Analysis of common defects in Zinc Alloy die castings

First, the zinc alloy die-casting surface has the pattern, and has the metal flow mark to produce the reason: 1, leads to the casting entrance place runner to be too shallow. 2, the pressure is too large, resulting in high metal flow rate, causing metal liquid splash. Adjustment Method: 1, deepen gate runner. 2. Reduce the pressure. Second, zinc alloy die-casting surface has the tiny convex lump production reason: 1, the surface is rough. 2. There are scratches, pits and cracks on the inner surface of the mold cavity. Adjustment Method: 1, Polishing Cavity. 2. Replace or repair the cavity. 3, the casting surface has push rod marks, surface is not smooth, rough reasons: 1, Push Rod (Push Rod) too long; 2, cavity surface rough, or debris. Adjustment Method: 1, adjust the length of push rod. 2. Polish the cavity to remove dirt and grease. 4. There are cracks or local deformation on the surface of zinc alloy die-casting parts. The causes are as follows: 1. Uneven distribution or insufficient number of ejector rods and uneven force: 2. The force on one side of the ejector Rod fixing plate is large and the force on the other side is small when the ejector rod fixing plate is inclined at work, deform and crack the product. The Wall of the casting is too thin, and it will deform after shrinking. Adjustment Method: 1, increase the number of ejector Rod, adjust its distribution position, make casting ejector force balanced. 2. Adjust and reinstall the push rod mounting plate. There are air holes on the surface of zinc alloy die-casting parts, the causes are: 1, too much lubricant. 2, the vent is blocked, the vent does not come out. Adjustment Method: 1, the rational use of lubricants. 2. Add and repair vent holes to facilitate smooth exhaust flow. 6. There are shrinkage holes on the surface of the casting. The reasons are: The craft of the die casting is unreasonable, and the thickness of the wall changes too much. The liquid metal is too hot. Adjustment Method: 1, in the wall thickness place, increases the craft hole, causes it thin thick even. 2. Lower the liquid metal temperature. 7, casting outline is not clear, unable to form, partial lack of material, the causes: 1, die-casting machine pressure is not enough, the injection ratio is too low. 2, the thickness of the feed port is too large; 3, the gate position is not correct, so that the metal has a positive impact. Adjusting method: 1, replace die casting machine which is bigger than die casting machine; 2, reduce the thickness of inlet runner; 3, change the position of gate to prevent the impact to the front of casting. 8, casting parts not formed, cavity filling is not full, the reasons: 1, die-casting mold temperature is too low; 2, liquid metal temperature is too low; 3, press pressure is too small, 4, liquid metal, injection speed is too high; 5, Air can not be discharged. Adjusting method: 1, raise die casting die, metal liquid temperature; 2, replace large pressure die casting machine. 3, add enough liquid metal, reduce the injection speed, increase the thickness of the feed port. 9, Die Casting Acute Corner filling is not full, cause: 1, Ingate Inlet is too big; 2, Die Casting Machine pressure is too small; 3, Acute Corner Ventilation is not good, there is air row. Adjustment Method: 1, reduce the inner gate. 2. Change to a high pressure die casting machine. 3, improve exhaust system ten, loose casting structure, strength is not high, cause: 1, die-casting Machine Pressure is not enough; 2, Ingate is too small; 3, Exhaust Hole Plug. Adjustment Method: 1, change the press. 2. Enlarge the INGATE. 3. Check the air vent to ventilate. There are air holes in the casting, the causes are as follows: 1. The flow direction of liquid metal is not correct, the die casting cavity has a positive impact, resulting in Eddy Current, enveloping the air, resulting in air bubbles. 2. The Gate is too small and the flow rate of liquid metal is too high. The vent is blocked prematurely before the air is discharged, leaving the gas in the casting. 3. The cavity of the moving model is too deep, which makes it difficult to ventilate and exhaust. 4, the exhaust system design is not reasonable, exhaust difficult. Adjusting method: 1, the shape of the shunt cone is too small to prevent the metal flow from impacting the cavity. 2. Enlarge the gate properly. 3. IMPROVE MOLD design. 4. Properly design exhaust holes and increase air pockets.