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Metal Cleaning: laser cleaning metal vs. metal pickling

Table of Contents

The traditional metal cleaning method is pickling metal way, and nowadays, the laser cleaning metal method is getting more and more popular, we will compare this two metal cleaning methods, and make some introduction for metal cleaning industry.

Pickling plate is an intermediate product between hot-rolled plate and cold-rolled plate in terms of surface quality and usage requirements (mainly cold-forming or stamping performance) after removal of oxidation layer, edge cutting and finishing by pickling unit, which ensures the surface quality and usage requirements and enables users to effectively reduce the procurement cost.

I. Metal cleaning pickled plate

The advantage of metal cleaning pickled plate

The advantages of metal cleaning pickled plate mainly lie in.

  1. good surface quality, because the hot-rolled pickled plate removes the surface iron oxide, which improves the surface quality of steel and facilitates welding, oiling and painting.
  2. High dimensional accuracy, after flattening, the plate shape can be changed to a certain extent, thus reducing the deviation of unevenness.
  3. Improves the surface finish and enhances the appearance effect after metal cleaning.

Pickled cleaning metal plate application

Pickled cleaning metal plate has a wide range of applications

It can be said that pickled plate is a kind of product with high cost performance between cold rolled metal plate and hot rolled metal plate. It is widely used in automobile industry, machinery industry, light industry and household appliances and various shapes of stamped parts, such as beams cleaning, sub beams cleaning, rims, spokes, carriage plates cleaning, fans cleaning, chemical oil drums, welded pipes, electrical cabinets cleaning, fences, iron ladders cleaning and so on. It has a broad market prospect.

Below we will introduce the technical process of pickling process and the alternative advantages of laser cleaning.

Metal cleaning pickling process

1 .Metal pickling principle.

Metal pickling is a surface cleaning process that uses an acid solution to remove oxidation and rust on the surface of steel, usually together with pre-film. Generally the parts are immersed in a solution of chemical agents such as sulfuric acid to remove the oxide and other films on the metal surface, is a pre-treatment or intermediate treatment for processes such as electroplating, enameling, rolling. Also known as wet cleaning.

Acid cleaning process mainly has the dipping pickling method, spray pickling method and acid paste rust removal method.

Most of the acids used are sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, chromic acid, hydrofluoric acid and mixed acids, etc.

2 .The process flow of pickling in metal cleaning.

Metal parts on hanging → chemical degreasing (conventional alkaline chemical degreasing or surfactant degreasing) → hot water washing → running water washing → the first step of metal pickling → running water washing → the second step of metal pickling → running water washing → transfer to the next process (such as: chemical coloring → recycling → running water washing → hardening treatment → running water washing → sealing treatment → running water washing → drying → finished products)

3. Metal pickling in metal cleaning common defects.

Iron oxide indentation:

Iron oxide indentation is a surface defect formed during the hot rolling rolling process. After pickling, the metal is often black dotted and long pressed in, with a rough surface, generally with a feel, and sporadic or intensive appearance. Often due to the heating process of pickling, descaling process, rolling process and other imperfections lead to.

Oxygen spot in metal(surface landscape painting):

refers to the hot rolled surface iron oxide washed off, leaving a dot, line or pit-like shape, the essence is the surface of the hot rolled strip iron oxide is not removed, by the subsequent rolling was pressed into the matrix, after pickling protruding. It has a certain impact on the appearance, but does not affect the use of performance.

Yellow spots in metal

yellow spots appear on the metal plate partially or on the whole metal plate surface, which cannot be covered after oiling and affect the appearance of product quality. Mainly because the surface activity of the strip steel just out of the pickling tank is high, the rinsing water fails to play a normal role in rinsing the strip steel, the rinsing tank jet beam and nozzle blockage, the angle is not right, etc.

Under pickling in metal

the surface of the strip has a local iron oxide removal is not clean, not sufficient, the plate surface is gray-black, fish scale or horizontal water ripple-like stains. It is related to the acid process, mainly because the acid concentration is not enough, the temperature is not high, the strip steel is running too fast, the strip steel is not immersed in the acid, etc.

Over pickling in metal

The surface of the strip steel is often dark black or brown-black, showing blocky, flaky black or yellow spots, and the surface of the plate is generally rough. The reason is the opposite of under pickling.

