How to choose a vertical injection molding machine
In general, clients are mostly engaged in injection molding industry has the ability to use their judgment and choose a suitable injection molding machine to production, but in some cases, the customer may need vendor help to decide which one specifications of the injection molding machine, even the customer may only sample of the product or idea, and then ask the vendor whether the machine can produce, or what kind of machine is suitable for, in addition, some special products may need to match the special equipment such as transformer, closed loop, injection compression, etc., to produce more effectively, thus, how to decide the right injection molding machine to production, is a very important problem.The following information for readers reference.Usually affect the injection machine selection of important factors including mold, products, plastic, molding requirements, therefore, must first be collected or before to choose has the following information: the mold size (width, height, thickness), weight, special design, etc.;Use the amount and type of plastic (single material or a variety of plastic);Injection molding the appearance of the finished product size (length, width and height, thickness), weight, etc.;Molding requirements, such as quality, production speed, etc.After get above information, then according to the following steps to select the suitable injection machine: line 1, select the right: determined by the product and the plastic model and series.Due to the injection machine has very many kinds, so at first to correctly judge which one kind of injection molding machine, this product should be or which one to produce series, such as general thermoplastic rubber or plastic raw materials or PET raw material and so on, is monochrome, two-color, multicolor, mezzanine or mixed color, in addition, some products need high stability (closed loop).High-precision, ultra high speed, high pressure or rapid manufacturing (multi loop), and other conditions, also must choose the appropriate production, series.2, put down: by the mold size for determining the machine within the "four pillars", "die thick", "mould minimal size" and "the mold size" whether appropriate, to confirm the mold is put down.The mould width and height should be less than or at least one side distance in less than four pillars;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 more than twice the height of the finished product in the switch mode direction, and the length of the vertical bypass (sprue) is required;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 makes the mold not open.The calculation of clamping force requirements are as follows: by 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) x;Cavity number x;The pressure in the mold (kg/cm2).Mould pressure varies according to the raw materials, raw materials commonly take 350-400 kg/cm2.Mold machine clamping demand outstrips stays 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 determine 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.Some engineering plastics need high injection pressure and the appropriate screw compression ratio design, just have good molding effect, so in order to make the finished product shoot better, also need to consider when choosing screw the needs of the radiation pressure and compression ratio.In general, smaller diameter screw can provide higher injection pressure.7, fast, and the injection speed.Rapid-fire out some finished products need overhead rate to stable forming, such as ultra-thin products, in this case, you may need to confirm the injection rate of the machine and firing rate, enough is tie-in transformer and closed loop control, storage devices, in general, under the same conditions, can provide a high pressure screw usually firing rate is low, on the contrary, can provide a low pressure screw usually firing rate is higher, therefore, choosing screw diameter, injection volume, injection pressure and injection rate, injection speed), cross considerations and tradeoffs.In addition, also can use more circuit design, in order to shorten the molding time synchronization composite action.After the above steps, can already decided to conform to the requirements of injection molding machine in principle, but there are some special problems may also must be taken into consideration, include: the size of the problem Under some special conditions, the customer's moulds or products may be small but needed to shoot the quantity is big, or small amount of mould is big but needed to shoot and under this condition, manufacturers are preset standard may not be able to meet customer demand, and must carry out the so-called "size", or "big wall small shot" or "small wall big shot" is that the original standard die units with larger injection screw, of course, also may die on collocation and injection level difference.Fast machine or the idea of high-speed machine: in practice, more and more customers will be asked to buy so-called "high-speed machine" or "fast" in general, the aim, in addition to the demand of the product itself, the other is mostly to shorten the molding cycle, increase the output of per unit time, and reduce the production cost, improve the competitiveness.In general, to achieve the above purpose, there are several kinds of practice: injection speed: the motor and pump, or add c accumulator (preferably with closed loop control);Feeding speed: motor, motor and pump or hydraulic motor in a feeding, accelerate the screw rotation speed;Multiloop system: adopting double circuit or circuit design, as a simultaneous composite action, shorten the molding time;Increase the mould waterway, mold cooling efficiency."There is no such thing as a free lunch", however, the machine performance promotion and transformation is to increase the production efficiency, but also tend to increase the cost of investment and operating costs, therefore, benefit evaluation should be weighed carefully before investment, can in the most suitable models to produce the highest benefit.
