News » Process flow and quality control of precision casting

The core of precision casting lies in the realization of high precision and complex structure. Its process flow covers key links such as mold design, melting, pouring, and post-processing. Take the typical lost wax method as an example:

Mold preparation and wax injection: A mixture of paraffin and stearic acid is used, and the wax injection machine is used for injection molding at 48±2℃ to ensure that there are no bubbles or cracks on the surface of the wax mold, and the dimensional error is less than 0.1mm.

Assembly welding and shell making: The wax mold is welded to the pouring system after trimming, and then dipped in multiple layers of ceramic slurry (surface layer, transition layer, reinforcement layer). Each layer needs to be air-dried for more than 8 hours after sanding, and finally a shell with strength that meets the standard is formed.

Dewaxing and melting: The shell is dewaxed in 95-98℃ steam, and then high-temperature roasting is performed. The alloy composition needs to be precisely controlled in the melting process. For example, titanium alloy needs to be melted in a vacuum induction furnace to avoid oxidation.

Casting and post-processing: The molten metal is poured under vacuum or protective atmosphere, and after cooling, it is subjected to vibration sand removal, cutting, heat treatment and other processes to finally obtain castings that meet the requirements.

Quality control runs through the entire process:

Chemical composition analysis: A spectrometer is used to monitor the composition of the molten metal in real time to ensure stable material performance.

Dimension detection: A three-coordinate measuring machine is used to verify the tolerance of castings, and complex surfaces are compared with the design model through 3D scanning.

Defect prevention and control: X-ray flaw detection and ultrasonic testing can identify internal pores and shrinkage, and the scrap rate is reduced from the traditional 15% to less than 5%.

Industry cases show that Hengli Hydraulics has increased the product qualification rate from 85% to 90% by optimizing the smelting process parameters (such as the amount of spheroidizer added), saving 2.4 million yuan in costs annually.