Influence of sand-sodium-silicate mixtures structured by steam-microwave solidification method on small castings quality

Abstract

Influence of sand-sodium-silicate mixtures structured by steam-microwave solidification method on small castings qualityThe purpose of the research is to evaluate the influence of the method of making molds from sand-sodium-silicate mixtures, structured by steam-microwave solidification method on the surface quality and cast products size accuracy and to establish the steam-microwave solidification method suitability for the production of small castings for general engineering purposes. Cast surface accuracy degree according to DSTU 8981:2020 and its roughness parameters have been investigated on Ø30×150 mm castings of steels 40Cr24Ni18Si2L and 30L, flake graphite iron FGI20, bronzes BrSn5Si5Zn5 and BrAl9Fe3L. Castings have been prepared in foundry forms manufactured of structured quartz sand cladded with silicon silicate solute in steam-microwave medium. Roughness parameters determination has been carried out by profilometry device equipped with information and computing complex of model 170622. Influence of molding mixture structuring method determination on casting dimensions accuracy has been carried out on "Grating plate" casting from steel 40Cr24Ni18Si2L. Investigation has been realized by comparing of "Grating plate" overall dimensions and their nominal value variables deviations, as well as comparison of defective castings number, which have been manufactured in forms that were structured by CO 2 process and by the method of steam-microwave solidification. Castings sizes have been measured by caliper with measurement error value up to 0.01 mm. Surface quality of castings from surface defects presence point of view has been evaluated visually. As per research results it has been found that in accordance with DSTU 8981:2020 degree of castings cast surfaces in the range 100 to 250 mm accuracy corresponds to 7-10 classes, which is at the level of accuracy degree of bronze shell forms molding from thermosetting mixtures. Steel and cast-iron castings are at the level of low pressure casting in chill mold without sand rods and higher than in castings produced in sandy-clay, vacuum-film forms and forms of sodium-silicate-solute selfhardened mixtures. Accuracy of castings dimensions made in forms by steam-microwave solidification method is slightly higher than castings made in forms of CO 2 process. In this case, in castings obtained in forms by steam-microwave solidification process, there are no gas cavities and cold laps, and the final lack of sizes mismatches and castings surface defects correctional lack, respectively in 3.7 and 13.5 times lower than in castings that have been made in forms of CO 2 process. The first examination and in accordance with DSTU 8981:2020 established the level of accuracy of the cast surface and parameters of its roughness for castings of size 100-250 mm of steels 40Cr24Ni18Si2L and 30L, flake graphite iron FGI20, bronzes BrSn5Si5Zn5 and BrAl9Fe3L, which were poured in foundry molds, the mixture of which was structured by steammicrowave solidification method. Obtained data will be ...