PUR flush sealing concept creates radical improvements

Significantly less glass breakage and trimming work on car glass

Senior sales and project manager Bernhard Satzger

Mindelheim, 05.02.2021. Car glasses, panorama windows and panorama sunroofs for cars can be better encapsulated with the new PUR flush sealing concept for tools.

Especially when encapsulating large panoramic windows and panoramic sunroofs for cars, frequent glass breakage and costly rework are the unfortunate norm. Bernhard Satzger, one of our senior sales and project managers, did not want to put up with this. At BBG, he has been involved for many years in the project planning of tools for glass finishing with polyurethane (PUR), thermoplastic elastomers (TPE) and polyvinyl chloride (PVC). For more than a year, he worked together with our specialist departments to improve the production quality of PUR encapsulation of automotive glass. With success, because the new PUR flush sealing concept from BBG creates radical improvements.

Why cars today have more and more glass

car with panoramic sunroof
    1. More glass in the car is the trend
      Large car windows, panoramic windows and panoramic sunroofs, and even the entire car roof made of glass, are all the rage. According to the automotive supplier Continental around five square meters of glass are already installed in an average car today. That is almost twice as much as at the end of the 1980s. A large panoramic sunroof adds another 2.5 square meters of glass surface area.
    2. Larger glass surfaces let more light into the car
      Panoramic windows and panoramic sunroofs let more light into the interior of a car. Bernhard Satzger: “A bright ambience with an open feeling of space is currently very much appreciated by car buyers.“
    3. Glass panels get additional functions
      Additional functions are being integrated into ever thinner and larger automotive glass. So-called switchable glasses can be darkened, for example.
    4. Panoramic windows are light
      Because panoramic windows are lighter than steel or aluminum body parts, the manufacturer can use them to reduce the overall weight of the car. In extreme cases, the entire roof panel can even be made of glass. The lower vehicle weight means that the car requires noticeably less fuel and CO² emissions are reduced.

Large car glasses are often wavy and uneven

Wavy edges of a panoramic sunroof

Increasingly thinner and larger glass panels and the integration of additional functions are presenting suppliers with growing challenges. This is because very large edge waviness and deviations in bending of up to 5 mm often occur in the manufacturing process for large glass panels. Satzger: "To the observer, they look inconspicuous at first glance. But if you look more closely, they are wavy and uneven.

This is not a quality shortcoming for their use in cars. The problem arises when the glass is given a frame made of polyurethane before being installed in a car. The glass panels are therefore difficult to handle and to encapsulate.

Risk of breakage and costly rework when encapsulating large car windows

cracked automotive glass

Curved glass in sizes of several square meters with complex geometries is usually made of multilayer laminated glass (LSG). As the name suggests, laminated glass consists of several layers of glass with a tear-resistant plastic film between them. In the event of damage, the plastic film ensures that the glass panel remains together in one piece and that no one is injured by flying splinters.

There are two problems with finishing, i.e. encapsulating these large glass panels with polyurethane:

  • The large and 4.8 to 6 mm thick glass panels are easily cracked during PUR encapsulation.
  • If they are very wavy, polyurethane often leaks onto the inside of the panel during the encapsulation process. Bernhard Satzger explains the consequence: "There is leakage of polyurethane, which causes imprecise edges, and then has to be laboriously removed by hand. This can take five minutes per panel.“

The PUR flush sealing concept technology developed by BBG helps overcome both problems.

No glass breakage, visibly better encapsulation result

precise boundary between glass and plastic - small skins can be easily removed

Alreadythe first practical experience with the new solution inspire our customer. We had no glass breakage! Normally, some glass panels break when a new glass encapsulation mold is run in. With our tool based on the new PUR flush sealing concept, on the other hand, we got it right from the very beginning. All further shots were equally successful.

The second problem is also solved, because the PUR flows exactly where it is supposed to. In the words of the sales and project manager: "The flush result is also excellent. The unwanted leakage of polyurethane on the inside of the glasses is completely avoided. Instead, a precise boundary is formed between the glass and the plastic when it is encapsulated with PUR. If the glass panel comes with wavy edges, there might some minimal small film residue but this can be easily removed with a pumice sponge“

The PUR flush Sealing concept can be used for single-pane tempered glass, as well as laminated glass, and “fragile” semi-tempered glass.

Good experience with the new PUR flush sealing concept

Manufacturing times and reject rates decrease considerably

Initial experience with the new PUR flush sealing concept has been promising: "Glass breakage has dropped dramatically and times for rework have fallen from four to one minute per glass panel in a benchmark comparison," reports Satzger

The cost have already paid off within in a short period of time

Our customer, a glass supplier for the automotive industry, is very satisfied with the result: His investment costs for reworking the existing encapsulation tool with the PUR Flush sealing concept are already paying for themselves in a short time.

Many customers can reduce their scrap with the PUR Flush sealing concept

We believe that many manufacturers can achieve significant savings. This was also the case with a glass supplier for the automotive industry, who complained to Satzger about a reject rate of up to 50 percent for 10,000 panoramic glass panels. Satzger presented to him the prospect of a scrap rate of less than one percent when using a mold with a PUR flush sealing concept.

The PUR flush sealing concept is also good for the environment

However, improved production will not only lower production costs but also result in the reduced consumption of resources. As the scrap rate decreases, fewer parts have to be produced, and CO2 emissions will be reduced accordingly.

Bernhard Satzger or your personal contact will be happy to provide you with further information about the PUR Flush sealing concept. We look forward to your questions.

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