The setting and adjustment of machine process parameters in die casting production can affect the quality of products directly. A plurality of defect parameters may cause the product, and the same defect of the same product may be associated with multiple parameters, changes in requirements analysis of process parameters in die casting production to carefully test for casting forming. Die casting manufacturers usually set and adjust machine parameters by special personnel.
Let’s take DCC280 horizontal cold chamber die casting machine production as an example. The main process parameters of die casting production settings are as follows:
First, the main process parameters are set as mentioned below:
(1) Injection time: injection time is proportional to the size and wall thickness of casting, casting quality for large injection, a speed slower and required a longer time. The injection time can be increased properly, generally more than 2s. The time of movement of the two speeds punch is equal to the filling time.
(2) Open (mold) time: open (mold) time generally exceeds 2s. The die-cast thick-open type is relatively thin (mold) for a long time, and the complex type (mold) is longer than the simple structure (mode) and the open type (mode). It can be a little longer at the beginning of the adjustment, then shorten the working procedure first, pay attention to the model (mode) and open the safety door to prevent the casting from splashing and incomplete cooling.
(3) Ejection delay time: minimize the delay time over 0.5s while ensuring the product is fully solidified and non-sticky.
(4) Top return delay time: under the premise of ensuring the successful removal of the casting, the top return delay time is reduced as much as possible by more than 0.5 s.
(5) The storage time: around 2S in general, machine cycles automatically at the time of operation, observe the energy at the end of the time, whether the pressure can reach the set value, in the premise to achieve the set pressure value to shorten the storage time.
(6) The number of thimble: set the number of thimble according to the requirements of mould.
(7) The pressure parameters are set to minimize the working pressure as long as the machine can work properly and the casting quality can meet the requirements.
Second, the following factors should be considered when select and set the injection pressure:
(1) The structural characteristics of die casting determine the setting of pressure parameters
Wall thickness: thin-walled parts, high injection pressure; thick-walled parts, more optional pressure.
The geometry of the casting is complex: the shape of the complex part, set high pressure ratio; the shape is simple, set low pressure ratio.
Rationality of the process: good technical rationality.
(2) The characteristics of die casting alloy determine the setting of pressure parameters
(1) Crystallization temperature range: when crystallization temperature range is large, select high specific pressure; when crystallization temperature range is small, select lower specific pressure.
Liquidity: good fluidity, choose low pressure; low fluidity, choose high injection pressure.
Density: when the density is large, the pressure of injection and pressurization should be larger; when the density is small, the pressure of injection and pressurization are all smaller.
(2) Specific strength: when the requirement of specific strength is large, the pressurization is higher than the pressure.
(3) Gating system determines the setting of pressure parameters
Gate runner resistance: resistance, mainly due to gate length, steering, in the same cross-sectional area, gate thickness is small and it should be chosen to be larger than the supercharger.
Forth, the heat dissipation speed of the runner:
If the heat dissipation speed is fast, the injection pressure is higher; if the heat dissipation rate is slow, the injection ratio is lower.
(1)The discharge system determines the setting of pressure parameters.
(2)Distribution of exhaust duct: the distribution of exhaust duct is reasonable. The pressure of injection and the pressure of pressurization are all higher.
(3)Exhaust channel section area: the exhaust channel section area is large enough, and the injection pressure is higher than the pressure selection.
(4)The gate speed requires high speed, and the injection pressure is higher than the pressure
(5)The temperature difference between the alloy and die casting mould is large: the injection pressure is higher; the temperature difference is small and the injection ratio is lower.
(6)The setting of injection speed
The injection velocity is divided into slow ejection velocity (also known as material one velocity), fast injection velocity (also known as material two speed) and pressurization movement speed.
Slow shot speed is usually in the range of 0.1 to 0.8m/s by the 0 movement speed increases gradually. The fast shot speed and ingate speed is proportional to the general regulation from low to high, without affecting the quality of castings under the condition with low fast shot speed namely ingate speed appropriately.
The time of pressurization motion is very short. The purpose of this method is to compact the metal and to make the casting compact. As for booster movement speed regulator, pressure is generally observed in the movement a slash rise evenly showing the value of injection pressure gauge pressure, and die casting products can be no loose phenomenon.
(7) Position adjustment principle of one speed and two speed induction switch
The first and two speed movement conversion should be carried out after the injection punch passes through the pouring port of the pressure chamber.
Generally, for thin wall small castings, one speed is shorter, while the two speed is longer
Generally, for thick wall castings, one speed is longer, while the two speed is shorter
According to the quality of the castings (such as edge, under-casting and bubble) transfer point, the temperature of molten metal is adjusted and the alloy liquid temperature can be displayed and set on the machine electric box panel. The pouring temperature of various alloy liquid is different, and the casting temperature of thick wall casting is lower than that of thin wall casting.
Each casting amount should be selected so that the thickness of the product exceeds the thickness produced in the range of 15 to 25 mm, and the volume of each alloy liquid is stable.
In die casting production, the mold temperature is controlled by a die casting (mold) type (mode). When the temperature of the liquid alloy is different for different mold temperatures, it is generally limited to the solidification temperature of the 1/2 alloy.