{"id":8227,"date":"2025-08-15T14:39:40","date_gmt":"2025-08-15T21:39:40","guid":{"rendered":"https:\/\/www.fictiv.com\/?post_type=cpt_blog&p=8227"},"modified":"2025-08-15T14:39:43","modified_gmt":"2025-08-15T21:39:43","slug":"injection-molding-design-guide","status":"publish","type":"cpt_blog","link":"https:\/\/www.fictiv.com\/articles\/injection-molding-design-guide","title":{"rendered":"Injection Molding Design Guide"},"content":{"rendered":"\n

The information in this article is also available as a free e-book download.<\/p>\n\n\n\n

Download the Injection Molding Design Guide<\/a> <\/p>\n\n\n\n

The Injection Molding Process<\/h2>\n\n\n\n

Injection molding<\/a> is a fast and efficient way to produce plastic parts. The tool that it uses, an injection mold, has two main parts: the core and the cavity. These two halves of the mold come together, and molten plastic is injected into the tool.<\/p>\n\n\n\n

Once the molten plastic cools, the two halves of the mold separate and the part is ejected. Depending on the construction of the mold and the part quantities that you need, this process can be repeated tens, hundreds, or many thousands of times. <\/p>\n\n\n\n

That\u2019s just a high-level overview, of course, but it lays the groundwork for the details you\u2019ll find in this design guide. As you keep reading, remember that injection molding design is a three-part process.<\/p>\n\n\n\n

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  1. Start your design<\/li>\n\n\n\n
  2. Upload your files and get design for manufacturing (DFM) feedback<\/li>\n\n\n\n
  3. Review part samples<\/li>\n<\/ol>\n\n\n\n

    This guide covers it all. Let\u2019s get started.<\/p>\n\n\n\n

    Step 1: Start Your Design for Injection Molding<\/h2>\n\n\n\n

    Starting your part design comes with ten major considerations.<\/p>\n\n\n\n

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    1. Material Selection<\/li>\n\n\n\n
    2. Wall Thickness<\/li>\n\n\n\n
    3. Transitions<\/li>\n\n\n\n
    4. Corners<\/li>\n\n\n\n
    5. Draft<\/li>\n\n\n\n
    6. Ribs and Bosses<\/li>\n\n\n\n
    7. Tolerances<\/li>\n\n\n\n
    8. Parting Lines<\/li>\n\n\n\n
    9. Gates<\/li>\n\n\n\n
    10. Ejector Pins<\/li>\n<\/ol>\n\n\n\n

      A. Material Selection<\/h3>\n\n\n\n

      Injection molding materials range from commonly used polymers<\/a> to specialty plastics and polymer blends<\/a>. There are literally hundreds of different plastic resins available, and they each have different end-use properties and processing requirements. Plus, there can be different grades of the same plastic material, including resin types with glass fibers or carbon fibers.<\/p>\n\n\n\n

      Here is a list of some common injection molded materials. You can also use our Materials.AI<\/a> to help select the right material for your application.<\/p>\n\n\n\n

      Injection Molded Polymers<\/h4>\n\n\n\n
      Resin<\/strong><\/td>Characteristics<\/strong><\/td><\/tr>
      Acetal (POM)<\/a><\/td>Excellent rigidity and thermal stability with low water absorption and good chemical resistance<\/td><\/tr>
      Acrylic (PMMA)<\/a><\/td>Strong, lightweight, shatter-resistant, optically clear, and UV and weather-resistant<\/td><\/tr>
      Acrylonitrile Butadiene Styrene (ABS)<\/a><\/td>Strong and impact-resistant, even at low temperatures<\/td><\/tr>
      Nylon (PA)<\/a><\/td>Tough with high heat resistance, high abrasion resistance, and good fatigue resistance<\/td><\/tr>
      Polybutylene Terephthalate (PBT)<\/a><\/td>Resistant to creep and used in parts with thin cross-sections<\/td><\/tr>
      Polycarbonate (PC)<\/a><\/td>Strong, lightweight, and naturally transparent, with stable properties over a wide temperature range<\/td><\/tr>
      Polyether Ether Ketone (PEEK)<\/a><\/td>Excellent mechanical properties and resistance to chemicals and thermal degradation<\/td><\/tr>
      Polyetherimide (PEI)<\/a><\/td>Combines stiffness and stability with low flammability and low smoke production<\/td><\/tr>
      Polyethylene (PE)<\/a><\/td>Generally used for indoor applications. Chemically resistant. Includes high and low-density materials. <\/td><\/tr>
      Polyphenylsulfone (PPSU)<\/a><\/td>High toughness, high flexural and tensile strength, and good resistance to chemicals and heat<\/td><\/tr>
      Polypropylene (PP)<\/a><\/td>Good chemical resistance and won\u2019t degrade when exposed to moisture or water<\/td><\/tr>
      Polystyrene (PS)<\/a><\/td>Lightweight, relatively inexpensive, and resistant to moisture and bacterial growth<\/td><\/tr>
      Thermoplastic Elastomer (TPE)<\/a><\/td>Processed like plastic but has the properties and performance of rubber<\/td><\/tr>
      Thermoplastic Polyurethane (TPU)<\/a><\/td>Rubber-like elasticity with good load-bearing capabilities<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

      <\/p>\n\n\n\n

      B. Wall Thickness<\/h3>\n\n\n\n

      Wall thickness<\/a> affects the strength, cost, and appearance of your injected molded part. Simply put, it\u2019s one of the most important design considerations.<\/p>\n\n\n\n

      There are three wall thickness terms that designers need to understand:<\/p>\n\n\n\n