Riser and Gating Residue Treatment Process for Mechanical Valve Castings
In the production process of mechanical valve castings, the presence of riser and gating residue is inevitable. These residues include risers, shrinkage cavities of risers and gates, and gating burrs, etc. Their existence not only affects the appearance quality of the casting but may also have a negative impact on the performance of the mechanical valve. Therefore, the treatment of riser and gating residue is a very important link in the casting production process. This article will elaborate on the causes of riser and gating residue, treatment methods, and process requirements from three aspects.
1. Causes of the generation of riser and gating residue
Riser and gating residue mainly occurs during the pouring process of mechanical valve castings, and the specific reasons are as follows:
Unreasonable design of the pouring system. If the design of the pouring system does not fully consider the reasonable design of the riser and gating, such as improper position of the riser and gating, too small or too large size, or unreasonable shape of the riser and gating, it will lead to the generation of riser and gating residue.
Too fast cooling speed of the casting. If the casting cools too fast during the cooling process, the internal gases of the casting will not be fully discharged, leading to the generation of riser and gating residue.
Improper selection of casting process parameters. For example, if the pouring temperature is too high or too low, or the pouring speed is too fast or too slow, it will affect the generation of riser and gating residue.
Improper selection of casting materials. If the casting material has poor fluidity or high shrinkage rate, it will lead to the generation of riser and gating residue.
2. Treatment methods for riser and gating residue
The main treatment methods for riser and gating residue are as follows:
Mechanical treatment method. Riser and gating residue is removed through mechanical processing, such as grinding, turning, and milling. This method is simple to operate, low in cost, but requires high processing accuracy and may affect the dimensional accuracy of the casting.
Chemical treatment method. Riser and gating residue is removed through chemical corrosion. This method can remove most of the riser and gating residue, but it may affect the surface quality of the casting and requires the use of strong corrosive chemicals.
Electrochemical treatment method. Riser and gating residue is removed through electrochemical corrosion. This method can precisely control the corrosion depth and will not affect the surface quality of the casting, but requires high equipment and technical level.
Heat treatment method. Riser and gating residue is removed through heat treatment. This method can remove most of the riser and gating residue, but it may affect the performance of the casting and requires high equipment and technical level.
3. Process requirements for the treatment of riser and gating residue
When designing the pouring system, full consideration should be given to the reasonable design of the riser and gating to ensure that the position, size, and shape of the riser and gating meet the requirements.
During the casting process, the pouring temperature and pouring speed, among other process parameters, should be controlled well to ensure that the cooling speed of the casting is moderate and to avoid the internal gases of the casting from not being fully discharged.
When selecting casting materials, materials with good fluidity and low shrinkage rate should be chosen to reduce the generation of riser and gating residue.
When treating riser and gating residue, appropriate treatment methods should be selected to ensure the treatment effect while ensuring the dimensional accuracy and surface quality of the castings.
In summary, the treatment of riser and gating residue is a complex task that requires consideration from multiple aspects such as design, process, and treatment. Through reasonable process design and treatment methods, it can effectively reduce riser and gating residue and improve the quality of castings.