More tips on designing for mouldability from Proto Labs

Here is an extract from Designing for Mouldability Volume 2: Undercuts and Through-Holes A Sideways Look at Rapid Injection Moulding Houses in Monopoly™ land have no doors or windows. Maybe the tiny people who live there spend a lot of time indoors, or perhaps they've perfected teleportation. More likely, it's because doorless windowless plastic houses are easy to make in simple two-part moulds. In the real world - including the world of plastic parts - life is more complicated. Houses have doors, and parts have indentations, through-holes, and other features that don't point straight up or down and could act as undercuts in a two-part mould. Designers using rapid injection moulding can address these challenges in a variety of ways, including side-action cams, sliding shutoffs, pickouts, and bumpoffs as discussed in this volume. Side-Action Cams The most obvious approach to undercuts is side actions - mould pieces that act from the outside of the part, moving perpendicular to the direction of mould opening. These produce side-facing features in a closed mould and then automatically withdraw, allowing the A-side mould half to withdraw, as the mould opens, and the part to be ejected from the B-side. In Figure 1, a side-action cam produces the door, sealing against the B-side core as the mould fills and then withdrawing to allow ejection. A similar technique could produce non-through indentations that would otherwise act as undercuts. To continue reading, download our Designing for Mouldability Volume 2: Undercuts and Through-Holes white paper here.