by Bob Beranek
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Recently we’ve seen an increase of original equipment (OE) glass purchases from dealerships. Why, because Advanced Driver Assistance Systems (ADAS) are being incorporated into new vehicles more often than not. This means auto glass companies that don’t recalibrate ADAS systems must depend on dealerships. By adding dealerships as a partner to complete auto glass services for their mutual customer, may mean the dealership will demand OE glass be obtained for the replacement to facilitate recalibrations.

What does that have to do with the title of this post? When OE glass is purchased from a dealer, it can sometimes come to auto glass shops pre-primed, especially if the vehicle is a new model or has just been manufactured for the new model year. This can pose a problem if the urethane adhesive you choose doesn’t allow use with unknown primers.

We all know technicians should never use a glass part with an unknown primer applied. If glass is delivered to your shop and the glass has a primer applied, it should be returned for a new part. The technician wouldn’t have a way of knowing how the glass was cleaned, primed, or prepared and what chemicals were used. You also wouldn’t know if the glass was cleaned properly and if the primer used was compatible with the primers the technician will use? None of these things are known and no one should assume the previous technician knew what they were doing when they prepped the part.

You may think, I’ll just clean it off, but will you, and can you? It may look clean and contaminant free when you’re done cleaning it, but is it really? If you use abrasives to remove any foreign materials some of the frit paint may be removed. The frit is a rough surface with peaks and valleys that are coated with chemicals that can’t be removed fully without removing a substantial amount of the frit paint. When frit paint is removed the frit is not as protective of the urethane as it was before. The adhesive will be more susceptible to ultraviolet light breakdown and reduction in mechanical bond.

So, what should we do to prep the pre-primed OE part? I asked that question to three of the top auto glass adhesive manufacturers’ in the industry. Unfortunately, each had a different answer, but none said you can’t prep an OE part properly with the right procedures. One of the top adhesive producers warned not all OE prepped glass was equal in terms of proper priming. OE’s make mistakes like everyone else. I’ve previously written about problems with priming that must be addressed if witnessed.

I urge all technicians and owners that read this article, to check with their adhesive representatives or check their adhesive instructions to verify the procedures in dealing with pre-primed OE parts. If your urethane of choice has neither a rep nor written instructions covering this issue, the only way you can be assured the primer on the OE part is compatible with the urethane used is to purchase the OE urethane kit with the OE glass part. Then follow the written instructions given to you by the OE adhesive company.

Last month I wrote an article on the terms used in the industry by auto glass professionals.  Today, I’m continuing it.

Plunge-cut – A plunge-cut has both a negative and positive connotation. It’s been seen negatively when it is used as a method of easing the use of a cold knife. The belief was that if you cut along the glass’s edge with a utility knife, the vertical cutting edge of the cold knife blade would be less of a drag on the tool, thus making it easier to pull. However, it would also score the floor of the pinchweld and cause oxidation to occur and undermine the urethane bead.

The positive connotation: it’s a technique to remove the flap of a “J” style moulding. Removing the extending flap makes it easier to remove the remaining portion of moulding and makes the cold knife cut smoother without hindrance. The trick is not to plunge the knife blade too deep where it contacts the pinchweld floor.

Gravity Stops – It’s the modern name for devices that support the bottom of the glass part and stops the glass from sliding off of the adhesive. Now, the OE manufacturers’ other means to support the glass while the adhesive cures that will do the job and not cause squeaking. The cowl panel is one method and additionally they use guide pins or hangers.

Guide Pins/Hangers – These are OE parts used by robotic machines that set the glass into place during assembly. You rarely see these parts used in the aftermarket, because they are usually located within about 8-12 inches from the top corner of the glass part and are held in place by double-sided tape or silicone adhesive. These guides serve two purposes: it helps the robot set the glass and keeps it in place until the urethane adhesive cures to its ultimate strength.

The above description does illustrate the use of guide pins in windshield mountings. However, there’s another use for guide pins when discussing other auto glass parts. Some side parts have a tilt-out style of mounting, like in quarter glasses and vents. These parts also use an extended “guide pin” that is threaded and used to attach the hinge to the vehicle frame. It’s also called a “T” bolt. These extended threaded bolts are usually a part of the hinge and helps the robot insert the part into the pre-drilled holes in the frame’s body. Then a nut is used to securely attach the part to the body.

“T” Bolt – “T” bolts are guide pins embedded into a plastic moulding around a glass parts’ edge. The extended bolts are used by robotic machines to set the glass part into place and to attach the glass part to the body.

Encapsulation – Encapsulation is a process where a glass part is placed into a mold and molten plastic is pumped into the mold to create a part where the glass and moulding become one.  Because the encapsulation is either PolyVinyl Chloride (PVC) or Reaction Injected Molded (RIM) plastic, the adhesives used to adhere the glass part to the body may need help to stick properly. That’s why the encapsulated parts are frequently equipped with “T” bolts embedded into the encapsulation or clips that hold the part in place until the adhesive cures.

Recently I was surprised to hear one of my colleagues had never heard of the term “decking.” That instance got me thinking, glass techs do speak a language of their own. A good example is from previous Education Committee debates, where I learned there are a lot of colloquial names for plastic sticks like, bones, fiber sticks, and the always popular “pooky sticks”; different terms were used based on the location.

I thought it would be beneficial to start a glossary of terms and add them to the dictionary of auto glass terminology. Here are some to start:

  • Decking

Decking refers to the act of pressing the glass downward into its final position on an applied adhesive. A common phrase would be, I decked the glass into position on the pinchweld.

  • Pinchweld

Considering this term doesn’t exist in my computer’s dictionary for some reason, I thought it might be added to our glossary for that reason alone. Everyone knows what a pinchweld is, a periodic weld between two layers of metal.

However, in the auto glass industry we look at a pinchweld as not just a thing, but as an item with multiple parts. It can be “L” shaped, “flat” or have a “Z” shape. It can also have a “floor” and a “wall.”

It’s a part of the vehicle frame that a glass part is adhered to.

 

  • Exposed-edged Part

An exposed-edge glass part is any glass part with an unprotected edge. It can still have an underside moulding attached, but the very edge of the glass is exposed.

 

  • Bead

The bead is an extrusion of the urethane adhesive, and is usually found on the under edge of the glass part. However, it can also be recessed on the bottom of the glass. Sometimes the bead is applied to the glass and other times applied to the vehicle frame (pinchweld).

  • Cowl

The true term for the “cowl” is the cowl panel. It’s a cover located at the bottom edge of the glass and extends to the front of the firewall. It covers the cowl/firewall drains. The panel usually surrounds the windshield wiper posts and covers the unsightliness of the drains and raw metal underneath. The cowl panel should be removed on most vehicles to perform a proper installation.

  • Tucking

Tucking is the act of inserting the glass under the cowl panel without its removal. Tucking can displace the applied adhesive and make the glass installation unsafe. It is usually used to save time removing the cowl panel and wiper.

  • SDAT/MDAT

These acronyms stand for Safe Drive Away Time and Minimum Drive Away Time. They have been used interchangeably, however the industry wants to begin using the later. To reach MDAT the urethane must reach the strength necessary to withstand the forces put upon the glass as defined in Federal Motor Vehicle Safety Standards 208 and 212. The titles of these standards are Passive Restraint Systems and Windshield Retention respectively.

These terms are only the start. If any of my readers have heard a term used they are not familiar with or if you have some terms we should add, please let me know.