For a fine part, the selection of the blank affects all […]
For a fine part, the selection of the blank affects all aspects of the part. When selecting the blank, the extreme conditions of the cold and hot conditions should be taken into account in order to reduce the processing cost of the workpiece under the most economical conditions.
For some complex shapes, the most suitable way to make the blank is to use casting. At present, castings formed by sand casting occupy the majority, while sand casting can be subdivided into wood mold manual molding and metal mold machine modeling. For the manual molding of wood molds, the castings produced by them have low precision, large surface allowance to be processed, and low production efficiency, and are only suitable for casting single-piece small batches or large workpieces. The metal film machine model is the opposite. It has high efficiency and high precision, but the cost is also high. The weight of the castings produced is also required, which is suitable for small and medium-sized castings for mass production. In addition, for small castings with strict quality requirements and small quantities, special casting methods such as pressure spindle and investment casting can be used.
Forging blanks are generally used for steel parts that require high mechanical strength. Forgings are also divided into two types, die forgings and free forgings.
Die forgings have high precision and high surface quality, and the shape of the forging can be complicated, so the cutting work can be reduced and the productivity is high. However, it requires special equipment and forging die, so it only Suitable for some large and medium-sized forgings.
Free forging forgings can be obtained by press forging, mechanical upsetting, and manual upsetting, and the three methods correspond to three blank specifications: large, medium and small. Forgings that are freely forged are generally of low precision, have large machining allowances, have low productivity, and have requirements for workpieces. The workpieces are required to have a simple structure and are only suitable for single-piece and small-volume production in the use of workpieces, or It is a large forging.