Injection molding, or injecting plastic material into a mold cavity where it cools and hardens to the composition of the hole, has traditionally been performed with high tooling costs and long lead times. However, recent advancements in 3D printing and additive manufacturing technologies have significantly improved the efficiency and cost-effectiveness of the process.  

Standard injection molding is typically a lengthy and costly process because tooling can take weeks or months using expensive materials and traditional tooling methods. The cost and time of tooling molds can be further complicated by factors like design mistakes that require the mold to be remade correctly (starting over) or the need to create multiple iterations before the final part design and quality are developed.  

These issues – and others – have left manufacturers more open-minded about embracing the use of 3D printed molds to create functional injection mold prototypes.  

Champions of additive manufacturing understand that 3D printing can produce molds up to 90 percent faster and 70 percent cheaper than traditional mold-making processes. Those are significant advantages because time is money when going to market with an innovative product. 

Reasons to Consider 3D Printing for Injection Molds  

Here are some significant reasons your business should consider 3D printing for injection molding: 

Low initial cost. With traditional injection molding, entry costs and minimum volume are typically high. 3D printing capabilities allow businesses to order any quantity of pieces that are appropriate for each project. Producing smaller volume runs means a low upfront cost.  

Changes are easy. Additive manufacturing makes it possible to quickly and easily make changes during the injection mold development process. This results in less wasted material, time, and cost. Plus, projects can be paused to make an adjustment and restarted – without starting over.  

Complicated designs made simple. There’s no faster and more cost-effective way to turn your ideas into a product than 3D printing. 3D printing’s process of adding layers one by one makes it perfect for creating intricate designs. Products with complex or organic shapes, angles, and dimensions are efficiently made using 3D printing versus traditional injection molds. 

Rush job friendly. You need that done now? No problem. Businesses can order what they need as soon as they need it. Additive manufacturing allows companies to control inventory levels and get the parts they need on the double.  

Is 3D injection molding for you? 

But are 3D printed injection molds a viable alternative for everyone? Here are a few situations where businesses or individuals can benefit the most from the process: 

  • Businesses where limited quantities of simple parts with large draft angles are needed. 
  • Companies where their tool-and-die team is familiar with the design rules of molds made with 3D printing. 
  • Businesses whose employees and machines are available to process and assemble the plastic tool. 

Case study results 

Producing injection molds using additive manufacturing vs. standard tooling methods saves a considerable amount of time in the process. For example, in one case study written about in Additive Manufacturing magazine, “the lead time for a final product created with a conventional aluminum prototype mold is typically one week, whereas production of a set of 3D-printed cavities was only two days.” 

The case study found overall savings in both cost (25 percent) and turnaround time (50 percent) when using the 3D-printed cavities. That time savings is thanks to significantly reducing the processing time and workforce needed to create the part.  

For reference, here is a comparison of the steps involved for producing a conventional aluminum prototype mold vs. using the additive process:  

Aluminum tooling process 

  1. Design the mold 
  1. Program and cut in CNC machine 
  1. Create the mold components 
  1. Build the frame 
  1. Final fitting 
  1. Polish 

Additive manufacturing process 

  1. Design the mold 
  1. Upload design to the printer 
  1. Create the mold components 
  1. Final fitting 

Steps in the aluminum process 2, 4, and 6 represent considerable time savings via the additive process, which virtually eliminates two steps in the process. Specifically, in Step 2, programming cutter paths and CNC machining the aluminum block takes several hours while uploading a CAD file to the 3D printer is nearly instantaneous. 

Using SLA additive process for injection molds 

One commonly used additive process for injection molds is Stereolithography (SLA) 3D printing, which provides a cost-effective alternative to machining aluminum molds. SLA 3D printed parts are solid and isotropic, and materials are available with a heat deflection temperature of up to 238 Celsius at .45 Millipascals (6.613 pounds per square inch) of pressure. That means they can withstand the heat and pressure of the injection molding process. 

SLA, or Selective laser melting, uses a high power-density laser to melt and fuse metallic powders. In this process, thin layers of fine metal powder are equally distributed using a coating mechanism onto a plate that moves in the vertical axis. This takes place inside a chamber containing a controlled atmosphere of inert gas, either argon or nitrogen.  

Once each layer has been distributed, each slice is fused by selectively melting the powder with a high-powered laser beam. The energy is intense enough to completely melt the particles to form solid metal. The process is repeated layer by layer until the part is finished. 

Additive manufacturing provides various advantages for injection mold making over standard processes.  

Pamton’s capabilities 

At Pamton, we create custom 3D print injection molds in-house to produce functional prototypes and various other projects. Contact us for more information or to learn how we can help with your next project. 

 
Sources 

Donaldson, B. (2018, March 5). 3D-Printed Prototype Molds Versus Aluminum Tooling. Additive Manufacturing. https://www.additivemanufacturing.media/articles/3d-printed-prototype-molds-versus-aluminum-tooling

Advantages of Additive Manufacturing in Injection Moulding. 3DIncredible. (2019, October 22). https://3dincredible.com/advantages-of-additive-manufacturing-in-injection-molding/

How 3D Printing is Transforming Prototyping in Injection Molding. Stratasys. (n.d.). https://www.stratasys.com/explore/whitepaper/inroads-injection-molding

3D Printing vs Injection Molding – Know the Differences. All3DP. (2019, July 22). https://all3dp.com/2/3d-printing-vs-injection-molding-know-the-differences/