A brief explanation of key stress factors for your plastic product

April 7, 2021

plastic moulding

When you’re planning on investing the time, energy and money to create a bespoke plastic product, it’s fair to assume that you’ll want to maximise its operational lifespan as much as you can. So, before we get started in earnest on rotomoulding your product here at Excelsior, it’s worth first taking a moment to think about the various stress factors that your plastic product could potentially be exposed to. To give you a headstart on that process, let’s take a moment to look at some of the most important ones.

The operating temperature and ‘humidity range’

Every type of plastic is affected by temperature changes to some degree, although some are more strongly affected than others. As you’d expect, that makes it a pretty important consideration in any type of plastic manufacturing, and it’s one of the first ones you should probably think about when you’re starting out.

Excessively high temperatures can be the result of natural phenomenons, such as heatwaves, or be produced as a by-product from the operation of heavy machinery. Either way, they can cause the plastic to soften, and dampen its chemical resistance (chemicals tend to be more aggressive at higher temperatures). Excessively low temperatures can have different but equally detrimental effects, as it can cause some types of plastic – such as High Density Polyethylene – to become more brittle, decreasing their impact resistance.

Now, your plastic product isn’t necessarily guaranteed to suffer these effects, as it depends on a variety of other factors too. But together they make up just one good reason why it’s worth carefully thinking about the placement and relative strength of your plastic product right from the off.

The effects of load on your plastic product

If you think that there’s a chance your plastic product will be supporting the weight of any other static or living thing, at any stage throughout its operational life cycle, you’ll need to know the general answers to at least two questions, namely: how much is your plastic product rated to bear, and for how long is it capable of doing this?

It’s also a good idea to bear in mind the nature of the load itself, as it can affect the capabilities of the plastic product in turn. For example, how might it perform while bearing a short term static load, and how might those performance capabilities change when it’s bearing a vibrational load? And most importantly, how often will your plastic product be able to withstand these pressures, and for how long?

plastic moulding

Sudden impacts

No matter how careful you are, almost everything in life endures its fair share of knocks and bumps, especially if it’s being used on a daily basis. (Just think how often people drop their phones!) So when you’re planning your plastic product, it’s best to be realistic about the frequency and intensity of the various sudden or hard impacts that it might have to endure over its operational lifespan.

Part of the reason this is so important is that it might end up having a knock-on effect (pardon the pun) on where you choose to position or store it. If it’s slated for use in a warehouse or shop floor, for example, you can reasonably expect it to have to endure a reasonable amount of punishment, but if its intended application is in a less intensive office environment, it might not have to have the same level of raw durability against sudden or repeated impacts.

Its resistance to wear and friction

Not all impacts are brute force. If your plastic product is going to be in constant or even occasional motion – say as part of a larger device or system – then you’ll also need to account for friction. This is a notably complex behaviour that encompasses adhesion, abrasion and erosion, all of which can have an effect on potential degradation of your part. Now, parts from low-friction polymers can sometimes last longer, but sometimes only under certain conditions. Essentially, some types of polymer might be wear-resistant under one set of conditions, but less so under another. All that means this can be a particularly complex factor to take into account, but worth it to ensure the maximum long-term operational lifespan of your plastic product.

To be honest, the likely duration, frequency and intensity of all these various stresses will probably all take some particularly careful thinking about well in advance of actually creating your plastic product, so that you make a reasonably accurate estimation of how well your bespoke plastic product will last.

In fact, that’s one of the reasons why rotomoulding is such an effective way of producing many types of plastic products. It’s brilliant for creating hollow products with even thicknesses, and no ‘stress points’. Since this type of plastic manufacturing forms products under low pressure, the final objects are in fact entirely stress free!

If you’ve got any more in-depth questions or you need more specific advice, we’re only too happy to help here at Excelsior. We’ve got over 50 years of experience in the plastic manufacturing sector, so you can trust our experts to know what they’re talking about. 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!