The Negative Step Deviation in Rapid Prototyping and Its Reduction Measurements

In order to raise the rapid prototyping precision,the measurements for reducing errors of step effect in FDM were investigated.In this paper,we analyzed the factors of errors in FDM on the basis of basic concept of layer-by-layer accumulation manufacturing,analyzed the negative deviation caused by staircase effect in the slice processing,plotted the two-dimension CAD mold,used the derivation calculation and analysis by listing the data,derived the formula of step effect,and obtained the graph of influencing factors.It was found that the step errors increase with the increase of the manufacturing thickness,angle α,and prototype surface curvature.When angle α is in the range of 0~60°,the increasing speed is fast,and it would gradually slow down to be a constant when α is 60°~90°.Four corresponding methods for reducing the step effect were presented as follows:small layered thickness,reasonable fabricate orientation,self-adaptive layer method,and inclined slice method,which is helpful for engineers to improve precision in FDM process.