4 Environmental pollution

The main pollutants of the production process are the cleaning wastewater from the water washing process at all levels, the dust from the sandblasting process, the acid mist of hydrogen chloride from the pickling process, and the waste tank solution, waste slag, waste cartridge, empty barrels of raw materials and packaging waste from the pickling, bleaching and rectification, phosphating, neutralization and rust prevention processes. The main pollutants are hydrogen chloride, pH, SS, COD, BOD, ammonia nitrogen, petroleum, etc.

II. The metal laser cleaning

1. Laser cleaning metal cleaning principle.

Laser cleaning metal process, is to penetrate the surface of the object with laser energy of laser cleaning machine, in about 100 femtoseconds of time, the electrons in the metal material to absorb energy vibration, the surface of the metal material to produce plasma; 7-10 picoseconds later, the electron energy transfer to the lattice so that the lattice began to vibrate, after 10 picoseconds, the metal object began to produce macroscopic temperature, the local metal material irradiated by the laser began to Heating, melting, vaporization, so as to achieve the purpose of metal cleaning.

2. laser cleaning metal process and effect.

Metal laser cleaning process is extremely simple compared to the acid cleaning method, no pretreatment, you can simultaneously remove oil, remove oxide layer and rust cleaning work by laser cleaning machine, Simply turn on the equipment out of light, and then cleaning.

Laser cleaning can reach the highest industrial cleaning grade of Sa3; the hardness of the metal material surface, hydrophobicity, etc. are almost no damage. Laser cleaning metal is more thorough than acid cleaning.

3. The comparative advantages of laser cleaning

1. process and operational requirements.

Compared with metal pickling methods up to a dozen of process, metal laser cleaning to do the most simplified process, basically do a step in place. Greatly shorten the cleaning time and material loss.

Metal pickling method has strict requirements for the operation process: metal workpiece must be thoroughly degreased to ensure the quality of rust removal; in the metal cleaning process to control the concentration of pickling solution, so as to avoid high acid concentration caused by corrosion of the workpiece; metal cleaning process to control the temperature according to process specifications, so as not to cause corrosion of the workpiece and equipment; pickling tank gradually deposited sludge, blocking heating pipes and other control devices, need to be removed periodically. In addition, need to pay attention to the metal pickling time, injection pressure, operation sputtering, exhaust equipment and so on.

Laser cleaning metal in the pre-set parameters can be achieved after foolproof operation or even automated unmanned operation.

2. metal cleaning effect and environmental pollution.

Laser cleaning metal in addition to stronger cleaning effect, there is an advantage of metal laser cleaning is more forgiving:.

Metal pickling method of operation often occurs due to errors such as oxygen spot yellow spot, red and black, the scrap rate is high.

Metal laser cleaning even if oversaturated cleaning still has a strong metallic luster, and does not produce hydroxide and other pollutants, the next step of welding and other processing methods will not have an impact.

Laser cleaning metal the whole process will not have waste liquid waste slag and other environmental pollution generated, is the greenest way of cleaning.

3. metal cleaning unit cost and conversion costs

Metal pickling method requires chemicals as consumables, so the unit cost composition of equipment depreciation + consumables costs.

Metal laser cleaning in addition to the purchase of equipment does not require other consumables. Unit cost is the depreciation of equipment.

Therefore, the larger the scale of cleaning, the longer the life, the lower the unit cost of laser cleaning metal.

The composition of the metal pickling production line requires a complex process, the ratio of different metal materials pickling agent is not the same, so the conversion of the production line will require a larger conversion costs, short-term cleaning of a single metal material, can not be flexible changes.

Laser cleaning metal is no conversion costs: the same cleaning machine switch software parameters can be achieved after the first minute cleaning steel, the next minute cleaning aluminum effect. Convenient for enterprises to implement flexible production.

National policy and environmental assessment audit

With these two years, China’s “carbon peak, carbon neutral” policy of the relevant documents issued, the transformation and upgrading of the manufacturing structure more and more stringent requirements, the environmental protection is increasingly important. The EIA report of metal pickling production line is also becoming more and more strict, and the profit margin of related enterprises is getting thinner and thinner. In turn, the support for high-tech has increased. The overall environment is more favorable metal laser cleaning.

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