Rib

• Ribs with excess thickness relative to the optimal measurement for the top wall can precipitate several issues, including sink marks on proximate surfaces and the formation of voids internally. While avoiding overly thick ribs is imperative to preclude these complications, undersized ribs may similarly be detrimental, causing anomalies on the filling surface and inducing warping. Thus, establishing the proper wall thickness is essential.
• To fortify the mold’s strength, ensuring a minimum distance between the ribs, which is twice the wall thickness, is fundamental. Proper rib design requires thorough consideration of various parameters: the product’s wall thickness, rear thickness and height, alongside the positioning and quantity of ribs and potential product warp. It is noteworthy that excessively thick ribs may cause sink marks and voids in the surrounding areas.
• Regarding the rib height (H), it is vital to carefully assess the product design and draft angle, ensuring it resides within a range that does not negatively impact filling pressure. If the height is insufficiently low, it may not only inadequately enhance rigidity but also potentially cause warping, thus underscoring the importance of determining an optimal height that effectively balances these considerations.

[Reference] Troubleshooting : Warping , Sink marks