Aluminum Windscreens

 

 

 

Aluminum windscreens. Yes, you read that correctly, ‘But aluminum is a metal, and a windscreen is made of glass?’ I hear you ask.

To help make this information easier to process, aluminum glass is actually, technically, transparent aluminum. A sample of transparent aluminum say, a tube, looks like a tube made of glass but it’s actually aluminum. Well, an asterisked aluminum; this is not elemental aluminum but rather a material made from it as the core ingredient.

Transparent Aluminum tube

Despite clearly not being a metal (and not a glass either; glasses are amorphous solids while ceramics are crystalline) transparent ceramics demonstrate impressive properties. Transparent aluminum is produced by a process called sintering. Powdered ingredients are poured into a mould, compacted under tremendous pressure, and cooked at high temperatures over long periods. The resulting translucent material is then ground and polished to transparency ready for use.

Aluminium Oxynitride ( “ALON” ) is a ceramic composed of aluminium, oxygen and nitrogen. .

Aside from being optically transparent (≥80%) in the near-ultraviolet, visible and midwave-infrared regions of the electromagnetic spectrum, ALON is four times harder than fused silica glass; 85% as hard as sapphire, and nearly 15% harder than magnesium aluminate spinel. Since it has a cubic spinel structure, it can be fabricated to produce transparent windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. Tests show that a laminated pane of ALON 1.6″ thick can stop a 50 caliber rifle round, something even 3.7″ of traditional “bullet-proof” glass can’t do. ALON also has better optical properties than regular glass in the infrared wavelengths; where most glasses absorb IR, ALON is essentially transparent to it. That makes ALON a great choice for the windows on heat seeking missiles and other IR applications.

ALON also demonstrates superior scratch resistance.

SHUT UP and TAKE MY MONEY!

While the technology exists, there is currently no demand for automotive windscreens. Unbreakable and damage-resistant glass is undoubtedly a game-changer which could spell trouble for many AGRR businesses. However, in applications such as mobile phones, the increased demand for such a material will drive costs down, but windscreens might take a while longer.

An ‘aluminum windscreen’ presently could cost in the region of £30,000-40,000, a price tag which even Monty Brewster might balk at.

 

 

Audi A3 Windscreen Replacement

 

 

 

 

An Audi A3 windscreen replacement. This particular car was an RS3 (in Catalunya Red).

3

Audi RS3 Windscreen Replacement

A-pillar covers. I like to take them off. It reduces the risk of damage, and with them out of the way you can check that the bond is making good contact on both the glass as well as the body. There’s a screw at the top of the cover, but before you go yanking on the moulded plastic, you need to free the bottom; and there’s a bit of trim which needs to be separated from the bottom of the A-pillar cover. In order to dothis, there is a cover on each side of the dashboard. These must be removed. The designers have been very helpful by providing a notch towards the bottom of the curved edge which allows you to slip the tip of a trim tool in as you start to ‘pop’ the covers off.

Removing A-Pillar Trim

Removing A-Pillar Trim

The trim can now be removed.

Screw Behind Airbag Cover

There’s a tweeter to disconnect from the cover too:

Tweeter

With the pillar covers removed, the next step is to remove the rear view mirror and the light (and rain) sensor behind it. The sensor is clipped in with a spring-loaded clasp. With the two sides of it released, the sensor will need to be eased out of the mounting bracket very carefully as it will be stuck to the glass with a sticky gel pad. Care must be taken not to go in from the bottom of the sensor as this is where the de-fogging sensor is hiding.

Removal of Rain Sensor

With the interior parts removed, the wipers and wiper cowl can also be removed. There are also two trims – one either side of the windscreen – which must also be removed in order to expose the windscreen edge.

The windscreen can now be released using a cut-out method. Whichever method is used, the emphasis should be on not to damage the paintwork. Here, a cutting wire is being fed into the car via a wire feeder tube. The tube pierces through the adhesive to allow the wire to pass through; a metal guard is positioned so that the act of passing the feeder through does not scratch the paintwork.

Wire Feeder

The windscreen is removed and old adhesive cut back taking care not to damage the paintwork. After cleaning and inspecting the bond line, the surface must be prepared in accordance with the polyurethane adhesive manufacturer’s guidelines.

Once the new windscreen is prepared for bonding, it’s a good time to reattach the rain sensor. A new gel pad is needed for this.

