Pickling cleaning
Chemical reactions are used to remove metal oxide skin. For small and medium-sized forgings, they are usually packed into the net basket in batches and completed by several processes such as oil removal, pickling corrosion, rinsing and blow drying. Pickling method has the characteristics of high production efficiency, good cleaning effect, no deformation of forgings, shape is not restricted. Pickling chemical reaction process will inevitably produce harmful gas to human body, therefore, pickling room should have exhaust device. Pickling different metal forgings should be based on the metal properties to choose different acid and composition ratio, the corresponding pickling process (temperature, time and cleaning method) system
Sand blasting (shot) and shot blasting cleanup
The sand blasting (shot) powered by compressed air makes the sand or steel shot produce high speed movement (the working pressure of sandblasting is 0.2-0.3mpa, and the working pressure of shot peening is 0.5-0.6mpa), which is sprayed to the surface of the forging to knock off the oxide skin. Shot blasting relies on the centrifugal force of high-speed (2000 ~ 30001r/min) rotating impeller to shoot the steel shot onto the surface of the forging to knock off the oxide skin. Sandblasting cleaning dust, low production efficiency, high cost, mostly used for forging with special technical requirements and special materials (such as stainless steel, titanium alloy), but must use effective dust removal technical measures. Shot peening is relatively clean, but also has the disadvantages of low production efficiency and high cost, but the cleaning quality is higher. Shot blasting cleaning is widely used because of its high production efficiency and low consumption.
Shot peening and shot peening cleaning can make the forging surface work hardening while knocking off the oxide skin, which is conducive to improving the fatigue resistance of parts. For forgings after quenching or tempering treatment, the work hardening effect is more significant when using large-particle steel pellets, the hardness can be increased by 30% ~ 40%, and the hardening layer thickness can reach 0.3 ~ 0.5mm. In the production according to the forging material and technical requirements to choose different materials and particle size of the steel shot. For forgings cleaned by sandblasting (shot blasting) and shot blasting, surface cracks and other defects may be covered, which may easily lead to missed inspection. Therefore, it is necessary to test the surface defects of forgings by means of magnetic flaw detection or fluorescence inspection (see physical and chemical inspection of defects).
Drum cleaning
Forgings in a rotating drum, by bumping or grinding each other to remove oxide skin and burr on the workpiece. This cleaning method uses simple and convenient equipment, but loud noise. It is suitable for small and medium-sized forgings which can withstand certain impact and not deform easily. The roller cleaning has no abrasive, only add triangle iron block or diameter of 10 ~ 30mm steel ball abrasion-free cleaning, mainly by striking each other to remove oxide skin. The other is to add quartz sand, scrap grinding wheel and other abrasives and sodium carbonate, soapy water and other additives, mainly by grinding for cleaning.
Cleaning of vibration
In the forging mixed a certain proportion of abrasive and additives, placed in the vibration of the container, the vibration of the container, so that the workpiece and abrasive grinding each other, the surface oxidation skin and burr grinding away. This cleaning method is suitable for small and medium-sized precision forgings cleaning and polishing.