The main types of plastic manufacturer – a quick rundown

December 6, 2019

Plastic Moulding

When you’re looking to create your own bespoke plastic product, it’s important to find the right plastic manufacturer who can bring your vision to life. We take a lot of effort and care to make sure that’s us here at Excelsior, but our customers still often find it helpful to do their research on the main types of plastic manufacturer in advance. So, we thought we’d save you a bit of time! You may find plastic manufacturers who offer several types of manufacturing services, but many of them tend to specialise. That’s why it’s all the more important to ensure you make the right decision! Here, we’ve summed up some of the main differences between them, so you can get kickstarted on the decision making process.

Injection moulders

You may already be familiar with the injection moulding process, but just in case you’re not, we’ll give you a recap on the basics. As the name suggests, injection moulding involves injecting melted plastic into a pre-made mould cavity. The plastic fills out the cavity completely, and then cools and solidifies, ultimately producing the desired final product.


Injection moulding tends to be more expensive than certain other forms of plastic manufacturing, unless large quantities are involved. That means most injection moulding plastic manufacturers will be used to taking orders of hundreds of products at a time, as these tend to be the most cost-effective. Partially because of these large orders, lead times will vary, but depending on the product in question it can sometimes take up to six months for production to reach the final stages.

Blow moulders (or extrusion moulders)

These types of plastic manufacturers share a lot in common with injection moulding companies, but the difference is that blow moulding is used to produce hollow shapes in large quantities, rather than solid ones. Drinking bottles, for example. As with injection moulding, it involves melting down the plastic and pushing it into a pre-formed plastic mould. It’s then filled with air, with the pressure pushing the plastic outward to the inner edges of the mould – much like blowing up a balloon.

Again, much like injection moulding the lead times vary, but generally requires large quantities to be properly cost effective – so it can sometimes take up to half a year for a full run of products to be completed.

Roto moulders

As you know, this is our specialty here at Excelsior. Over more than 100 years in operation, we’ve accumulated decades of experience in this form of plastic manufacturing, and have a fantastic track record of producing results for our clients. Essentially, like blow moulding it also creates hollow products, but in quite a different way. Our roto moulding page has the full details, but to give you a breakdown: it involves plastic pellets being put into a hollow mould. This mould is then spun on its axis while being gradually heated, so that the plastic inside melts as the centrifugal force throws it outwards to stick to the inner sides of the mould. When it cools, the result is a hollow, seamless shape with no stress points.

Roto Moulding

Roto moulding plastic manufacturers like ourselves are generally used to taking smaller batch orders, but accordingly roto moulding often has a shorter lead time compared to the other forms of plastic manufacturing, as production times are generally much quicker. It’s usually highly cost-effective for prototypes, too.

However, these are only broad definitions – they might not be as prohibitive as they first appear! If you’re struggling to narrow down your decisions, we recently covered the most important questions to ask your plastics manufacturer, so you can work out whether you’re making the right decision. Having said that, we’re always happy to provide some answers ourselves – just give us a call on 0161 765 2010, and our friendly members of staff will see what we can do for you!