What are the causes and remedies of following casting defects – misrun, hot tear, shot metal?
Causes: · Lack of fluidity in molten metal · Faulty design Remedies: · Adjust proper temperature · Modify design HOT TEARS Causes: · Lack of collapsibilty of core and mould · Hard ramming Remedies: · Improve collapsibilty · Provide soft ramming SHOT METAL Causes: · Too low pouring temperature · Excess sulphur content Remedies: · Use higher pouring temperature · Reduce sulphur content Q. State the advantages and disadvantages of carbon dioxide moulding process. A. ADVANTAGES: · Uses conventional equipments for moulding & sand mixing. · Suitable for heavy & rush orders. · Operation is speedy. · Floor space requirements is minimal. · Eliminates the need for internal support for cores & for drag & cope elements. DISADVANTAGES: · Difficulties in reclaiming used sand. · Moulds & cores are more expensive compared to conventional processes. · Bench life of sand mixture is much shorter than for most of the mould & core mixes. · Mould & cores deteriorate noticeably after being stored under norma
