Windshield bending technologies have come a long way since the first commercial pieces of glass were bent in the late 1940s. Initially, the simple one-directional bending method required minimal technology. However, the introduction of double curves in the late 1950s sparked an ongoing evolution in the field. Despite the many sub-processes involved in windshield production, the bending process remains crucial for achieving optical quality and shape accuracy. Without perfect bending, the entire manufacturing process can fail. Today, three primary bending methods are employed: gravity bending, press bending, and press-assisted bending.
Gravity Bending
Gravity bending is a cost-effective method for creating a variety of shapes, including deeper sags and wrap-around corners. This process is particularly advantageous when a wider range of coating options is needed. Gravity bending is ideal for short production runs, as it allows for the simultaneous use of many different types of molds. This flexibility makes it the preferred bending process for automotive replacement glass manufacturers (AGRs), as only one mold is required for short runs.
In the past, shaping was challenging due to heat being applied solely from above. However, advancements in technology now allow for focused overall heating with power regulation and double-actuated molds equipped with triggering devices. These improvements enable much more precise shape control, resulting in better end quality.
Press Bending
Press-based bending systems are relatively simple from a process standpoint and do not require focused heating or complicated molds. The process involves two main phases: heating the glass in a furnace and using molds to press it into the desired shape. This method provides very high output, good repeatability, and tight tolerances.
However, the construction of press bending systems is complex and requires expensive shape-specific tooling. Due to the high initial investment and tooling costs, press bending is primarily suitable for original equipment manufacturers (OEMs) who need very high-volume production.
Press-Assisted Bending
Press-assisted bending systems offer high output, good repeatability, and tight tolerances, making them suitable for long-series OEM production. This bending process combines the benefits of both gravity bending and press bending. When integrated with a gravity-based system, the furnace can function as either a gravity bender or a press bender. This versatility makes it an ideal tool for medium-scale operations that require operational flexibility and long-series OEM windshield production.
Stay tuned for our upcoming blogs, where we will share more tips and insights for windshield manufacturers.
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