Why the choice of materials begins even before the mold is ready

When developing a new plastic product, material selection is often viewed as a step that comes later in the process: first the design, then the mold, and only then the question of exactly which material will be used. In practice, doing it the other way around works much better. The sooner material becomes part of the discussion, the greater the chance of a successful product and the lower the risk of costly surprises down the road.

Requirements stem not from the design, but from the application

In fact, a large portion of the material requirements isn’t determined by the design itself at all, but by the market segment and the application in which the product will be used. Consider certification requirements such as flame retardancy, or food and water approvals when a product comes into contact with food or drinking water. These are requirements imposed by laws and regulations or by the industry itself - not something you, as a designer, can determine on your own.

If these requirements are identified early on, a large portion of the potential materials is immediately ruled out. This not only saves time but also prevents the need to switch to a different material later in the process, with all the consequences that entails.

The triangle that makes the difference

An approach that works well in practice involves early consultation among three parties: the end customer, the injection molder, and the material supplier.

• The end customer has the best understanding of its own objectives and the requirements for the product.
• The injection molder has expertise in the manufacturing process, molds, and a solid understanding of what is and isn’t possible with materials.
• The material supplier or expert contributes material knowledge and helps assess the feasibility of the requirements.

By bringing these three parties together early on, challenges are identified at an early stage rather than only after the mold has already been made. And that makes a significant difference, because once a mold is made, many choices are already set in stone.

Why waiting too long is costly

Any adjustment needed later in the process costs money. Modifying a mold, retesting a product, or switching to a different material at the last minute - these are all steps that end up being much more expensive than if those same decisions had been made early in the process.

That doesn’t mean that a thorough preliminary process doesn’t take time. Scheduling a simulation or an additional meeting can easily add a few weeks to the timeline. But in almost all cases, that initial investment is nothing compared to the costs of remediation that arise when a problem isn’t discovered until later. In short: the time and energy you invest up front will pay off many times over later on.

Simulation as a tool for early evaluation

Simulation software is a useful tool for evaluating, at an early stage, whether a material and design are a good match. Based on a 3D design and the materials from a shortlist, flow simulations and mechanical simulations can provide insight into how a part will perform in practice.

This makes the following clear in advance:

• Whether the product can be filled properly during injection molding.
• Whether there is a risk of warping, and whether a different material could reduce that risk.
• Where flow lines or flow seams form - areas that are not only visually noticeable but also mechanically weaker.

These insights make it possible to resolve issues before a mold is manufactured, rather than only after the problem arises in practice.

Starting early pays off

Choosing the right material is therefore not the final step in the development process, but rather one of the first steps that deserves serious attention. By sitting down with the right partners from the start and leveraging their expertise and simulation capabilities, problems are prevented rather than solved later on. And that’s exactly where an experienced injection molding partner can make a difference: not just by contributing ideas once the mold is already in place, but right from the start of the process. Contact us for more information.