First, let’s look at the principle of anodizing: anodizing is the use of electrochemical methods in the appropriate electrolyte, alloy parts as the anode, stainless steel, chromium; or the conductive solution itself is the cathode, under certain voltage and other conditions, it is the process of anodizing, which makes the surface of the CNC parts obtain the anodizing film.
The advantages of aluminium anodizing are as follows: it’s light and durable, has excellent weatherability, can be dyed for a beautiful end result, the anode coating can also be used as the primer for further coating, it has a high resistance value, and lastly, it has a high wear resistance.
Our company offers various types of anodizing to meet the needs of our customers’ products.
The five types of anodizing treatment are as follows:
(1) Sulfuric acid anodization (5~20um): This is an anodizing film that is easy to dye and has high hardness. It is the main protection and decoration method for aluminium and aluminium alloy.
(2) Chromic acid anodization (2~5um): The anodizing film is opaque, not light grey or milky white, with low porosity. The process is used for precision parts, with thick film.
(3) Oxalic acid anodizing (8 ~ 20um, up to 60um): Oxalic acid anodizing is easy to produce a thick film, high hardness of anodizing film, low porosity, high corrosion resistance, good electrical insulation, but the cost is higher than sulfur anodizing, generally used for special requirements of the surface, such as making electrical insulation protection layer, surface decoration of daily necessities.
(4) Hard anodizing (also known as thick film oxidation, 250-300um): The hardness is very high, generally 400-600hv, and the current density is 2-3 times that of ordinary anodizing.
(5) Porcelain anodizing (6-20um): The anodizing film has an opaque grey appearance, which generally does not change the surface roughness of parts or affect their dimensional accuracy. It is suitable for surface protection and decoration of precision parts such as instruments and daily necessities.
Precautions for anodizing:
(1) If there are sharp corners, sharp edges and burrs, these parts tend to concentrate the current and generate a lot of heat, which will cause the CNC parts to burn.
(2) When the film is thick, there will be a lot of microcracks in these parts, and there will be grey-white loose parts that can easily fall off. Therefore, the sharp angles on the CNC parts should be rounded, and the radius should not be less than 0.5mm.
(3) The surface roughness of the CNC parts with a rough surface can be smoothed after hard anodizing treatment, while the surface roughness of the CNC parts with low surface roughness can be increased by 1 ~ 2 grades after anode treatment.
(4) After hard anodizing, the dimension allowance will increase the size of the CNC parts, which is about half of the film thickness. Therefore, the dimension of machined parts before anodizing must be determined according to the film thickness and the allowable tolerance of dimension, to reach the specified tolerance range after anodizing. Machining allowance shall be reserved for the parts to be further processed after anodizing.
(5) For partial protection, when hard anodizing is required on the surface of the CNC parts, the part that does not require anodizing shall be insulated and protected. The insulating method shall be applied by spraying, brushing or dip coating the prepared insulating rubber. The coating is required to be thin and uniform. After each coating, it is dried once and coated 2~4 times. After anodizing, the insulating rubber can be washed away with thinner or with hot water of 50~70 degrees celsius.
At the same time, Weimi can also carry out: Brushing/anodizing or straight line brushing.
The surface of the aluminium plate is processed by mechanical friction to process the straight line, which has the dual function of brushing off the scratches on the surface of the aluminium plate and the surface of the decorative product.
Random brushed: Under the high-speed operation of the copper wire brush, the aluminium plate is moved back and forth, left and right, and rubbed to obtain a kind of irregular, no grainy matte silk pattern. This processing has high requirements on the appearance of aluminium and aluminium alloy plates.
Corrugated brushing: Generally, it is made on the brushing machine or the rubbing machine. Using the axial movement of the upper group of magic rollers, the surface of the aluminium or aluminium alloy panel is brushed to obtain the wave pattern.
Rotary brush: A kind of silk thread obtained by rotating and polishing aluminium and aluminium alloy plates with lining oil or polishing grease using cylindrical felt or grinding stone nylon wheel.
Brushing + anodizing to achieve beautiful, anti-erosion, etc. Make your product both beautiful and durable, which is one of the reasons for the popularity of the process.
Polishing + anodizing: Polishing is a process in which the material is rendered clean and tidy by the mechanical action of friction, but does not affect corrosion resistance. The anodic oxidation is to close the tiny pores on the surface of the material by an electrochemical reaction, thereby improving the corrosion resistance of the material to the environment.
If the material surface is dirty or uneven, it should be polished before anodizing, so that anodizing can be carried out better and the surface is more perfect.
Sandblasting + anodizing: Sandblasting is a process of cleaning and roughening the surface of the substrate by the impact of high-speed sand flow. Using compressed air as power to form a high-speed jet beam to spray materials (copper ore sand, quartz sand, emery, iron sand, Hainan sand) to the surface of the CNC parts to be treated at high speed, to change the appearance or shape of the surface of the CNC parts. Combined with anodizing, the mechanical properties of the CNC parts surface will be improved, to improve the fatigue resistance of the CNC parts, increases the adhesion between it and the coating, prolongs the durability of the coating, and also facilitates the levelling and decoration of the coating.
Our products after turning and milling can also guarantee a surface finish of R0.8, without any knife marks on the gloss of the product. At the same time, you can perform anodizing according to the performance of your product.