铝箔轧制的常见缺陷

铝板带箔常见主要缺陷及控制浅析摘要：随着社会发展，带动着我国各行业的高速发展。

由于铝及铝合金具有一系列的优异特性，近年来发展速度非常快，同时客户对产品质量的要求也越来越高，各大企业对铝加工产品缺陷的控制也越来越重视，本文重点阐述铝板带箔产品缺陷的分类及生产过程中常见的典型缺陷产生的原因及预防措施，方便企业进行产品缺陷特征分析和预防。

进而通过对缺陷的周期进行分析，可准确推断出此类缺陷产生的位置及原因，为有效改善铝板带箔产品质量提供了良好基础。

另外对目前各大铝加工企业存在的现状问题进行分析，并供同行参考资料。

关键词：铝板带箔;轧制;周期性缺陷;技术人才;引言中国的铝板带箔加工企业，多数只是掌握了一般产品生产线的工艺技术，对高精端产品和特殊生产线的工艺技术尚处于模仿阶段。

比如，中国已经建成了多条铝合金厚板生产线，其生产能力占世界总产能的一半以上，但因工艺技术不成熟，实际生产能力还不足三分之一;中国建成了一条2000mm级当今世界最大的连铸连轧生产线，年生产能力超过250kt，却因工艺技术没有完全掌握，开机率还不足五分之一，成品率普遍偏低，产品加工费用偏高;中国从二十世纪八十年代末期就开始研发并生产PS版铝板基，目前超过10家以上企业拥有专门生产PS版铝板基的生产线，而因产品质量缺陷的控制及技术工艺始终没有获得突破，产品至今还处于中低端水平[1]。

1、铝板带箔加工企业铝合金带材缺陷的分类1.1铝合金带材缺陷分类按照缺陷出现的原因分类如下：1.1.1轧制缺陷。

有厚差、板形不良、表面波、金属或非金属压入、压折(斜角)、水迹(腐蚀)、皱折、打折、开缝、松卷、串层(塔形)、针孔、亮点、不规则亮带、张力线、辊印或辊眼、油污或条印、亮印、裂边和翘边。

1.1.2包装和储运缺陷。

有磕碰伤、压陷和腐蚀不同的缺陷分类方法适台于不同的场合.例如，按生产工艺流程来分，对购买毛料的厂家很有参考意义；按缺陷性质分类，有助于用技术手段解决问题，按缺陷形态分类，便于成品检验。

