A Study on the Improvement for Mixing Conditions of Foundry Sand by Orthogonal Array

직교표에 의한 주물사 배합조건의 개선

The purpose of this study is to cut down cost of production and improve the productivity of industry through quality improvement of castings and reduction of defectives by applying the experimental design to the foundry sand mixing operation done at molding department in the foundry. Among the related foundry sand mixing factors which have an effect on casting the experiment of which factors have a dominant effect on quality improvement was performed between two different levels by means of "$2^n$ type orthogonal array." The results cail be summarized as follows ; (1) The optimum conditions per each foundry sand mixing between two different levels proved to be such as $A_2$(used sand) : 24 unit (172.8kg), $B_2$(unused sand ) : 2 unit (15.0kg), $C_2$(binder) : 2.5 unit (4.4kg). $D_2$(addition agent) : 1 unit(1.4kg) and $F_1$(moisture) : 7.4%(14.6kg). (2) As a result of the application of experimental design, the fraction defective during the foundry sand mixing operation turned out to be reduced front 6.6% to 2.04%. (3) For the purpose of cost-down, It was found that the optimum level decision of foundry sand mixing for various castings is required to be made by means of experimental design.al design.