Drawing and sandblasting recruitment

Ten common surface treatment methods: polishing, sandblasting, wire drawing, anodizing, electrophoresis, PVD, electroplating, etching, spraying and laser engraving.

First, polishing

Polishing refers to the processing method of reducing the surface roughness of workpiece by mechanical, chemical or electrochemical action to obtain a bright and flat surface. Polishing tools and abrasive particles or other polishing media are used to modify the surface of the workpiece.

Polishing does not improve the dimensional accuracy or geometric accuracy of the workpiece, but aims at obtaining smooth surface or mirror luster, and is sometimes used to eliminate luster (extinction). Polishing wheels are usually used as polishing tools. Polishing wheel is generally made of multi-layer canvas, felt or leather, with two sides clamped by metal circular plates, and its rim is coated with polishing agent, which is evenly mixed with micro-powder abrasive and grease.

When polishing, the high-speed rotating polishing wheel (the circumferential speed is greater than 20m/s) presses on the workpiece, so that the abrasive slightly rolls and cuts on the surface of the workpiece, thus obtaining a bright machined surface, and the surface roughness can generally reach Ra0.63~0.0 1+0 micron; When using non-greasy matte polishing agent, the bright surface can be matte and the appearance can be improved.

According to different polishing processes: rough polishing (basic polishing process), middle polishing (fine polishing process) and fine polishing (polishing process), selecting the appropriate polishing wheel can achieve the best polishing effect and improve the polishing efficiency.

Second, sandblasting.

The process of cleaning and roughening the substrate surface by the impact of high-speed sand flow. Using compressed air as power, a high-speed jet beam is formed, and spraying materials (copper ore, quartz sand, emery, iron ore and Hainan sand) are sprayed on the surface of the workpiece to be treated at high speed, so that the appearance or shape of the outer surface of the workpiece surface changes.

Due to the impact and cutting action of abrasive on the surface of the workpiece, the surface of the workpiece has a certain cleanliness and different roughness, which improves the mechanical properties of the surface of the workpiece, thus improving the fatigue resistance of the workpiece, increasing the adhesion between the workpiece and the coating, prolonging the durability of the coating, and being beneficial to the leveling and decoration of the coating.

Third, wire drawing

It is a kind of surface treatment method which forms lines on the surface of workpiece by grinding products and plays a decorative role. According to the different lines drawn, it can be divided into straight line drawing, random drawing, ripple drawing and spiral drawing. Surface wire drawing treatment is a kind of surface treatment means to form lines on the surface of workpiece by polishing products and play a decorative role. Because surface wire drawing treatment can reflect the texture of metal materials, it has been loved and widely used by more and more users.

Fourthly, anodic oxidation.

An electrolytic oxidation process in which the surface of aluminum and its alloy is usually converted into an oxide film, which has the functional characteristics of protection and decoration. According to this definition, anodic oxidation of aluminum only includes the process of forming anodic oxide film.

Using metal or alloy as anode, an oxide film is formed on its surface by electrolysis. Metal oxide film changes the surface state and properties, such as surface coloring, improving corrosion resistance, enhancing wear resistance and hardness, and protecting metal surface.

Such as anodic oxidation of aluminum, aluminum and its alloys are put into corresponding electrolyte (such as sulfuric acid, chromic acid, oxalic acid, etc.). ) as an anode, electrolysis is carried out under specific conditions and applied current. Anode aluminum or its alloy is oxidized, and a thin layer of alumina is formed on the surface, with a thickness of 5 ~ 30 microns, and the hard anodic oxidation film can reach 25 ~ 150 microns.

After anodic oxidation, the hardness and wear resistance of aluminum or its alloy are improved, reaching 250 ~ 500 kg/mm2, with good heat resistance. The melting point of hard anodic oxide film is as high as 2320K, the insulation is excellent, the breakdown voltage is as high as 2000V, and the corrosion resistance is enhanced. It will not corrode for thousands of hours in ω=0.03NaCl salt spray.

There are a lot of micropores in the thin oxide film, which can absorb various lubricants and is suitable for manufacturing engine cylinders or other wear-resistant parts. The microporous membrane has strong adsorption capacity and can be dyed into various beautiful and gorgeous colors. Non-ferrous metals or their alloys (such as aluminum, magnesium and their alloys). ) can be anodized.

This method is widely used in mechanical parts, aircraft and automobile parts, precision instruments and radio equipment, daily necessities and architectural decoration. Generally, aluminum or aluminum alloy is used as anode and lead plate is used as cathode. Aluminum and lead plate are put together in an aqueous solution, which contains sulfuric acid, oxalic acid, chromic acid, etc. Electrolysis, forming oxide film on the surface of aluminum and lead plate.

Verb (abbreviation of verb) electrophoresis

The process is divided into anodic electrophoresis and cathodic electrophoresis. If the coating particles are negatively charged and the workpiece is an anode, the coating particles are deposited on the workpiece under the action of electric field force to form a thin film, which is called anodic electrophoresis; Conversely, if the coating particles are positively charged and the workpiece is cathode, the coating particles are deposited on the workpiece to form a thin film, which is called cathodic electrophoresis.

