Technical challenges in car glass bending

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2 Technical challenges in car glass bending 1 st Glass bending seminare Author: Frank De Ridder Bekaert/Bekintex

3 Summary Trends & needs in automotive glass Heat resistant textile products & applications Products used in In furnace tempering technology Glasstech DB4 Why using sleeves on ceramic rollers? Features for in-furnace applications Why using sleeves for covering ceramic rollers? Bekaert in-furnace sleeves Why using mold cloth? Product performance chart New generation V02 cloths Impact on glass furnace process parameters; trouble shooting Way of stretching the cloth? How to apply the right stretch? Steps to stretch the cloth over the ring and mold. Why using quench ring covering? Why quench products are used? Trouble shooting Next best alternatives products Questions?

4 Trends & needs in automotive glass - Visibility & safety Enhance visibility in all weather conditions by repelling water or technologies to remove fog or frost from windows Advance driver assistance (ADAS) Head up displays UV block glass - Comfort & convenience Reduce noise and increase thermal comfort Small or panoramic sunroofs De-ice windshields - Design & style Dark tinted glass or chrome framed windows Unique shapes, colored patterns - Infotainment & connected vehicle Vehicle to infrastructure or vehicle to vehicle connection Entertainment, real time traffic information Need for incorporated antennas - Environment Glazing products reflecting invisible infrared solar rays to lower CO2 emissions by reducing air conditioning needs Thin glazing to reduce the weight of the vehicle (specially for electrical cars, trains, busses, trucks) Source:

5 Heat resistant textile products & applications In furnace roller covering KNT To cover ceramic rollers in the tunnel and in the bending zone 100% steel ; fiberglass/ss knitted sleeve products Out furnace roller covering KNT/BRT To cover ceramic rollers in bending zone and in cooling zone 100% PBO; SS/PBO; SS/Kevlar knitted & braided sleeve products Quench ring coverings KNR To cover the quench ring 100% SS; 100% PBO ; PBO/SS knitted products Male mold covering KNC To cover the ceramic or steel male mold 100% stainless steel knitted products Female press ring covering FAT To cover the press ring 100% SS woven tape products Female out of furnace press ring covering NP To cover the female press ring PBO/SS ; Kevlar/SS; 100% PBO needle felt products Out of furnace covering rollers To cover the rolls in the cooling zone and transport rollers 100% Kevlar; Kevlar/PBO; 100% PBO

6 Products used in In Furnace Tempering DB4 Ceramic roller covering: KNT2/60 KNT200/60 KNT220/60 Improved lifetime Quench covering: KNR42 KNR43 KNR51 KNR52 KNR53 KNR16 KNR20 KNR25 KNR26 KNR30 KNR31 KNR32 KNR12 KNR14P KNR18P Improved lifetime and marking Hot press ring: FAT12/60 NEW Mold covering: KNC1 series KNC12 series KNC3 series KNC15 series KNC5 series KNC16 series KNC7 series KNC17 series KNC9 series KNC10 series Roller covering: KNT6 KNT7 NFT (tubular felts) NEW

7 Why using sleeves?

8 Features for In-furnace sleeve applications Criteria for a sleeve Capable of withstanding temperatures to C Stay tight onto the roll and resist sagging Sustain temperature flux Fit ceramic rollers mm diameter Should last 6 months before replacement 8

9 Why using sleeves for covering ceramic furnace rollers? In-furnace roller sleeve products Engineered for performance High temperature resistance Reduces surface defects Long life Cost justified Source: Glass Worldwide Magazine July/Aug 2011 Gilbert Rancoule Vesuvius Source; 3D analyses Bekaert, surface damage on glass Trouble shooting Provide a protective layer Prevent pitting and deposits on the rollers Reduce defects and increase yield Stop using S02 9 <<Speaker>> 16/05/2011

10 Bekaert in-furnace sleeves Current products KNT11/60 and KNT220/60 Stainless steel/fiberglass blend Holds tight to the roller without sagging Long life performance Next generation KNT200/60 New 100% stainless sleeve No sagging effect Longer life performance Lower TCO 10

11 Why using mold cloth?

12 Why using moldcloth? Press cloth design in function off Complexity of lites Glass thickness Installation angle Production volume Lowest TCO 12

13 New generation V02 cloths

14 Trouble shooting Glass parameters Bending process Parameters Edge stress of the glass Quench process settings Shape contour of the glass Optics in transmission and reflection Optical cosmetics of the glass Temperature settings Mold contour and other tooling's Pick up vacuum and blow off setting The cloth can have an impact on the process furnace and glass parameters!

15 Way of stretching the cloth? The way how the cloth is stretched over the mold will influence the furnace - and glass parameters; Air permeability (L/dm2/min 100Pa) will increase where the highest stretch is applied Thickness (mm) will decrease specially at the sides of the mold Weight g/dm² will decrease where the highest stretch is applied As the thickness is decreasing the compressibility (µm) will also decrease what has a negative influence on the lifetime of the cloth and the optics of the glass. Thickness variation by 10% strain and a change in depth Pre strain 10% depth 100mm Pre strain 10% depth 120mm Measured on KNC1000

16 How to apply the right stretch? - The use of a dummy mold is necessary and advised - Apply the stretch like Bekaert suggested => target stretch is different for all series of KNC!

17 Steps to stretch the cloth over the ring and mold?

18 Why using quench ring covering?

19 Why using a qunech ring covering? Quench ring coverings are needed to prevent glass from thermal shock that can cause glass breakage during the quench process Quench materials in combination with the ring pattern tooling will have an influence on edge stress in the glass. Quench materials with bigger holes can have a positive Influence on the edge stress in glass. The quench material cannot block the holes of the ring pattern tooling The glass cannot though the quench ring tooling during quenching otherwise the glass will break. Bad cutting and edge work will result also in glass breakage Good cutting and breakout Bad cutting and breakout Example of a good mounting on the ring Good edgework example Bad edgework example Example of a bad mounting

20 Trouble shooting Matching customer requirements by incorporating fiber and textile design Problem: undulation effect Solution: Smaller hole pattern with softer fiber selection Problem: Glass breaking from edge stress Solution: Increase airflow by 50% with larger holes Problem: Longer campaigns and capacity constraints Solution: More robust yarn/textile selection to resist cutting effect and to remain soft

21 Next best alternatives KNR26 KNR32 KNR30 KNR18P Lifetime: ++ Lifetime:++ Lifetime:+ Lifetime: + Edge stress:+ Edge stress:+ Edge stress:+ Edge stress: - Marking: - Marking: - Marking: + Marking:++ Tested against standard KNR52

22 Questions

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