superficial and the whole mass is permanently affected means that the treated material can be machined or grinded without any problem if some maintenance is required or a modification is needed. On the contrary, greater accuracy and better surface finishing can be achieved in the treated material due to the lower residual stress levels. In addition, these processes are perfectly compatible with PVD coatings and thermo-mechanical treatments such as nitriding. In this latter case, the multistage cryogenic treatments can double, or even more, the life of the nitrided material in certain applications.

troqueles3As noted, the materials most commonly used in these applications are steels from various grades. But also cast iron, bronze and high strength brass are used and, when toughness is not a concern, cemented carbide is an option too. All these materials also respond very positively to the cryogenic process, something that can also be illustrated by numerous examples of industrial applications.