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Reduce cost by tree assembly of investment castings

Investment casting is also called lost wax casting,namly made out wax pattern using fusible material white wax,stearic acid coated refractory and puring metal liquid,then investment castings are produced after cooling.Now we would like to discuss the effect of tress assebly of investment castings on production cost with practical samples :

Casting yield is the percentage of actual casting weights and pouring weight.But to detailed investment castings,yield is the percentage of total casting weight in same tree assembly and the quantity of tree assemblies.It has reationship with casting structure and tree assembly way.The casting yield has obvious effect on casting cost.But it do not mean the higher the casting yield,the better it will be.Too high yield will reduce the  feeding capacity of gating system,lead to low feeding and produce shrinkage and shrinkage cavity defects.On the other hand,yield of some investment castings,especially castings with irregular shape and thin wall,will be hard to increase for casting structure and assembly way,so when we calculate the price for these investment castings,we could take this factor into consideration.

Example 1:We,Fly foundry,manufacture engine brackets for certain car company.The weight is 6.61kg.The pouring bar is 4.2kg.Original wax pattern assembling way is one piece each group(see photo 1),the yield of such assembling way is 62%.If we choose 2pcs each group,then pouring bar is 5.6kg,the yield will be 71%.


                                                    Photo 1                                            Photo 2      

Example 2:Casting weight is 1kg and the weight of pouring bar is 3.9kg.Original tree assembling way is like Photo3.The yield of such assembling way is 60.96%.Now we adopt another wax pattern assembling way(see photo 4),the weight of pouring bar is 3.9kg,and the yield have been increase to 72.01%.


                                                   Photo 3                                            Photo 4

So we should pay attention to such questions to improve production capacity and reduce cost of investment castings.Of couse,there are also some other ways.Just need our action.