Tips to minimise cycle time in injection moulding

Cycle time is a key factor in determining the cost and time efficiency of creating a plastic component

To ensure that cycle times are working as efficiently as possible and delivering for customers, there are three stages of the injection moulding process that need to be analysed:

• when heated material is injected into the mould and cavities
• when continued pressure is applied to make sure all cavities are filled• when the material cools to a solid state and parts are ready to be ejected.
• By routing out inefficiencies at each of these stages, manufacturers can work to streamline their cycle time and deliver customers’ components quickly, for a good price.

Consider the mould

Designing the mould to be as efficient as possible sets a good base for an efficient, cost-effective process. One way this can be done is to design wall thicknesses to the minimum needed for your part to work as it should.

This doesn’t mean compromising on quality but cutting down injection time and the volume of material needed to inject into mould cavities. Another gigantic bonus is that less cooling time is required, which speeds up this process. However, this must be balanced with the strength of the part, which needs to be as high quality as possible for customers.

Insulating the mould can also help to cut down on the cycle time. Without insulating, it will take extra time for the material to cool down. Unexpected heat in the mould can also affect flow rates, which impact the success of the entire process. By insulating your mould, temperatures and other physical properties can be controlled more effectively.

Choose the right materials

Selecting materials with the right characteristics for a customer’s component is as important for the efficiency of the process as it is for the qualities of the final product.

Some materials will have higher fill pressure ratings or higher flow rates. This means they can enter the mould and fill all cavities faster. Some will have a higher viscosity or temperature resistance, meaning they’ll react differently to the addition of heat and may run more slowly through the machine. By balancing the needs of the part with the efficiency of the process, it’s possible to give customers a high-quality component that’s also cost-effective.

Select the right machinery

Choosing the right process with the right machinery is a fundamental part of making cycle times efficient. Tooling design should be considered as part of the injection moulding process, along with alternative processes such as co-injection and micro-moulding.

The two most common cooling agents are water and air, which a well-designed mould will ensure are efficiently distributed. Maintain the cooling channels and keep them clean. This will help parts to cool quickly and consistently. It’s worth noting that inconsistent cooling plays a big part in causing defects and, as a result, parts being rejected. More machine time, of course, means longer cycle times.

Keeping the machine maintained will also help to avoid performance issues and ensure proper injection pressure and speed. This is especially necessary with older machines, which are prone to inconsistent fill time. By keeping your machine fine-tuned with skilled injection moulding engineers, you can ensure fast and effective cycle times.

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