Injection molding is a commonly used plastic parts fabrication manufacturing process. There are so many products that are manufactured using this method and they vary in complexity, size and application. Automotive parts are some of the products that use this manufacturing process. Injection molds are achieved using injection molding machines, mold and raw plastic material. In the process the plastic is first melted in the molding machine before it is then injected into a mold where it is allowed to cool and solidify into the desired final part.
Injection molding produced thin walled plastic for various applications. The most popular product that is got from the process is plastic housing that is required for automotive dashboards, power tools, and household appliance and even for consumer electronics. Apart from largely being used in the automotive industry, the injection molds are used for other applications including making medical devices like syringes and valves. Automotive injection molds, however still take up a large percent in this method. Perfect as it might be, it is a method that also faces a number of challenges making it difficult to achieve accurate automotive injection molds. Below are some of the challenges and defects that make the process difficult.
Flash - This is occurrence of molten material when it seeps out of mold cavity and then solidifies. It means that after ejection of the part, there is the presence of a thin layer of material attached along the parting line of the part interfering with the final quality of the product. It is a problem that usually comes from a clamp force that is too low or injection pressure that is too high.
Warping - It is when the part goes though permanent bending when some sections end up shrinking much faster than others. This occurs as a result of cooling rate that is not uniform and is a very common challenge for the mold manufacturers.
Sink marks – The other difficulty that is faced when molding is the occurrence of sink marks. They are marks that result of shrinking of molten material that ends up filling voids that could be present on part sections that solidify first when the material gets injected into the mold. Usually, the sink marks occur when the injection pressure is too low or when the cooling rate is not uniform.
Bubbles – Bubbling also affects the possibilities of achieving the desired final automotive parts. The final product affected by this problem has bubbles on the surface affecting the look, feel and even the quality of the mold. It happens when the material used has too much moisture or when the injection temperatures are too high.
Unfilled sections – This is another problem that is commonly faced with automotive injection molds. It simply means that the final product will have sections that are not correctly and thoroughly filled because of the material flow rate that was too low or shot volume that was not sufficient enough during the process.
Ejector marks – When the ejection force is too high or when the cooling time is too short, then it is very possible for the injection mold to have ejector marks on it.
Post time: 04-07-2017