Common defects and reasons for aluminum alloy profiles

A. Scratch. Along the direction of the casting surface of the open mold appears striped pull marks, there is a certain depth, serious for one side of the scar. The other is the metal liquid and mold to produce welding, adhesion and pull. So that the surface of the casting is more meat or lack of meat.

Reason:: cavity surface damage, mold direction slope is too small or inverted, top-out skew, pouring temperature is too high, mold temperature is too high leading to alloy fluid adhesion. The use of release agent is not good, iron content is less than 0. 6% etc.

B. Bubbles. Aluminum alloy profile surface has rice grain size bulge also has the formation of holes under the skin.

Reason: alloy liquid in the pressure chamber full of low, easy to produce coil, high pressure rate, mold exhaust poor, melt not degassing, smelting temperature is too high, mold temperature is too high, metal solidification time is not enough, strength is not enough, and premature opening mold top castings, pressure gas expansion, release agent too much.

C. Cold separation. Aluminum alloy profile surface has obvious, irregular, subscession linear pattern (there are penetration and non-penetration of the two) shape small and narrow, sometimes smooth junction edge, under the influence of external forces have the possibility of development.

Reason: Two metal flows are connected to each other, but not fully fused and not mixed between them, the two metal combined milk is weak. Pouring temperature or die mold temperature is low, the selection of improper alloy, poor flow, pouring position is not right or flow too long, real charge speed is low, the pressure ratio is low.

D. Discoloration, spot. The Aluminum alloy profile surfaces appear different from the metal color of the substrate.

Reason: Inappropriate release agent, release agent use too much, overwork, containing graphite lubricant in the graphite into the casting surface.