New Gel Pad on Rain Sensor

Steps must be taken not to trap any air anywhere when sandwiching the gel pad between sensor and glass.

Gel Pad Fitted

The new windscreen can now be fitted to the car. I like to date the inside of the glass and provide product details for the adhesive used. The installer’s name and a code for whom it was fitted may prove useful should there be any issues after fitting.

 

Traceability

Glue on glass or body: opinion is divided. I’m an advocate of applying the adhesive on the glass. You get to discharge the product in one go which means one start/stop point (therefore one join) and the glue gun can be held perpendicular to the glass during extrusion in order to minimise the risk of an effect called tunneling in the glue.

Urethane on Windscreen

The windscreen should be bedded down sufficiently so that when the side trims are refitted, there is no gap between the trim and the glass. If the adhesive is compressed to much gaps can show as the trims are held in on a fixed metal track which does not allow adjustment.

Trims

Audi RS3 windscreen replacement: done.

Comments and questions welcomed.

 

Dealer Approved Car? Check the Windscreen

 

 

Something to consider when buying a dealer-approved, used car.

A returning customer got in touch after he bought an ‘approved’ car from a main dealer. He wanted the non-standard windscreen removed and replaced with a genuine ‘OE’ part. As an engineer, he’s fastidious about most things in his life, especially when it comes to cars; for example his garage wasn’t designed to house his previous car (an Audi S8) so he measured the floor-space and calculated that the car would fit but, it would need to be millimeter perfect if he wanted to a) get of the car after parking it, and b) close the (electric) up-and-over door behind it. In order to achieve this – right first time, every time – he articulated a laser guidance system. It was setup to allow a tolerance of +/- 5mm on one side and 20mm at the front. Aligning witness marks on the driveway, bonnet and door mirrors against the red laser lines as he entered the garage served as checkpoints ensuring he was within tolerances. No tennis-ball-on-a-string for this chap!

Our friend’s keenness to demonstrate how precise his system was sets the tone for why he wanted his new car to be perfect. I watched him approach the garage opening, and the theme for Mission Impossible began to play in my head as he guided the car through an intricacy of omnidirectional lines. The parking was absolute and true to his blueprint. To measure the gap between the nearside door handle and the wall you probably would need a feeler gauge (which no doubt wouldn’t have been far from his digital vernier caliper). Excessive? Perhaps. But his commitment to the cause was wholly admirable. It can also serve as one of the best appraisals of your work when such a customer gives you their approval.

As I noted his latest instructions we discussed the age of the car, “2017” he stated. The mileage – as ultra low as it was – was irrelevant; this car would still be covered by a manufacturer warranty. With this in mind, I suggested that he speak to the seller about what the outcome would be if there was an issue with the windscreen, or an electronic device connected to it such as the rain sensor or Lane Departure Warning camera. In the event of a (device) malfunction, or issue with the windscreen and/or installation, the manufacturer warranty would not entertain any claim if there is a non-genuine part fitted. The workshop will just kick it out, or at least until the ‘fake’ part was replaced with a genuine one.

There was no resistance from the selling dealership as he negotiated the cost of an Original Equipment replacement from them, and a contribution towards having an approved installer fit it. Moving forward, the car now is 100% genuine, with authentic parts throughout, and will now accord with the warranty criteria.

 

 

 

ADAS Recalibration After Windscreen Replacement

 

 

 

Have you had your windscreen replaced recently? Is your car equipped with an Advanced Driver-Assistance System? Were you advised (or even warned) about the need to recalibrate that device? Whether your ‘smart’ windscreen has been replaced or not, there is a realistic chance that it might need to be in the future, and this is where you could be faced with more questions… or perhaps not. The subject of recalibrating ADAS devices is a Pandora’s Box full of unsubstantiated claims.

For those new to the technology, some background: ADAS systems are designed and developed to automate and enhance vehicle systems for safer and better driving. These features are designed to help with monitoring, warning, braking, and steering tasks. ADAS relies on inputs from multiple data sources, including automotive imaging, LiDAR, RADAR, image processing and computer vision. These devices are mounted in various places in and around the vehicle; some are mounted behind the windscreen.

ADAS

Advanced Driver-Assistance Systems

Advanced driver-assistance systems are one of the fastest-growing segments in automotive electronics. In terms of car design and evolution, motorists are in safe hands. Ultimately, and until we have autonomous vehicles, the motorist’s hands should however still be on the steering wheel.

