Moulds and dies are essential parts in series production lines. They have many applications in metalworking for manufacturing parts, and are also used in other industries such as food. But how are moulds and dies machined?
Uses of moulds and dies
In production processes, moulds and dies play an essential role in manufacturing parts. For example, moulds are used in injection moulding to shape resin, and also in casting to create parts of different shapes. There is a huge variety of moulds: for making screw heads, for producing cans for the canning industry or for creating rings in jewellery.
Dies are used, among other things, for stamping and for forming metal sheets or plates, as well as for working other shapes in this material. They are also used to manufacture car parts.
Thanks to today’s technology, it is possible to create moulds and dies with great precision, making it much easier to produce parts in series for various industries.
Characteristics of moulds and dies
Moulds and dies are characterised by specific, highly precise shapes, an excellent finish and high-quality materials. It is important that the materials used to make moulds and dies can withstand high and low temperatures since, for example, molten metals may be poured into a mould at high temperatures. That is why it is important that moulds and dies do not deform.
These parts are usually made from steel with high hardness properties. Hardness affects not only the strength of moulds and dies, but also the cutting geometry.
In terms of shape, these tools have a three-dimensional profile, so the machines used to make them must be able to machine 3D surfaces.
What is die making?
Die making is a branch of metalworking which, as its name suggests, is devoted to developing techniques for manufacturing moulds and dies (tooling), needed for series production of parts. In die making, parts are generally made from metal sheet or plate, and machining is done without chip removal.
The term die making also refers to cutting and forming sheet metal without chip removal, using tooling known as moulds and dies. Making this tooling and forming the sheet metal requires a specialist operator, known as a die maker.
Because of its high production cost, die making is only advisable for manufacturing moulds and dies for series production, since only then can the cost of this tooling be recovered. However, it is worth noting that the tooling can produce parts in a matter of minutes, as the machines that carry out these processes can produce from 12 to 1,200 parts per minute.
Die making is characterised by the low volume of waste generated, since it does not involve chip removal. This allows optimum use of materials: between 75 and 80% of the sheet used is utilised.
Machining of moulds and dies
Various machining techniques are used to make moulds and dies: turning, milling, drilling and so on. Of these, milling is the most common because the parts have very complex shapes with several cavities and folds that require very precise work. That is why these processes are increasingly carried out on multi-function machine tools that can combine several machining techniques.
Because of the complexity of this tooling, die making was one of the first fields to adopt new technologies, using advanced software and CNC machining processes, such as high-speed and high-feed milling. That is why the latest machine tools are used to make these parts.
Various machining techniques are used to repair moulds and dies that wear and become damaged over time. This tooling can be repaired by welding, laser treatment or thermal metal spraying; all these methods are applied directly to the surface of the damaged part. The machines used both to manufacture moulds and dies and to repair them must be advanced cutting tools able to handle very hard layers of material as well as softer ones.