by Claudia Bruemmer

Automotive glass manufacturers face many challenges. While lower demand due to the economic downturn has been one problem, the major challenge in automotive glass manufacturing is to produce a quality product in a multi-phase production cycle. Glass windshields can be rendered defective at the end stage of production because each production cycle is complex and prone to error. As a result, craftsmanship and quality control are critical during the manufacturing process. To remain competitive, automotive glass manufacturers must improve efficiency and production output while cutting costs.

The process of manufacturing automotive glass is complex and involves many steps from the raw glass warehouse to the cutting table. The initial phase includes grinding, washing, long pair powdering, short pair powdering, drying, printing and pairing. This is the cold-end of the manufacturing process. At this point, the glass is half way through the entire process chain. This processing methodology varies widely. While it’s common for some companies to hand cut and apply separating powder manually, larger companies use automated production lines with robots and automatic measurement procedures. These companies target different markets, and both can make a profit.

Without proper knowledge and quality control of the cold-end process, automotive glass can be defective. While automatic quality control monitoring is available for this manufacturing process, many firms allow quality control operators to do it manually to cut costs. Unfortunately, lack of precision in the grinding and powdering process can cause breakage and defects later in the bending process. Quality control is critical during the cold-end process and throughout the entire process chain.

Bending, or the hot-end process, which takes place following the cold-end process, is the most demanding process in the entire process chain. After bending, the pvb assembly, vacuum and autoclaving processes follow. Bending is important because it involves the extremely complex process of shaping the new car windshields. While every part of the glass manufacturing process is important, bending is the most demanding part. Without successful bending, the entire assembly process can result in failure.

The cielo and panoramic type windshields with deep cross curvatures, tight wing shapes and small installation angle, along with thin, colored glass combinations, create a situation that requires careful, professional precision during development and production. Bending these difficult windshields with basic gravity bending furnaces is anything but simple.

A critical task is to achieve perfect optical quality. Besides meeting ECE 43 optical regulations, each car manufacturer has its own standards. The vehicle manufacturers’ standards are usually more demanding than ECE optical regulations. Besides the optical challenge, glass windshields are difficult to handle because of the deep cross curvature where the center section contains flat parts that are not smooth and continuous and have reverse bending. These flat and reverse areas can cause problems in “wiper ability.” In worst case scenarios, defects can cause reflections on the windshield. The challenging characteristics of the windshield and the quality requirements require perfect heating configurations and advanced tooling during the bending process.

Quality is of essence in glass manufacturing. While the ECE 43 regulations determine the basic guidelines for conformity, there are many decisions to be made along the way in order to achieve a quality end product. Automotive glass manufactures must achieve good craftsmanship and ensure strict quality control measures throughout the manufacturing process. This will improve production levels, save costs and result in quality end products.