A deeper
dive into Injection molding
If you’re developing a new product, you know the importance of testing your design in real-world conditions. Prototype injection molding allows you to create functional, high-quality parts without committing to full-scale production style tooling. At this level you get to take advantage of the wide array of resins available (thousands!) to help your product perform and look exactly the way you envisioned it in a time frame similar to prototyping standards.
At Onit MFG, we’ve designed our Modular Unit Die (MUD) system to help keep costs low and turnaround times quick, while providing more production-like features than many competitors. Our MUD system uses a range of special mold bases that can accommodate interchangeable core and cavity inserts, allowing us to fabricate tools faster and more efficiently. This Insert style injection molding can be used for parts up to 10” x 10” x 5”
Unlike other injection molding vendors, we won’t ask you to simplify your designs just to fit within our mold system. If it’s moldable, we’ll work with you to incorporate any features your product requires. Whether it’s slides, lifters, or other complex elements, we’ve got you covered.
For prototype tooling that includes intricate features, we often use hand-loaded inserts or specialized tool actions. While these techniques can make the process more labor-intensive, they help keep tooling costs down, making it an ideal solution for low-volume production where detailed testing is essential.
Bridge tooling serves as a critical link between your prototype and production stages, helping you bridge the gap while refining your product. In an ideal world, you’d have the budget to build each phase—prototype, bridge, and production—sequentially. But with bridge tooling, you can get the best of both worlds: the durability and customization of a production tool, while still benefiting from the flexibility and quick turnaround of prototype tooling.
This option provides the longevity, specialized gate designs, broad processing parameters, and interchangeability that a prototype tool can’t offer. It’s the sweet spot for getting everything you need without committing to full-scale production tooling right away.
Bridge tooling is a great choice for scenarios like testing a unique valve gate scheme on a single cavity before scaling up to multiple cavities. Or, if you need a tool with interchangeable core and cavity inserts to produce multiple unique part numbers, bridge tooling gives you the versatility to do so.
Simply put, bridge tooling is the most popular option for clients who need a balance between speed, flexibility, and cost-efficiency, making it the ideal middle ground between prototype and high-volume production.
Placing inserts directly into the injection mold prior to molding is often the best-case scenario for strength and cost-effectiveness. However, this method may not be ideal in cases where reworking misplaced inserts is necessary, as corrections can be more challenging.
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Get StartedOnce your business model and product are validated and ready for the next phase, production tooling becomes the key to scaling your operations. This stage is all about creating tools designed for high-efficiency, long-term production—ensuring your parts are manufactured in the most effective way possible.
By the time you reach production tooling, most companies have already worked through the initial rounds of tooling and are ready to accelerate on all fronts. Your assembly lines are set up, vendor contracts are in place, and you likely have a dedicated shop or a trusted contract manufacturer, like Onit, in place to handle full-scale production.
Production tools are made from harder steel and typically feature multi-cavity designs, ensuring they can handle higher-volume runs. The setup time to get these tools up and running is slower compared to earlier stages, but once they’re in motion, your business can move at a much faster pace. At this point, your engineering team can take a breather—after the tool validation, they can celebrate the milestone before getting back to work on your next product.
This stage also opens the door to refining advanced production techniques. We can focus on optimizing injection techniques, cycle times, foaming agents, and other variables to fine-tune your process and achieve major gains in efficiency and downstream production.
Lead Time: 45-80 days to build tools
At Onit MFG, we guide you in choosing the right methods, so you balance speed, cost and functionality.
The most significant cost factor in injection molding is the tooling, which can range anywhere from $5K to $500K+ depending on size and complexity. Managing key micro-factors can help you reduce these costs, ultimately leading to significant savings. Below are 8 important areas that influence injection molding costs:
1. Manufacturing Location: Where your tooling is made can have a significant impact on both cost and timing. At Onit MFG, we offer the flexibility of facilities both overseas and domestic, so we can help you choose what works best for your needs.
2. Mold Classification: The Plastics Industry Association (PIA) defines several mold classes, each suited for different production needs. Choosing the right class can significantly impact tooling costs.
3. Mold Complexity: The complexity of your part design can drive up both tooling and manufacturing costs. Tight tolerances, intricate details, undercuts, and inserts increase tooling expenses and can complicate production. Simplifying part designs wherever possible, such as adjusting parting lines or draft angles, can reduce costs. A thorough Design for Manufacturability (DFM) analysis with our experts can help identify and mitigate costly complexities early on.
4. Mold Cavitation: The number of cavities in a mold affects production volume and tooling costs. While adding cavities can reduce the cost per part, it increases the upfront investment. For projects with low to moderate production needs, adding unnecessary cavities can lead to excessive costs. It’s important to balance the need for more cavities with your actual production requirements.
5. Mold Material Selection: The choice of material for the mold affects its lifespan, performance, and cost. Steel molds are durable and suited for high-volume production, while aluminum molds are more cost-effective but have a shorter lifespan. The chosen plastic material also plays a role, especially if it is corrosive or requires specific properties, which can affect both tooling and maintenance costs.
6. Gate Type: The type of gate used in the mold can influence the cost, cycle time, and aesthetics of the part. While two-plate molds are standard, three-plate molds offer more precise gating for larger or complex parts, at a higher cost due to added complexity. The gate design depends on the part size, complexity, and production needs.
7. Runner System: Injection molds use either cold or hot runners to distribute molten plastic. Cold runners are less expensive and simpler but can create waste and increase cycle times. Hot runners are more complex and expensive but eliminate waste and reduce cycle times, making them ideal for high-volume production.
8. Mold Finishes: The finish of the mold directly impacts the part’s appearance. Mold finishes vary in polish and texture, with each option adding cost. While aesthetic finishes are important, they can significantly increase tooling expenses. Close collaboration with your manufacturer ensures that the finish matches the material and design needs of the part.
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Get StartedUnderstanding your tooling material options is critical to balancing cost, production volume, lead time, and part quality. Different steels and aluminum grades each come with their own benefits—ranging from faster machining and lower up-front expenses to longer tool life and tighter tolerances for high-volume production. By selecting the right material at the outset, you set your project up for success, ensuring reliable performance and the best possible return on your investment.
At Onit MFG, we understand that choosing the right injection molding resin is key to ensuring your product’s performance, durability, and cost-effectiveness. With so many material options available, selecting the best one for your specific application can be overwhelming. Our experts are here to guide you through the process, helping you choose the right resin that meets your needs—whether you're looking for high-performance materials for complex parts or more cost-effective solutions for larger volumes. With Onit’s expertise, you can trust that the right resin will deliver the results and long-term reliability your project deserves.
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Get StartedDid you know? Material typically makes up about 20-30% of the total cost of an injection-molded part. The type of resin, part design, and the amount of material needed all play a big role in determining that cost.
Check out the chart below to see price ranges for the Top 10 Thermoplastic Resins. Keep in mind, these ranges don’t include extras like additives, recycled content, or variations depending on where you’re sourcing the material.
We often classify thermoplastics as either semi-crystalline or amorphous based on how their molecular chains are arranged and how they behave under heat. Semi-crystalline materials form highly organized areas (spherulites), which gives them a defined melting point and good strength, wear, and chemical resistance, although they can show more dimensional instability. In contrast, amorphous polymers have randomly oriented molecular chains, meaning they melt over a range of temperatures, are easier to thermoform, and typically boast better impact resistance but are more prone to stress cracking.
Understanding these differences helps us guide you to the right resin for your project
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