Die casting

When the metal liquid passes through the gate, its filling method can be divided into three ways: layer flow filling, jet flow filling and atomizing flow filling. When the gate speed is low, the filling mode shows laminar flow. When the speed increases, the liquid metal is no longer a continuous outflow, but a coarse granular ejecta; At higher speeds, the water bursts out in a mist of fine particles. Laminar flow filling or mist flow filling can produce satisfactory castings, but coarse particle flow filling is not good because of the heat loss in the filling process. Generally speaking, the thinner the gate, the higher the gate speed to achieve the atomization flow state
 The flow state of the metal liquid into the cavity is determined by the form of the runner and the inner gate. At present, there are two types of fan-shaped runner and cone-shaped runner in use. The pouring system consists of three parts: straight runner, cross runner and inner runner. Fan-shaped runner is more suitable for products with shorter inner gate length, and conical runner is suitable for products with longer inner gate length. Whether it is a fan runner or a conical runner, the cross-sectional area from the runner to the inner gate should be gradually reduced to ensure the control of the flow state of the alloy liquid and prevent gas from being involved in the pouring system; The runner should have a certain length to stabilize the flow and guide the metal liquid

Die casting mold design – Gate

The design of gates and runner generally follows the following principles: 1). Fill the most difficult places first 2). The size of each gate should be proportionally allocated according to the casting volume of its main filling part 3). The location of the gate should avoid being located in places where the liquid flow is easily blocked or directly impacting the core 4). The cross-sectional area of the runner and the cross-sectional area of the gate must be balanced 5). The bend or tail of the runner should be provided with a prominent part or buffer package to buffer and absorb impurities 6). Avoid sharp turns in the runner and sudden changes in cross-sectional area, so as not to cause turbulence into the air 7). When the flow channel turns, the cross-sectional area should be moderately reduced so as not to involve air

Die casting mold design – exhaust

In order to improve the quality of die casting parts, the gas in the cavity should be eliminated as far as possible in the process of filling the cavity with metal liquid, and the metal liquid mixed with gas and polluted by the coating residue should be eliminated from the front flow, which requires the overflow and exhaust system, including the overflow tank and exhaust tank.

Die casting mold design - slag removal

The overflow trough has the following functions: a, to discharge debris, discharge gas; b, maintain mold temperature balance; c, improve the flow direction (drainage) effect; d, the role of ejecting platform; e, accept the first cold metal flow (slag collection) role. The depth of the slag discharge port of the zinc alloy overflow groove is generally 0.2-0.3mm, and the depth of the exhaust channel at the back of the overflow groove is generally 0.05-0.12mm. v In order to fully discharge the gas in the cavity, the cross-sectional area of the exhaust groove is generally 20%-50% of the cross-sectional area of the inner gate.