WEBINAR: The Key to Digital Tooling Is Ceramic Fiber Reinforcement

4 Design Tips to Whet Your Appetite

Ben Arnold, Fortify VP of Business Development says, “The obvious fundamental difference between steel molds and printed molds is the material they are made out of. A good rule of thumb is to design 3D printed tools to be more ‘forgiving’ than a steel tool.”

1. Shut off angle: In a steel tool, it is recommended to have an angle of at least 3 degrees when designing shut off features. Any less and you run the risk of the features wearing out or breaking too quickly. For a 3D printed tool instead of 3 degrees, 5 degrees is recommended.

2. Draft angle: Draft angles of features on steel tools are typically 1 or 2 degrees, and can go down to 0.5 degrees or less. 3D printed tools follow that same trend, except 3 degrees is recommended, and certain features are able to be molded with much less.

3. Ejector pin: Determining the placement of ejector pins on a mold so a part doesn’t break during ejection is important. In steel tools this is pretty straightforward and usually minimizes the amount of ejector pins needed. In 3D printed tools, designs need to also consider small and delicate features, and have pins placed so that the parts won’t flex during ejection. This can be accomplished by placing a pin next to a high aspect ratio extrusion or at the base of a rib rather than next to a rib. The great thing about adding in all of these ejector pins is that they provide excellent opportunities for ventilation.

4. Ventilation: 3D printed molds are unable to withstand the kind of pressures that steel molds can endure. One way to compensate for this is to add in more ventilation than there otherwise would be in a steel tool. This can take the form of surface vents, ejector pins, and vent holes to name a few. The goal with this ventilation is to always give the air in the cavity an easy path to escape so that the flow of the plastic is never restricted.