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The most common surface treatment for sheet metal parts is sandblast oxidation(sheet metal processing)

Dec 03,20

The most common surface treatment for sheet metal parts is sandblast oxidation(sheet metal processing)

Materials to manufacture more of the sheet metal processing, hot plate, electrolytic plate, white iron, stainless steel, aluminum alloy plate and profiles, such as copper, the material is exposed to the atmosphere, and after a good contact with moisture and oxygen in the air, can produce electrochemical reaction, thus the surface corrosion of the materials, and touch each other between the physical and chemical properties of different materials will also be due to the potential difference between each other to form a galvanic cell, resulting in the contact corrosion.In order to avoid the corrosion of materials in each processing procedure and the storage and use of finished products in sheet metal processing, the surface treatment of materials in production is used to control or delay the generation of corrosion, so as to reduce the production of repair or scrap due to corrosion.
Sandblasting (Sand Blasting) processing
Sandblasting (Sand Blasting) treatment in the application of the metal surface is very common.

The purpose is to overcome and cover up some defects in the machining process of aluminum alloy and to meet the customer's special requirements on the appearance of the product.
The principle is to accelerate the abrasive particles to the metal surface impact, and to remove the golden show, deburring, oxidation layer or surface pretreatment, it can change the metal surface finish and stress state.Common sand materials are glass sand, emery sand, steel ball, silicon carbide and so on
Benefits of sandblasting process
Sand blasting process can be divided into pneumatic spray gun and shot two impeller, and the advantages of sand blasting process is that it can, in addition to the beatles peak removal after forging, stamping, flame cutting and pressing the burr, burr of thin workpiece and pore effect is better, it can clean sand casting process of residual sand, iron or steel rust stains, clearing heat treatment, welding, hot forging, rolling, such as thermal process in addition to the scale.In addition, in coating applications, it may remove the existing coating or protective layer and provide a gloss surface for defects such as cracking or cold lines that cover the casting.In addition to the surface stress, it can provide a consistent roughening surface, oil and spray effect, in high stress metal parts such as springs and connecting rods by local continuous beating, will produce deformation and show the strengthening phenomenon.This strengthening effect requires the use of round abrasive such as jinxiusteel shot, in high energy shot blasting machine or special strong sand blasting machine used.To determine the surface hardening effect of the machine, the Almen test workpiece is shot blasted or sandblasted and the deformation is measured to see if it meets the requirements.
Oxidation -- anodic oxidation
1. Prevent corrosion of aluminum products
Since the anodized film itself is stable enough in the atmosphere, the anodized film on the surface of aluminum can be used as a protective layer.The anodic oxidation of aluminum in chromic acid solution resulted in dense oxide film with good corrosion resistance.The pores of the oxide film obtained from sulfuric acid solution are larger than the former, but the film layer is thicker, and the adsorption capacity is very strong. If properly filled and sealed, the corrosion resistance is also very good.It is pointed out that the anodic oxidation method of chromic acid is especially suitable for anodic oxidation treatment of riveted parts and welding parts.
2. Protection - Decorative products
For most aluminum and its alloy products requiring surface finishing, the transparent oxide film can be obtained after chemical or electrochemical polishing and then anodized with sulfuric acid solution.The oxide film can absorb many kinds of organic dyes and inorganic dyes, so it has a variety of bright colors.This layer of color film is not only anti-corrosion layer, but also decorative layer.Under some special technological conditions, protective decorative oxide film similar to porcelain can also be obtained.
3. As a hard wear resistant layer
By hard anodizing aluminum and aluminum alloys, thick and hard Al2O3 film can be obtained on the surface.The film has not only higher hardness and thickness, but also lower roughness.In sulfuric or oxalic acid solutions, hard and thick oxide films can also be obtained by anodic oxidation on aluminum products.
Porous thick oxide film can reserve lubricating oil, so it can be effectively applied to aluminum products working in friction state, such as automobile and tractor engine cylinder, piston, etc. after anodizing, can greatly improve its wear resistance.
4. As an insulating layer for electricity
Anodized aluminum and aluminum alloy products after the oxidation of the oxidation film has a large resistance, so it has a certain role in improving the electrical insulation of some products, can be used to anodize the dielectric layer of capacitance, can also be used to prepare the surface of the aluminum oxide insulation layer.
5. As a base for painting
Due to its porosity and good adsorption capacity, anodic oxidation film can be used as the bottom layer of paint and other organic film, so that the paint film and organic film and products firmly together, thus increasing its corrosion resistance.
6. As the bottom layer of electroplating
Before electroplating aluminum and aluminum alloy products, the bottom layer must be applied to them in advance before electroplating.There are many ways to apply the bottom layer on the substrate surface. Besides electrogalvanization, zinc dipping and electroless nickel plating, anodic oxidation is also one of the important methods.