Specialised lathes for machining long workpieces such as segments of drill strings. Additional electrodes make it possible to weld thicker workpieces. Solder alloys are metallic materials that are used to connect metal workpieces. Many industries use GTAW for welding thin workpieces, especially nonferrous metals. Suitable collets may also be used to mount square or hexagonal workpieces. Hydraulic cylinders are used for shorter length workpieces. Tab base nuts are designed for spot welding on flat workpieces. When the surfaces are adequately heated, the solder will flow around the workpieces. Cutting workpieces to length is usually done with a bandsaw. End-feed grinding is best for tapered workpieces. In commercial woodworking facilities, vacuum bags are used to laminate curved and irregular shaped workpieces. The process works by tumbling and/or abrasively blasting the workpieces at cryogenic temperature levels. The roll bending process induces a curve into bar or plate workpieces. These processes prepare the workpieces for further forging processes. Five and six-axis machines also permit cutting formed workpieces.