The biggest challenge in injection molding is the process of designing a mold. There are almost no limits to your creativity , but you can do the designs in clever and less clever way from a manufacturing point of view. Plastic manufacturers highlight this aspect as the most crucial part of injection molding. There will be no successful plastic part designs for injection molding if there is no perfect mold from where it is formed. The biggest factors to designing a mold are part and tool design. Getting these factors right means faster production, better quality and reduced costs while having them wrong could substantially affect these production aspects in a negative manner. Here are other factors you need to consider with injection molding during the product development and prototyping.
1. Wall thickness
Thin walls are advisable in plastic manufacturing for shorter cycle times and being able to produce more plastic part designs in shorter production lead time. Thinner walls also makes the cooling process faster. Ideal wall thickness from 0.08? (2mm) to 0.16? (4mm), but thin wall injection molding can go as thin as 0.02? (0.5mm).
However, wall thickness also depends on the type of plastic material being used. Here are the recommended wall thickness for various plastic materials; ABS resin is between 0.045 and 0.140 inches, Acrylic is at 0.025 ?0.150, Liquid crystal polymer at 0.030 -0.120, Nylon at 0.030?0.115, Polycarbonate at 0.040 ? 0.150, Polyester at 0.025 ?0.125 and Polypropylene at 0.025? 0.150.
2. Ribs
Adding ribs helps increase the bending stiffness due to the increased moment of inertia. This is a suggested option instead of adding thickness to the wall. Here are recommendations with ribs in plastic production;
Rib?s thickness should not be more than 60% of the nominal thickness value.
Height should be three times lower than the wall thickness.
Draft angle is at 25 degrees.
The ribs position must be perpendicular to the axis where the bending occurs.
Corners of the attachment points must be rounded instead of having them pointed.
3. Bosses
Bosses are layers wherein fasteners are attached and threaded inserts are located. Recommended specifications for bosses are the following;
Bosses? wall thickness should not be more than 60% of the main wall.
Base radius should be at least 25% thickness of the main wall.
Bosses should be supported by ribs connecting to walls adjacent from their position or gussets at the bottom the mold design.
Ribs should be used to isolate bosses in corners of the design.
The biggest challenge in injection molding is the process of designing a mold. There are almost no limits to your creativity, but you can do the designs in clever and less clever way from a manufacturing point of view. Plastic manufacturers highlight this aspect as the most crucial part of injection molding. There will be no successful plastic part designs for injection molding if there is no perfect mold from where it is formed. The biggest factors to designing a mold are part and tool design. Getting these factors right means faster production, better quality and reduced costs while having them wrong could substantially affect these production aspects in a negative manner. Here are other factors you need to consider with injection molding during the product development and prototyping.
There are many factors to consider for injection molding, but the part design and tool design are two of the most important.Getting them right could mean lower entry cost, high production quality, shorter cycle time, and quick assembly. Getting them wrong, on the other hand, can be very costly indeed.
Designing plastic parts is a complex task involving many factors that address a list of requirements of the application. “How is the part to be used?” “How does it fit to other parts in the assembly?” “What loads will it experience in use?” In addition to functional and structural issues, processing issues play a large role in the design of an injection molded plastic part. How the molten plastic enters, fills, and cools within the cavity to form the part largely drives what form the features in that part must take. Adhering to some basic rules of injection molded part design will result in a part that, in addition to being easier to manufacture and assemble, will typically be much stronger in service. Dividing a part into basic groups will help you to build your part in a logical manner while minimizing molding problems. As a part is developed, always keep in mind how the part is molded and what you can do to minimize stress.