Does your camera (or device) need recalibrating after the windscreen has been replaced?

There are a variety of factors to consider, but to cover all bases the blanket response would be to say yes it does. However, before the recalibration apparatus was made available to repair shops, windscreens on cars with ADAS were still being replaced. If the answer is to be yes, why haven’t those vehicles been recalled? The counter argument to that could also be that none of those vehicles needed adjustment, or even, none of them went into default mode after having the windscreen replaced and, worse still, crashed as a result of a misaligned device. There are no reported cases of crashes, injuries or fatalities which were attributed to an uncalibrated camera. Meanwhile, the same cameras are still being recalibrated today.

A motorist emailed me to ask if his device needed calibrating post windscreen replacement. His vehicle featured ‘road sign assist’ which he said he didn’t use anyway. The company who were replacing his windscreen stated that he must drive the car to another one of their sites (30 miles away) to have the camera recalibrated. There was an additional cost implication to this procedure (over £150) as well as his time and fuel to get him there and back. If it was – according the repairer – paramount for his safety why were they sending him on his way, in the compromised car, to another destination 30 miles away? He went ahead and had his windscreen replaced but decided against the recalibration procedure on the basis that he didn’t agree with paying what they were asking for, and then having to embark on a 60-mile round trip in order to get it. Interestingly, he later had his vehicle checked by a manufacturer main agent and there were no flags or faults in the vehicles computer system. Everything worked as it should. The Road Sign Assist device checked out okay.

Traffic Sign Assist

When replacing the windscreen on a vehicle, if the windscreen is a genuine OE product and you are fitting it using the correct bump-stops/trims/damming/mounting components, and within OEM tolerances, as long as you do not disconnect the ADAS device and put the vehicle through an ignition cycle, there is nothing to detect the new part.

Put simply, if you are using manufacturer branded products, fitting them to millimeter precision, and do not put the vehicle through an ignition cycle [with a device disconnected] the car will not know the windscreen has been replaced. It is therefore unlikely that you will encounter any issues. Furthermore, many (if not most) devices are auto-calibrating. They have to be, to allow for constant variables during use. The issues occur mostly (in terms of windscreen replacement) when non-genuine parts are used (referred to as aftermarket parts). Comparing an OE windscreen to an aftermarket copy of it, the differences often become immediately apparent such as misaligned brackets (to which the ADAS device is mounted) or that the material used is inferior. When you mount a camera to its bracket or plate which itself is not positioned correctly, the accuracy of that device is immediately compromised. This therefore, is a scenario where recalibration would be needed. Original parts do not offer any such issues.

The (American-based) Insurance Institute for Highway Safety conducted testing of windscreen-mounted advanced driver assistance systems in 2017 and found that a misaligned camera [on a test vehicle] led to issues with the vehicle’s autobraking and lane-departure warning functions. Honda Collision Marketing Assistant Manager Scott Kaboos summarised after the research that Honda required OEM windscreens be used and that they had seen “many issues” where aftermarket glass led to a situation where the calibration would not “take properly.” After the [repair] shop replaced the windscreen with an OEM edition, “everything worked fine again.” Kaboos stated.

IIHS senior test coordinator Sean O’Malley stated that this demonstrated the need for calibration rather than a ban on aftermarket parts concluding that, “The bottom line is that it could still be calibrated to work as intended.” While a factory-misaligned bracket was found on an aftermarket windscreen, the IIHS found no real issues with aftermarket glass itself, according to O’Malley. Chemical composition, laser refraction and refractive index testing found largely that ‘glass is glass’.

In the UK there have been no reports or stories in the press about firms – nor individuals – being taken to task over negligence. Why? Is it because there have yet not (and thankfully)  been any incidents? Could it also be that there actually isn’t any requirement for an installer to carry out a recalibration? In the same way that any Fred-in-a-shed-with-a-bag-of-tools can replace a windscreen among all the cries of how important structural rigidity is, and how airbags rely on the windscreen to be adequately bonded in order to be effective (provided the occupants are wearing seatbelts in the first instance) anyone can also replace the windscreen on a car equipped with ADAS technology. Is it compulsory to recalibrate those devices? No. Is it necessary to recalibrate them? Maybe.

Whether recalibration is compulsory (after windscreen replacement) or not, are they being checked correctly? Where are the before and after test results? Who is regulating that part of the industry? Who is policing it? How do we know that the procedure was actually carried out? Where is the second printout showing how much adjustment is or was needed? Proof? Is it merely a box-ticking exercise to distance from blame, or something to staple to the invoice to validate the extra charge?

