{"id":162389,"date":"2021-01-26T06:48:46","date_gmt":"2021-01-26T06:48:46","guid":{"rendered":"http:\/\/facfox.com\/docs\/?post_type=kb&p=162389"},"modified":"2021-01-26T06:50:17","modified_gmt":"2021-01-26T06:50:17","slug":"design-stronger-molded-parts-with-ribs-gussets-and-durable-materials","status":"publish","type":"kb","link":"https:\/\/facfox.com\/docs\/kb\/design-stronger-molded-parts-with-ribs-gussets-and-durable-materials","title":{"rendered":"Design Stronger Molded Parts with Ribs, Gussets, and Durable Materials"},"content":{"rendered":"

Product designers build strength into their injection-molded parts in different ways and for different reasons. Dissecting part application is a good first step in determining if additional strength should get designed into a part. How will customers be using your product and what environment will it live in? You may need parts that can withstand repetitive impact, resist wear, or bear heavy loads. It may be as simple as integrating ribs or gussets into your design, or a more complicated combination of design elements involving support features, material, wall thickness, and more. Finding the proper balance of design considerations will help address your part\u2019s need for strength and stability.<\/p>\n

\"\"
Gussets, as seen here on a free-standing boss, provide structural support and overall stability in parts without having to increase wall thickness.<\/figcaption><\/figure>\n

Plastic Rib Design<\/h3>\n

Ribs are thin, wall-like features typically designed into the geometry of a part to add internal support to walls or other features like bosses. In a similar fashion, gussets are support features that reinforce areas such as walls or bosses to the floor. Just as bridge beams and columns are supported at their vertex with gussets to add critical strength to the structure, the same concept applies to plastic injection molding.<\/p>\n

Reinforce Bosses and Walls with Gussets<\/h3>\n

Both ribs and gussets provide stability in parts without having to increase wall thickness, and are particularly beneficial for parts with already thin walls that could potentially be compromised by end-user wear and tear. It\u2019s important to note that ribs and gussets should be no more than 60 percent of nominal wall thickness. These features are kept thinner than the primary walls in an effort to avoid overly thick sections where ribs and gussets intersect with the wall. When you have a surplus of material meeting at internal rib-to-wall intersections, sink marks can appear on the visible side of the part.<\/p>\n

Product designers can play with different ribbed formations<\/a> to create square, rectangle, diamond, triangle, or honeycomb patterns that stiffen the part. A pattern of ribs is equivalent to coring out unneeded material, leaving only the rib support system\u2014it also reduces the weight and cost of the part. But, remember to not remove surfaces and features that interface with the other parts in the product assembly.<\/p>\n

\"\"
Fillets, as seen in this example (1) and in the close-up inset view (2), are curved faces where ribs meet walls to help eliminate additional mechanical stress around sharp corners.<\/figcaption><\/figure>\n

Fillets and Radii<\/h3>\n

Because sharp corners weaken parts, fillets\u2014curved faces where ribs meet walls\u2014can also be designed into part geometry to eliminate additional mechanical stress concentrations on a finished part. Much like gussets, a fillet that is too small will fail to accomplish its task of stress reduction, but a fillet that is too large can once again create sink. Identifying the proper size and locations of fillets (and ribs and gussets) are important. When adding a fillet to the inside of a corner, also add a radius to the outside of the corner, if possible. If the risk of sink is too high in some sections, then other strength-building methods should be considered.<\/p>\n

Durable Thermoplastics<\/h3>\n

Material selection<\/a> also plays a role in the stiffness, durability, toughness and other characteristics of parts; balancing the relationship between those material properties and part functionality is key. For example, product designers can choose a thermoplastic resin that will make a stiff, rigid part, but if its application demands a high degree of impact resistance, the brittleness of an inflexible part may cause it to break. Material properties differ from resin to resin\u2014here\u2019s a glance at some of our more frequently used resins:<\/p>\n