Why is wall thickness important in plastic manufacturing?

February 24, 2022


Consistent wall thickness is one of the key advantages of roto moulding, alongside other useful qualities like its versatility, low tooling costs, and ability to create a wide variety of different surface textures. But while the benefits of some of these qualities are almost universally clear, the advantages of having a consistent wall thickness might not be quite as obvious right off the bat. So to put it bluntly, why should you care about having the wall thickness of your product?

A consistent wall thickness means a stronger, more durable product

In a word, it’s all about integrity. The short version is that a consistent wall thickness basically helps to maintain the structural integrity of your product, because it minimises the number of ‘stress points’ – in other words, areas where it’s most vulnerable to damage from casual knocks or sudden impacts.

OK, so that’s the simple version. To get a bit more technical; the majority of plastic manufacturing processes use thermoplastics, which are plastics that can be repeatedly melted and reformed before they start to lose their structural integrity. Now, you probably already know that when plastic melts, the materials expands, and when it cools, it shrinks. It’s no different with plastic manufacturing – when a newly-formed plastic product is taken out of the mould, it needs a little time to cool and harden.

This is arguably one of the most crucial stages of the entire plastic manufacturing process, because if there are any inconsistencies in the product itself, that’s where they can start to affect its overall structural integrity.

Specifically, if some sections of the part or product are thinner than others, that can result in:

  • Warping – twists or bends in the shape that could give way to major structural defects
  • Sink marks – small craters that can appear when the molten plastic doesn’t cool completely in the mould
  • Cooling rate issues – if different sections of the part or product take different times to cool, that can end up slowing down the entire production run, with knock-on effects on costs and efficiency. It could also render some individual parts unusable

Those are just a couple of the key problems can occur, but far from the only ones!

How can rotomoulding provide a consistent wall thickness?

Wall thicknesses are fairly easy to control in rotomoulding, mostly because of the nature of the process. Roto moulding is short for rotational moulding, so named because it involves melting plastic into a liquid form while spinning it very quickly on multiple axes. That generates centrifugal force so that the melted plastic is flung out to coat the inner sides of the tool, resulting in a reliably consistent wall thickness.

What’s more, our experience and expertise here at Excelsior means that we can increase the wall thickness substantially if required. We typically manufacture products with anything from a 2mm to an 8mm wall, so as with almost every other aspect of your plastic product, we can tailor it to suit your requirements.

We’ve got more than a century of history behind us here at Excelsior, so you can always rely on us to help bring every inch of your plastic product to life. And if you’ve got any further questions about rotational moulding, or you need specific advice about your situation, we’re happy to help. Just take a look at some of our successful case studies for previous clients, or give us a call on 0161 765 2010 to see what we can do for you!