When you are used to working with rigid thermoplastics like PVC, switching to silicone might seem straightforward. But that is not quite how it works. Silicone extrusion manufacturing behaves very differently, especially when you are dealing with profiles that need to perform in harsh conditions. The same specs and design rules that work fine for PVC will not work here. Extrusion Technologies International has been operating since 1996 as a leader in advanced extrusion technology, so our team has seen first-hand how different materials demand different approaches.
We have had a few conversations lately where designs intended for PVC were applied directly to silicone, only to hit issues with curing, flow, or worst of all, post-install failure. The specs are not just guidelines, they are factors that determine both fit and function. The material might seem familiar, but its behaviour is different. That is why it is important to look at how silicone performs and why it needs its own set of rules.
Understanding How Silicone Behaves Differently
Silicone has some useful properties, but it does not behave like PVC. It is bendy, it stretches, and it handles heat better. That makes it great in many applications, but harder to control on the production line.
A few of the key differences we see in silicone extrusion runs include:
• Silicone does not hold shape as persistently as PVC. Once it leaves the die, it can flex or sag if the line is not set up correctly.
• The way silicone flows through tooling is different. Compared to PVC, it needs time to cure or set during the process, which changes timing and equipment settings.
• Where PVC profiles remain stiff and defined, silicone ones can flex and twist if your designs do not factor in expansion, shrinkage, or wall thickness changes.
In our broader production work we regularly extrude PVC, ABS, and ASA profiles, which makes the contrast with silicone behaviour even clearer.
All of that means you cannot just reuse the same process and expect good results. Even minor profile features can react differently. That is why a fresh look at the specs is needed before the first batch runs.
Tooling and Design: Do Not Copy-Paste Your PVC Specs
One of the most common problems we notice comes from copying over existing PVC specs into a silicone run. Just because the profile works in plastic does not mean it will hold up in silicone. Our design and development work draws on experience from more than 500 different tools, so we know how small shifts in tooling can change the way a profile behaves in production.
Here is what usually goes wrong:
• Silicone needs different draft angles to release cleanly from tooling. If the angle is too sharp, it sticks or tears.
• Wall thickness plays a much bigger role. Too thin and it collapses, too thick and it holds heat too long, affecting cure time.
• Standard venting setups for PVC might not be enough. Silicone can trap air in complex shapes, leading to bubbles or incomplete fills.
Another big issue is tolerance. Silicone expands and contracts much more than most thermoplastics. If your design uses tight tolerances and does not adjust for that movement, your end product might not line up or install properly. Matching the spec to the material keeps things moving without rework or delays.
Why Silicone Profiles Often Serve High-Stress Use Cases
We are often asked why someone would not just stick to PVC or go with basic rubber options. The answer is that silicone is usually chosen when nothing else will hold up. It is the material you pick when the job throws challenging conditions your way.
Some of the most common reasons to specify silicone include:
• Strong heat resistance, especially in industrial plants or transport applications
• Electrical insulation or seals in switchboards or machinery
• Safe use in medical, kitchen, or food-related settings where other plastics cannot meet the spec
Because these applications are demanding, they come with much stricter standards. That can include flame rating, UV resistance, compression set, or materials compliance. We find that imported profiles or generic runs often fail these checks, which becomes a bigger issue when the profile is halfway through install.
If the spec is wrong, the fault lands on your desk. That is why it is worth building specs from the ground up with the correct material.
How Local Knowledge Helps Get It Right the First Time
Working with silicone means many of the details need to be looked at up close. That is not easy when designs are sent overseas or when suppliers do not understand local building or compliance needs. Here in New South Wales, many builds and project sites face a mix of strong heat, sun exposure, and long duty cycles that can stress profiles quickly.
Here is where practical experience helps:
• Real-world testing in local conditions helps determine whether the design will hold up.
• Local knowledge of compliance and customer expectations builds trust early.
• Quick prototyping reduces the risk of long delays or major redesigns after install.
We have heard enough stories of rework, late changes, or poorly fitting products that caused major project delays. Most of those could have been avoided if the initial profile was designed for this material and not just copied from another job.
The Right Specs Make All the Difference
Switching to silicone should be about lifting performance or solving a problem, not creating new ones. That only happens when specs are built to match the material and the job. We have seen what happens when things are not adjusted and it does not go well.
To avoid those field issues, we recommend a few steps up front:
• Re-evaluate the design for thermal movement and flexibility.
• Review tooling and flow behaviour with cure time in mind.
• Align performance expectations with certification needs beyond just shape or fit.
Getting this right at the beginning saves hours of stress later. Each material has its limits and silicone is no exception. By taking the time to tune specs properly before the first order, you avoid the common pitfalls and keep the project moving smoothly.
Getting Silicone Right From Day One
Silicone brings major advantages when you need flexibility, strength, and heat tolerance. But it is not a direct replacement for thermoplastics like PVC. It moves, it flows, and it responds to stress in different ways. If that is not considered in the design spec, you are likely to see fitment issues at install or failures in the field.
To prevent those outcomes, it is worth building the right specs from the ground up, based on how silicone performs. That is the best way to prevent mismatches and keep both the design and the project on track.
At Extrusion Technologies International, we help teams across New South Wales avoid the pitfalls of copy-paste engineering by understanding how flow and tooling change under real-world conditions. Our Australian-based expertise means we know how silicone extrusion manufacturing differs from conventional runs and how to get it right from the beginning. Let’s make sure your next project installs smoothly and without surprises. Contact us to discuss your requirements.
