Surface Treatment
1、 Electroplating
Die castings undergo electrolysis in a solution containing the desired metal for plating. The casting is the cathode, and the desired metal plating is the anode to obtain a firmly bonded metal film on the surface of the casting.
2、 Painting
Used for decoration, protection, and signage. Hiding surface defects through painting increases or reduces surface friction. The problems that are prone to occur in this process are orange peel, pinholes, dullness, oil accumulation, and oil splashing on the surface of the casting. Therefore, it is necessary to adjust the concentration and amount of paint, ensure that the surface of the casting is clean, and strictly follow the operating procedures.
3、 Chemical film-forming treatment
The use of chromate treatment generates a tough film on the surface of the casting, which has various colors and improves the corrosion resistance of the casting. The surface is aesthetically pleasing and can also be easily painted and colored.
4、 Electrostatic spraying
A high-voltage electrostatic field is formed between the spray gun, nozzle, and the coated casting, causing atomized paint particles to carry negative charges in the high-voltage electric field and fly towards the positively charged surface of the casting, forming a uniform paint film. Provide a protective layer for castings, achieve a beautiful and smooth surface, and provide good corrosion resistance.
5、 Infiltration treatment
Under vacuum and pressure conditions, the liquid infiltration agent is allowed to penetrate into the micro pores of the casting, which are solidified and sealed to achieve the purpose of sealing.
Casting cleaning
1、 Methods for removing sprues and burrs
A. Manual homework: Use simple tools such as hammers, files, pliers, etc. to strike and remove excess parts of the casting pouring system. The advantages are convenience, simplicity, and speed, but the disadvantages are uneven cuts, which can easily damage the casting and deform. Not suitable for parts with thick gates, complex parts, and large castings.
B. Mechanical homework: Using mechanical equipment such as edge cutting machines, punches, dies, and band saws. The advantage is that the incision is neat, and the cleaning efficiency is high for large and medium-sized castings.
C. Polishing: Select steel sand wheels, nylon wheels, cloth wheels, flying wing wheels, grinding wheels, etc. according to the requirements of the casting for polishing treatment.
D. Automation of cleaning process: Using robots to clean castings, completing tasks such as removing burrs, polishing, and trimming. Thus achieving clean and efficient production.
2、 Shot blasting cleaning
Under the action of the shot blasting wheel, the projectile impacts the surface of the casting, causing it to absorb the kinetic energy of the high-speed moving projectile and produce plastic deformation, presenting residual compressive stress, thereby improving the surface strength, fatigue strength, and corrosion resistance of the casting, and achieving the purpose of cleaning and strengthening.
3、 Sandblasting cleaning
Using purified compressed air, vigorously spray quartz sand onto the surface of the casting, utilizing impact and friction to remove impurities such as burrs, oxide skin, and dirt from the casting. Clean the surface of the casting and roughen it to improve the adhesion between the coating and the substrate.
4、 Grinding and polishing
By using vibration grinding machines, centrifugal polishing machines, and other equipment, grinding stones, abrasives, water, etc. are used to achieve the effect of deburring and polishing the surface by rubbing against the die-casting parts during high-speed vibration (rotation).
5、 Proofreading
When the casting undergoes deformation due to solidification shrinkage, ejection deformation, or edge cutting, it is necessary to calibrate the deformed casting through measuring instruments and fixtures, manually calibrated with a wooden hammer or calibrated with a hydraulic press.
