Plastic injection molding is such a dynamic and powerful manufacturing technology that the question isn’t how much does a plastic mold cost—it’s how much does a plastic mold cost that achieves your unique goals?
Your desired production volume, the size of your part, the level of precision you need, and the material you choose will all affect the cost of your mold and the final unit cost of your part. And so, while there’s not one straightforward answer to how much a mold will cost you, we can help you think through some of the questions you’ll have to answer as you design your mold.
How Complex Does Your Design Need to Be?
It goes without saying: the more complex your final part, the more it will cost to manufacture. A simple design may cost no more than $10,000, but intricate molds may cost you hundreds of thousands.
Fortunately, talented DFM engineers can help you optimize your design to achieve all the functionality you require with as simple (and affordable) a mold as possible. To do so, the engineers will primarily optimize your design along these five components.
1. Parting Line Placement
Plastic injection molding involves forcing material into two halves of a mold—the cavity and the core—and so a seam, or “parting line,” is inevitable. Placing these lines on curved or complex surfaces will dramatically increase your costs, so a skilled engineer will help you find the optimal place to put them.
2. Smooth Core Extraction
After your material is injected, the core must be extracted before you can remove each part from its respective cavity. It’s therefore crucial to eliminate undercuts, protrusions, and other complications in your design that can obstruct or even prevent a smooth core removal.
3. Cavity Depth
The deeper your cavities, the larger and more complex your mold will also have to be. Fortunately, the proper orientation and design of each cavity can sometimes yield the parts you need with less depth—and therefore at less total cost.
4. Moving Steel Shut-Offs
With shut-offs in your mold, you can create more complex parts without post-injection machining. These shut-offs increase short-run costs, but, since they also reduce the wear on the mold, may save you money in the long run.
5. Gate Locations
The bigger the gate, the more it can stress and distort your mold. It’s therefore critical to carefully calibrate the gates so that they are as small as possible while still permitting your material to fill the mold before hardening.
What Manufacturing Volume and Timeline Do You Need?
As if all the preceding design elements aren’t enough to consider, you also have to factor in your timeline and your production target when designing your mold.
If speed is important to you, you might want to reduce cycle times with the addition of a complex cooling system. This added cost will make sense if you need to do many runs in a short period of time. A similar calculation must be made about the number of cavities you choose for your mold. The greater the number of cavities, the higher your upfront costs—and the more parts you’ll have in a short period of time.
Your production volume should also influence your decision about how complex—and how costly—a mold you want to design. Heated runners, sprues, and valve gates will all make your mold more expensive—but also reduce the material you waste with each run, savings that will add up in a long production run. An engineer can help you do the cost-benefit analysis of each design component.
What Material Will Achieve Your Goals at the Lowest Cost?
Again, it’s important to remember that there’s not one single material that’s the best for injection molding—there’s only the material that’s best for you. To figure out which material that is, you have to be as clear as possible about your goals, your objectives, and your constraints from the start.
That’s because your choice of material will affect other design decisions you need to make. Certain materials require specific heating or cooling processes to accompany the injection, which can dramatically influence the optimal mold design. So, if you want to make the most of one of these materials, you need to incorporate the material’s constraints into your mold design from step one.
Ready to leverage the full power of plastic injection manufacturing by optimizing your design? Talk to one of SigmaPro’s engineers today! Together, we’ll get you the mold—and, more importantly, the part—you need with no stress and no wasted cost.
