Design Tips for Minimizing Injection Molding Defectives
One of the most common methods of mass-producing plastic parts is injection molding. At Creatingway, we consider it ideal for producing rapidly vast numbers of identical parts with features of tight tolerances. In the design and manufacturing industry, we use 3D printing only to create and verify prototypes that would be later injection molded. There is an advancement in the technology of 3D printer accuracy, surface finish, and a wider range of material used. We now manufacture the molds directly from 3D printers. The blog discusses how we use 3D printing for manufacturing injection molds. It also provides an insight into possible mold configurations, available 3D printing mold materials, and the best design practices for creating accurately printed injection molds.
What is The Injection Molding Process?
Injection molding is the process of creating components by injecting pressured melted materials into a die. The melted material fills the hollow cavities of the die later cooling and solidifying in the process. The solidified material takes the shape of the die. The die then opens up and ejects the solidified material, and the process repeats itself. Automation of this process results in yields of a high production rate. Materials commonly used include thermoplastics, but it is possible to utilize certain thermosetting plastics.
Why use 3D printing to Minimizing Injection Molding Defectvices?
First, you have to consider if the mold will be used to make 20 or 30000 parts. Formerly, molds need to be CNC machined with a requirement of very high tolerance from metal. The material mostly used is aluminum or steel. The materials offer good wear resistance to the repeated injection molding, opening, and closing of the mold, and different temperature gradients. These are constant conditions to which the injection molding exposes the molds. The only disadvantage is the large initial investment needed in setting up the metal molds.
The case is different for low-run molding, where wear resistance is not a critical factor in production. There is an improvement in 3D printing technologies with abilities to produce high accuracy injection mold parts. They also possess an excellent finish. This, coupled with the modern temperature resistant 3D printing materials, enables 3D printed molds to be a more viable option for manufacturing injection molding dies.
The reasons why we consider choosing 3D printed molds include:
- Fast turnaround times (1-2 week as opposed to 5-7 weeks)
- Parts that are small (less than 150 mm)
- Mold designs with probable changes and iterations
Which Are The 3D Printed Mold Configurations?
There exist 2 standard configurations included below:
- Mold inserts in aluminum frames
- Stand-alone molds
Mold inserts in aluminum frames
One of the most common 3D printing configuration that produces accurate parts. After 3D printing of the mold, we insert the mold a rigid aluminum frame that provides support against the pressure and heat produced by the injection molding nozzle. The frame also prevents the mold from warping after repeated usage, thus improving the accuracy of the parts produced.
Stand-alone molds
The mold, in this case, is fully 3D printed. There is no support in the form of rigid aluminum support. It allows the integration of intricate cooling channels in the mold. The demerits increase in both print and cost time. Also, the mold is more prone to warping, thus lowering the accuracy of parts produced.
How to Design 3D Printed to Minimizing Injection Molding Defectvices?
Materials
The materials used for 3D printing have to possess certain properties. They include:
- High-temperature resistance
- High stiffness/toughness
- High level of detail
SLA and material jetting are the 3D printing technologies that cover the best of these requirements.
Mold design
Discussion of specifics in the technical design of mold features may be beyond the scope of this article. We have thus provided a quick overview of what designers should consider doing with their design molds. Below is a list of some good practices you should follow when designing a 3D printed model.
- You should design molds undergoing SLA printing with inner faces of the mold oriented so as no support comes in contact with them. It improves the surface quality, as no support marks will present on these surfaces, thus avoiding post-processing.
- Include shallow air vents (0.05 mm deep) at the edge of the cavity for the expulsion of air during the molding process.
- Embossed and engraved details should be offset by at least 1 mm.
Designing Parts for Injection Molding
We recommend designers to consider:
- Maintaining uniform wall thickness across the entire part
- Keeping features and walls as thin as possible
- All edges and corners to include radii
- Adding a draft angle of a minimum of 2 degrees that aids in the removal of the part from the mold
- If you are considering increasing strength, include thin ribs and gussets rather than increasing wall thickness
Need advice on your injection mold project, kindly contact Creatingway today. Creatingway is concentrated on CNC machining manufacturing, prototype machining, low-volume manufacturing, metal fabrication, and parts finishing services, provide you the best support and services. ask us one inquire now.
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