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When to move your custom project to injection molding  

Time is a precious commodity in the working life of a product designer or engineer. When you get to a certain point in your product development cycle and need to find the right vendor to produce your custom parts, it can be a long and arduous process. This process involves contacting suppliers, emailing the CAD drawings, waiting for quotes, benchmarking against other suppliers and then managing the process until you receive your parts.

All this time-consuming and energy-sapping hassle is eliminated by Xometry, a technology company established in 2014. As a manufacturing platform, Xometry plays the role of matchmaker, or, what is commonly known as production-as-a-service. The Xometry Partner Network has over 2,500 vetted manufacturers across the US – combined they have over 8,000 machines, 13 manufacturing capabilities and the ability to manufacture using 200 different types of material. Xometry leverages its knowledge and experience with its network to select a manufacturing partner that best matches the designer’s requirements and lead time.

This is all done instantly, too. Xometry’s Instant Quoting Engine^SM will analyze the uploaded CAD file and provide DFM (design for manufacturing) feedback, lead times and pricing in real-time. For further ease of use, SolidWorks and Autodesk Inventor users can do all of this directly inside their CAD environment using Xometry add-ins.

“But we are not just a computer input and output service. As part of our kick off process we have live engineering support,” says Gregory Paulsen, Xometry’s Director of Molding and New Manufacturing Technologies. “For instance, when I talk to a customer at the start of a project, I very often ask them the same question twice: when do you need these parts by? The first time they say ASAP and the second time you often get a different and more detailed answer. From there, we are able to much better understand where they are in the product development cycle and can recommend a solution that fits them at their current stage of progress.”

Molded parts can be both highly detailed and highly functional

Not affiliated with one particular brand or technology, Xometry approaches each project with an open mind, focused on understanding the designer’s needs and helping them identify the right manufacturing solution. For instance, while a customer may have come to Xometry to 3D print their project, a consultation may reveal that the best process for the job is actually plastic injection molding.

Mostly associated with the mass production of end-use parts, injection molding is a process that, simply put, involves injecting molten material into a mold cavity, where it cools and solidifies to the configuration of the cavity. This means that the process involves not only the design of the product but also the mold or tool, which is machined from metal. Although the tooling cost could look daunting at first, the benefits of this process include identical, high precision, repeatable parts with tight tolerances that can be made rapidly from a wide material selection.

A set of parts with a snap fit for assembly

Using its manufacturing network, Xometry can provide the cost-effective production of parts from 100 to over 10,000. This makes injection molding ideal for applications ranging from prototyping to production and as a bridge to production tooling.

“When we look at the requirements of a job, there are two things that usually scream at me that could make it suitable for injection molding,” says Paulsen. “The first is if a customer wants a higher quantity and the second is if they require some sort of cosmetic finish. With molding you can get a better cosmetic finish from the get-go whereas with almost all 3D printing processes, finished parts need some amount of post-processing work,”

“I’ve seen volumes of 50 units that can actually save money, look better and perform better with injection molding than with 3D printing because the part can benefit from the exact thermoplastic material and the mold provides a better surface finish. Additionally, the scaling is there too because the principal advantage of injection molding is the ability to scale production,” adds Paulsen.

However, to reap the benefits of injection molding, the product has to be designed to suit this manufacturing process. Xometry can provide assistance here too in ensuring the part is easily moldable while meeting the customer’s structural and cosmetic requirements.

“With injection molding, you’re also making the tool and that’s why there’s a much higher consideration for getting the design right. We will often spend another 24 to 48 hours working with a customer to add a rib here or a draft angle there to ensure that the part can be easily removed from the mold. There may be an iterative cycle of design changes before we move further into the process,” describes Paulsen.

For instance, Bruce Kyles, an engineer at Thermaco, a North Carolina-based technology company specializing in the field of oil and grease extraction from wastewater, contacted Xometry with an injection molding requirement. While having used its Xometry’s Instant Quoting Engine^SM for a number of 3D printed prototype parts in the past, this was its first endeavor in low volume tooling. The requirement was for four parts: one of which was a color-match blue ABS part with mold texturing and the remaining three were glass-filled polypropylene non-appearance parts for an assembly.

The cosmetic side of Thermaco’s part, showing mold texturing and text

Upon receiving their quote, Xometry went over Thermaco’s material choices, with Kyles clearly defining the color and texture needs of the project. “I was duly impressed with the array of injection molding materials that Xometry offered, which is important to me as an engineer,” comments Kyles.

The non-cosmetic side of Thermaco’s part, showing coring, ribs, and ejection locations

From there, Xometry provided a detailed DFM report for his parts and in this instance, Paulsen and his team highlighted its parting, ejection, and gating approach as well as some concerns on draft and texturing.

With these changes made and the design ready for production, Xometry managed the entire process, providing Kyles with regular emails about the part’s journey. “Because of a successful kickoff, we had a very smooth production and provided him with the parts he needed on time,” says Paulsen.

The result is not only high quality, cost-effective and timely custom parts but by partnering with Xometry, Kyles gets to reclaim the time and effort it would have taken to source and manage this process internally. As a new breed of sourcing partner offering production-as-a-service, Xometry is fast becoming a very appealing proposition for engineers and product designers.