The Cause Of The Porosity Of Die Casting(2)

- Apr 30, 2019-

Factors of the machine (equipment, mold, tooling):

Mainly refers to mold quality and equipment performance.

1 Is the design of the die-casting mold reasonable, will it cause pores?

Reasons for die casting molds:

1. The choice of the position of the gate and the shape of the flow guide are improper, causing the molten metal to enter the cavity to generate a frontal impact and generate a vortex. (Reducing the injection speed and avoiding eddy currents)

2. Is there any poor design of the runner shape?

3. Is the speed of the ingate too high, causing turbulence?

4. Is the exhaust air not smooth?

5. Is the mold cavity position too deep?

6. Is the machining allowance too large? Penetrate the dense layer on the surface to expose the subcutaneous pores? The machining allowance of die-casting parts should be smaller, generally about 0.5mm, which can reduce the weight of castings, reduce the amount of cutting processing to reduce the cost, and avoid the exposure of subcutaneous pores. The remaining amount is preferably not more than 0.5 mm, so that the processed surface is substantially invisible to the pores because of the protection of the hard layer.

2 Is the vent hole blocked and the gas exhausted?

3 Is the punch lubricant too much or burnt? This is also one of the sources of gas generation.

4 Gate position and flow guiding shape. Is there any metal liquid to close the overflow system on the parting surface first?

5 Is the position of the gate unreasonable, the metal passing through the gate immediately hits the wall and creates eddy currents, and the gas is drawn into the metal flow?

6 The exhaust passage is not in the right position, resulting in poor exhaust conditions.

7 Is the area of the overflow passage large enough, is it blocked, is the position at the last filling place? Is the mold exhaust part cleaned frequently? Avoid losing the exhaust due to blockage of the release agent.

8 Is the mold temperature too low?

9 Is the runner turning smooth? Appropriately increase the ingate?

10 Is there a vent plug in the deep cavity or is it added in the form of inserts to increase the venting?

11 Is there any unreasonable design for die-casting, which is difficult to vent?

12 Is the total cross-sectional area of the overflow port less than 60% of the total cross-sectional area of the ingate, and the slagging effect is poor?

13 Is there any way to increase the thickness of the ingate to reduce the filling speed while satisfying the well-formed condition?

14 Is there any venting speed that is too high, the turbulent movement is too much, and the metal flow is involved in gas?

15 Is there a small cross-sectional area of the ingate that is too small?

16 Is there a sequential filling to facilitate the discharge of the cavity gas, and the sprue and runner are of sufficient length?