This is a subject that will run for a while, and during that time the ones making the loudest claims in favour of recalibration are also looking for a return on their investment into what is being sold throughout the motor industry as a revenue stream.

Have you had an experience to do with ADAS and windscreen replacement, good, bad or indifferent? Please get in touch.

 

 

Tailgate Glass Transplant

 

 

 

Some of the unsung work we, as windscreen fitters do, is in bodyshops (or accident repair centres). Working as the subcontractor for a crash repair garage can be bread and butter for some firms or the staple income for a lot of windscreen companies. Here is an example of a quick turnaround job: the tailgate transplant.

The new tailgate is painted as the old, crashed one is removed from the car and stored. On the day of the swap, the new painted tailgate will be hung on the car, and work to transfer all the parts begins. The bodyshop fitter will remove all the parts leaving the glass to the specialist:

Tailgate Transplant

The donor tailgate

There are various ways to remove the glass, some methods are better than others. This glass was removed with a square-profiled wire.

Heated rear windscreen removed

Work then begins or preparing the newly painted tailgate. A minimum period of 24 hours must pass after bake before a bonded application can be introduced to fresh paint. With this in mind, a few checks are still necessary to satisfy the installer that the substrate is suitable for bonding to. The new tailgate preparation begins:

New tailgate

There are many polyurethane adhesives on the market. For this job, Sika’s Sikatack Drive was used. Despite its excellent primer-less application, the manufacturer recommends use of a primer – or adhesion promoter – on freshly painted surfaces. But before that, the surface is ‘scratched’ over the bond line to provide a ‘key’ for the primer to adhere to:

Surface preparation: key

Following Sika’s guidelines, the surface is ‘activated’ as preparation for the primer, but also to remove any particles of dust or contaminants. After observing the requisite flash off time, the (black) primer can now be applied:

Adhesion promoter by Sika.

Whilst the primer dries, the glass can be prepared. This is a delicate process of cutting back the old cured adhesive and cleaning the surface. Care is taken not to catch or damage ant hardware on the glass, especially the heater elements. Again, following manufacturer instructions, the  glass  is  prepared  before  fresh  (polyurethane)  adhesive ( “PUR” )is applied. The glass is marked indicating the date, the installer’s identification as well as the corresponding batch numbers for the PUR for traceability.

Heated rear windscreen

Finally, the ‘transplanted’ heated rear windscreen:

Peugeot 3008 glass transplant

Comments and questions welcome.

Manufacturer Warranty: Windscreens

 

 

I replaced a windscreen for an Audi dealer, however, there was nothing wrong with the glass. I asked what the change was for, and it was pointed out that there was an issue with the automatic rain and light sensor. So why was the windscreen cited as the issue?

In his report, the investigating Audi technician concluded that the sensor was not functioning due to the car having a non-genuine windscreen replacement; the (aftermarket screen in it was made by AGC Automotive). As the car was to be sold whilst still under manufacturer warranty the investigation ended there, and could not be resumed until a genuine, Audi branded glass was in place. I duly obliged. However, shortly into the strip-down I discovered what the cause of the issue really was: a damaged rain sensor. The previous installer had damaged the circuit board inside (there were screwdriver marks in the casing).

The car in question was registered in 2016, so much of its warranty would have still been in place; just as long as any parts replaced were authentic, Audi branded.

Rain Sensor 2

Windscreen Rain Sensor

 

Another similar situation unfolded when a Volkswagen main agent was investigating a sensitivity issue on a rain sensor on a fairly new Golf; the owner said the automatic wipers didn’t seem to react as well as he though they should. The VW technician noted the windscreen, an aftermarket version by Saint Gobain (Sekurit) and quickly surmised that it was the cause of the problem. I went along to give a second opinion.

The first place to look for obvious things that could be wrong with a poorly functioning rain sensor is the rain sensor module. I removed the rear view mirror assembly and immediately saw that the rain sensor was not seated properly in the mounting bracket. A push and a click later, the wiper sensitivity was restored to optimum level. However, VW did tell the Golf owner that if there was an issue with the rain sensor (or windscreen) whilst the car was under manufacturer warranty, it would not be covered owing to the non-genuine windscreen in the car.

