Editing Windshield (section)

==Replacement{{anchor|Windshield replacement}}==

Windshields that cannot be repaired have to be replaced. Replacement of a windshield typically takes less than an hour. To ensure the vehicle is safe to drive, time values called the [[Safe drive away time|Safe Drive Away Time]] have been established. Windshields which have been replaced must cure or bond sufficiently until they are able to withstand the forces of a crash. Knowing the minimum time needed to cure the glass bonding adhesives is therefore important. This '''safe drive away time''' (SDAT) or '''minimum drive away time''' (MDAT) refers to the time required until a windshield installation or glass replacement is considered safe to drive again.<ref>{{cite book | last1 = Cognard | first1 = Philippe | title = Handbook of Adhesives and Sealants | publisher = Elsevier | year = 2006 | isbn = 978-0080447087}}</ref> Criteria are specified in [[National Highway Traffic Safety Administration|U.S. Federal Motor Vehicle Safety Standards]] 212/208 (see [[Federal Motor Vehicle Safety Standards|FMVSS]]) to ensure the reliability of adhesive systems.  Typically the SDAT is verified with [[crash test]]s as well as with high-speed laboratory test methods.

Consumers may be unaware that the MDAT or SDAT time is focused on safety and not necessarily on the quality, durability, or warranty of the installation. Care must be taken not to drive the vehicle prior to the SDAT/MDAT.

[[Airbag]]s deploy at speeds up to {{convert|200|mph|km/h mph m/s|abbr=on|order=out}} and in some cases exert tremendous force on the windshield. Occupants can impact the airbag just 50&nbsp; ms after initial deployment.<ref>Bob Stenzel: Determining SDAT, AGRR Magazine, March/April 2012, page 29-30</ref> Depending on vehicle design, airbag deployment and/or occupant impact into the airbag may increase forces on the windshield, dramatically in some cases.
Forces of occupants on the airbags - and hence the potential forces on the windshield - are lower for belted occupants.<ref>Exposing Industry Shortcuts to SDAT Recommendations,  [https://www.glass.net/blog/tips/volkswagen-recall-is-a-reminder-of-auto-glass-importance/ Volkswagen Recall is a Reminder of Auto Glass Importance]</ref> As consequence, [[adhesive]] suppliers usually inform their customers about the level of security achieved:

1)  Example: Security exceeding FMVSS 212/208 belted

2)  Example: Security exceeding FMVSS 212/208 unbelted<ref>Premium Adhesive Systems, AGRR Magazine, March/April 2012, Page 15</ref>

With the advent of quick-cure adhesives, mobile windshield replacements have become more prevalent.  Often the temperature and humidity cannot be controlled for mobile installations. For most common glass adhesives the ideal environment is {{convert|70|F|C|order=flip}} and 50% [[humidity]]. Variations from the ideal curing environment can increase the time needed for a sufficiently safe bond to form. Because of the variables and difficulties involved in mobile windshield replacement, many vehicle manufacturers do not recommend this method of installations.