本规程描述了铝箔生产过程中常见缺陷的定义、特征、产生原因及预防消除措施。

1.针孔箔材穿透的无规律的孔眼。

随厚度减薄，针孔数量增多，迎光可见似针尖细小孔眼，有时密集成行。

1.1 产生原因1.1.1坯料中带有夹杂、气道、擦划伤、金属或非金属压入物等缺陷。

1.1.2轧辊表面粗糙或有缺陷。

1.1.3轧制时后张力太大。

1.1.4轧制油不清洁。

1.1.5坯料表面有严重麻皮(松树枝状)。

1.1.6铝箔轧制时，各种原因造成的金属及非金属压入。

1.1.7轧辊出眼。

1.1.8 外部环境差、灰尘大。

1.2 预防措施1.2.1提高铝箔坯料的质量，采取有效措施，加强对铝熔体的净化，消除气道、夹杂废品。

1.2.2 轧制过程中防止金属及非金属压入。

1.2.3 箔材轧制时严格控制后张力的合理给定。

1.2.4 加强对轧制油的过滤，减少夹杂、脏物的产生。

1.2.5 对铝箔的生产，箔轧机的外部环境很关键，因此要搞好环境卫生，做到文明生产。

2.开缝铝箔经轧制后按纵向自然裂开。

2.1 产生原因2.1.1 轧制时后张力太小。

2.1.2上道次板形控制不当，来料两边紧、中间松或一边紧一边松。

2.1.3辊型控制不当。

2.1.4双合滴油过大或不均匀。

2.2 预防措施2.2.1 轧制时，在允许的范围内尽量增大后张力。

2.2.2 控制来料的板形，使其平整。

2.2.3 轧制时合理的控制冷却润滑油的喷射量和位置。

2.2.4 轧辊磨削严格按规定的参数执行。

2.2.5 双合滴油时，使滴油嘴畅通并控制滴油量。

3. 松树枝状花纹（麻皮）箔材表面呈现的有规律的松树枝状花纹。

表面有明显的色差，但较光滑。

3.1产生原因3.1.1轧制时道次压下量过大，金属在轧辊间由于摩擦力大，流动速度慢，产生滑移。

3.1.2辊型不好，温度不均。

3.1.3轧辊粗糙度不均。

3.1.4由于添加剂含量不够等原因造成油膜强度不够。

3.1.5 轧辊局部温度过高。

3.2 预防措施3.2.1 轧制时适当控制道次压下量。

第三部分箔铝轧机专用题库一、填空题1、铝箔依据的国家标准是 GB/T3198-2003《铝及铝合金箔》。

2、铝箔车间生产产品主要有家用箔、药箔、空调箔、奶粉盖、防潮箔、复合箔、电子箔、酒标等。

3、产生辊眼的主要原因是金属或非金属压入，辊眼规定的超标范围是直径≥0.3mm 时超标4、铝箔表面缺陷主要有黑线条、腐蚀、油斑、亮线、白条、辊眼、压坑、起棱、辉点等（任写五个）。

5、铝箔板形缺陷包括中松、肋松、边部松或紧。

6、铝箔端面质量包括串层、裂边、毛刺、箭头、磕碰伤。

7、轧辊磨削后，不允许有螺旋纹、振痕、横纹、走刀痕、颗粒划伤及其它影响铝箔表面质量的缺陷。

8、公司从涿神公司引进的现代化铝箔轧机，可轧最小铝箔厚度0.0085（双张）或0.015（单张）mm，最高轧制速度为1200 mm/min。

9、铝箔轧机全称为1600四辊不可逆式铝箔轧机。

10、“O”态铝箔坯料，随着轧制力增加，其抗拉强度越大。

11、你所在轧机轧制油粘度为 1.0-2.0 ，闪点为80-90 ℃。

12、我国规定，铝箔厚度为＜0.2mm 称为铝箔。

13、你所在机台通常使用磨削砂轮号为粗轧80# 粗糙度范围0.30-0.40 ；中轧220#粗糙度范围0.08-0.10 。

14、双合轧制0.01mm铝箔应采用220# 工作辊。

15、生产铝箔坯料主要合金牌号有8011 、1235 、3102 、1100 。

16、经过低温除油退火后，其铝箔的抗拉强度变小。

17、铝及铝合金箔GB/T3198标准中0.01-~0.02mm铝箔针孔数（个/m²）规定A级10个B级20个C级30个。

18、为了避免亮点的产生，双合时用的是低闪点双合油，且要喷涂均匀。

19、检测空调箔三项指标具体为抗拉强度、延伸率、杯突，其杯突用（IE）表示。

20、根据GB/T3198标准中药用铝箔对表面润湿张力最低应达到32×10-3N/m 。

二、回答题1、请问铝箔产品常见的缺陷有哪些？答：尺寸超差、亮线、亮条、辊眼、辊印、超棱、超鼓、起皱、串层、腐蚀、针孔数超标、裂边、亮点、白条、压坑2、销售下计划时只注明成品为H18 0.02mm药箔，其潜在的要求是什么？答：针孔≤1个/m2；表面润湿张力32×10-3N/m；板面平整；无油污；3、铝箔坯料有哪些质量要求?答：不允许有毛刺、裂口；塔形≤10mm；串层≤3mm；打底不良不超过≤10mm；对中偏差≤30mm;板面平整、洁净、不允许有热带、孔洞、擦划伤、气道、腐蚀、铸轧辊龟裂造成的凹坑、横向条纹、纵向条纹、裂纹、金属或非金属压入等影响使用的缺陷。

铝箔轧制常见缺陷的一般特征、原因及措施在轧辊的表面与机体中形成高微裂纹的铬层。

这种高高微裂纹的网状结构有利于轧制油吸附在轧辊表面，以便润滑。

网状结构的铬层可以承受轧制力高达2000吨以上的的压力。

以下是其与传统镀铬的金相结构图的比较对照表：轧辊镀铬的铬层硬度是随着镀铬的技术条件变化而变化的。

科德工作辊服务集团的镀铬层硬度通过其技术的创新可以达到900-1100VICKERS PN。

这么高的硬度值就是所谓的“镀硬铬”技术。

通过这样的硬度值来增加轧辊的耐磨性能。

它的硬度要比通常的铸铁或者热处理的锻钢工作辊的硬度还要高。

镀铬层的摩擦系数更低，以下是一些金属表面的摩擦系数表：铝箔轧辊的镀铬对铝箔的生产带来了较好的效果。

工作辊—所有机架（粗轧→中轧）冷轧镀铬辊的所有绩效在铝箔轧辊上都能体现出来，此外，还具备以下优点：（1）、能够成倍减缓随通过量轧制速度下降的趋势从而获得稳定的轧制速度；（2）、能够从窄到宽的变规格轧制；（3）、大幅度改善润滑状态减少了不明断带；（4）、获得稳定一致的板型和表面质量。

