Prototype Injection Molding
What is Plastic Injection Molding?
Plastic injection molding is the process used to create the plastic parts that are used in most of the products you use every day. Plastics are used in a wide range of applications, from simple buttons to complex implantable medical devices visible under x-ray and everything in between. This is why plastic resin manufacturers offer over 60,000 grades of plastic. Plastics are well suited for manufacturing due to their relatively low cost per part, part consistency, and ability to fabricate large numbers of parts quickly.
The basic principle of injection molding hasn’t changed substantially since it was first patented in 1872. Over the last 150 years, innovations have involved the addition of electronic control and automation of the molding process. Plastic injection molding consists of two essential parts: an injection unit and a clamping unit. The injection unit is where the plastic resin is added to the machine, and heat is applied to change the plastic resin to a flowable liquid state. The clamping unit contains the mold.
The mold is a machined assembly that contains the part detail to be molded. Once the mold is split into two sections, it allows the clamping unit to open and close the mold as needed. In order to mold a part, the clamping unit closes the mold, and the injection unit pushes the liquid plastic into the mold. The plastic quickly cools. The clamping unit opens the mold, and the part is ejected. The process then repeats.
Prototype Injection Molding Process
When developing a new product, it is typically necessary to fabricate a prototype injection mold to perform functional testing of the product. There are a couple of key reasons engineers utilize prototype injection molding rather than production molds. A production mold typically takes 2-3 months to fabricate. It would be a very long time to wait for parts. Prototype molds can be fabricated in as little as one week, allowing engineers to proceed more quickly with testing.
What TypesTypically, engineers discover during testing that their part design needs changes in order to meet product requirements. In that case, a mold iteration is needed. Prototype molds are faster and easier to iterate due to the softer metals that are used. Iterations are typically completed within a few days. Production molds are made out of hard steel. While mold iterations are possible in production molds, they tend to affect the mold’s life negatively. Ideally, the part design is finalized when the production mold is fabricated, and no iterations are needed. This allows the production mold to meet the full life cycle and optimize the investment.
What Types of Materials are Used in Injection Molding Prototypes?
Materials that are compatible with plastic prototype injection molding are known as thermoplastics. Within thermoplastics, there are approximately 70 different types. Commonly known types include polycarbonate, polypropylene, nylon, etc. Each thermoplastic type has a set of unique characteristics and usage scenarios that distinguishes itself from other types. Material selection for a part can be challenging because the engineer must be familiar with the 70 different types and know which type to select for the particular application.
For example, polycarbonate would be an ideal type to select if a part requires transparency and high strength. Once the type is selected, the next step would be to select a particular grade of material. Websites such as matweb.com and ulprospector.com are helpful plastic resin databases that make it possible to select a particular grade.
Continuing to use the polycarbonate example previously discussed, we find that there are over 6000 grades of polycarbonate available. Selection of a particular grade requires a review of the part design and its product requirements such as mechanical, cost, tolerances, environmental conditions, assembly, sterilization, regulatory, aesthetics, and any special requirements.
For example, this polycarbonate part may be a relatively thin wall part requiring a high melt flow grade. It could also be a medical part requiring gamma sterilization, requiring an additive to prevent color shift. These requirements can be searched on matweb.com and ulprospector.com to compile a list of the grades that meet those requirements. The final step would be to contact the distributors of those material grades for pricing and availability, then place an order for the selected grade of polycarbonate.
Arburg Molding Machines
Protoshop uses only Arburg injection molding machines, a high-quality brand built in Lossburg, Germany commonly used in production injection molding. Our goal is to replicate production molding as closely as possible and using a production quality injection molding machine is critical. Testing and development using a high quality prototype part that closely replicates production makes transfer to manufacturing an exercise rather than a step involving risk.
Complex Part Geometry is Our Specialty
We specialize in challenging molding applications. We have successfully designed and fabricated thousands of prototype molds and don’t reject complex part geometry like other prototype molders. If a part is moldable, we can do it.
Hear From Our Satisfied Customers
We work regularly with Protoshop on a variety of complex components for various projects. They are an excellent company to work with providing a vast history of experience to help their clients optimize designs. We have worked with them on microfluidic chips with small feature sizes, over molded sealing parts and flexible parts. They have experience working with many materials including Topas (COC), polycarbonate, TPE, PE, and PP. I would highly recommend reaching out on your next project. The team is very responsive to design changes as well as delivering to tight timelines. They also offer design advice and best practices which have helped expedite design iterations.
- Garrett G.
Dylann and team are wonderful to work with. On multiple programs, they have delivered quality product in a matter of days. The design for moldability support is unparalleled to ensure your part is ready to order.
- Chad F.
Having worked with Dylann and Jimmy prior to Protoshop, I knew the immense level of expertise they have for this business and it proved to carry through. They are honest straight shooters that will help guide you and find the best solution for your molds. We needed a mild that could be versatile and allow us to easily change out one side of the design. Dylann helped us come up with an approach that will allow us to continuously iteration the design without having to make a whole new mold every time.
- Stacie D.
Dylann at Protoshop is excellent to work with: highly responsive and proactive. This is possibly the fastest, high-quality work I have ever witnessed. 1 week…from payment (start) to delivery (after CTQ measurements at Protoshop), we had 100 test samples of a component we intend to use in high volume manufacturing. Thank you for the tremendous work! I would highly recommend Protoshop, and will plan to use Protoshop services in the future.
- Wendell W.
Great experience with Protoshop. Dylann is extremely responsive and great to work with. Very fast turn-around. Worked with us on our order to get what we needed. I was able to drop ship 3d printed parts from another vendor to Protoshop to have them match-fit and incorporated into our tooling. I will be back again.