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Resources Blog Factors that Impact the Cost of Your Mold

A well-designed and well-constructed mold is one of the most important factors in producing consistent and quality Injection Molded plastic (IM plastic) parts. Your tooling cost, what you spend to produce your mold, is also likely the biggest cost driver for your project. 

So, how do you create a mold that can properly support your part’s intended use and production volume but doesn’t also price you out of the market? Knowing the factors that affect mold cost upfront, as you begin to conceptualize and design your part, will ensure your project is set up for success.

Design

As with most manufacturing projects, design is a critical driver of your production costs. This applies not only to the design of your part but also to the mold itself. Of course, some complexity may be required to achieve the desired part; however, having a critical eye to avoid unnecessary complexity is a sure way to avoid unnecessary costs.

mold mirror finishing

Part Complexity: A more complex part requires a more complex mold, which takes longer to produce and requires additional and/or more precise machining. Design decisions related to your part – the finish, for example – will affect how your mold is produced. A very smooth part will likely require a harder and more costly metal for your mold. Some specialty finishes may not be machinable, creating the need for costly hand-finishing. The need for close tolerances and the presence of design features such as holes, threading, and undercuts (which make it difficult to eject your part from the mold) are additional factors that add complexity to your part and will increase your tooling cost.

Mold Complexity: Complexities related to the mold itself, especially the size and number of cavities, can make it more difficult and costly to produce. The more cavities, the more machining will be needed to form the mold. What’s more, increasing the number of cavities increases the chance for inconsistencies in quality and finish of your final parts. This recent article from the Mold Making Technology Magazine provides some ideas on how to avoid filling imbalances and temperature variations within a multi-cavity mold.

Size of Part: A larger part requires a larger mold, which in turn requires a larger mold base. This requires more materials, more machining, more time, and – you guessed it – more money. Additionally, the larger the part, the fewer pieces can be produced with each mold. This increases the number of production cycles to make the same number of units.

As an aside, larger parts are also more susceptible to quality variations and should be tested thoroughly prior to moving into full production.

Design for Manufacturing, and Maintenance: By incorporating Design for Manufacturing (DfM) from the onset of your project, the placement of the parting line, sprues, runners, etc. is considered as part of your initial mold design. Optimizing wall thickness, draft angles, corners, and transitions can have a big impact on the success of your mold and are also considered as part of DfM best practices. Incorporating these best practices into your design can both help to avoid costly modifications once your mold has been constructed, as well as lower production costs by increasing your mold’s efficiency. 

One often-overlooked element of mold design is what Plastics Today calls Design for Maintenance, or DFM2. By considering maintenance as part of the design process, you can extend the life of your mold and save on future replacement costs. Read the full article for additional tips on how to incorporate DFM2 into your process.

CNC machining mold

Production Needs

While injection molding is most well-known for high-volume production, it can support many different output levels and circumstances. Your project’s specific production needs can greatly affect your tooling costs and should be considered thoroughly and early on in the process.

Mold Material and Lifespan: The type of metal that is appropriate for your mold will vary based on your anticipated production volume and how long you plan to use the mold. As an example, the longevity and strength requirements for your mold will vary greatly if you’re producing a one-time batch of 5,000 pieces vs. ongoing production in the millions of units. The resin you select for your part can also affect your mold material choice: a more abrasive resin may degrade softer metals, necessitating a mold made from abrasion-resistant steel.

The Plastics Industry Association (formerly known as the Society of Plastics Industry, or SPI) has issued standards to help manufacturers determine what type of mold material is appropriate for various uses. Check out our blog for additional information about these standards.

Volume and Speed Considerations: Especially in high-volume applications, the ability to turn out a high number of parts per cycle is paramount. While maximizing the efficiency of your mold will save money in production costs in the long-run, we’ve already established that a mold with multiple cavities costs more to construct and runs a higher risk of quality issues. To avoid potentially costly issues down the road, it’s critical to weigh any efficiency gains against increased tooling costs and testing requirements.

Choice of Manufacturing Partner

As it relates to selecting who will construct your mold, there are several factors to keep in mind to ensure you’re working with someone who can get it right the first time.

Experience: It likely won’t surprise you that experience can be a key cost driver in producing your mold. An experienced toolmaker understands what’s important in terms of cost and quality, is familiar with the materials and machinery that will be used, has the know-how to avoid common mistakes, and can generally save you time and money during tooling. A partner who has worked on similar projects may even be able to minimize customization to your mold by finding a similar design in their catalog of past work.

Technology: Not all manufacturers are created equally when it comes to technology. Working with a partner that employs Computer-Aided Design (CAD) and  Computer-Aided Engineering (CAE) – or, even better, one that has integrated CAD and CAE systems – allows you to really test your mold design before even starting fabrication. This enables you to identify and correct potential issues ahead of time, avoiding costly corrections once your mold has already been produced.

Team overseeing injection molding

Equipment: Based on the specifications identified for your mold, you’ll need to ensure your chosen tool shop has the right type of equipment to support your needs. In a best-case scenario, your manufacturer will have the needed tooling equipment in-house, simplifying the process and saving time and money transporting your mold to the factory prior to first article creation (and, hopefully, not back to the tool shop thereafter). According to Plastics News, as of 2020 only about 5-10% of processors had the capability to build their own molds, so working with someone who knows the market and various vendors’ capabilities can help you find the right manufacturer for the job.

Location, Location, Location: It’s not just true for real estate – location can also impact your tooling cost. A partner like Chainlogix, who has relationships both domestically and internationally, can help advise regarding the most ideal location to produce your mold and manufacture your plastic parts – not only from a cost perspective, but to ensure your finished product meets or exceeds quality expectations.

While working with a tool shop in another country can add small costs in travel and/or shipping, generally these costs pale in comparison to the savings created – both from a labor cost perspective as well as the time/quality benefits that an experienced team can bring to the project. While simulations, test reports and validations, and visual inspection via video are important steps, you’ll most certainly want to complete your first article inspection in person. A well-vetted outsourcing partner with team members on the ground in-country can assist with inspections and oversight, saving you the time and expense of travel.

Conclusion

With so many factors to keep in mind, working with a reliable and experienced team will create a smoother project and lower your tooling costs. Chainlogix can help you ask the right questions, scope your project thoroughly from the start, and produce the most cost-effective mold for your project. Once tooling is successfully complete and the output has been thoroughly tested, you can enjoy the low-cost production that has made injection molding such a universally popular production method.

Want to learn more? Find additional information about producing IM plastics and choosing a manufacturing partner on our website.