Surface cleaning of aluminum forgings

In order to reduce die wear, avoid oxide skin pressing into the forging, or prevent the existing surface defects from expanding during forging, the raw materials and intermediate blanks should also be cleaned. The methods to remove the raw materials and to analyze the local surface defects of forgings with intermediate blanks are as follows: (1) Air shovel cleaning; (2) Grinding wheel cleaning (3) Flame cleaning. After cleaning, the groove on the surface of the workpiece should be smooth, and the width height ratio of the groove should be greater than 5. Sukezhong aluminum forgings indicate that there are three methods to clean the oxide scale of hot billet before forging: (1) Tool clear. The method of removing oxide scale with wire brush, scraper, scraper and other tools. (2) High pressure water cleaning. The heated billet is rapidly passed through the high pressure water jet device at the speed of 0.2-0.5m/s, and the high-pressure water of 15-20mpa is sprayed to the blank from all sides. The oxide scale on the surface of the billet shrinks sharply and cracks when cooled, and is quickly washed away by high-pressure water. Because the process time is very short, the temperature of the billet itself drops little, the cleaning effect is good and the efficiency is high. (3) The blank making process is removed. The oxide scale can be removed by hot forging. After forging or heat treatment, there are four widely used cleaning methods for oxide scale on forged or heat treated Forgings: roller cleaning, sandblasting cleaning, shot blasting cleaning and acid pickling. (1) Roller cleaning Forgings in the rotating drum, by collision or grinding each other to remove the scale and burr on the workpiece. This method is simple in equipment and easy to use, but it has high noise. It is suitable for medium and small forgings. (2) Sand blasting (shot) cleaning The working pressure of sand blasting is 0.2 ~ 0.3 MPa, and the working pressure of shot blasting is 0.5 ~ 0.6 MPa. Quartz sand with particle size of 15 ~ 2 mm or steel shot with particle size of 0.8 ~ 2 mm are sprayed onto the forging through nozzle to remove oxide scale. Generally speaking, the efficiency is low. (3) Shot blasting cleaning Bythe centrifugal force of high speed rotating impeller, the steel shot is shot on the forging to remove oxide skin. Steel shot usually contains 0.5% ¡« 0.7% carbon and 0.8 ¡« 2 mm diameter. The surface stress and microcracks can be eliminated by shot blasting at the same time. And can play a strengthening role. For the forgings which have been quenched or quenched and tempered, the processing strengthening degree is more obvious. This method is efficient, effective and noisy. (4) Acid cleaning Sulfuric acid or hydrochloric acid is used as pickling solution for carbon steel and alloy steel forgings. The removal of oxide skin mainly depends on the dissolution of oxide skin in hydrochloric acid solution. The reaction between base metal and hydrochloric acid is much slower than that between oxide scale and hydrochloric acid. The effect of acid cleaning is good and the efficiency is high, but it has great pollution to the environment.

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