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Custom Plastic Injection Molding

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Ultem Molded Parts

Very intricate PEI molding

Two station vertical insert molding

ABS moldings

Enclosures

Plastic injection molding provides tight tolerances and repeatability and is ideal for high volume production of plastic molded parts. Injection molded plastic parts can be manufactured using a wide range of thermoplastic polymers, resins and elastomers, making it an ideal and cost-effective process for various industries and applications. 

Injection molded parts are created by pouring raw plastic resin into a hopper, then heating the resin and injecting it into a custom mold. Pressure is used accommodate shrinkage and once the plastic molded part has fully cooled, the mold is opened, and the parts are removed. Because of the tight tolerances, plastic injection molding is a suitable option for both standard and intricate plastic molded parts of all sizes.

Stack Plastics specializes in custom plastic injection molding (or "moulding") and provides services for industries  including aerospace, medical and consumer products. With our precision injection molding capabilities, we can create thousands or millions of identical parts. From simple to complex designs for parts between 0.01 g and 10 oz., we deliver precision plastic injection molding to match your unique specifications.

Innovative Plastic Injection Molding Techniques

While the basic process of plastic injection molding is relatively simple, involving only a handful of key elements, mastering the process at the level that Stack Plastics has is considerably more difficult. We think of our specific methods as "scientific molding"—we experiment with different variables and collect data that helps us optimize our injection molding processes. This helps us achieve maximum efficiency, provide superior quality custom plastic injection molded parts, and maintain perfect repeatability for parts in quantities in the millions.

Custom Plastic Injection Molding Capabilities

Plastic molding involves several processes including injection molding, overmolding, insert molding and micro molding, each of which produces a different result. Selecting the right process for your application depends on part size, dimensional tolerance and material, and whether the part requires material bonding or interior strengthening.

  • Overmolding: involves combining two or more elastomer or plastic molded parts to fabricate a single component. This process can produce tight tolerances and is typically used to create soft-grip surfaces, improve ergonomics or create color contrast for aesthetics.
  • Insert molding: an injection molding process where elastomers, thermosets or thermoplastics are molded or formed around metal and other non-plastic parts.
  • Micro molding: a tight tolerance process used to create incredibly small plastic molded parts. This process is frequently used for the fabrication of intricate medical and surgical devices. 
  • and more

Stack Plastics has been in business for over 20 years and has experience working with various plastic injection molding methods. Our experts can help you determine which injection molding process is best based on your product design and application requirements.

What Are Design the and Engineering Considerations for Plastic Injection Molding?

Since each plastic molding process is different, it is important that your design and tolerance requirements are compatible with injection molding and that you understand any limitations associated with the process. Retooling can be costly and slow down your production time, so you want to make sure you address any design concerns in the beginning to prevent issues during production.

With more than 20 years’ experience in plastic injection molding, we know what works and what doesn’t. We can provide design and engineering advice, as needed, to help make manufacturing our customers’ products faster, more efficient, and less expensive. We can review your design and advise certain changes that will allow us to produce your plastic injection molded parts or components more efficiently, more quickly, and with better quality, without sacrificing performance.

If no such changes are possible, Stack Plastics can add more levels to our quality inspection processes, to ensure that your injection molded parts will meet our high standards for quality, and yours.

Is Clamping Force a Determining Factor in Injection Molding Design?

Clamping force relates to the amount of pressure that is required to close a mold. Having the right amount of force is essential not only for holding the mold closed but for ensuring the force of the molten resin being poured does not cause the mold to come apart. Since each resin can generate a different amount of force, it is also important to take injection molding clamping force into consideration when selecting a material. The size of your die also determines the required tonnage of the press that is used during the injection molding process.

Stack Plastics understands that each die and plastic material has different clamping force requirements and that appropriate force is critical to achieving high quality plastic molded parts. Contact us to discuss your design and tooling specs and we will work with you to determine whether you should use injection molding or a different plastic molding process for your application.

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How Do I Select the Right Plastic Materials for Injection Molding? 

People often wonder what type of plastic materials can be used for injection molding.  Before selecting a material, you need to consider the performance requirements of your final product. This includes hardness, durability, heat and chemical resistance, and other factors determined by the use and operating environment.

Stack Plastics works with a wide variety of thermoplastic polymerselastomers, and resins to create the perfect injection molded parts for your needs. Our expertise with standard specialized materials and exotic resins enables us to produce plastic injection molded parts and components to match the precise specifications of any project. The injection molding plastics we work with most often include, among many others:

  • ABS provides high resistance to heat, chemicals and impact and has a tensile strength between 6,1000 and 6,500 psi. The excellent flow characteristics and high versatility of ABS makes it an ideal choice for plastic injection molding applications.
  • Polycarbonate is a strong thermoplastic polymer that has high stiffness and impact strength, and excellent strength retention at high temperatures.  It is easy to work with and can be used for a variety of plastic molded parts.
  • PEEK is highly versatile and is commonly used to replace metal. It provides high chemical resistance at elevated temperatures, withstands autoclave sterilization, and has high hardness, stiffness and strength.
  • Ultem is similar to PEEK but has lower impact strength and temperature properties. Despite this, it is one of the most dimensionally stable thermal plastics available and is highly resistant to environmental stress and cracking.

Contact Us for Custom Plastic Injection Molding

Stack Plastics are the injection molding experts providing a range of injection molding solutions including overmolding, insert molding and more as well as tooling and design assistance. Request a quote to get started on your custom plastic molding project, or contact us to learn more about our injection molding capabilities.