The similarities … As a rule, there are two ways to mould and replicate plastic parts: injection moulding and vacuum forming. Whichever angle you take, the output is almost always identical in terms of shape, material properties and overall quality.
… and differences The only thing is, how you get there – depending on what you’re making – still means sitting down and working out the best method in each individual case. One useful rule of thumb: with higher volumes it normally makes sense to use injection moulding; with lower to average volumes it’s generally better to use vacuum forming.
You start to notice the differences when you look at lead times, production rates and the overall flexibility offered by each approach – not to mention tooling costs as a proportion of end-product costs.
Injection moulding With injection moulding you have to plan in much more time between development of the mould and first production. And tooling costs for the mould are higher – frequently 8 to 12 times higher. Once moulds are ready it is also much more resource- and cost-intensive to make alterations. Given the relatively high overheads, it takes high volumes to break even. If you would like alternative costings for production using vacuum forming, we would be glad to calculate them for you.
Vacuum forming The hallmark of vacuum forming:shorter lead times, lower costs, straightforward creation of moulds (which is more user-friendly when it comes to making alterations), quicker fitting, and greater overall flexibility – even during production. The only drawback with this approach is that it is more cost and labor-intensive in post-processing and doesn’t perform as well in terms of moulding speed. Despite this, if you want up to 10,000 units a year, good samples and prototypes, and pre-production samples, vacuum forming typically turns out to be more economical, faster, and thus plain common sense – especially with big parts.