The method for the production of metal casting under high pressure (HPDC) provides for forced filling (with a high inlet speed from 0.5 to 120 m/s) of the mold cavity under the influence of external forces and solidification of the casting under excess pressure.
This method provides efficient production of castings with high dimensional accuracy (for the 3-5th class of accuracy) and low surface roughness (for the 5-8th class) from non-ferrous alloys in mass and serial production. Cold chamber die casting can be made with finished holes, knurled, threaded, numbers, and inscriptions, while the minimum wall thickness of the casting can be 0.6 mm. By the level of mechanization, productivity, accuracy of castings, and the minimum duration of the technological cycle, the injection molding method surpasses all known methods of precision casting production.
The most popular injection molding method
In industrial practice, the most widespread are cold chamber die casting with a cold horizontal pressing, capable of developing significant locking and pressing forces, having large pressing chambers, which favors their use for the manufacture of castings from aluminum, copper, and magnesium alloys. As well as injection molding machines with a vertical hot pressing chamber, which is intended for the manufacture of small, thin-walled castings, because It is difficult to create the high pressure required to obtain large-sized castings in pressing chambers operating in a liquid melt.
The high-pressure casting method makes it possible to obtain, with high productivity, thin-walled castings of a complex configuration, with high accuracy and low surface roughness. The high rate of metal cooling in a metal mold under excessive pressure contributes to the refinement of the structure of the casting material, an increase in strength characteristics, and a decrease in shrinkage defects.
Die casting is widely used in all areas of mechanical engineering, but the most demanded consumer of this casting in the automotive industry, which is currently very actively developing, and in the competition between leading automakers, the availability of lightweight, durable parts leads to a decrease in the weight of the car, which creates significant competitive advantages. All this contributes to the development of injection molding production and a constant inflow of investments. Typical castings for the automotive industry: cylinder blocks, heads, gearbox housings, steering parts, etc.
Qualitative indicators: example
The dimensions and weight of castings depend on the power of the machines on which the production is carried out: the greater the clamping force of the mold is created by the machine mechanism, the greater the pressure is created by the pressing mechanism.
The higher the speed of the pressing mechanism, the larger castings can be obtained on the machine. As an example, let’s note that today the machine model OL 4600R of the company “IDRA”, develops a closing force of 4691 tons and an injection force of 2255 kN, which makes it possible to produce castings from aluminum alloys weighing 83.7 kg.
Machine-made injection molding makes it easy to mechanize and automate production. Injection molding machine developers are currently producing automated and robotic injection molding cells. The production of castings is carried out without human intervention: automated supply of metal to the pressing chamber, extraction of finished castings from the molds, separation of the pressure switch, cutting out flash, stripping, transportation, impregnation, etc.