Understanding Silicone Rubber Tolerances

When you begin to read more about silicone rubber parts and how they are created, you may encounter the word tolerance. We know what this means in terms of tolerating things ourselves (or not, in some cases). But what does it mean when we’re talking about silicone rubber?

We’re going to delve into this topic in more detail here. If you are planning to order some parts sometime soon, we hope this knowledge will help determine whether you need to think about tolerance in more detail before you place that order.

What does tolerance mean?

In this case, tolerance refers to a range within which the dimensions and qualities of a silicone rubber part must fall. To give a simple example, let’s assume you want to buy some silicone rubber washers. These washers are measured at 5mm thick.

However, while that is the accepted measurement, there will be tolerances involved. For example, for a washer to ‘pass’ as a 5mm washer, it may need to be between 4.9mm and 5.1mm. Those are the tolerances for the thickness of the washer.

In most cases, tolerances are far finer than this. However, we hope this example demonstrates the meaning of tolerance within this sector.

It is also important to recognise that the tools used to create the parts can affect the outcome. In cases where a mould must be made, perhaps to allow for extrusion of the parts, prior knowledge is important. Should those parts be precise in their nature or is there room for some variation between them? That variation may not be visible to us, but it could make a significant difference when those parts are in use.

Do you need your silicone rubber items to have precise tolerances?

It is important to think about this before you go ahead and order any parts. In many cases, off the shelf items such as rubber tubing, washers, or sheets come within basic tolerances that would be fine for your requirements.

However, in some cases – especially where the parts are made to fulfil a specific role – there can be very little tolerance involved. When this is the case, the manufacturer must know in advance. It could affect the entire process from developing a mould to creating the silicone rubber parts that are needed.

Considering critical parts

Since the tolerances can indeed be fine, it is important to talk to your chosen manufacturer about the role the silicone rubber parts must play once complete. You can benefit from their experience when looking at the end user, the end role for that part, and therefore how it should be made before that point is reached.

There is also the issue of consistency. Obviously, when parts are made to traditional tolerances, there is more leeway to get things right. However, when part of the silicone rubber item is critical to how it must be used (or indeed the whole thing), more care must be taken before and during the creative process.