by Bob Beranek
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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.

Photo Courtesy of Trifive.com

I can always tell when a technician was trained by an “old-timer” like me. How? They “spank” or slap the glass into position rather than smooth it in place to make the seal. It comes from the old days when glass had to be spanked and seated into a gasket or when dense butyl tape needed to be forced down to contact uneven pinchwelds. Liquid urethanes call for smoothing the seal, not spanking or slapping the glass into place.

First, let me say it’s not necessarily wrong to slap the glass. It is, rather, ill-advised. There are two negative results that can happen when a glass is slapped rather than smoothed.

  • If the glass is thin, chipped or scratched, then the chance of premature breakage is increased. If the glass is “hot,” the glass is more volatile and can fracture. Some of these issues can and should be caught by the technician prior to installing. However, how hard is too hard to slap the glass into place? It only takes one break to lose your profit and possibly a customer to inconvenience.
  • The second negative issue involves leaking and bonding. Curved glass has a spring to it. It can be depressed as much as a couple of inches before breakage and then sprung back to its original shape or curvature. If the bead of urethane is short and the glass is slapped at its apex, it can make contact and then “string out,” causing leaks and bonding problems. If it is smoothed-out, the urethane bead is redistributed into weak areas, making for a more solid bond and leak-free installation.

If I said I never spanked or slapped the glass, I would be a liar. There are instances where a slight slap is necessary. If you have a large, tall or awkward vehicle where leveraged pressure can’t be applied to the edge of the glass, such as in large service vans, then a slight tap on the top and bottom center may be called for. Of course, this is after a careful inspection of the glass part conducted during the prep stage and that the glass is not exposed to excessive heat.

My advice is to use slapping only when you must and only when the glass was carefully inspected for pre-installation damage. Keep the glass out of bright hot sunlight for as long as possible prior to installation into the opening. Reduce the violence used in past installations as much as you can. The customer will feel less anxious if watching the process and vehicle and glass damage will be reduced to increase profits.

 

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.