1. There are smooth holes of different sizes in the inner, surface or near surface of the bed casting. The holes are round, long and irregular in shape, single or aggregated into sheets. The color is white or with a dark color, sometimes covered with a layer of oxide scale. Reduce the amount of metal inhalation in smelting. Reduce the gas emission of sand mold in the casting process, improve the structure of the bed casting, improve the permeability of sand mold and core, so that the gas in the mold can be discharged smoothly.
2. Small and incoherent shrinkage holes gather in one or more places in the bed castings. The grains are coarse, and there are very small holes between grains. Water seepage occurs during hydraulic test. As far as possible, reduce hot joints and minimize pouring temperature and pouring speed.
3. Sand holes are filled with molding sand inside or inside the casting bed. Strictly control molding sand performance and molding operation.
4. Cold cracks have penetrating or non-penetrating cracks (mainly straight) on the bed castings, and the metal epidermis is oxidized at the cracks.
5. There is a kind of incomplete fusion gap or pit on the bed castings, and its boundary edge is smooth. Improve pouring temperature and pouring speed. Improve gating system. No interruption during pouring.
6. Viscose sand on the surface of the bed castings is completely or partially covered with a layer of metal (or metal oxide) mixed with sand (or paint) or a layer of sintered moulding sand, resulting in rough surface of the bed castings.
Bed castings are widely used.
It can be used in the processing of instruments, electronics, light industry, standard parts, bearing industry, auto parts industry and other parts. Wear resistance and dimensional stability directly affect the accuracy and maintenance life of the bed castings.
