Technological watch

While there is a general move away from the use of plastics for disposable packaging, there is still a great need for products made out of reusable (and ideally recyclable) plastics. Possibly the most obvious example of this is large-scale packaging, such as handling systems, but there are many others from plastic toys to cafeteria trays and car windshields. You’ll even find airline seats made from recycled plastic. Many of these products are made through a process known as thermoforming.

The pros of thermoforming

At present, thermoforming is the only viable process for creating large items out of plastic sheets. The items produced by thermoforming are typically very durable and have a high degree of structural integrity, which helps to protect them and, if relevant, their contents from the effects of weather and other environmental factors.

What’s more, the process is capable of customizing products. It’s a bit more complicated than just changing the settings on a thermoforming machine and so this is something you would discuss with the company creating your mold. However, if you wish, you can make your products colorful and paintable as well as strong.

Thermoforming can produce a variety of shapes and sizes in thicknesses from 250 microns to 8 mm. Image courtesy Ansini Ltd.The process of thermoforming has been around for a very long time. It’s hard to put a date on exactly when industrial thermoforming was invented, but it was certainly being attempted as far back as the early 19th century and really began to gain ground in the early 20th century.

This means that it is widely taught and understood, making it relatively straightforward to recruit the necessary staff. It also means that thermoforming machines are fairly affordable when compared with similar technologies such as injection molding.

The cons of thermoforming

At the current time, thermoforming depends on non-biodegradable plastics. While these plastic products are intended for extended and repeated use, there is a natural end to their lifecycle.

There is also the possibility of breakage, especially when the products are exposed to extremes of temperature. In principle, there is nothing to stop thermoformed products from being recycled rather than sent to landfill, but in practice, the ability to recycle the plastics used in thermoforming can be highly variable.

Basically, this is a fairly inevitable consequence of a manufacturing process that essentially amounts to feeding large sheets of plastic into a thermoforming machine over and over again until the end product is created.

It also means that thermoforming is a fairly wasteful process; when compared to injection molding, however, you can recycle the leftover plastic. Even when the plastic is recyclable, this wastage does add to production costs.

Why thermoforming is necessary

Thermoforming is necessary for the simple reason that no other process currently can achieve the same results at a comparable speed and cost.

Thermoforming can produce a variety of shapes and sizes in thicknesses from 250 microns to 8 mm. Production tooling can cost 20% of a similarly sized injection mold.

Turnaround time from design concept to prototype tooling and first part of the tool can be as little as one week, with aluminum tooling on the first part taking around four weeks.

About the author

Nick Mills is the general manager at Ansini, which specializes in the manufacturing of vacuum-formed plastic components for the packaging, automotive, and aerospace industries.