1, select the right type is determined by the products and plastic model and series.

 Due to injection molding machine has very many kinds, so at first to correctly judge the product should be what kind of injection molding machine, or a series of production, such as is the general thermoplastic plastic bakelite raw materials or PET raw material and so on, is monochrome, two-color, multicolor, sandwich or mixed color, etc.In addition, some products need high stability (closed loop), high precision, ultra high speed, high pressure or rapid manufacturing (multi loop), and other conditions, production must also choose the appropriate series.

2, put down: by the mold size for determining the machine "big column interval", "die thick", "mould minimal size" and "the mold size" if appropriate, to confirm the mold is put down. The mould width and height should be less than or at least one side is less than the big column interval; Mould width and height of the best in the mold size range; The thickness of the mould should be between the injection molding machine mold thickness; Width and height of the mould must be in accordance with the recommended minimum injection molding mold size, not too small.
3, and it is concluded that: from mould and finished the "travel" and "travel" is enough to make the finished product. 

Mould schedule at least should be greater than the height of the finished product in the direction of switch mode more than twice, and contains the length of the vertical gating (sprue); 

Travel need enough to finished product out.
4, lock up, determined by the product and the plastic "clamping force" tonnage. 

When raw material with high pressure into a mold cavity can be induced in a hold the power of the mould, so the clamping unit of injection molding machine must provide adequate clamping force "that mold is not open.Clamping force demand calculation is as follows:

The finished product and finished product appearance size in the direction of the switch mode projection area; Brace = finished mold in the direction of the switch mode projection area (cm2) *

the pressure in the mold cavity number (kg/cm2); Mould pressure varies according to the raw materials, raw materials commonly take 350 ~ 400 kg/cm2. Machine mold clamping force should be greater than support, and to be on the safe side, machine clamping force is usually accompanied by greater than last more than 1.17 times of the mold. 

So far has been preliminary decision model of the specifications of the unit, and an approximate model tonnage, then must be the following steps,to make sure which one screw diameter of the injection unit is required.
5, and be satisfied: by finished product weight and cavity number needed to "shoot dosage" and select the appropriate "screw diameter".

 Calculation of the finished weight cavity should be considered (one module and a few holes);
 For stability's sake, injection amount is more than 1.35 times the weight of the finished product, i.e. the finished weight for injection amount to less than 75%.

6, good shot: made of plastic to judge "screw compression ratio" and "injection pressure" and other conditions.