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Detection and resolution of scratch-causing roller side defects

Post Time:Apr 22,2019Classify:Company NewsView:984

Metal scrapers, which do not scratch uncoated glass, are used by window cleaners throughout the world to clean quality uncoated tempered and annealed glass surfaces in an efficient, effective, environmentally friendly manner. Metal scrapers are also commonly used within the glass, painting and automotive industries.

Some tempered glass, however, scratches easily during cleaning, as a result of having travelled on furnace rollers contaminated with glass fines. The roller side then bears numerous fine defects which cause scratches when cleaned with a common metal scraper. Complaints of tempered glass scratching this way are widespread in the US market, though not unheard of in other markets.

The author proposes a simple surface quality test using a standard window cleaning scraper and common smartphone or shop microscope. His presentation is intended to increase awareness and promote the discussion and resolution of tempered glass roller side defects.

Introduction

Numerous microscopic roller side defects are caused when tempered glass is processed on furnace rollers contaminated with glass fines; these defects in turn cause numerous fine scratches during cleaning with common metal scrapers.

A few of these microscopic defects is no problem – a surface with too many defects will scratch badly. By our count, this is the 9th paper presented at GPD to discuss roller side problems related to glass fines, and the 5th to discuss the glass fines/scratch problem. We hope to further the discussion. Does your company have a plan to minimize this problem?

Glass Fines

Scratch-causing roller side defects are a result of microscopic glass fines entering the furnace - perhaps on unwashed or poorly washed glass. Infrequent cleaning of rollers may contribute to the problem. Everyone understands this should not occur to excess, but too often it does occur. How closely is this monitored?

Do frontline people understand? Particles on furnace rollers have the weight of softening glass pressing against them, and may cause a surface defect. The defect might be mechanical damage (a chip or a bump) - or the particle may be transferred from the roller to the glass.

There are many rollers in the heating chamber of a horizontal furnace, and every particle on a roller will touch the glass several times. It’s easy to see how a glass fines problem can get out of hand on the roller side, while the top may be unaffected. (There is no roller side issue for older vertical furnaces, and newer gas hearth furnaces.).

Source: www.gpd.fiAuthor: Shangyi

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