How expensive is injection molding? A complete answer to this question needs to address a number of different engineering factors, consider the cost advantages of offshoring versus reshoring, and pay careful attention to hidden factors that can inflate the cost of your injection molding job.
In this article, we walk through each of these factors to provide a comprehensive guide to injection molding costs.
Factors That Influence Injection Molding Costs
The most fundamental factors affecting the cost of an injection molding process come from the design itself:
- Material selection: an injection molded part should employ a plastic that is aligned with the part’s required characteristics, with a direct impact on unit costs.
- Design complexity: a more intricate design may require more complex molds and longer machining time.
- Tooling expenses: important tooling expenses for injection molding projects include mold design, fabrication, and maintenance.
- Production volume: tooling expenses mean that the overall batch size can have a strong impact on per-unit costs, and injection molding projects tend to exhibit substantial economies of scale.
- Quality and tolerance requirements: more strict tolerances and quality standards can drive increased costs due to an increased need for inspection and rework, higher scrap rates, and potentially slower production times.
Hidden Plastic Injection Molding Costs
Beyond the direct cost drivers discussed above, it is crucial to consider less obvious factors that may be baked into the cost of an injection molding project. For example, secondary post-molding operations like assembly, finishing, and packaging will add to the project cost.
More broadly, any injection molding operation will ultimately have to pass along its overhead expenses, including energy, labor, and facility maintenance. While these costs may not appear on the invoice, working with an efficient, forward-thinking injection molder is ultimately an important contributor to cost reduction.
Finally, lead times and supply chain costs are crucial factors to consider. A small marginal cost savings can result in far greater lost revenue if it leads to a lost market opportunity, inflated transportation costs, or a less reliable supply chain.
How can I generate a more cost-effective design for injection molding?
When designing your injection molded part, it is important to consider the principle of “design for manufacturability” (also called “design for manufacturing”), optimizing part design to minimize production costs relative to requirements for form, fit, and function.
Of course, a comparatively expensive part may be appropriate if it delivers strong value in its end-use case. But in many cases, an arbitrary or purely aesthetic design choice may lead directly to a more complex mold and needlessly inflated cost. Striking the right balance of cost and capability for a part requires a value-engineering approach to weigh the costs and end-user value of various design features.
We recommend working with your injection molder to evaluate the manufacturability of your design. Some helpful tips include:
- Align raw materials carefully to the part’s required characteristics. An over-specified material may cost many times more than a more fit-to-purpose grade of plastic.
- Machining time will be largely influenced by the size of the required press and the required wall thickness. In many cases, unduly thick walls inflate cycle times.
- Carefully evaluating the need for certain design features may increase the need for rework or other quality control steps that inflate costs.
- Identify any design features that preclude automation and thus inflate operator costs. For example, manually cutting runners to gate individual parts can drive up labor costs per unit. By switching to a self-degating design, production may be substantially streamlined.
A hands-on injection molding vendor should be willing to work with you to optimize manufacturability for your design while maintaining the required quality and functionality. In many cases, subtle changes to characteristics such as wall thickness can make an outsized difference to overall costs. Taking the time to solidify a cost-optimized design can drive savings both for the project at hand and future production runs of the same part.
Onshore Versus Offshore Injection Molding Costs
Overseas injection molders may be able to offer lower labor rates, overhead, and material costs compared to domestic manufacturers. But it’s crucial to consider additional costs and risks associated with offshoring plastic injection molding projects:
- Transportation costs may offset some of the cost advantages of reduced labor costs, and increased lead times make adapting to quality issues slower and more costly. A domestic producer can commonly offer shipping in the 2-day range, and production can be quickly corrected if quality issues are detected when the first batch arrives. This situation looks far different if multiple cargo ships are already en route after the initial batch arrives after an 8-week lead-time from an overseas producer.
- Lack of intellectual property protections in many world geographies may put valuable company design secrets and know-how at risk, with few options for remediation in case of intellectual property (IP) theft.
- Communication and coordination costs can be elevated when working with a supplier from the other side of the world. In our experience, timely communication and opportunities for in-person collaboration and oversight play an important role in ensuring a successful project.
For a deeper analysis of the true costs of onshore versus offshore manufacturing, we recommend the work of the Reshoring Initiative.
Future Trends in Injection Molding Costs
In our work with plastic injection molding clients across a variety of industries, we have noticed a sharp increase in the demand for parts made using recycled materials. While we are typically able to accommodate this need using a range of post-industrial (and increasingly post-consumer) materials, the underlying costs have shifted alongside the recent growth in sustainability concerns.
In many ways, the plastic injection molding industry was one of the original industries to offer more sustainable, recycling-based manufacturing options. Scrap plastics have been widely available for decades; in the past, they offered a lower-cost alternative. Today, with increased demand for recycled materials, these materials often command a price premium compared to newly manufactured materials.
How Molding Dynamics Helped One Client Dramatically Reduce Production Cycle Times
When one telecom industry client presented a new fiber optics equipment part design to Molding Dynamics, our team quickly spotted some serious manufacturability issues. In this case, the design employed 86 different nuts and bolts, each one requiring manual assembly and increasing cycle times.
Molding Dynamics worked with the client to understand the part’s requirements. Our analysis suggested that the design would perform as intended with a dramatically reduced number of pop rivets. This change reduced the cycle time for this project from about one day per part to about ten minutes.
Conclusion: A Trusted Supplier is the Best Way to Control Costs
For all of the reasons discussed above, understanding the full array of factors driving the ultimate cost (and long-term value) of an injection molding job is rarely straightforward. But there are proven best practices for minimizing waste and aligning costs closely to a given part’s form, fit, and function requirements.
Ultimately, the best way to reliably control costs is to work with a trusted supplier who is committed to cost transparency and willing to work with you to optimize manufacturability.
Interested in working with Molding Dynamics to manufacture your injection-molded part? You can request a quote here.
