ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2026 15 productivity and quality drove developments in early automation. Harry D. Morton was granted a patent in 1918 on modulating wire feed speed by using welding current to regulate continuous feeding of a wire electrode into the melt pool[9]. This process became known as automatic welding. Welding with continuous spools of wire dramatically increased through- put as frequent electrode changes were eliminated. In 1920, H.L. Unland combined automatic welding with mechanized movement of the welding torch. The resulting system increased weld consistency, throughput, and enabled additive build-up of weld material on worn shafts and wheels (Fig. 3)[10]. Gas metal arc welding (GMAW) can trace its origin to the 1920s. In 1924, Paul O. Noble patented the combination of a manipulable handheld torch with automatic wire feed[11]. That same year, Peter P. Alexander filed a patent on utilizing a hydrogen-shielded arc with continuous wire electrode and reported increased weld ductility utilizing hydrogen shielding[12]. The 1920- 1930s saw further development of shielding gases such as helium and argon by Henry M. Hobart and Philip K. Devers, respectively[13,14]. The similar- ities in patent figures and attorney signatures between the works of Alexander, Hobart, and Devers, as well as common assignment to GE, suggest the existence of a focused corporate effort during this period (Fig. 4). SHAPE WELDING FOR LARGE CASTINGS AND FORGINGS Further mid-20th century developments in automation and control eliminated the need for a manual operator and gave rise to automated systems that built up weld metal into three-dimensional shapes in a process termed “shape” or “form” welding, as it involved producing shapes entirely from weld metal. This approach yielded benefits such as on-site manufacturing of massive components, multi-material structures, ease of in-situ inspection and repair during manufacture to reduce waste, and reduced lead times. Early examples involved axisymmetric geometries created with continuous printhead motion or template-follower systems. P.G. Weeber reported in 1968 on efforts in the Netherlands to develop a submerged arc welding (SAW) system capable of producing axisymmetric flanges of up to 1.4 m diameter and 0.77 m tall at 7.4-9.1 kg/h[15]. In Germany in 1971, R. Müller built on these efforts using SAW, producing an asymmetric curved flange via analog programming of the welding head using a sheet metal template (Fig. 5a). Additionally, Müller demonstrated multi-step manufacture of a 1.5 m diameter hemispherical pressure vessel cap weighing over 2000 kp (kp, or kilopond, is a historic unit for weight equivalent to approximately 9.81 N and 1 kg mass on Earth) with integral bosses for later pipe attachment. This required refixturing the workpiece in a tilt-turn welding positioner (Fig. 5b)[16]. In 1983, Kussmaul et al. documented a project by Thyssen Company that resulted in production of a 72-ton thick-walled pressure vessel (6 m long, 1.136 m inner diameter, 1.840 m outer diameter) in 6 weeks by using four tandem SAW welding heads operating at a combined 80 kg/hr material deposition rate (Fig. 5c)[17]. WIRE ARC ADDITIVE MANUFACTURING The late 20th and early 21st centuries have seen an explosion in GMAW and gas tungsten arc welding (GTAW) Fig. 3 — Mechanized automatic welding system developed by H.L. Unland at The General Electric Corp., showing configurations for circular welds (top) and build-up on shafts (bottom)[10]. Fig. 4 — Illustrations from patents by GMAW pioneers P.P. Alexander, H.M. Hobart, and P.K. Devers demonstrating different shielding gases and continuous feeding of wire electrode from a spool[12-14].
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