What are the methods of surface cleaning of die forgings?

In order to improve the surface quality of forgings and improve the subsequent cutting conditions of forgings, the oxide skin formed in the process of die forging should be removed. Surface cleaning is also required to check the surface quality of forgings. In addition, cold fine pressing and precision die forging also require a good surface quality blank. The methods of cleaning the hot blank oxide skin before die forging are as follows: clean it with steel wire brush, scraper, scraper wheel and other tools, or clean it with high-pressure water. In the hammer die forging, the billet step can also remove part of the oxide skin of the hot billet.

For the oxide skin on the forging after die forging or heat treatment, the following cleaning methods are widely used in the production:

1, roller cleaning

Drum cleaning is the forging (or mixed with a certain proportion of abrasive and filler) installed in the rotating drum, by mutual impact and grinding, cleaning the forging surface oxide skin and burr. This cleaning method is simple, easy to use, but noisy, suitable for small and medium-sized forgings that can withstand a certain impact and not easy to deformation.

Drum cleaning is divided into two kinds of non abrasive and abrasive cleaning, the former does not add abrasive, but can be added to the diameter of 10~30mm steel ball or triangle iron, mainly by collision with each other to remove the oxide skin; The latter to add quartz stone, waste grinding wheel fragments and other abrasives and soda, soapy water and other fillers, mainly by grinding to clean up.

2, sandblasting (shot) cleaning

Sandblasting or shot blasting are powered by compressed air, the quartz sand or steel shot, through the nozzle spray to the forging, in order to knock off the oxide skin. This method is applicable to forgings of all structural shapes and weights.

3, shot blasting

Shot blasting and cleaning depends on the centrifugal force of high speed rotating impeller, the steel shot is thrown to the forging to remove the oxide skin. Shot blasting cleaning productivity is high, 1~3 times higher than sandblasting cleaning, cleaning quality is also good, but the noise is large. In addition, impressions are made on the surface of the forgings. Shot peening and shot blasting, while shooting down the oxide skin, make the surface layer of the forgings produce work hardening, but the surface cracks and other defects may be covered, Min, for some important forgings, magnetic inspection or fluorescence inspection should be used to test the surface defects of the forgings.

4. Acid cleaning

Pickling cleaning is to put forgings in pickling tank, by acid and iron chemical reaction to achieve the purpose of cleaning. The surface quality of pickling cleaning is high, and the surface defects of the forgings after cleaning (such as cracking, folding lines, etc.) are exposed and easy to check. It is difficult to clean up parts of forgings, such as deep holes, grooves and other obvious effects, and forging will not produce deformation. Therefore, pickling is widely used in complex structure, thin thin thin and easy to deform and important forgings carbon steel and low alloy steel forgings pickling solution is carbonic acid or hydrochloric acid. High-alloy steels and non-ferrous alloys use mixed solutions of various acids, and sometimes alkali-acid compound pickling is required.