Rational Systems - Plastic & Machining Products

20 www.rational.co.il 1. Wall thickness: 2. Rib design and configuration: 3. Draft Angles: Design Tips for rigid Polyurethane RIM Keep an uniform wall thickness. In local areas, material thickness can be reduced to below average thickness. Thicker walls have higher stiffness. In flat parts doubling the thickness of the part stiffness will increase by factor of eight Thin wall parts have shorter mold-cycle times. Taller, thinner ribs are more effective than shorter, thicker ones. Every surface parallel to the direction of draw needs draft (2/1 a degree min) for demolding. As the part height increases draft should increase. Add ¼ degree draft for each additional inch of draw over 1”. Ribs should run from side to side or from corner to corner whenever possible.