What is Metal finishing

- Jan 13, 2019-

After metal plasticity, a series of operations are performed to meet the user's final requirements for the product in terms of surface quality, size, shape and some properties. It mainly includes flame cleaning, cooling after hot working, coiling, cutting, straightening, physical testing and grinding, marking and packaging of defects. Some products require special finishing processes, such as various heat treatment and quenching of steel rails to fully expose surface defects and to facilitate grinding pickling, to meet the requirements of product properties. Expand the surface processing of product variety, such as tin plating, galvanizing, coating plastic can also be included in the finishing range.

   In other words,In order to make the rolled steel meet the technical requirements of size, shape and various properties, a series of processing procedures are called finishing. According to the variety of steel, finishing process is also different. Finishing includes flame cleaning, cooling, straightening, cutting and other processes.

    The ordinary finishing process as below:


    The surface defects of steel billet are burnt by using the gas cutting and melting of high temperature flame. In billet production, it is an important process to ensure the quality of billet. Flame cleaning is a kind of surface cleaning method with high productivity and low cost. Cleaning lt billets with flame is more than half the cost of cleaning them with a pneumatic shovel, a tenth of the cost of grinding a grinding wheel. The cleaning speed is 10 ~ 15 times higher than that of air shovel. It is widely used in cleaning carbon steel, low alloy steel and partial alloy steel. Manual cleaning and mechanical cleaning are available for flame cleaning, and online hot cleaning and supplementary cleaning after cooling of billet can be carried out.

Reduce the temperature of hot

    Reduce the temperature of hot - processed steel from the high temperature at the end of processing to room temperature. Different microstructure can be obtained during the cooling process of rolled steel, which affects the performance of the product. Therefore, the cooling method after hot processing should adopt natural cooling, forced cooling, slow cooling and other methods respectively according to the technical requirements of the product and the characteristics of steel.
    The process of reducing hot rolled steel from rolling to room temperature. Post-rolling cooling affects the properties and shape of the rolled material and sometimes the output of the mill. The cooling after rolling can be divided into natural cooling, forced cooling and slow cooling. According to different cooling methods can be divided into air cooling, reactor cooling, air cooling, water cooling, spray cooling, pit cooling, furnace cooling, etc. Different kinds of steels adopt one cooling method or two or more cooling methods in combination according to their steel type and performance requirements.

Other finishing process 

    The process of cutting according to size requirements after cutting off metal plasticity. Remove the irregular parts at both ends or edges of the processed blank or finished product to obtain the required scale and width. When a material defect is so serious that it cannot be repaired, it should also be partially removed.

    Straightening to correct the shape defects of metal plastic products. Shape defect is caused by uneven deformation, uneven cooling and collision of steel during processing or cooling and transportation.

    To coil an extremely long rolled piece, such as wire or strip, for storage and transport. The coiling is done on the coiler. It is divided into hot roll and cold roll according to the rolling temperature. The products are directly rolled out to customers.

    The uncoiling shears open the coiling strip on the uncoiler, after leveling and shearing, cut into single sheet steel plate or cut the broadband roll vertically into several coils for the customer.

    Inspection the size, shape and surface defects of the finished product before delivery to ensure product standards or requirements of the customer. According to the situation, the defects were treated by repair, grinding, resection or waste. The mechanical and structural properties of the steel were examined after sampling.
    In order to facilitate the use and transportation of the products and to track the quality of the products, all ex-factory products shall be marked. Signs can be printed directly on the product or tied to the product with a label. The mark content includes steel type, specification, steel number, batch number of furnace, factory mark, etc.
    In order to facilitate the transportation of the products and prevent damage during the transportation, the products should be packed and packed before leaving the factory. Baling methods vary according to products, such as small sections of profiles and bars can be tied or made into plates, strips into rolls, cold-rolled thin plates with boards or sheet metal packaging protection.