The mould trial from A to Z
2 October 2019
What is the process of an injection moulding trial? A mould trial is a process by which a new mould is optimised in order to produce the desired products as efficiently as possible. This makes it one of the most important aspects of injection moulding. Fred Bijsterveld, project manager and injection moulding expert, explains how mould trials work at Rompa Group.
The moulds Rompa uses for its injection moulding are made by specially selected toolmakers from all over the world. Before the moulds are transported to one of Rompa Group’s production sites, mould trials are conducted. Rompa is closely involved in this process and does some of the testing itself. “It is important to us to share our process knowledge with the toolmakers and develop sustainable partnerships with them,” Fred explains. “It is important to make sure that this process is conducted in exactly the same manner everywhere. We leave nothing to chance.”
The mould trial process
How does the mould trial process work, exactly? Fred: “Before the start of the mould trial process, we work on the mould design. Together with our toolmaker, we discuss the mould constructions and technical solutions. We do this to avoid unnecessary mistakes in the mould and make sure that the first phase of the mould trial (first out of tool) already provides us with a good product. Most of the time a standard mould trial process consists of three test phases. Sometimes, we conduct several mould trials during a single phase. If necessary we keep testing and optimising until the product meets the customer’s and our exact requirements and wishes.”
The three phases of a mould trial
Phase 1: first out of tool
The first phase is called “first out of tool” (FOT). This is the first time we inject molten plastic into the mould. We test whether the mould closes perfectly, whether there is sufficient cooling, whether the product comes out neatly and whether there are any flashes, airtraps or deformations. We draw up a report with our findings, in which we specify the modifications that have to be made. The toolmaker then proceeds to optimise the mould and samples are sent to the customer to provide a first impression.
Phase 2: feedback from the customer
Once any imperfections have been resolved, we conduct a new mould trial with the optimised mould. We present the resulting product to the customer. Together, we go over the cosmetic aspects and the cycle time. Did we produce an appealing and functional product, are the dimensions correct, can we manufacture it within the calculated cycle time and does it meet the customer’s other requirements and wishes? The part is then released for testing and the customer is given ample opportunity to test the product. We send the toolmaker another report, which includes the customer’s feedback this time. A second round of optimisation follows.
Phase 3: the finishing touch
Finally, we conduct a third mould trial with the fully optimised mould. During this phase, it is all about the finishing touch. Think of e.g. choosing between a matt or glossy texture. Once the product has been perfected and every detail checks out, we run a long trial. After this run the mould is transported to one of our production sites. We will always conduct a final on-site mould trial, because certain conditions, e.g. the temperature of the cooling water, are not the same everywhere. Once we are convinced that there is no more room for error and the part is released by the customer, the mass-production process can begin!
Would you like to know more about the mould trial process?
You can contact our injection moulding experts.