The general process flow of anodic electrophoresis is: workpiece pretreatment (degreasing → hot water washing → derusting → cold water washing → phosphating → hot water washing → passivation) → anodic electrophoresis → workpiece post-treatment (clean water washing → drying).

1, degreasing. The solution is generally a hot alkaline chemical degreasing solution, the temperature is 60℃ (steam heating), and the time is about 20min.

2, hot water wash. The temperature is 60℃ (steam heating) and the time is 2 minutes.

3. Rust removal. Use H2SO4 or HCl, such as hydrochloric acid rust removal liquid, and the total acidity of HCl is ≥43 points; Free acidity >; 4 1 min; Add cleaning agent1.5%; Wash at room temperature 10 ~ 20min.

4. Wash with cold water. Rinse with cold water during flowing 1 min.

5. Phosphating. Medium temperature phosphating (60℃ 10min) can be used as phosphating solution.

The above process can also be replaced by sand blasting and water washing.

6. Passivation. At room temperature, the phosphating solution (provided by the manufacturer selling phosphating solution) was used 1 ~ 2 min.

7. Anodic electrophoresis. Electrolyte composition: H08- 1 black electrophoretic paint, solid content 9% ~ 12%, distilled water content 88% ~ 9 1%. Voltage: (7010) v; Time: 2 ~ 2.5 minutes; Paint temperature:15 ~ 35℃; Paint PH value: 8 ~ 8.5. Pay attention to the power failure when the workpiece enters and exits the groove. During electrophoresis, the current will gradually decrease with the thickening of the paint film.

8. Rinse with water. Wash in running cold water.

9. Drying. At (165 5)℃

Sixth, PVD.

PVD is the abbreviation of Physical Vapor Deposition, which means that under vacuum conditions, the target is evaporated by arc discharge technology with low voltage and high current, the evaporated substances and gases are ionized by gas discharge, and the evaporated substances and their reaction products are deposited on the workpiece by the acceleration of electric field.

Physical vapor deposition technology has the advantages of simple process, environmental improvement, no pollution, less consumables, uniform and dense film formation, firm combination with substrate and so on. This technology is widely used in aerospace, electronics, optics, machinery, architecture, light industry, metallurgy, materials and other fields, and can be used to prepare thin films with wear resistance, corrosion resistance, decoration, conductivity, insulation, light guide, piezoelectric, magnetism, lubrication, superconductivity and other characteristics.

Seven, electroplating

It is a process of plating a thin layer of other metals or alloys on the surface of some metals by electrolysis, and a process of attaching a metal film on the surface of metals or other materials by electrolysis to prevent metal oxidation (such as corrosion) and improve wear resistance, conductivity, reflectivity and corrosion resistance (such as copper sulfate). ) and enhance aesthetics. Many coins are also electroplated.

Eight. Etching print

Etching, also called photochemical etching, refers to removing the protective film from the area to be etched after exposure and development, and contacting with chemical solution during etching to achieve the effect of dissolving corrosion and forming concave-convex or hollow molding.

Process flow:

Exposure method: the project is sized according to the drawings-material preparation-material cleaning-drying-film pasting or coating-drying-exposure-development-drying-etching-demoulding -OK.

Screen printing mode: cutting → cleaning plate (stainless steel and other metal materials) → screen printing → etching → demoulding →OK.

Nine, spraying

Spraying is a kind of coating method which is applied to the surface of the coated object by spraying gun or disc atomizer and dispersing it into uniform and fine droplets by means of pressure or centrifugal force. It can be divided into air spraying, airless spraying, electrostatic spraying and various derivative forms of the above basic spraying forms, such as high-flow low-pressure atomizing spraying, thermal spraying, automatic spraying and multi-group spraying.

Spraying operation has high production efficiency and is suitable for manual operation and industrial automation production. Widely used in hardware, plastics, furniture, military industry, ships and other fields, it is the most widely used painting method at present.

Spraying operation needs a clean workshop, and the environmental requirements range from one million to one hundred. Spraying equipment includes spray gun, spray booth, paint supply room, curing oven/drying oven, spraying workpiece conveying equipment, defogging and waste water and waste gas treatment equipment.

The characteristics of high-flow and low-pressure atomization spraying are low atomization air pressure, low air injection speed and low running speed of atomized paint, which improves the rebound of paint on the surface of the coated object. The coating rate is increased from 30% ~ 40% of ordinary air spraying to 65% ~ 85%. In the finishing of light leather, the finishing is sprayed on the leather surface with a spray gun or a shotcrete machine.

Laser engraving

Also called laser engraving or laser marking, it is a surface treatment process based on optical principle.

The high-intensity focused laser beam emitted by the laser is used to oxidize and treat the material at the focal point. The function of scribing is to expose deep substances through evaporation of surface substances.

Either light energy causes the chemical and physical changes of surface substances to leave traces, or light energy burns some substances to "carve" traces, or light energy burns some substances to show patterns and characters to be etched.