You should choose your moulding process based on your component’s function, material, shape and production volume. The aim is to meet your specification at an acceptable total cost, including assembly, testing, packing and transport.
At Talisman Group, we offer injection and compression moulding. Here’s how we’d assess five products from the sectors we serve. From food-packaging caps to railway seats, these examples show how a wide range of different product requirements can influence your choice of process.
How do you mould an automotive pedal with an overmoulded grip?
A car pedal needs a body that withstands repeated loading and a contact surface that provides grip. If you’re developing a plastic pedal, we assess injection moulding for the body and overmoulding for the contact area.
Using injection moulding, we can form the pedal’s ribs and pivot features in one part. We could then overmould the contact area with a thermoplastic elastomer (TPE), a rubber-like material that can provide grip and wear resistance. This removes the need for a separate grip pad and the work needed to attach it.
We’d assess material compatibility and how the bond performs under the pedal’s operating conditions. Some designs also need features that lock the materials together.
Overmoulding can increase your tooling costs, so we’d compare this investment with the assembly work it removes at your expected production volume. If you need a replaceable grip, you may prefer separate assembly after all.
When is compression moulding suitable for a railway carriage seat?
Rail seating must withstand heavy passenger use and regular cleaning while meeting the stringent project’s fire safety and performance requirements. You also need the seat to retain its shape and fit its mountings throughout its service life. And, importantly, it must also be comfortable.
A one-piece seat may be best suited to compression moulding with a fibre-reinforced thermoset compound. We place a measured amount of material in a heated mould, then close it and apply pressure to shape the material as it cures. This allows us to form the seat’s broad shape and reinforcing features in one component.
Of course, using compression moulding doesn’t necessarily mean the seat meets your requirements. We’ll help you assess the compound and wall sections against the required tests. Changes to the material or design may require further validation.
Should you use compression or injection moulding for an electrical insulator?
Your insulator needs to prevent unwanted current flow while withstanding the heat and loads in your equipment. A suitable thermoset material can meet these requirements, making compression moulding an option.
We may also consider thermoset injection moulding. The choice depends on the part’s shape, how closely its dimensions must match the drawing and how many you need.
For the threaded fixing, we can mould the plastic around a metal insert or fit the insert after moulding. We’ll assess which method suits your design and keeps the insert from turning or pulling out under load. We’ll also check that its position allows the required clearance and creepage distances between conductive parts.
How do you mould a leak-tight fluid transfer housing?
If you’re developing a pump or valve housing, injection moulding can combine ports, seal grooves and mounting features in a thermoplastic part. It supports repeat production when your quantities justify the tooling investment.
The first thing we do is check the material against your fluid, operating temperature and pressure cycles. Chemical exposure can cause swelling or stress cracking, which could compromise sealing, even if the part initially meets its dimensional specification.
Depending on your design, we might machine a bore, fit an insert or ultrasonically weld two thermoplastic sections together. We’ll account for these secondary operations when designing the moulded parts.
We also offer leak-decay (pressure-decay) testing, which measures pressure changes under defined conditions. Agreeing the test pressure and acceptance limits gives you a way to check the assembled product, beyond inspecting individual mouldings.
Why use injection moulding for food packaging caps?
We can use thermoplastic injection moulding to form a cap’s screw thread or push-fit rim and sealing surfaces in one part. We design these features to match your container and use the repeatability of injection moulding to keep them within specification across production runs.
We can assess whether a multi-cavity tool, which produces several caps per cycle, makes sense for your order quantities. We’ll weigh the likely investment in tooling against your required output, delivery schedule and cost per cap.
At our Malvern site, we manufacture LDPE caps and closures in a BRCGS Packaging Materials-certified environment. For food-contact applications, we also check the material and finished cap against your intended contents and conditions of use.
How do you choose the right moulding process for your product?
At Talisman Group, we work with your design team to choose the material, moulding process and any finishing or assembly work your product needs. We’ll consider the complete manufacturing route, including tooling, moulding, assembly, testing and the potential cost of scrap or rework.
Send us your drawings or an early requirements list, along with your expected quantities and any standards your product must meet. We’ll help you choose a manufacturing route before you commit to tooling. Get in touch today.