1. Use The Right Material And Not Too Much Of It!
Which material you choose has a significant impact on your costs. The material you initially select is not always the most economical.
A rule of thumb: the more specialized the material, the higher the price is likely to be. So don't reinvent the wheel and use materials that have a proven track record for similar parts and applications.
- To find suitable alternatives, compare different materials and their impact on the process in advance, using good simulation software.
- Use less pure material
Obviously, you don't want to fill parts massively. Instead find the lowest wall thickness that will allow you to save material while achieving your functional goals. A simulation helps you to check the influence of wall thicknesses on the results. This will also help you to reduce cycle times (see below).
- In addition, check whether you might be able to stretch your material by using fillers. In this way, you reduce the consumption of the possibly expensive desired material and also reduce the tendency to warpage.
2. Time Is Money! Shorten The Cycle Time
The time from closing the mold, to injecting the melt, to cooling the material, to demolding and ejecting is your cycle time. The shorter your cycle time is, the more parts you can produce in the same time. The bottleneck here is usually the cooling time after which the part can be ejected. To minimize the cycle time, you need the part to cool down as quickly as possible.
The following things can help:
- An optimally designed temperature control system that cools the mold evenly and efficiently and doesn’t cause hot spots. Test and optimize your design using simulation software, to avoid surprises and find better solutions.
- Using inserts made of highly conductive alloys at specific locations in the mold
- Good material selection: Some materials can be injected at lower temperatures, with less pressure, or faster. This saves injection time and, as a nice windfall effect, energy and machine size.
- The material of the mold also affects the cooling time of the plastic. For smaller batch sizes, you can choose aluminum if necessary. Aluminum cools faster than steel, but is more susceptible to damage.
3. Eliminate All Unnecessary Cosmetic Features
This may seem obvious, but try to avoid unnecessary complexity in surface structures, whenever possible. Use draft appropriately. Often expensive rework is necessary otherwise. You can also create grip, for example, through other ergonomic shape adjustments. You can even save on something as indispensable as serial numbers: just leave out the serifs.
4. Avoid Undercuts
Areas that can't be demolded in the main demolding direction require sliders, which are very costly. You can save this money, with good part design. You may also be able to use an elastic material to provide a solution for ejection.
5. Invest Time In The Beginning Of Your Process, Not In The End: Shrinkage And Warpage Should Be Considered In Advance
Every material shrinks as it cools, and often it warps because it rarely shrinks uniformly. Good mold makers naturally take this into account when building the mold. However, they will not always hit the bull's eye. Then, expensive mold corrections are necessary.
With a good simulation solution, you can optimize the geometry, the gating situation or process parameters in such a way that the warpage is minimized from the start. Although sampling is still necessary, the remaining corrections will usually be more minor, and the number of correction loops is significantly reduced.