document: Layer-based machining : recent development and support structure design There is growing interest in additive and subtractive shaping theories that are synthesized to integrate the layered manufacturing process and material removal process . Layer-based machining has emerged as a promising method for integrated additive and subtractive shaping theory . In the paper , major layer-based machining systems are reviewed and compared according to characteristics of stock layers , numerical control machining configurations , stacking operations , input format and raw materials . Support structure , a major issue in machining-based systems which has seldom been addressed in previous research , is investigated in the paper with considerations of four situations : floating overhang , cantilever , vaulted overhang and ceiling . Except for the floating overhang where a support structure should not be overlooked , the necessity for support structures for the other three situations is determined by stress and deflection analysis . This is demonstrated by the machining of a large castle model
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