Thin-walled components those with main walls that are less than 1.5 mm thick may require special high-performance molding equipment to achieve the required filling rates and injection pressures. This could possibly drive up the molding costs and offset any material savings. Thin-wall molding is normally more fitted to dimension or weight decline compared to expense savings. Components with wall thicknesses greater than 2 mm may also be regarded as thin-walled components in case their flow-length-to-thickness percentages are much too higher for conventional molding. Usually, low-shrinkage plastics, such as the majority of amorphous or stuffed resins, can accept nominal wall thickness versions about about 26% without having significant filling, warpage, or appearance problems.
Unfilled crystalline resins, because of their higher molding shrinkage, can simply tolerate about part greatly thickness variance. These guidelines pertain to the components’ principal walls. Ribs and different protrusions through the wall should be thinner to avoid sink. Several blueprints, especially those converted through cast metallic to polymer, have thick portions that could result in sinks or voids.
When adapting these blueprints to polymer components, consider the subsequent:
1. Core or redesign thick areas to produce a more uniform wall size
2.Create the exterior radius one wall-thickness larger than the interior radius to keep constant wall thickness through corners;
and 3.Round or taper thickness transitions to reduce read-through and possible blush or gloss differences .
Blending also decreases the built-in stresses and stress focus associated with abrupt changes in size. In some cases, thickness-dependent attributes such as flame retardency, electrical resistance, and reliable deadening determine the lowest required size. If your part requires these attributes, be sure the polymer offers the required functionality at the thicknesses selected. UL flammability ratings, for instance, are listed with the lowest wall thickness which is why the rating applies.