Glass Manufacturing Workers

Glass manufacturing involves a number of basic operations, including mixing and melting materials; forming molten glass by blowing, pressing, casting, drawing, or rolling; heat-conditioning and controlled cooling; and finishing glass by polishing, coating, and using other surface processes. Different kinds of glass may involve different processes and require specialized workers. Most of today's glass manufacturing workers tend to specialized machines used as part of a continuous mechanized operation.

Glass is usually made from sand (silicon dioxide), limestone (calcium carbonate), soda ash (sodium carbonate), and other raw ingredients. In many plants where glass is made, mixers tend equipment that blends ingredients. They either weigh and mix batches of materials or monitor machines that automatically supply the correct mix for melting in furnaces. Cullet crushers tend machines that crush and wash cullet, or broken waste glass, which will be recycled and melted with the raw ingredients. In some plants, batch-and-furnace operators control automatic equipment that can weigh and mix ingredients, then dump them into a furnace. Combustion analysts test and regulate the temperature of the furnace to manufacturing specifications. When the temperature is properly controlled, bubbles and impurities can be eliminated.

Many workers are concerned with machine-forming the hot glass so they can take advantage of glass's malleable quality. Among these workers are forming machine operators, who set up and operate machines that press, blow, or spin lumps of molten glass into molds to make a wide variety of glass products, such as bottles, containers, and cathode-ray tubes. Under operator control, the machines deliver gobs of hot glass from the supply emerging from the furnace. Often, a puff of air is used to blow the glass firmly into a mold. The glass temperature is regulated until the molded item is ejected for further processing. Pressers tend press molds that force molten glass into shapes, making cast glassware items such as plates and automobile headlights. Others tend machines that extrude fiber-glass filaments, mold optical glass blanks, form bulbs, and shape other glass products.

Flat glass is an extremely important product for windows, doors, and many other items. The float-glass process is used to produce much of the flat glass made today. In this process, molten glass flows from the furnace where it has been heated onto the surface of a pool of molten tin. The result is a glass with a good polish and flatness that requires less costly finish processing than other flat glass.

The glass manufacturing workers who make flat glass by other methods include drawing-kiln operators, who operate machines that process molten glass into continuous sheets by drawing molten glass upward from a tank and cooling it before it runs and loses its shape. Sometimes sheets of glass are made by rolling-machine operators, who operate equipment that rolls molten glass flat.

Some workers form hot glass by hand. They include glassblowers, who shape gobs of molten glass into glass-ware by blowing through a blowpipe, in much the same way that glass has been blown for centuries. Glassblowers produce certain kinds of special scientific equipment, as well as unique tableware and art objects. Other craft-workers shape and attach hot glass to other objects to make handles and pedestals.

Some glass is further processed with controlled reheating and slow cooling to eliminate flaws and internal stresses. Lehr tenders operate lehrs, which are tunnel-like automatic ovens used to heat-treat flat glass and glassware and fuse painted designs on glass.

Many glass products are not complete until they have been given other finishing treatments. Among the workers who do these tasks are glass decorators, who etch or cut designs into the surface of glass articles. Glass grinders remove rough edges and surface irregularities from glassware using belt or disk grinders. Polishers polish the edges and surfaces of flat glass, using polishing wheels.