Moulds 

Tools for the design of plastic products 

A mould is a precision tool used to inject plastic into a specific shape under pressure. The quality of a mould largely determines the accuracy, reproducibility and finish of the end product. Moulds therefore form the heart of every injection moulding application, whether it involves technical components, packaging or reusable trays. 

What is a mould? 

A mould is usually made from hardened steel or aluminium and consists of two halves: the cavity and the core. When these are closed together in the injection moulding machine, a sealed space is created in the shape of the desired product. Molten plastic is injected into this space and then cools to form a solid shape. Once the product has hardened, the mould opens and the part is ejected. 

Depending on the design, moulds may feature multiple cavities (multi-cavity moulds), sliding parts (sliders), cooling systems and venting channels. Every detail influences both the end result and the production cycle time. 

Types of moulds and their applications 

The choice of the right mould depends heavily on the type of product, the desired volume and the technical requirements. Some common types: 

• Single-cavity mould: One product per cycle; suitable for smaller batches or prototypes. 
• Multi-cavity mould: Multiple identical products per cycle; increases production capacity.
• Family mould: Multiple different parts from a single mould; efficient for sets or assembled products.
• Hot runner mould: Less material waste and shorter cycle times thanks to a heated injection system.
• 2K or multi-shot mould: For injection moulding of two (or more) materials into a single product, e.g. hard plastic with a soft-touch grip. 

Why is the quality of the mould so important? 

The mould determines not only the shape of the product, but also the material thickness, surface texture and cooling time. A well-designed and correctly manufactured mould: 

• Minimises production defects, such as flash, sink marks or warping.
• Reduces cycle time through efficient cooling and ejection.
• Extends service life, particularly when used in high-volume production.
• Reduces the cost per unit through less downtime and less waste.

In series production, a well-designed mould can make the difference between profitability and loss. 

Would you like to know how Didak uses moulds for customer-specific applications, or are you curious about the possibilities within our custom moulding processes? We’d be happy to discuss this with you. From initial design to finished product.