There will be various defects in the casting process, so we need to know the causes of these defects and the prevention of these defects.appear.Today,Foundry FactoryThe causes and methods of preventing these defects have been identified. Let's comeUnderstand it.

Features: Holes are holes that exist on the surface or inside the casting, which are round, oval or irregular. Sometimes, multiple pores form air masses, often pear-shaped under the skin. The shape of the choke hole is irregular and the surface is rough. Air pockets are grooves on the surface of the casting with a smooth surface. Visible pores can be found by visual inspection, subcutaneous pores can only be found after processing.

Foundry FactoryFor everyone to introduceCause of formation:

1. The preheating temperature of the mold is too low, and the liquid metal cools too fast when passing through the gating system.

2. The mold exhaust design is poor, and the gas cannot be discharged smoothly.

3. The paint is not good, the exhaust gas is not good, and even the gas is volatilized.

4. There are holes and pits on the surface of the mold cavity. After liquid metal is injected into the holes and pits, the gas will rapidly expand and compress the liquid metal, thereby forming blocked holes.

5. The surface of the mold cavity is corroded and not cleaned.

6. Raw materials (sand core) stored improperly, not preheated before use.

7. Poor deoxidizer, insufficient dosage or improper operation, etc.

BelowFoundry FactoryFor everyone to sharePrevention methods:

1. The mold should be fully preheated, the particle size of the coating (graphite) should not be too fine, and the air permeability should be good.

2. Use the inclined pouring method to pour.

3. Raw materials should be stored in a ventilated and dry place, and should be preheated when used.

4. The pouring temperature should not be too high.

Foundry FactoryDefects are often repaired in order to bring castings up to service standards and to reduce losses and waste. Commonly used maintenance equipment is argon arc welding machine, resistance welding machine, cold welding machine, etc. For casting defects with low quality and appearance requirements, high-heat, high-speed welding machines such as argon arc welding machines can be used for maintenance.

However, in the field of defect repair of precision castings, due to the huge heat effect of argon welding, the repair will cause deformation, hardness reduction, blistering, local annealing, cracking, pinhole, wear, scratches, undercut or insufficient bonding force and internal stress damage and other secondary defects. Cold welding machine is to overcome the above shortcomings. Its advantages mainly lie in the small heating area, no preheating and cold welding repair at room temperature, so there is no deformation, undercut and residual stress, no local annealing, and no change in the metal state of the casting.This isFoundry FactoryIn order to repair defects commonly used methods.