Roller Cleaning and Maintenance

The ceramic rollers should only be washed with water,never use detergents（洗涤剂）!Detergents will chemically react with the rollers,resulting in devitrification（不透明） and roller failure.Due to the extremely low thermal expansion,the rollers can be washed hot.Glass debris（碎片；残骸） on the roller surface can be thermal shocked off of the rollers when cold water is properly applied to a hot roller. Precautions（预防措施；防护措施） should be taken to prevent the end caps from getting hot during the cleaning process.Rollers can also be effectively cleaned at room temperature.Lint free towels（不脱毛的手巾或毛巾） and certain abrasive（有腐蚀作用的；粗糙的） pads such as 3M’s Scotch Brite™are effective.The rollers should be dried following cleaning.If the rollers are soaked（沉浸；浸泡） with water and heated too quickly,steam may develop in the roller and cause it to fail.

Other cleaning methods include the use of tack（劣质材料） cloth to remove surface dust.Sandpaper can be used,but should be avoided if possible.Sanding may induce（带进；引入） waves or an out-of–round condition to the roller surface.On certain rollers,the surface specification requires a textured （粗糙纹理；有纹路的）finish.Sanding the rollers may remove the finish and polish the surface.If sanding is required,take great care and be absolutely certain to avoid introducing the dust into the furnace environment.

The frequency of how often rollers should be cleaned varies greatly and is usually determined by the cleanliness of the tempering environment.As discussed throughout this presentation（陈述；报告；演讲）,the plant environment,furnace cleanliness（清洁度；洁净度）,fabricating practices（实行；进展）,glass cleanliness,SO2 usage,etc.will influence the roller cleanliness.There are methods and measures for determining the cleaning frequency for each furnace.

Refurbishing（重修；重清理） may also be performed on rollers that have excessive surface build up and a moderate amount of surface damage.Usually this involves re-machining the rollers and removing up（除去；去除） to 0.13mm(.005 in.)from the diameter.Before proceeding,consider the TIR of the rollers,wear, and end cap condition.A roller with excessive TIR may look better after refurbishing,but it may not perform better.Refurbishing should include 100% inspection of the rollers,surface reconditioning（重新调整；重新调节） to the OEM specification,end cap replacement if necessary,and final inspection.It is recommended that rollers be re-machined only one time to avoid significant diameter changes.

Example case:

Ceramic Roller Problems - Horizontal Tempering

Q:We are running across a large scale problem with brown lumps （块；块状；片状）accumulating （积累；累加）on our fused silica rollers in our horizontal tempering furnace. We have cleaned out our SO2 manifold（印子；复写；复印；增多；使多样化） and even swapped tanks（砂出的印子） - any ideas on what else to try?

The brown lumps are accumulating sporadically（慢慢积累到） across the entire roller hearth in odd corkscrew（螺旋形的） patterns, with the largest accumulation in the last zone. I have pictures for those interested in helping me solve this problem.

Side problem- Concurrently（同时） there I have another issue with excessive （过多的；过量的）white line on the glass appearing in squiggling（[ˈskwɪɡəl]，squiggle的分词，成波浪形的） lines across the glass. Most of the white line is in the form of a powder that can be removed with a clean glove, but the short scratches leave behind a hazing （烟雾的；迷糊的；）effect on the surface.

Can this also be directly related to the SO2 problem?

Any help would be greatly appreciated!

A:The brown lumps are Sodium（钠） Sulphate. Sodium Sulphate forms when the SO2 gas comes into contact with Sodium in the surface of the glass. The Sodium Sulphate is liquid at furnace temperatures and provides lubrication（润滑） between the roll and the glass, and condenses（凝结） onto the rolls (especially on the high spots which is the spiral of the roll grinding or mold cast during manufacture, which is why you are seeing a corkscrew（螺旋形的） pattern). The spots have a coefficient of expansion whereas（然而，at the same time） the rolls effectively do not, so during a cool down the spots solidify (凝固)and contract and there is a danger they will crumble（弄伤；弄碎） the surface of the roll. Once the roll is cold they can be washed off using plain hot (70 degrees C) water (DO NOT use abrasives（化学腐蚀剂） or solvents（化学溶剂). Basically you are using too much SO2 because you should only see a brown stain（污点；瑕疵；污染） on the rolls, not spots.

The white marking is because the glass is not riding flat in the early stages of heating (try using aspirators（英['æspəreɪtəz，吸气器） to keep it flat) and the weight of the glass is concentrated into smaller areas where it contacts the rolls and is either crushed（弄皱；挤皱；挤压） or abraded（刮擦的；擦伤的）. If the factory is dusty (concrete dust is especially bad) dust from the load table will be taken into the furnace on the bottom surface of the glass exacerbating（exacerbate的分词，使加重；使恶化） the problem.

You mentioned short scratches – these may be due to the main conveyor snatching（突然拿取；突然用力） during reversals（回转） causing the glass to skid slightly.