In modern workshops, injection molding machines are no longer common, but injection molding machines are large-scale electromechanical equipment. For manufacturers, the purchase of injection molding machines is not a small investment. If they are too large, It will definitely cause waste of production, but if the injection molding machine is bought small, it can not meet the daily production needs. Therefore, the selection of an injection molding machine that meets the needs of the enterprise has become the most concern of every production buyer.

At present, domestic and foreign manufacturers of injection molding machines are blooming everywhere, and the specifications, models, and quality grades of injection molding machines provided by each injection molding machine manufacturer are also different. Editor recommends: users are best based on the actual situation of their products and the company’s The situation, combined with long-term interests to choose.

When purchasing, first of all, users need to clarify many factors such as the performance, material, size, weight, annual output, etc. of the products they produce (for example, manufacturers of plastic cups and manufacturers of precision instruments and plastic parts, purchase At the time, the focus is different), when selecting the model, you can refer to several important technical parameters and important components of the injection molding machine to specifically select the specifications of the plastic machine.

In the actual selection process, we must first collect the following detailed information

♦ Mold size (width, height, thickness), weight, special design, etc.;

♦ The type and quantity of plastic used (single raw material or multiple plastics);

♦ The appearance dimensions (length, width, height, thickness), weight, etc. of the finished injection molded product;

♦ Molding requirements, such as quality conditions, production speed, etc.

After obtaining the above information, you can follow the steps below to select the appropriate injection molding machine.

1. Select the right type: the model and series are determined by the product and plastic.

Since there are many types of injection molding machines, it is necessary to correctly determine which type of injection molding machine is suitable for your product, or which series can be produced from the beginning. For example, it is a general thermoplastic plastic or bakelite raw material or PET raw material. Color, double color, multi color, interlayer or mixed color, etc. In addition, some products require high stability (closed loop), high precision, ultra-high rate of fire, high injection pressure or rapid production (multi-loop), and must also select the appropriate series to produce.

2. Put it down: Determine whether the "large column inner distance", die thickness, "minimum die size" and "die plate size" of the machine are appropriate according to the die size to confirm whether the die can be placed properly.

♦ The width and height of the mold must be less than or at least have a small column and a large column inner distance;

♦ The width and height of the mold should be within the size of the die plate;

♦ The thickness of the mold must be between the thickness of the injection molding machine;

♦ The width and height of the mold must meet the minimum mold size recommended by the injection molding machine, too small.

3. Lockable: Tonnage of "clamping force" is determined by the product and plastic.

When the raw material is injected into the cavity at a high pressure, a force to support the mold will be generated, so the clamping unit of the injection molding machine must provide enough "clamping force" so that the mold will not be stretched. The calculation of the clamping force requirement is as follows:

♦ Obtain the projected area of the finished product in the direction of the switch mode from the appearance size of the finished product;

♦ Mold support force = projected area of the finished product in the direction of the switch mold (cm) X mold cavity number X mold internal pressure (kgf/cm2);

♦ The pressure in the mold varies with the raw material, the general raw material is 350~400kgf/cm2;

♦ The clamping force of the machine requires a large clamping force, and for safety reasons, the clamping force of the machine usually requires more than 1.17 times of the clamping force.

So far, the specifications of the mold clamping unit have been preliminarily determined, and the tonnage of the model has been roughly determined. Then, the following steps must be performed to confirm which of the injection unit's screw diameter is more suitable.

4. Full injection: Determine the required "injection amount" from the weight of the finished product and the number of mold cavities and select the appropriate "screw diameter".

♦ The number of mold cavities (a few mold cavities) should be considered when calculating the weight of the finished product

♦ For stability, the injection quantity must be 1.35 times more than the weight of the finished product, that is, the weight of the finished product must be within 75% of the most injected.

5. Good injection: The conditions such as "screw compression ratio" and "injection pressure" are judged by the plastic.

Some engineering plastics require a higher injection pressure and a suitable screw compression ratio to have a better molding effect. Therefore, in order to make the finished product shoot better, the need for injection pressure and the compression ratio must also be considered when selecting the screw .

Generally speaking, a screw with a smaller diameter provides a higher injection pressure.

6. Fast shooting: the confirmation of "shooting speed".

Some finished products require high-injection rate injection to stabilize the molding, such as ultra-thin finished products, in this case, you may need to confirm whether the injection rate and rate of injection of the machine are sufficient, whether you need to match pressure accumulators, closed-loop control and other devices. In general, under the same conditions, a screw that can provide a higher injection pressure usually has a lower rate of fire. Conversely, a screw that can provide a lower injection pressure usually has a higher rate of fire. Therefore, when selecting the screw diameter, the injection quantity, injection pressure and injection rate (injection speed) need to be considered and chosen.

In addition, a multi-loop design can also be used to shorten the molding time by synchronous compound action.