Surface treatment is one of the important processes of antirust coating. The quality of anti-rust coating of construction machinery depends largely on the way of surface treatment.
According to Imperial Chemical, the coating life is restricted by three factors: surface treatment accounts for 60%, coating construction accounts for 25%, and coating quality accounts for 15%.
The surface treatment methods of different parts in the construction machinery industry are different.
Mechanical cleaning can effectively remove rust, welding slag, oxide skin on the workpiece, eliminate welding stress, increase the binding force of anti-rust coating film and metal substrate, thus greatly improving the anti-rust quality of construction machinery parts. The mechanical cleaning standard shall meet Sa2 of ISO8501-1:1988 Level 5. The surface roughness shall reach 1/3 of the thickness of the antirust coating. The steel shot used for shot blasting shall meet the requirements of GB6484.
The surface treatment of sheet metal stamping parts is generally called chemical surface treatment. The process flow is:
Manual pretreatment → hot water washing → pre-degreasing → degreasing → industrial water washing I → industrial water washing II → surface adjustment → phosphating → industrial water washing III → industrial water washing IV → pure water washing I → pure water washing II → pouring water → drying
The above process can also be adjusted according to the oil and rust of the sheet stamping parts, or the pickling process or the pre-degreasing process is not required. Degreasing and phosphating are the key processes in the chemical treatment process, which directly affect the quality of the chemical treatment of the workpiece and the quality of the antirust coating. Relevant process parameters and relevant auxiliary equipment are also factors that can not be ignored that affect the quality of surface treatment. workmanship
Due to the wide range of construction machinery, multiple specifications, complete machine weight and large parts, painting is generally adopted. Spraying tools include air spray gun, high-pressure airless spray gun, air-assisted spray gun and portable electrostatic spray gun. The spraying efficiency of the air spray gun is low (about 30%), and the high-pressure airless spray gun wastes paint. The common feature of both is that the environmental pollution is relatively serious, so they have been and are being replaced by the air-assisted spray gun and the portable electrostatic spray gun. Small and medium-sized parts can also use water curtain spray booth or pumpless spray booth. The former has advanced performance, while the latter is economical, convenient and practical. Because the whole machine and parts of construction machinery are heavy and have large heat capacity,
Therefore, the anti-rust coating is generally dried by uniform hot air convection. The heat source can be steam, electricity, light diesel, natural gas and liquefied petroleum gas according to local conditions.
(1) Basic painting process painting procedure: DISTRESS damage treatment; Color trimming of SAP STAIN materials; SMOOTH COAT background color (1); REL STAIN background color (2); WASH COAT cementing; SANDING sanding; GLAZE wiping; SEALER primer; SANDING sanding; SPATTER spray point; DRY BRUSH dry brush; COW TAIL oxtail; FIRST TOP COAT finish; BREARWAY FILL grey wax; SANGING sanding; PAD STAIN color shoot; SHADING; TOP COAT topcoat (2). (2) Description of coating process flow 1. Distress damage treatment
Objective: To achieve the effect of antique treatment on the appearance of new furniture products
① Continuous damage treatment is easy to operate, and it will not affect the coating and design of products too much; ② It is necessary to strictly refer to the color plate sample to do damage to the product; ③ Pay attention to the destruction patterns and actions made by the destruction handling staff;
④ Damage treatment of edges and corners is very important in any damage treatment, and the softness of the dent determines the severity of product damage; ⑤ All damages (wormholes, file marks, loose knocks, stone knocks, etc.) should be evenly distributed on the product surface and the edge of the product
Objective: To unify the wood color and make the overall effect and color of the product more harmonious.
① SAP STAIN is generally used for light-colored wood to make it close to the overall color and neutralize any abnormal wood color; ② When doing SAP STAIN, employees will spend 50% of their time on observation, and then spend the other half of their time on spraying products; ③ The color trimming of solid wood is basically a judgment process. Try to keep the employee in the color trimming position;
④ Incorrect spraying will lead to greater color difference of a product and lead to blurred color and incorrect feeling, so requiring employees to form good habits will help to make the product coating meet the requirements;