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210 ISCAR DEEP HOLE DRILLINGMachining of high-precision holes by deep drilling is a widespread technological operation today in the field of metalworking.Modern deep hole drilling methods were developed in the late 19th century and throughout the 20th century to meet the needs of the military industry.In the 1870s, following the invention of smokeless powder by a French chemist (which increased power more than six times that of black powder), arose the need for much stronger rifle barrels. Before that, they were made by forging.The steel sheet was cut into strips, the length of each segment corresponded to the length of the barrel and the width of each segment corresponded to the caliber. Each piece was heated and rolled into a tube. The resulting seam, in the area where the edges of the segment meet, was smoothed with hammer blows. Then the notches were made with a broach. By this method, the inner diameter was very accurate, but the smokeless powder tore apart the barrels after several shots. The engineers decided to make the cannons by drilling solid rods.The first development for deep drilling was the Gundrill. In the late 1800s, start the production of the first weapon with Gundrills: Mauser rifles made in Germany, Springfield rifles in England and USA.During World War II, it became necessary to dramatically increase the production of warships and submarines. The STS (Single Tube System) was developed to produce naval guns, submarine periscopes and propeller shafts. The system enabled the work four times faster than Gundrills.An Ejector system was developed in the 1950s. Unlike the STS, which required special machines, it was believed that the ejection system was adapted to conventional machines. The ejector system consists of two tubes, internal and external. The Ejector system, like the STS system, allows faster work than drilling with a gundrill, and ensures better accuracy.