3D Printed Injection Molds
Mold the Impossible!
Merging 3D Printing and Injection Molding
FIM Process Overview
The Freeform Injection Molding process begins just like any other 3D printing process – you upload your files and place an order. Although instant quoting is not yet available we are offering manual quoting at this time. We take the responsibility of designing the mold and helping you conform with the best practices of injection molding. We offer thorough design review and documentation standard.
Our advanced tooling composite will last several hundred parts and can handle high heat or abrasive resins like glass-filled nylon or PEEK. If time is of the essence or must violate the rules of molding, tools are completely dissolvable in a lye bath.
Once the mold is printed, we run it on a standard injection molding machine. Currently part size is limited to 4.5″x4.5″x2.5″ – we hope to increase that very soon! Injection molding machines produce dozens of parts per hour and utilize almost every available resin on the market.
After the part cools it is ejected, post processed, quality controlled and shipped out. RapidMade offers many secondary post processes like heat stake inserts, bead blasting and automotive paint.
3D Print
Inject
Dissolve
Available Injection Molding Plastics
| PLASTIC | BENEFITS | APPLICATIONS | NOTES | 3D PRINTABLE? |
|---|---|---|---|---|
| ABS (Acrylonitrile Butadiene Styrene) | General purpose plastic. Cheap, rigid and dimensionally stable. Very popular plastic for a reason. | Cosmetic parts, consumer products, electronics devices | For best results follow best practices for injection molding part design. Not suitable for snap fits | Yes |
| POM or Acetal (Polyoxymethylene) | Durable, rigid, strong, lubricious, solvent resistant, elastic, low creep, excellent fatigue resistance. | Gears, pumps, impellers, conveyor parts, blades and scrapers, food contact surfaces | Stiff, stable and durable, a staple of automation applications. Low friction and approved for food contact. | No |
| PMMA or Acrylic (Polymethyl Methacrylate) | Clear, glossy, scratch-resistant, stable shrinkage. Naturally UV resistant. | Light pipes, diffusers, shades, outdoor covers | Can be brittle, requires significant draft, poor chemical resistance; printed molds will not have optical clarity, diffused finish similar to SLA | No |
| PC (Polycarbonate) | Clear, strong, impact resistant, stable shrinkage, heat resistance, high cosmetic finishes. | Lighting, electronics, automotive and aerospace, phone housings, medical devices, safety glass. | Top mechanical properties. Poor chemical and UV resistance without additives. Often fire retardant and medical/food grade. | Yes |
| PET (Polyethylene Terephthalate) | Good moisture barrier properties, stiff and flexibile, food contact clear | Bottles (food grade), packaging, clam shells, snap fits | Very poor UV properties and not the highest mechanical strength | Yes |
| PA or Nylon (Polyamide) | Balanced stiffness and flex, reinforced options for high strength and temperature tolerance, Chemical resistant. | Thin-walled parts, gears, bearings, structural components. | Very common material for mechanical applications, high warp potential, hygroscopic | Yes |
| HDPE (High-Density Polyethylene) | Extremely high impact UV and chemical resistance, high shrink, low dimensional stability, inexpensive. Very low stiffness | Outdoor furniture, containers, toys, gas and other chemical contact applications | Ultimate in chemical resistance. Extremely low cost. Beloved in chemical and food applications. Very easy to clean. High shrinkage makes it hard to control tolerance | No |
| PP (Polypropylene) | Cost-effective, impact resistant, flexible, acid/base resistant, floats. Very low stiffness | Living hinges, snap fit lids, packaging, medical devices | Similar to HDPE in stiffness and chemical resistance. Lower Density than HDPE and more flexibile - semi-rigid | Yes |
| TPU/TPE | Families of elastomers from shore 5 - 95A; medical and food grade | Electronic insulators and strain relief, seals, gaskets, hoses, grips, end effectors | Extremely high compression, rebound, and stretch properties. Wide range of hardnesses. Chemical and abraison resistant | Yes |
| Silicone | Wide range of LSR resins with high heat and tear resistance; medical and food grade | prosthetics, gaskets, seals, end effectors, lab equipment, medical devices | 2 part system requires extra mixing and cure time, highly coveted in many industries | No |
| Custom Material / Customer Supplied | Give us your toughest challenges! | Special colors, composites and additives. Glass, carbon, aluminum fill. UV resistance, lubrication and other additives. Special grades of listed plastics. | Customers can supply materials or pay us to source them. | N/A |
3D Printed Injection Mold Design Guidelines
Wall thickness: Consistent wall thickness between 0.060″ and 0.200″ will yield the best part quality. Fillet all sharp edges and joints to reduce stress during shrinkage. Concentrated mass causes concentrated contraction and that will warp your parts.
Ribs and Gussets: To avoid thicker walls use ribs for enhancing part strength and stiffness, as they minimize material use and cooling time while maximizing strength. These features improve dimensional stability by stiffening the design. With printed molds, complexity does not add cost! Ideal ribs and gussets are 50- 60% of the wall thickness. Overly thick features cause sink.
Parting line, draft angles and other considerations: Dissolving molds can be expensive – but getting repeat production molds that eject volume parts is not that simple either! For customers who want to reuse their molds we must consider where the mold will separate. Interference, called an undercut, is a feature that prevents removal of a part from a mold. Sometimes a core is necessary to form a cavity inside a part. Generally a half degree of draft and ejector pins are needed to remove the parts. An injection port is always neccesary to shoot the mold. These are design considerations that require up front engineering costs but saves substantial money over hundreds or thousands of parts.
Understanding tolerancing and other limitations: 3D printing is not as accurate as machining, so a printed mold is not as accurate. Milled production molds will be milled between 0.001″ – 0.005″: while printed molds typically hold between 0.010″ – 0.015″. This additional variance will pick up in your parts. Additionally, the molding resin will also shrink. We will adjust for this shrink rate but shrinkage causes additional part variance which limits the tolerances we can offer. For customers with the most demanding drawings post machining is available.
Additionally this is a new process with limited finish options. In-model textures work astoundingly well but customers must supply them. Traditional injection mold tooling companies have a lot of chemical etch finishes that we cannot offer at this time.
Additional technical process information will be available in the near future as it is validated and published.