Injection compression molding can increase the molding accuracy, saving energy and reduce production cost, and the purpose is to reduce the injection and holding pressure at molding, and to reduce the distortion of product and internal residual stress. Injection compression can upgrade the product quality and evenly promote the product density,allowing easier molding of thin and large pieces.

In injection compression molding, there are Rolinx 、injection compression and partial compression.

Injection compression molding has certain requirement on accuracy of metering, mold platen parallel, compression speed, compression starting time and compression force. 

In the control of compression stroke, toggle type clamping unit uses mostly movable mold platen detection to control compression stroke, and the detection can be done through checking the location of cross-head to determine the location of movable mold platen. Hydraulic cylinder piston stroke and movable mold platen stroke ratio can be as high as 35:1, meaning 1mm shift of movable mold platen will have 35 mm shifting of Cross-Hd mold platen. In this way as accurate compression stroke control is attained.

Bi-injection is generally refer to the molding of two color or two type of resin. Since in Bi-injection, there are two independent injection elements and nozzles, the color of product is normally clear-cut in color, without mixing together. On the other hand, the interval Injection uses compound nozzle to join the resin from two sets of injection element and match with the injection speed, pressure and time changes to cause the color to mix, to fade from one to other or to generate prints on product. As to Sandwich injection, it uses compound nozzle to join the two type of resin, but there shall have special design that one of the material is sandwiching the other to form core material and skin material. So, unless t he product is cut sectional, it is normally unable to see the core material but the skin material.

Bi-injection unit is different from general injection molding machine mainly in the injection element and movable mold plate design. Generally, Bi-injection has two independent injection elements, but only one with general injection unit. The deployment of two injection element has various type different from designs of one to another manufacture, such as horizontal parallel, horizontal Y uni-direction, horizontal L type, Vertical L and vertical Y, even in horizontal parallel contra-direction arrangement for two plats clamping structure. As to movable mold plate design, it has to have rotating mechanism. Frequently seen designs include rotary table or rotary axis mechanism to provide 180 deg. Reciprocal rotating function to allow cycling alternate motion. Still other special Bi-injection units do not need rotary table or rotary axis mechanism, but for the mold to provide the alternate or horizontal rotation.

Interval injection and sandwich injection are almost same general injection molding unit, and the only difference is the interval injection and sandwich injection unit both has two set injection elements injecting material into molds from common nozzle, and the difference between interval injection and sandwich injection is in the design of compound nozzle.

GAIM is injecting nitrogen into mold cavity during injection molding process and using the nitrogen to perform pressure holding , making hollow products to reduce weight and prevent retraction sinking, and cut down pressure required. It is also call Nitrogen Hallow Injection Molding or Lowe Pressure Hollow Injection Molding. But it is different from Blow Molding.

GAIM is basically including the following 4 steps:
1. Injecting fixed quantity of material into mold.
2. Injection nitrogen to hollowing product to reduce weight and assist the fluidity of material.
3. Nitrogen pressure holding: As the material is cooling and retracting, the nitrogen will undergo secondary penetration and prevent the product from sinking or spring-back.
4. Release of high pressure nitrogen: releasing nitrogen in the mold cavity.

1. For bulky / thick products
a. Saving material, reduce weight by 20~50%.
b. Shortening molding cycle（reducing cooling time）to 20%.
c. Reduction of mold cost.
d. Saving in post-processing.
2. For flat products
a. Increase in design varieties.
b. Appearance improvement and better electroplating effects.
c. Eliminating thick rib sinking of products.
d. Realizing low pressure molding and reducing clamping force.
e. Less residual stress in product and reduce the distortion and deformation.
f. Increase the structural rigidity of products.
g. Reduce number of parts.

It needs 98% purity nitrogen or higher, because nitrogen is easily available, low prices and will not react with the material. The oxygen in high air may mix and combust with molten resin, so the later is rather not suitable.

It needs 98% purity nitrogen or higher, because nitrogen is easily available, low prices and will not react with the material. The oxygen in high air may mix and combust with molten resin, so the later is rather not suitable.

The following equipment are required to apply GAIM techniques.
1. Injection molding machine.
2. Gas Assisted Injection equipment.
3. Nitrogen Generator or Nitrogen Cylinder.
4. Air Compressor.
5. Necessary molding peripherals.

Techniques involved with GAIM include mold design, product design, gas pin location design and analysis, gas assisting device techniques, injection molding techniques, solution for defective molded product and mold flow analysis.

Not necessary, GAIM system of Fu Chun Shin can match with other brands of injection molding machine.