Unlocking DIY Plastic Injection Molding: Craftsmanship in Your Own Workspace

Image of 3D injection molding machine

Injection molding has long been the linchpin of manufacturing processes, giving birth to the vast array of plastic products we encounter daily. Yet, this traditional method, reliant on CNC machined metal molds, presents daunting cost barriers and extensive lead times for those seeking low-volume production or prototyping. Enter 3D printed injection molds, a solution that offers agility and cost-efficiency. This innovation empowers engineers and designers to craft, test, and refine molds at a pace unparalleled by traditional CNC machining, all at a fraction of the cost.

Harnessing the power of a stereolithography (SLA) 3D printer, DIY injection molding becomes an accessible reality. In this guide, we embark on a journey into the world of DIY injection molding, equipping you with the essential tools and insights to unleash your plastic molding capabilities in-house.

The Art of Injection Molding with 3D Printed Molds

Establishing your DIY plastic molding setup necessitates an initial investment of both time and resources. However, this cost is typically dwarfed by the expenses associated with a single metal mold. The eventual time and cost savings make this endeavor a worthwhile pursuit once your operation is up and running.

The Essentials: What You Need to Begin

To commence your DIY injection molding adventure, the following components are indispensable:

  1. A high-performance desktop SLA 3D printer. This printer excels at crafting precise molds with impeccable detail and a smooth finish, ensuring the production of high-quality molded parts.
  2. A 3D printing material capable of withstanding the temperature and pressure exerted during the injection molding process. We recommend the following materials:
    • Rigid 10K Resin: An industrial-grade, highly glass-filled material that exhibits remarkable strength, extreme stiffness, and thermal stability (HDT of 218°C @ 0.45 MPa).
    • High Temp Resin: Designed for high molding temperatures, this material boasts a heat deflection temperature of 238 °C @ 0.45 MPa, making it ideal for certain injection molding applications.
    • Grey Pro Resin: While it has a longer cooling time due to lower thermal conductivity, Grey Pro Resin offers flexibility and durability, particularly suited for certain mold applications.
  3. A benchtop injection-molding machine, with various options available depending on your budget and requirements. Consider brands such as Minijector, Morgan, APSX, or Micromolder for different features and capabilities.
  4. Plastic pellets suitable for your intended purpose.
  5. CAD software for designing the mold insert. Blender is an excellent choice, available for free download.

Embarking on the DIY Injection Molding Journey

Let’s delve into the process of DIY injection molding, step by step:

  1. Designing the Mold Insert: Begin by selecting your preferred CAD software; in this example, we use the open-source Blender. Download the blank mold insert design files, which can be adjusted to fit various injection molders and mold frames. Alternatively, you can create your mold insert using the cavity diagrams of master mold frames.
  2. Import and Prepare: Import both halves of the mold core and the 3D design you intend to produce into your CAD software. Toggle off one half of the mold using the scene explorer’s eye icon. Set both mold halves to the “wire” draw type under the Object menu.
  3. Positioning and Alignment: Ensure your object aligns seamlessly with the inlet for the molten plastic during the injection molding process. Simplify this task by using orthographic mode (engaged via “toggle perspective/ortho”). Toggle visibility between mold halves to ensure proper alignment with both inlets.
  4. Creating the Mold: Utilize the “boolean difference” function in Blender to subtract the area of intersection between objects. Select the first half of your object, choose the boolean option under the Modifiers Menu, select the object you’re cutting, and set the operation to “difference.” Repeat the process for the other side.
  5. Export the Mold: Export each mold half, ensuring you check the “Selection Only” box in the Blender exporter.
  6. Material Selection: For 3D printing the mold, choose a material capable of withstanding the temperature and pressure of the injection molding process. Refer to the provided criteria table for guidance.
  7. Print Preparation: Set up the print using software. If your mold design necessitates support structures, ensure the cavity faces upward to simplify post-processing and ensure a superior surface finish.
  8. Printing Efficiency: Depending on your mold’s geometry and size, you can optimize efficiency by printing multiple molds simultaneously on a single build platform.

GAIM Plastics Inc. recognizes that all this work requires expertise, skill, and equipment to build your DYI Plastic Injection Molding project. Rather than doing it on your own, why not allow us to build your rapid prototyping injection molding and 3D printed molds for you? It is much more efficient, cost-effective and made with less mistakes for your critical molding projects. 

GAIM Plastics – Your Plastic Injection Molding Company

If you have any questions concerning manufacturing your plastic components, reach out for a free, no-obligation consult.