Analysis of Common Defects in Zinc Alloy Die Castings

First, zinc alloy die casting surface pattern, and there are metal flow traces of the causes: 1, to the casting inlet runner is too shallow. 2, pressure injection ratio pressure is too large, resulting in metal flow rate is too high, caused by the splash of the liquid metal. Adjustment method: 1, deepen the gate runner. 2, reduce the injection pressure.　　Second, zinc alloy die casting surface has a small convex tumor cause: 1, surface roughness. 2, cavity surface has scratches or pits, cracks. Adjustment method: 1, polishing the cavity. 2, replace the cavity or repair.　　Third, the casting surface has a push rod marks, the surface is not smooth, rough causes: 1, push piece rod (top rod) is too long; 2, cavity surface roughness, or debris. Adjustment method: 1, adjust the length of the push piece rod. 2, polishing cavity, remove debris and oil.　　Fourth, zinc alloy die casting surface cracks or local deformation Causes: 1, the top material rod distribution is not uniform or the number is not enough, the force is not uniform: 2, the push rod fixing plate in the work of the skewed, resulting in one side of the force is large, one side of the force is small, so that the product is deformed and cracks. 3, the casting wall is too thin, shrinkage deformation. Adjustment method: 1, increase the number of top feeder rod, adjust its distribution position, so that the casting top out of the force balanced. 2, adjust and re-install the push rod fixed plate.　　Five, zinc alloy die casting surface with air holes Causes: 1, too much lubricant. 2, exhaust hole is blocked, air holes can not be discharged. Adjustment method: 1, reasonable use of lubricants. 2, increase and repair the exhaust hole, so that its exhaust smooth.　　Sixth, the casting surface has shrinkage holes Causes: die casting technology is unreasonable, wall thickness is too big change. Metal liquid temperature is too high. Adjustment method: 1, in the wall thickness of the place, increase the process hole, so that the thickness of the thin uniform. 2, reduce the temperature of the metal liquid.　　Seven, the casting outer contour is not clear, into the shape, local underfeeding Causes: 1, die-casting machine pressure is not enough, injection ratio pressure is too low. 2, the thickness of the feeding port is too large; 3, the gate is not in the correct position, so that the metal occurs in a positive impact. Adjustment method: 1, replace the die casting than the pressure of the die casting machine; 2, reduce the thickness of the inlet runner; 3, change the location of the gate, to prevent the casting of the positive impact.　　Eight, the casting part is not formed, cavity filling is not full Causes: 1, the die-casting mold temperature is too low; 2, the metal liquid temperature is low; 3, the press pressure is too small, 4, the metal liquid is not enough, the ejection speed is too high; 5, the air can not be discharged. Adjustment method: 1, improve die-casting mold, metal liquid temperature; 2, replace the big pressure die-casting machine. 3, add enough metal liquid, reduce the ejection speed, increase the thickness of the feeder.　　Nine, die casting acute angle filling is not full Causes: 1, the inlet gate is too big; 2, die casting machine pressure is too small; 3, acute angle at the ventilation is not good, there is air out. Adjustment method: 1, reduce the inner gate. 2, change the pressure of the die-casting machine. 3, improve the exhaust system ten, casting structure loose, strength is not high Causes: 1, die-casting machine pressure is not enough; 2, the inner gate is too small; 3, the exhaust holes are blocked. Adjustment method: 1, change the pressure machine. 2, increase the inner gate. 3, check the exhaust hole, to repair the ventilation.　　XI, castings have air holes in the casting Causes: 1, the liquid metal flow direction is not correct, die casting cavity occurs in the front impact, resulting in eddy current, the air will be surrounded by air, resulting in bubbles. 2, the inner gate is too small, the liquid metal flow rate is too large, in the air is not discharged before the air is prematurely blocked the exhaust hole, so that the gas stays in the casting. 3, the dynamic model cavity is too deep, the ventilation and exhaust difficulties. 4, the exhaust system is not designed reasonably, exhaust Difficulty. Adjustment method: 1, correct the diversion cone is too small and the shape to prevent and metal flow caused by the cavity of the positive impact. 2, increase the appropriate inner gate. 3, improve the mold design. 4, reasonable design of the exhaust holes, increase the air hole.　　Twelve, the casting contains impurities Causes: 1, the liquid metal is not clean, there are impurities. 2, the alloy composition is impure. 3, the mold cavity is not clean. Adjustment method: 1, pouring into, the impurity and slag clear away. 2, replace the alloy. 3, clean mold cavity, make it clean.　　Thirteen, die-casting process, the liquid metal spilled Causes: 1, dynamic, fixed mold between the close is not tight, gap is large. 2, clamping force has enough. 3, pressure motor, fixed template is not parallel. Adjustment method: 1, reinstall the mold. 2, increase the clamping force. 3, adjust the die casting machine, so that the dynamic, fixed mold parallel to each other.