Injection molding is a manufacturing technique that produces identical plastic parts with special machines to promote mass production. The molding process involves melting polymer granules and injecting them into a mold under high pressure, where liquid plastic cools and solidifies. Thermoplastic polymers, used in injection molding, can be combined with additives such as colors for quality products. Injection molding can be used to design wall thickness, but you need to follow the below tips to attain the best results.
Ensure uniform wall thickness
Uniform wall thickness is an essential component when designing plastics. Varying wall thickness in the same product can cause shrinkage in some parts, leading to warping and dimensional accuracy issues. The use of cores in thick-walled parts can help you obtain uniform wall thickness. Avoiding thick wall molding discrepancies minimizes the risk of void formation and prevents internal stress.
Use minimum wall thickness
The minimum wall thickness you choose should meet the process, material, and component requirements. Ensure the walls are thin as possible without compromising mechanical integrity to enhance minimal product cost. You can use materials like gussets to increase the rigidity of thin-walled areas. When choosing designs for injection mold parts, the ratio of the flow path to wall thickness influences mold fill.
Replace thick wall sections with ribs
Some plastic designs require high rigidity for efficient working. Ribs improve the quality of parts needed by reducing the risks of voids and microporosity. Ribs minimize costs by reducing material required and cycle time. Using multiple evenly distributed ribs will work better than one large rib. Although other features can add strength, ribs are the most commonly known.
Appropriate draft design
A draft should be appropriately designed for easy removal of molded components. The incorrect design increases the rejection rate as parts are damaged in the withdrawal process. In most cases, the draft covers at most three degrees per side. Misallocation may also lead to unique processing phases like using parting spray or mold coatings to improve the quality of the end product. Including additional processing stages and materials increases production costs.
Make gradual transition for different wall thickness
When you encounter different wall thicknesses of plastic parts, avoid sudden changes in size. Different cooling rates can cause deformation and voids. If the difference in wall thickness is too much, there is a greater risk and significant internal stress. Transform poor wall thickness smoothly to promote efficient results. Parts will form better if you change from superior to lesser wall thickness.
Undercuts increase component cost by adding complexity and cost of the mold. Undercuts need a separate core and cam action to develop the feature because the material cannot be removed from the mold. If possible, eliminate the undercut or use a less expensive mold design. External undercuts bring up problems when separating parts of the mold. Adjusting parting lines can help accommodate undercuts.
Include bosses in your design
Bosses are hollow, cylinder-shaped protrusions essential in designing to allow screws or other mating constituents. It would be best if you secured bosses by attaching them to the wall so that they remain straight and accept the part it was designed for without difficulties. Forty to sixty percent of the surrounding area helps to avoid sinking.
Choice of material
There are many different materials you can use when designing wall thickness. Choose the material that fits the wall thickness you have in mind. You will find a wide variety of materials to choose from, which can be challenging. You can consult a reliable company or designer to make the best decision. Check the material that fits environment factors, strength, durability, and color if important.
Consider the use of radius
During the manufacturing process, the high impact can cause the failure of plastic shrinking after molding, leading to stress accumulation in sharp corners of your product. To prevent this damage, use radii on hubs where ribs, sidewalls, or other features connect. The size of the radii depends on the level of stress impacted. The outside corner radius should match the inside corner and wall thickness to enhance a constant cross-section.
In some cases, the quality level needed for a specific product may vary from the standard guidelines required for wall thickness designs. Proper component design and mold can lower costs, quality products and reduce expensive designs changes in future developments.