The Complete Guide to Metal Finishing (Part 1)

I. Mechanical surface treatment

This encompasses sandblasting, shot blasting, grinding, rolling, polishing, and brushing.

Characteristics:

This process alters the form and roughness of the metal surface through physical means.

Additionally, it is essential to remember the following information about surface treatment methods for metal materials:

1.???? Sandblasting:

Sandblasting utilizes compressed air to propel abrasive materials (e.g., copper ore sand, quartz sand, emery, iron sand, Hainan sand) onto the workpiece surface at high velocity. This impact modifies the appearance and shape of the surface, achieving a certain level of cleanliness and roughness.

The technical characteristics are as follows:

1. Sandblasting treatment effectively removes dirt, such as rust, oil, and oxidized skin, from the surface of the workpiece, ensuring a high degree of cleanliness. This method is especially effective for rust removal on metal surfaces.

2. Sandblasting treatment, a technically advanced process, allows for the selection of various degrees of roughness to meet different process requirements. This is achieved by using abrasives of varying grain sizes, which play a crucial role in determining the roughness levels.

3、The sandblasting treatment is known to enhance the fatigue resistance of workpieces, extend the lifespan of coating films, and improve the adhesion between the workpiece and the coating.

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2.???? Polishing

whether done mechanically, chemically, or electrochemically, aims to reduce the roughness of a workpiece's surface to achieve a smooth, bright finish. This process typically involves the use of polishing tools and abrasive particles or other media for the finishing process.

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Mechanical polishing is a precise procedure involving the cutting and plastic deformation of the material surface to eliminate surface irregularities and attain a flawless, smooth finish. It is a dependable method within surface treatment processes.

Characterized by its low cost, simple operation, and occasional surface irregularities, mechanical polishing is suitable for minor surface treatments. This method often involves the use of tools such as oil stone strips, wool wheels, and sandpaper, mainly through manual operations.

The resultant effect of polishing is that the roughness average (Ra) value of the metal surface can reach 0.3 to 3.0μm.

Chemical polishing, on the other hand, involves the use of chemical reagents on the surface of the sample to selectively dissolve uneven areas, remove abrasive marks, etch, and level the surface.

Characterized by its highly efficient process that ensures uniform surface roughness of the treated parts and is a productive method in surface treatment processes.

Disadvantages of chemical polishing:

The chemical polishing solution used in the adjustment and regeneration is complex and may produce harmful gases.

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?Electrolytic polishing:

This technique involves using the polished workpiece as the anode and an insoluble metal as the cathode, offering significant benefits. By immersing the two poles in the electrolytic tank through direct current and selective anodic dissolution, the workpiece's surface brightness is significantly enhanced.

Technical characteristics:

- Consistent color inside and outside

- Long-lasting luster

- Requires a small amount of polishing

- Controllable size and shape accuracy after polishing

- High polishing rate not affected by the hardness of the material

- Simple process with a small investment in equipment

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Disadvantages of electrolytic polishing:

- More complex pre-polishing treatment required

- Poor generality of the electrolyte

- Short service life

- Inability to eliminate the original surface of the "coarse ripples."

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Powder spraying:

This technique involves evenly adsorbing dry powder on the workpiece through electrostatic spraying and forming a solid and bright coating after high-temperature curing.

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Technical characteristics:

1. Good environmental protection: Does not contain organic solvents, reduces VOC emissions, and is environmentally friendly.

2. Saving resources: No water resources, avoiding secondary solid waste treatment.

3. Recyclable and reusable: The sprayed powder can be recycled and reused, saving production costs.

4. Good coating quality: High coating adhesion and mechanical strength, providing long-term corrosion resistance.

5. High production efficiency: Suitable for automated assembly line coating, significantly improving production efficiency.

Application:

Powder coating equipment is a versatile tool used in various industries, such as automobiles, machinery, electronics, furniture, and construction. It provides a protective layer resistant to corrosion, abrasion, heat, and scratches.