Study on the Key Technology of Preparation and Regeneration of Fused Ceramic Sand

Higher requirements on the quality of castings

Modern foundry industry puts forward higher requirements on the quality of castingsAt presentthe production of small and mediumsized highprecision castings are often used precision casting processbut it has complex processhigh standards of materials and equipment investmentCoated sand shell casting process not only can ensure the quality of castings also greatly reduce the cost of productionwhich has drawn more and more attentionHoweverthere are limitations of traditional original coated sandFor silica sandit has large angular coefficient and thermal expansion ratewhich making the casting surface finish decreasedThe new type artificial spherical sand ceramic sand has excellent comprehensive performancegradually being used as the original sand in casting productionAt a low resin addition amountfinegrained Fused Ceramic Sand can reach high strengthThe surface precision of the shell castings can be comparable to precision castingsHoweverthe price of pearl sand is higher than silica sandthere are few research works on the Fused Ceramic Sand related process at presentThereforethe outstanding performance characteristics and advantages compared with other casting sandFused Ceramic Sand are not fully utilized


In this article, Fused Ceramic Sand preparation processcuring process and regeneration process are studiedwhich in order to obtain high quality coated sand and achieve zero emissions of casting production and efficient recycle of resources


By means of OMSEMmolding sand strength testing machinemolding material gas generation tester and thermal analysisthe Fused Ceramic Sand performance and quality of recycled sand were evaluatedOrthogonal experiment method was used to optimize the coating process of 100-200 mesh pearl sandDetermining the reasonable process parameters of pear coated sand curing process and regeneration processand analyzing the used sand regeneration mechanism

The following conclusions were obtained

(1)Through orthogonal testthe optimal coating parameters of 100-200 mesh pearl sand are as followsthe resin adding temperature is 150℃,the mixing time is 80sthe curing agent adding temperature is 120 and the mixing time is 60sThe lubricant adding temperature is about 85 and mixing time is about 45sAt this pointFused Ceramic Sand tensile strength reached 262MPa and flexural strength reached 6.21MPa

(2)The maximum tensile strength and flexural strength of 1 00-200 mesh Fused Ceramic Sand Can be obtained under curing conditions of curing temperature of 230 and curing time of 120srespectively 1.64MPa and 4.78MPaAt this timethe main fracture mode between sands is cohesive fracturewhich can realize the maximum bonding efficiency

(3)100-200 mesh used Fused Ceramic Sand thermal regeneration process parametersheating temperature is about 680℃~700℃,holding time is 20minthe heating temperature of thermal-mechanical regeneration process is 600℃.The tensile

strength and flexural strength of Fused Ceramic Sand that prepared by recycled sand were close to or even better than the new coated sand with the same coating patternand the gas production decreased

(4)Thermal regeneration provides thermal energy for pearl sand during thermal regenerationThe residual resin on the surface of sand was decomposed and the surface quality of the sand has improvedThe thermal-mechanical regeneration method make the brittle inert membrane rupture and fall off by the external force of mutual collision and frictionwhich achieving the better regeneration effect