Many clients have asked me “what determines the cost of a mold?” or “how to get plastic injection molds made for low prices in China?” So I asked one of our engineers for an explanation.
The short answer is, “it all depends”. Mold tools can cost anywhere from a few thousand dollars to hundreds of thousands of dollars and the main factors are the complexity of the part, size and the number of cavities required in the tool.
If there are undercuts or screw sections that need molding, this requires additional moving sections to be added to the tool, which will add cost to the tool.
Let’s take a dashboard in a car that is produced by injection molding and look at some of the elements required to mold this type of product.
To start with, this is a relatively large part and would require a large tool in order to mold such an item. Along with the physical size, a dashboard has a complex shape with surfaces at all different angles as well as apertures and different wall thicknesses all over it. This requires a complex tool.
Every feature that cannot be produced from the mold in the straight open and shut direction will require a moving part added to the tool. Some of these moving sections are referred to as sliders, collapsible cores, and unscrewing molds. Each of these moving parts makes the tool bigger, requires more work and ultimately increases the price.
The surface finish of the part can also affect the price of the tool slightly. If the surface finish is not critical then a machined finish may be acceptable — this does not require secondary finishing thus reducing the time and cost to produce the tool. Hand polishing takes time and effort and has to be built into the cost of the tool.
Another factor when it comes to cost is the material selection. Simplified, this can be broken down into the following options:
- Rapid tooling – Aluminium or soft steel – produce between 100’s and a few 1000 shots
- Low volume parts – P20 or 718S steel – produce around 300,000 shots
- Medium volume parts – 718HH or 1.2728H – produce 600,000 shots
- High volume parts – H13 or 1.2343 – produce 1,000,000 minimum shots
(Note: volumes will depend upon polymer used.)
The basic rule of thumb is ‘a higher volume of parts will require a superior material, which costs more money’.
Many businesses choose to have their tooling manufactured in China where you can typically see a cost saving of upwards of 40% compared with a typical tool price from Europe or the USA.
Getting a tool made in China can save a lot of money on the capital expenditure, however you need to take into consideration the expenses of travelling to the factory a number of times to ensure the tool is built and runs correctly. The cost of this can run into the thousands of dollars.