If you are making your parts via plastic injection moulding, be prepared to bear the high initial upfront costs of making the hard tools (in aluminium or steel). The tooling costs can be several thousand pounds (depending on complexity), however, the part costs range between a few pennies to a few pounds, making the high initial investment worthwhile. While it is a given that tooling will be costly, there are several ways you can reduce its costs, here’s how:
1. Use Aluminium Tools for Lower Volume Runs and Prototypes
Rapid plastic molding tools are made from either steel or aluminium. Steel is often considered the ideal mould material, but it is also more expensive due to the longer life span it offers (which is typically double the life span of aluminium tools at HLH). If the mould will just be used for lower production runs and prototypes, consider getting it in aluminium, as it is a more cost-effective choice.
2. Only Specify Tolerances When Necessary
Tighter tolerances require better mould definition, which drives up the CNC machining costs associated with tool making. If there’s room for flexibility in a part’s tolerance, avoid defining tight tolerances. Only specify tolerances when necessary. If a specific tolerance is not defined on the technical drawing, the moulds are machined to typical CNC tolerances of ± 0.500 mm (0.020”). This is sufficient for most non-critical features.
3. Modify Moulds Instead of Tooling New Ones
If a part goes through several iterations before a workable design is finalised, you may be able to cut costs by modifying the existing moulds rather than tooling new ones. This eliminates the need for multiple rounds of tooling. As the process of creating a new tool is the main cost driver in injection moulding projects, doing so often reduces development costs drastically.
4. Eliminate Undercuts
Undercuts are typically used to mold vertical threads, holes for buttons, and snap-and-latch features (found in many medical devices). To save on costs, avoid undercuts where possible, as they’ll add to the complexity and cost of the tool.
5. Remove All Text and Lettering
Adding text to your injection molded part can significantly drive up cost because it requires additional mould machining time. To reduce costs, remove all text and lettering. If text is necessary, choose a more cost-effective text-adding solution, such as painting or silk screening.
In conclusion, keep the designs of your mould simple. Injection mould tools are often made for long-term use, so its also vital to plan your designs with the future in mind.