A Novel VHF Heating System to Aid Selective Laser Melting

A novel approach is proposed for penetrative heating of metal powders for component manufacture using selective laser melting (SLM). Large volumes of metal powders have been shown to have unusual properties at higher RF frequencies, whereby magnetic fields can penetrate into them almost completely, at depths much greater than the expected skin depth. A resonant structure at VHF (100–500MHz) and a medium power VHF source (delivering up to 75 W) are described, analyzed and demonstrated, to efficiently heat tungsten carbide powdered samples of volumes of 40cm³ to above 700°C. Further development of this technique will help alleviate the thermal instability problems widely encountered in SLM which lead to large thermal stresses and mis-shaped components.