Whilst these examples may seem excessive, windscreens can be much more complex than the two highlighted here. With radio antennae; heater elements; GPS hardware; Lane Departure Warning sensors; Autonomous Braking hardware; Head Up Display and more, the windscreen is no longer just a piece of glass shielding the car’s occupants from wind and flies. The best available parts, especially if the car is still under warranty (or the more technology connected to the glass) will always be what the vehicle manufacturer endorses.

 

To See, or Not to See

 

 

Now You See It…

An illustration of Before and After stages of a typical windscreen repair. 

Have you recently had your windscreen repaired? Were you pleased with the results? Was there a discernible between the before and after appearances of the damage? Would you know a good repair if you saw one? A lot of repairers don’t, never mind how to achieve one.

Windscreen Repair c

Windscreen Repair

A recent thread on Pistonheads  highlighted a common, and proliferating issue in windscreen stonechip repair. There appears to be a perceived acceptance in what a repaired chip looks like, and judging by a lot of evidence, not many people actually know what an aesthetically, structurally and technically sound repair should look like.

Generally speaking, if there is no difference between the ‘before’ and ‘after’ states, it’s not a good repair. In fact, it is likely that the damage – technically speaking – has not been repaired. “It’s been sealed” was the closing line the TVR Wedge owner got on the Pistonheads thread after he questioned the repairer when he claimed to have finished the job. Looking at the end product of the attempted repair, it could be argued that the repairer had little or no grasp of what he (or she) was doing. Irrespective of what the repairer’s assessment of his or her work is, a botch should not be accepted, nor paid for. And as far as assessments go, the repairer – an experienced repairer – can usually anticipate what the likely outcome will be before attempting a repair. In the case of the TVR owner, the windscreen is now potentially ruined, and the car may even fail its next MOT.

What does a ‘good’ repair look like?

The answer is quite simple. If, by looking at the windscreen, you can easily see the damage you shouldn’t be able to see it without looking for it once it has been repaired. This, however, is subjective to a few important factors:

  1. size;
  2. position on the windscreen;
  3. type of damage;
  4. the age of the chip (or how long it has been exposed to water and contaminants).

Ambient temperature, lighting, equipment, quality of consumable products and the experience of the technician are vitally important aspects which the repairer relies on in order to give prominence to his or her skill. The following image shows a common stone chip on a windscreen.

Chipped Windscreen

Damaged Windscreen

The chip is showing an impact crater (in the middle of the arc shape) and two smaller chips above it. There is one visible crack emanating from the centre of the impact point and threatening to travel southwest; the arc shape is often referred to as a ‘half moon’ although it almost has bears a resemblance to a ‘beeswing’. Underneath the arc shape are two more cracks: one feint crack perpendicular to the southwest pointing crack, and one dissecting the two smaller upper impacts. Placing a mirror behind the break adds clarity:

Mirror Behind Stonechip

Mirror Behind Stonechip

Using a mirror allows the technician to see how the break is responding as various repair techniques are utilised. These are carefully honed skills which enable the break to be manipulated in order to allow the repair resin to penetrate fully into each crack.

Windscreen After Repair

Windscreen After Repair

With the repair complete, and the apparatus removed, the above image shows what the (now repaired) damage looks like with a mirror reflecting light back through the glass. In technical terms (or optics) the light propagating through a medium (in this example, glass) has a refractive index or index of refraction: a dimensionless number which determines how much light is bent, or refracted, when entering a material. With the mirror removed light no longer reflects back through the glass:

Repaired Stone Chip with Mirror Removed

Repaired Stone Chip with Mirror Removed

As good as a repair can look when finished, there is no miraculous vanishing trick. There will always be at least some trace of the damage. This is usually the outline of the impact crater and some visible evidence of the bonded cracks:

A Shadow of its Former Self

A Shadow of its Former Self

It should be noted that whilst there is a mirror present, there is no smoke to trick you into looking elsewhere. Given the nature and definition of glass (it’s transparent!) resolution and focus will always be difficult to replicate from shot to shot when capturing images. A camera will passively focus on an area detected by the autofocus – or AF – sensor(s). The camera in all images was on a standard iPhone 6 device, and by placing it on a predetermined, X, Y and Z axis. The AF was allowed to detect what was in front of it, and the same three manual overrides were used before each image was taken. In no way was it an accurate science. These images were capture in a very basic exercise in order to illustrate the before and after of a windscreen stone chip repair.

As with all posts, comments and feedback welcomed, and gratefully received.