What are the problems in the process of metal die casting

What are the problems in the process of metal die castingd3741f007e6ce_1200x500

Pouring line overflow

Requirements for the straight runner of the die on the cold chamber horizontal die casting machine:

  • The diameter of the pressure chamber should be selected according to the required specific pressure and the full degree of the pressure chamber. At the same time, the deviation of the inner diameter of the gate sleeve should be appropriate to enlarge a few wires than the deviation of the pressure chamber diameter, so as to avoid the problem of punch stuck or serious wear caused by the different diameter of the gate sleeve and the pressure chamber, and the wall thickness of the gate sleeve can not be too thin. The length of the gate sleeve should generally be less than the ejection lead of the ejection punch to allow the paint to come out of the pressure chamber.
  • The inner hole of pressure chamber and gate sleeve should be polished after heat treatment, and then grinded along the axis direction. The surface roughness is less than or equal to Ra0.2μm.
  • The concave cavity of the shunt and the formation of the coating, the depth of the concave is equal to the depth of the runner, the diameter of the gate sleeve diameter, along the direction of the release has a 5° slope. The filling degree of the pressure chamber can be improved by shortening the effective length of the pressure chamber.

Mould requirements

  • The entrance of the horizontal runner of the cold horizontal mold should generally be located at more than 2/3 of the inner diameter of the upper part of the pressure chamber, so as to avoid the metal liquid in the pressure chamber from entering the cross runner prematurely under the action of gravity and beginning to solidified in advance
  • The cross-sectional area of the cross runner should be gradually reduced from the straight runner to the inner runner. In order to expand the cross section, negative pressure will appear when the liquid metal flows through, which is easy to inhale the gas on the parting surface and increase the eddy current gas trapping in the liquid metal flow. Generally, the outlet section is 10-30% smaller than the inlet section.
  • The runner should be of a certain length and depth. The purpose of maintaining a certain length is to stabilize the flow and guide the flow. If the depth is not enough, the liquid metal cooling fast, the depth is too deep, because the condensation is too slow, both affect the productivity and increase the amount of return charge.
  • The cross-sectional area of the runner should be larger than that of the inner runner to ensure the speed of the metal entering the type. The cross-sectional area of the main runner shall be greater than that of the branch runner.
  • Both sides of the bottom of the cross runner should be rounded, so as not to appear early cracks, two sides can be made of about 5 degrees of slope. The surface roughness of the cross runner is less than or equal to Ra0.4μm.


  • The parting surface should not be closed immediately after the metal liquid enters the type, and the overflow groove and exhaust groove should not impact the core positively. The flow of liquid metal into the type as far as possible along the cast ribs and heat sink, from the thick wall to the thin wall filling.
  • Choose the location of the inner gate to minimize the flow of liquid metal. In the case of multi-spool inner gate, it is necessary to prevent the convergence and mutual impact of several strands of metal liquid after entering the mold, resulting in defects such as eddy current air inclusion and oxide inclusion.
  • The THICKNESS OF THE INNER gate OF the THIN-walled parts should be smaller to ensure the necessary filling speed, and the setting of the inner gate should be easy to remove, and do not make the casting body defect (meat).

The overflow tank

  • The overflow tank should be easy to remove from the casting, and try not to damage the casting body.
  • When the exhaust groove is set up on the overflow groove, attention should be paid to the position of the overflow port to avoid blocking the exhaust groove prematurely and making the exhaust groove ineffective.
  • Do not open several overflow openings or open a very wide and thick overflow opening on the same overflow tank, in order to avoid the cold liquid, slag, gas, paint in the metal liquid return to the cavity from the overflow tank, resulting in casting defects.