How to Design and Produce Injection Molded Parts For Your Medical Device

From toys and automotive parts to cell phones and mechanical components, injection molded parts can be found in many of the objects we interact with each day. In fact, it would be difficult to picture our world without them. And the same goes for medical devices, which are often designed with injection molded parts in mind.

Injection molding is a common manufacturing process in which molten materials (such as plastic and metal) are forced into a mold to create a three-dimensional part or product. But not all injection molded parts are created equal. Which means that if you are developing a new medical device, you need to cultivate a basic understanding of this process. Not just that — you must develop a strategy for designing and manufacturing the right injection molded parts for your product.

The Genesis of Modern Injection Molding

An American inventor named John Wesley Hyatt developed injection molding in 1868. Building on the preexisting work of a German chemist, Hyatt developed a plastic material he called celluloid. The first commercial injection molding machines and plastic materials were quite limited but they gave birth to an entire commercial industry.

Today, injection molding equipment and processes are much more refined and diverse. It’s now possible to produce a wide range of parts and products with a high degree of accuracy and very little waste (fewer than four defects per 1 million parts produced).

Developing a Strategy for Your Medical Device’s Injection Molded Parts: MindFlow’s Four-Step Process

Your medical device company is responsible for the quality of your finished products. That’s true whether you physically manufacture your device or contract with third-party suppliers. And as with any design and development process, injection molded parts take time and effort. There are no shortcuts to a good outcome.

And the stakes are high. Molding a medical part requires a different level of cleanliness, care, and documentation. Get it wrong, and you could undermine the quality, safety, and efficacy of your medical device.

If you haven’t previously managed the task of producing injection molded parts, you might not know where to begin. At MindFlow, we have the experience and expertise necessary to guide medical device companies like yours through this complex process from start to finish.

Here’s how.

Step One: Injection Molded Part Design

First things first. We start by designing your part so that it meets your product’s needs — in addition to being effective, safe, user-friendly, and attractive. Of course, that’s standard product design fare. However, designing injection molded parts involves a number of unique considerations, including:

• Plastic part design techniques. These industry-standard techniques incorporate strategic, functional, and technical requirements as well as stress-reduction best practices.

• Material selection. Each individual material is best suited to different applications. Selecting the right material for your injection molded part can spell the difference between success and failure.

• Design tolerances. Depending on your product’s unique specs, application, and environment, you will need to anticipate and define a set of specific manufacturing tolerances for your injection molded parts.

Step Two: Design Analysis and Risk Reduction

Once we’ve landed on a preliminary design for your injection molded parts, we run a handful of analyses. The following inquiries ensure the design is moldable, will function as expected, and meets required safety parameters.

• • Stress analysis. An injection molded part’s design determines the level of stress (or weak areas) that might be found in the finished product. To minimize the presence of stress, we run a Finite Element Analysis (FEA), also called a stress analysis. To perform an FEA, we run a design through a number of simulations that demonstrate a designed item’s likely response to real-world conditions. In doing so, the FEA uncovers potential issues, such as weak spots and other design defects.

• Draft analysis. In a draft analysis, we simulate the process of removing the finished part from the mold cavity. The purpose is to double-check that each of a part’s surfaces is designed so that it can easily withdraw from the mold without getting locked up.

  

• Preliminary mold flow analysis. A mold flow analysis uses specialized software to simulate the movement of specific plastics within a designed part. This important analysis is critical to creating an accurate mold. Specifically, a mold flow analysis sheds light on possible trouble spots within your design so that you can correct them prior to moving into tooling and manufacturing.

Based on the results of our analyses, we refine your injection molded part’s designs and finalize a complete set of part specifications.

Step Three: Identify the Right Injection Molder

Selecting the right plastic part mold maker is yet another key decision point in the injection molded part development process. For one thing, plastic part quality ranges from manufacturer to manufacturer. Additionally, not all injection molders have the same strengths and capabilities.

For example, as a medical device company, you wouldn’t want to partner with an injection molder that specializes in making garden furniture. Likewise, if you are planning to produce a tiny part with extra-tight tolerances, you shouldn’t select a supplier that usually produces larger items.

Molding a medical part requires special care and attention to detail — not to mention an added layer of paperwork, documentation, and validation. We screen injection molders with this in mind. For example, we won’t even request a quote from a supplier that doesn’t have a certified Quality Management System (QMS) in place. In addition, we qualify vendors to confirm that they are truly capable of producing the parts in question according to our stringent specifications. Many suppliers are willing to take on projects on the extreme outer limits of their capabilities. We source injection molders whose capabilities are ideally suited to your project.

After identifying a handful of appropriate vendors, we put together a package of quotes for your team to review. After that, it’s up to you to select the best vendor(s) for the job.

Step Four: Transfer to Manufacturing

Once you’ve selected a supplier, we’ll continue to act as a mediator throughout the manufacturing process. Transparent communication and aligned expectations are critical. At this stage, our goal is to keep you and your supplier on the same page — and on the right track — as you take your injection molded part across the finish line.

Want to learn more about how MPE (Formerly Mindflow) can guide your medical device company in successfully designing and producing injection molded parts?