Injection molding of Pet Preform is considered a “main” manufacturing process. The following outlines the items required to calculate the actual injection molding manufacturing costs.
There are several basic concepts in component design that, if followed, will help alleviate many of the problems that plague injection molding machines. These include:
Keep the wall thickness as uniform as possible. A difference of only 15 – 25 % in thickness usually results in a thicker portion forming a dent. In the worst case, there are gaps that can affect performance. Rigidity can usually be imparted by introducing a stepped portion (see corrugated shingles), even by slightly rounding the corners to make the box-shaped portion more rigid while maintaining its uniform thickness. If ribs and bosses are to be introduced, sinking marks may occur and it is difficult to avoid. A useful rule is to make the ribs two-thirds of the normal wall thickness and similarly design the bosses so that the holes penetrate one third of the wall thickness.
The wall thickness should not be greater than the thickness required to provide the required strength and stiffness. This keeps the use of materials to a minimum and provides the shortest possible time period – careful use of multiple gates may solve the problem of mold filling.
Undercut and recessed shapes create additional costs in mold production and molding time (side core operations typically increase the time period) – they can usually be avoided by using simple assembly methods for two or more components. . One of the most popular is the interference fit, where one component has a clip or other device that securely engages the other component and holds the two together (see poppet). It is also possible to use friction welding, hot plate welding or ultrasonic welding, but in general, custom molding machines are not recommended to use solvent or solvent based adhesive bonding due to fire and toxicity hazards and solvent recovery problems.
Avoid using molded inserts if possible. Instead, the pile or spring clip is inserted into the blind hole, which is easier to manufacture by injection molding. Insert molding is often a waste of operator and machine time, which is often the most expensive part of the process.
Give the largest possible radius. Sharp corners, whether external or internal, are natural stress-increasing factors, but a radius of 0.06 inches (1 – 5 mm) will significantly alleviate this and may increase the impact strength by 5 to 10 times. .
Component designers may ask for something that is difficult to shape. As the manufacturer of a well-known brand of hand tool makers said in the advertisement: “Occasionally, very few, in fact, people will feel guilty about mentioning it. It is well known that the things created by designers are just a little difficult to manufacture. Things. Of course, producers like this kind of challenge. Without these challenges, English will be even worse. “Maybe injection molding machines are also true.”
The designer may work in an ignorant state – not knowing the conditions of use of the part, not knowing the performance of the material, and not knowing many of the factors involved in the design of the part to the completion of plastic forming.
Education is needed, but it is more necessary to negotiate and cooperate with China Plastic Cap Manufacturers. Regular contact between end users, component designers, mold designers and mold technologists will prevent many of these problems.