June 25, 2019 Glass/Glazing

Whether launching a new product line, improving an existing product’s performance or reducing manufacturing costs, manufacturers of curtain walls and architectural glass and glazing go to great lengths to create new or improved extrusion designs.

This list should help you avoid common mistakes in the rubber extrusion design process.

Design mistake #1 – No radii for corner extrusions
90 or sharp corners can create the ideal conditions for a leak. The best way to avoid this type of problem is to incorporate a small radius in the rubber extrusion sealing surface design instead of a 90-degree angle.

Design mistake #2 – Not anticipating (broader) rubber tolerances
Most people assume rubber tolerances are the same as for other materials. They expect small variances, because they’re used to a very high level of precision with machined metals, but rubber has broader tolerance ranges than other materials. That means it’s crucial to account for this difference when designing the part.

Design mistake #3 – Not accounting for the movement of the part
This design aspect is particularly important in structural glazing applications, because compression loads vary greatly.

You need to know and inform your suppliers of the uncompressed shape as well as the compressed shape to validate requirements. Otherwise, the part may be too big and you won’t be able to compress it. Conversely, if the seal is too small, you won’t get enough compression and it will leak.

Design mistake #4 – Not prototyping before investing in tooling
Asking your supplier for some 3D-printed samples to validate the design before investing in tooling is always a good idea. It will help you figure out both fit and form, which ultimately speeds up the production process and minimizes the risk of costly mistakes. Just be aware that since the 3D-printed part is not made of rubber, it cannot validate function.

Design mistake #5 – Not taking advantage of hollow designs
While often overlooked, this is actually a great way to save on costs. The advantage of using a hollow design is that it produces the same compression values but with less material. And when you save on materials, you save on costs. You’re also playing a role in creating environmentally friendly solutions.

Using a hollow centre does affect the hardness, though. As a result, you’ll need to adjust the design to compensate for your compression force requirements and use a harder rubber material.

Design mistake #6 – Telling only part of the story
Context is everything, so you have to make sure that ALL the requirements have been clearly communicated to your supplier.

The only way your suppliers can alert you of potential issues is if they understand how you want to use the part and how it interacts with other parts, such as sliding into a track. Making sure they know the whole story will likely guarantee a perfectly suited rubber extrusion for your application.

Design mistake #7 – Designing it alone
You may have a specific design in mind but are not familiar with how rubber behaves under specific conditions. Rubber is very different from plastic or aluminum, and rubber materials themselves can differ greatly.

It is in your best interest to work with your supplier to optimize your design and select the most suitable material.

While not meant to be exhaustive, this list should give you an idea of the kind of pitfalls to avoid when designing rubber extrusions.

More often than not, glass and glazing manufacturers experience unexpected setbacks when they design their own rubber extrusions for the first time. Then they study what went wrong and improve from there. Why not work with an experienced supplier who has already done the legwork for you?

Since 2004, we have been designing and manufacturing custom rubber parts for companies and industries around the world.

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