Processing technology of die casting mold parts
Thu Jul 06 15:28:03 CST 2023
Characteristics of die casting process
The molds used in die-casting are usually made of alloy materials with higher strength than the parts to be processed. This process is somewhat similar to injection molding. The cost of casting equipment and molds is generally relatively high, so it is not suitable for processing small batches of parts. However, due to the relatively simple processing of parts by die-casting, generally only four main steps are required, and the incremental cost of each item is very low, so it is very suitable for the manufacture of high-volume parts.
General features of mold parts design
In the mold design output, 3D modeling is used to describe the mold structure and as the basis for NC machining, while 2D drawings are the basis for part processing design. Therefore, the design of mold parts requires the output of two-dimensional drawings of mold parts. The design of mold parts processing technology not only conforms to the general characteristics of mechanical processing technology design, but also must be flexibly adjusted according to its own special requirements. Its general characteristics include the following aspects:
Identification and determination of benchmarks
The design basis of mold parts includes two aspects: part basis and processing basis. The part datum describes the assembly surface of the part, and the machining datum should generally coincide with the part datum.
Identification and determination of cooperation relationship
Mold is a combination of parts. Therefore, it is an important purpose of process design to identify the relationship between each part of the mold and ensure its matching accuracy.
Meet the manufacturing precision
Manufacturing accuracy refers to the conformity between the actual size, shape and position of the processed part surface and the ideal geometric parameters required by the drawings. It is expressed by part size tolerance, shape and position tolerance and surface roughness. In process design, it is necessary to determine what process method to use.
Selection of process methods and processing routes
Due to the characteristics of the die-casting process, such as high-temperature molten metal, the molding process under high-speed and high-pressure conditions, the processing technology of die-casting mold parts will have some special process requirements:
1. Since the mold parts will work in a high temperature environment, the cooperation of the working parts of the mold will change to a certain extent compared with that at room temperature. Therefore, when processing related parts, the design of the fit clearance must take into account the expansion of the mold after heating, and sometimes even the final processing size can only be determined after a mold trial.
2. Due to the varying degrees of complexity of the geometric shapes of each part of the mold, the thermal expansion coefficient of the preset cavity may change locally, which will affect the size change of the die-casting part. It is necessary to reserve a machining allowance and process it again after the mold test.