What are the disadvantages of injection molding?

When should you consider alternative manufacturing methods to injection molding?

1. Initial cost

If you are committing to steel mold tools for high production volumes (100,000+) then it can take a great deal of time and machining to produce and this can be a significant capital cost. If you need lower volumes of parts then this will affect your cost per part price and it may be worth exploring other options such as using aluminum molds instead.

2. Initial lead times

It can take up to 12 weeks to produce steel tooling. If you need to get production running before this then take a look at our on-demand production; by using aluminum molds and digitizing our front-end process we can ship anything from 25 to 10,000+ parts in 15 working days or less from the point that you first upload your CAD. Sometimes parts shipped in as little as one day.

For very low production runs there are other technologies such as 3D printing or CNC machining which could provide a more cost-effective answer more quickly.

3. Design limitations

You will need to consider certain design elements, such as:

①Using draft and radii to help ejection of the parts

②Avoiding undercuts and sharp edges

③Controlling wall thicknesses

You also need to consider where to place your gates, ejectors and cooling lines if aesthetics are important. And remember it’s also hard to change the design of a mold – you can remove part of the mold, or add plastic to your final part, but not the other way round.

For smaller production runs, 3D printing allows you to design virtually any shape or geometry that you require. As a rapidly developing technology there is an increasing number of plastic and other materials, even metal, that we can produce.

4. Small part runs are not always cost effective

Most people think that they should only turn to injection molding for orders of 100,000+ parts; but there are other options when you can use this process for smaller production runs.

Using more affordable aluminium molds and quick turnaround times (as fast as a day) our on-demand service helps keep your per part cost down. It is ideal for anything between 10,000 and 25,000 parts, but can help control costs for production runs even smaller than this.

For low production runs measured in the hundreds or less then it is also worth exploring other manufacturing technologies such as 3D printing and CNC machining. With these technologies the cost per part will be lower and you will not face the initial set up costs or lead times involved in producing molds.

Injection molding is an excellent manufacturing technology for producing mid- to high-volumes of parts in plastic and liquid silicone rubber. It is evolving over time so it is worth exploring new ideas which could help you reduce your part cost for smaller production runs.

It’s also worth investigating whether other technologies such as CNC or 3D printing could provide a better option for small production runs or even custom-built parts.

As a digital manufacturer we can help you make the right choice for your needs.