Study On Improving Riser’s Feeding Efficiency Of Lost Foam Steel Casting

Riser design and layout, which has great effect on casting quality and productioncost, is crucial in steel casting production. Lost Foam steel castings will have largeshrinkage cavity easily in the process of cooling, so that much metal feeding liquidrequired. At the same time, blind riser widely used in lost foam casting reduces feedingefficiency because of its characteristic that the outer metal crusts easily when coolingwhich causes metal liquid can only rely on self-weight to feed the casting. Dozens ofcompanies which produce lost foam casting have been researched, the survey found thatrisers are designed empirically and there is no systematic theoretical guidance in theseenterprises, which bring out large and high-riser existence, result in lowing the castingproduction rate and increasing the company’s production costs.Inspired by the Williams-core patents, combined with the characteristic of heat riser,the author designed a heat cone in three different sizes, which can increase the blindrisers’ feeding efficiency of lost foam casting. Because of their small size, they use lessheating material and accordingly low the heat cones’ costs. What’s more, the practicaloperation of setting the heat cones is simple: just insert the heat cones on the top of theblind riser. When the heat metal liquid be in touch with the heat cone in the process ofpouring, there is chemical reaction and releases large number of heat, which extends thesolidification time in blind riser, so that the blind riser outer can’t crust easily, therebyincreasing feeding efficiency of the riser. In this paper, differential scanning calorimeterDSC shows that the designed heat cone can be used in blind riser for lost foam steelcasting, and a series of pouring experiments proves that feeding efficiency can beincreased by using heat cone in the blind riser. The riser size range and steel casting sizerange which different heat cones apply to were also put forward in this paper. Finally bymetallographic analysis the paper preliminarily evidences that heat material will not affected casting material.In addition, this paper summarizes the types of riser’s structure and risers dimensioncalculate. Insulating riser sleeve and exothermic riser sleeve were used in crankshaft andsteel ball casting with lost foam. The feeding efficiency of ordinary riser and insulatingexothermic sleeve riser were compared with experiments of pouring the casting. Castingsimulations were carried out to compare the common and insulation riser’s feedingefficiency. In addition, the feeding effect of heat side riser and cold top riser weresimulated. The experiment and simulation results showed that the insulating exothermicriser and heat side riser can improve the blind riser feeding efficiency of lost foam steelcastings.