Arc spray forming of steel tools has recently drawn great attention in the field of rapid tooling with its potential to make large tools for mass production.  Although the dimensional inaccuracy problem in spray-formed steel shells has been solved successfully by controlling residual stress, several challenges still remain in the arc spray forming process for expanding its applications to mass production.  Property improvement of the spray-formed steel shells can be the most important one since the most of their mechanical properties are inferior to conventional tools.

In the present study, modification of the nozzle of arc spray equipment has been attempted in order to reduce oxides and pores of the spray-formed steel shells since these defects mainly degrade the overall properties of the tools.  Effects of design parameters such as nozzle dimensions and process conditions have been statistically analyzed using Taguchi methods.  These results demonstrate that the defects of the spray-formed steel shells can be reduced to the one-third levels of the original ones with an optimized design.