1.First process improvement and verification tracking
(1) Change to bottom pouring system. The layout of the ingate of the casting should avoid the original thick position to reduce the risk of overheating at the ingate position. Change the original middle pouring system into the bottom pouring system, modify the inner runner to 5 cylindrical runners (as shown in Fig. 1), and move to the bottom navel of the exhaust side, keeping the original total runner cross-sectional area unchanged.
(2) Pouring production verification tracking results. After pouring and cleaning 40 sets, the casting defects were tracked. Five ingate defects were concentrated at the rightmost position (as shown in Fig. 2), and the casting defect rate was as high as 80%.
2.Second process improvement and verification tracking
(1) Improve the bottom pouring system. Remove the ingates where casting defects occur (as shown in Fig. 3), and increase the cross-sectional area of the other four ingates to ensure that the total casting cross-sectional area remains unchanged.
(2) Pouring production verification tracking results. After pouring and cleaning 40 sets, the casting defects were tracked and the shrinkage casting defects were eliminated, but the porosity casting defects were abnormal, and the porosity casting defects rate was 20%.
3.The third process improvement and verification tracking
(1) Improve the bottom pouring system. Restore the setting of the right most ingate, and change the shape of the ingate to a sheet-like flat runner (as shown in Fig. 4).
(2) Pouring production verification tracking results. 40 sets of casting were verified, no shrinkage casting defects were found, 3 sets of porosity casting defects were found, and the porosity casting defect rate was 7.5%. In the follow-up, it is necessary to continuously optimize the pouring exhaust system and continuously improve and track it.
(3) Modify the exhaust structure of the inlet core and the lower sandwich core (as shown in Fig. 5), and increase the size of the overflow riser at the matching position with the chassis core. Through the follow-up mass production of 500 units, no shrinkage casting defects were found, and the porosity casting defects were controlled within 0.6%.