Consumer products are made with many metal and plastic parts. Metal and plastic machine workers set up the machines that produce the parts, and operate them during production. Hundreds of thousands of machine workers in the manufacturing industry work in different phases of production: following blueprints, they set up the machinery to produce the correct product. Machine setters prepare the machines before production and perform test runs of the initial batches, making repairs or adjustments as needed to ensure quality control. Then, operators take over, and may have to load the machine with metal or plastic materials or adjust machine controls during production. They periodically inspect the parts and conduct minor maintenance. At completion, they remove and test finished products, then document production numbers. Metal and plastic machine operators may specialize in a particular type of machine, for example: Computer-controlled machine tool operators operate robots to perform functions on workpieces. Computer numerically controlled machine tool programmers called CNC workers develop computer programs to control automated processes. They require more training than other machine workers. Extruding and drawing machine workers push out thermoplastic or metal materials in the form of tubes, rods, or hoses. Cutting, punching, and press machine workers run machines to saw, bend, or straighten materials. Molding, coremaking, and casting machine workers run machines to form metal or thermoplastic parts or products. Multiple machine tool setters, operators, and tenders set up or operate more than one type of cutting or forming machine tool or robot. Manufacturing facilities typically employ machine workers full time, usually in shifts that include evenings, weekends, and frequent overtime. With automation, multiple machines may be controlled at the same time, so workers train on different machines and gain a variety of skills. Because these workers operate powerful, high-speed machines, most usually wear protective equipment, such as safety glasses, earplugs, and steel-toed boots. Respirators are common for those in the plastics industry who work near materials that emit dangerous fumes or dust. Employers prefer to hire candidates with high school education, then train machine operators on the job.