Push-Pull Injection Molding

Injection Molding is the most advanced typical method of molding rubber products. Injection molding produces the most consistent results by automating all aspects of how the rubber gets into the mold. In injection molding, the rubber is worked and warmed and then squirted into the mold at controlled speeds, pressures and temperatures. Advantages of Injection Molding are: Provides the maximum product consistency, Allows the most control of flash, Because the rubber is warmed before going into the mold, fastest cycle times, Disadvantages of Injection Molding.

The Plastic injection molding machine has two parts: the injection unit which melts the plastic and injects the plastic into the mold, and the clamping unit which holds the mold. The injection molding unit clamps the mold in a closed position during injection, opens the mold after cooling, and ejects the finished part. Injection molding's efficiency varies by the number of parts you plan to produce. For a small quantity, such as 10 parts, it may be less expensive to simply machine the desired part utilizing a milling machine. On the other hand, if you desire several thousand parts, injection molding is ideal. When you submit your order for an injection molding part, the websites will assign staff to help evaluate the most appropriate mold material which will vary by part tolerance and number of units anticipated.

Making polymers is a fantastic science. Then there is the matter of shaping the plastic into useful objects....another fantastic science. One of the most common methods of shaping plastic resins is a process called injection molding. Injection molding is accomplished by large machines called injection molding machines. A type of mold used in the process of injection molding. The mold usually comprises two sections held together by a clamping device with sufficient strength to withstand the pressure of the injected, molten plastic. The mold is provided with channels for heating, cooling and venting.

The 2-shot injection molding process creates the first plastic component, and the material molded round it, using a single mold and a 2-shot injection molding machine. 2-shot machines have two-barrels (one for each material) and they have the ability to rotate the mold. The machine injects the first shot material into cavities on one side of the mold, rotates the mold 180 degrees, and then injects the second shot material onto the first shot. The first and second shots occur at the same time. When the mold opens, it ejects the completed parts from the second shot cavities and it rotates the mold to position the first shot for the second shot. This is accomplished in a machine running in an automatic cycle. Because the 2-shot injection molding process is fast and highly repeatable, the shrinkage of the first shot is very consistent and two materials can be molded together with virtually no flash. 2-shot molding is the process of choice when molded-in graphics or other fine details are required. The elimination of the shrinkage variable allows 2-shot molding to produce details impossible to achieve with over-mold injection molding.

Thermoplastic injection molding is the most widely used of all plastic processing methods. The injection molding machine reduces pelletized raw material and colorants into a hot liquid. This "melt" is forced into a cooled mold under tremendous pressure. After the material solidifies, the mold is unclamped and a finished part is ejected. Injection molding offers the lowest piece prices available, but tooling prices are generally the highest. Thermoset injection molding is similar to thermoplastic injection molding except that uncured thermoset resins are mixed, injected, and held in the mold until cured. As with thermoplastic molding, the price per piece can be low, but the tooling prices are generally very high.