First, the zinc alloy die-casting process needs to consider the following issues

1. Whether the molten metal can flow cleanly and smoothly in the pouring system without separation and eddy current.

2. There are no sharp corners or dead zones.

3. Whether the pouring system has a change in cross-sectional area.

4. Is the position of the exhaust sump and overflow tank correct? Is it big enough? Will it be blocked? Can the gas be effectively and smoothly discharged? The application of the computer simulation filling process is to analyze the above phenomena and use the judgment to select reasonable process parameters.

Second, the paint generation gas analysis

Coating properties: If the amount of gas generated is large, it has a direct influence on the porosity of zinc alloy die-casting parts.

Spraying process: too much use, resulting in a large amount of gas volatilization, too much punch lubricant, or burnt, is a source of gas.

1. A solution to the pores of zinc alloy die castings

First analyze the cause of the stomata, and then take the appropriate measures.

(1) Dry, clean alloy material.

(2) Control the melting temperature to avoid overheating and degassing

(3) Reasonable selection of die casting process parameters, especially injection speed. Adjust the high speed switching starting point.

(4) The sequential filling is beneficial to the discharge of the cavity gas, and the sprue and the runner have sufficient length (>50mm) to facilitate the smooth flow of the alloy liquid and the gas to be discharged. The thickness of the gate, the direction of the gate, and the overflow groove and the exhaust groove can be set at the position where the air hole is formed. The sum of the cross-sectional area of the overflow product shall not be less than 60% of the total cross-sectional area of the ingate, otherwise the slagging effect will be poor.

(5) Select a good performance paint and control the amount of spray.

Third, how to measure the furnace temperature?

1. The best melting temperature of zinc alloy die-casting: The melting point of zinc alloy for die-casting is 382 ~ 386 °C. Suitable temperature and shortness control is an important factor in the control of zinc alloy composition. In order to ensure the good fluidity of the alloy liquid filling cavity, the temperature of the molten metal in the zinc casting pot of the die casting machine is 415 ~ 430 °C, and the upper limit of the die-casting temperature of the thin-walled parts and complicated parts can be taken; the lower limit of the thick-walled parts and simple parts can be taken. The temperature of the molten metal in the central melting furnace is 430 ~ 450 °C. The temperature of the molten metal entering the gooseneck is basically the same as the temperature in the zinc pot. The pouring temperature can be accurately controlled by controlling the temperature of the zinc pot metal.

2. (when the melting temperature is too high)

The reaction between the iron strontium and the zinc liquid is accelerated, and the oxidation reaction of iron on the surface of the ruthenium produces an oxide such as Fe2O3. The iron element also reacts with the zinc solution to form a FeZn13 compound (zinc slag), which is dissolved in the zinc solution. When aluminum and magnesium are burnt, the metal oxidation rate is increased, the amount of burning is increased, and the dross is increased. Thermal expansion can cause a stuck hammer. The iron element in the cast iron crucible melts into the alloy more, and the reaction between zinc and iron is accelerated at high temperatures. Hard particles of iron-aluminum intermetallic compound are formed, causing excessive wear of the hammerhead and gooseneck. The iron element in the cast iron crucible melts into the alloy more, and the reaction between zinc and iron is accelerated at high temperatures. Hard particles of iron-aluminum intermetallic compound are formed, causing excessive wear of the hammerhead and gooseneck. Fuel consumption has increased accordingly. The higher the temperature, the coarser the castings and the lower the mechanical properties.

3. (when the melting temperature is too low)

The alloy has poor fluidity, which is not conducive to forming and affects the surface quality of the die casting.

4. (How to keep the temperature stable)

The current die casting machine melting pot or furnace is equipped with a temperature measurement and control system, timing check to ensure the accuracy of the temperature measuring instrument, and the actual temperature of the furnace is measured regularly with a portable temperature detector (temperature meter) to be corrected. The experienced die-casting union observes the melt with the naked eye, and if the slag is scraped, the melt is not too thick.