The modern windshield factory relies heavily on robotics and automation. In the first step of the process, cutouts in the shape of a windshield are cut from sheets of glass. To make the cuts, a plotting machine with a rolling blade scores the glass, and then a flame torch held by a robotic arm goes over the score and the thermal shock cleanly splits the glass.
A machine then lifts the cut-out glass using suction cups and takes the sheet to a sanding station where sharp edges and burrs are removed with wet sanding belts. The process is automated so the machine holding the glass follows a set tilting pattern over the belts to finish all the edges. It’s called seaming.
The glass is then conveyed through a soap wash and rinsed with a water-talc mixture. The talc prevents the glass sheets from sticking to each other in the next processing steps. A robotic system lays two sheets one on the other, lined up exactly at the edges.
This is a temporary arrangement and the sheets will be separated later. Next a painting apparatus silk screens a black coating around the border of the glass, and this will become the inside of the windshield. Then automated arms bring it to a station where samples are inspected visually.
After that, rollers transfer the glass to automatic squaring pucks to line it up for a machine to lift it and carry it, setting it precisely on four metal pins. The pins recede and the glass settles on a bending iron. The iron is shaped for a specific windshield.
A conveyor takes the two glass sheets on the bending iron into an oven called a glass bending furnace. The oven heats the sheets to 750 degrees Celsius, causing the glass to slump down, taking the shape of the bending iron. Then the glass goes through a slow cooling cycle to anneal, or toughen the glass in the new shape.
The two sheets are then separated. A vinyl sheet is cut in the shape of the glass and is laid upon one of the glass pieces. Then the second sheet is lowered onto the vinyl, creating a sandwich. It is this layered structure that gives the windshield resistance to impact and breakage.
At this point, there is no clear view through the milky white vinyl. The first step in making it clear is forcing trapped air out from between the layers with a machine called a nipper. The nipper squeezes the glass between a series of rubber rollers squeezing out air pockets. Now the view through the vinyl is a bit clearer.
Squaring pucks now line up the glass for a robot to attach brackets for the rear view mirror. Groups of windshields are then stacked vertically next to each other in a caddy and heated under pressure and steam in an autoclave for about an hour. This makes the glass completely clear.
A rail system transports the windshields to a manual inspection station. The examiner looks for cracks, chips, or any contamination between the layers and also views the windshield through polarized light to reveal stress defects.
To confirm the glass meets performance requirements, a 2.25 kg steel ball is dropped from 4 meters onto a test windshield. The glass passes as long as the ball doesn’t go through.
More windshield additions may be added include rain sensors and other conveniences. Now the windshield is ready for the road.
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