The plastic injection molding process parameter is very important to produce injection molded parts. It directly influence the quality and efficiency of a molding production. Sometimes it will affect the mold making process, therefore we would like to share some useful experience on how set up a correct injection molding process parameter
Before injection molding process, we must install the plastic mold onto an injection machine. The clamp pressure usually exists at the other end of injection machine, which gives clamp pressure is to keep the injection mold closed against injection pressure. normally, different type of resins requires totally different clamp pressure, the material with good flow-ability requires less clamp pressure. but the stiffer flow material will requires more clamp pressure. Therefore we need to see specific plastic part and material to determine how much clamp force we should use.
The mold temperature is very critical to an injection molding parts. As it will affect part shape defect, (deformation), dimensional precision, surface appearance, and mechanical properties. For example, if you make an ABS or polycarbonate plastic part, we should set the mold temperature as a relative lower level, since the higher mold temperature would result in bad impact resistance, strength resistance, as well as fatigue performance parts.
Melt temperature is one of the most important factors in the injection molding process. It directly or indirectly affect the resin flow-ability. If the melt temperature is too low, the resin might not be able to be melted that the resin keeps the original hardness of raw material. If the melt temperature is too high, the resin will be burned and looks worse appearance.
To set up a proper mild temperature, you should balance the material flow-ability, part shape, and usage. In case you are not sure what temperature you should give, you can gain it from your raw material supplier.
Injection volume means how many meld raw material to be injected to the injection mold, so as to obtain the desired part shape and dimension. If a oversize material injected, it will result in flash in part, conversely, if a less amount of material injected, the part might be incomplete. While injection molding process, we can adjust different volume of injection material,
The injection pressure is another important molding parameter . Normally, the highest pressure and fastest fill rate are the best condition. However, high pressure will increase molded-in stress. If the injection pressure is too low, an incomplete part could happen. If the pressure is too high, the part will come with flash.
Nozzle temperatures impacts the flowability, the cooling speed, and the performance of plastic parts, If it is too high, the melting plastic material will drool in the nozzle, if the temperature is too low. Materials may also block the nozzle. And you have to take times to fix out the block material problem. If a high production volume, we can design the mold with hot runners that extend the nozzle system inside the plastic mold. In this way, there is less waste material and quicker for injection process.
Material Flow Rate
It is very critical for a injection molding process, since the material flow rate will direct affect the injection time, filling time, and filling condition of a plastic molded parts. For example, ABS has much worse flow rate than PP material, if for a large size of part, we should choose a better flow rate material when product design. Otherwise there will result an incomplete shot problem