在生产10—30um的箔材中，由于支撑辊的原因常常损坏工作辊。

而对支撑辊的镀铬可以改善工作辊的损伤，减少氧化物的产生和线条的产生。

在铝箔精轧中，使用镀铬工作辊可以获得更稳定均匀的表面质量，延缓线条产生。

抑制原料带来色差的倾向。

分切常见缺陷及调整措施工艺参数与铝箔质量产量的关系COMALCOFOIL DIVISIONDEFECT CATALOGUEDanyang Training VisitMay 1992Comalco Aluminium Ltd SMP 7479.00Yennora Words Page 1 of xxxFoil Division Date 9.9.91Standard Metallurgical Practices Prepared by: C. Cleary Foil Division Defect CatalogueScopeThis S.M.P. is for all foil personnel and covers the description and classification of various defects found in the Foil Division. It describes defects which occur during rolling, slitting and annealing.This catalogue describes the defect, why it occurs and when possible, tells you how to eliminate it.The numbering system follows the Comalco Claim System used site wide for categorizing claims from external customers (see page 2 and 3 for a full listing).This S.M.P. covers the following defects:0.1 Stickiness0.1.1 Orange Peel0.1.2 Exploded Areas0.2 Wettability1.6.1 Hot Spots1.9 Tension Cuts2.1 Water Stain2.2.1 Herringbone2.2.2 Line of Holes2.2.3 Roll Holes2.2.4 Chatter2.2.5 Mill Lines2.2.6 Bruised coil2.2.7 Indents2.2.8 Splits2.5.1 Dross2.5.2 Staining2.6.1 Chicken Tracks2.7 Broken Matte2.7.1 Streaky Matte6.3 Step Outs6.4 Telescoping6.5 Out of Round6.7.1 Edge Cracks6.7.2 Laminations6.10 BridgingFULL LISTING OF SITE WIDE DEFECTS0.0 Annealing 0.1 Stickiness 0.1.1 Orange Peel 0.1.2 Exploded Areas 0.2 Wettability1.0 Dimensional 1.1 Gauge1.2 Width1.3 Lateral Bow1.4 Length1.6 Flatness 1.6.1 Hot Spots1.6.2 Creasing1.7 Edge Burr1.8 Mass1.9 Tension Crease2.0 Surface 2.1 Water Stain2.2 Metal Surface 2.2.1 Herringbone2.2.2 Line of Holes2.2.3 Roll Holes2.2.4 Chatter2.2.5 Mill Lines2.2.6 Bruised Coil2.2.7 Indents2.2.8 Splits2.3 Surface Condition2.4 Applied Coating2.5 Surface Contamination 2.5.1 Dross2.5.2 Staining2.6 Blade Marks 2.6.1 Chicken Tracking 2.7 Broken Matte 2.7.1 Streaky Matt3.0 Metallurgy 3.1 Alloy3.2 Mechanical Properties3.3 Earing3.4 Inclusion3.5 Failure To Form Cans4.0 Document 4.1 Specification4.2 Planning4.3 Sales5.0 Packaging 5.15.2 Identification6.0 Coil Cond n 6.1 Loose Wraps6.2 Broken Welds6.3 Step Outs6.4 Telescope6.5 Out of Round6.6 Coil Size6.7 Broken Edge 6.7.1 Edge Cracks 6.7.2 Laminations 6.8 Edge Damage6.9 Handling Damage6.10 Bridging7.0 Transport 7.1 Seafreight7.2 Road/Rail8.0 Acc Reject9.0 No Defect 9.1 BU/CP Wrecks0.1 StickinessWhat is stickiness?Stickiness is a measure of how difficult it is to pull a single layer of foil from the coil. This defect can cause problems, especially when it occurs in light gauge foils such as insulation and flexible packaging metal.When does stickiness occur?When the annealing process is out of specification or the wrong annealing cycle has been used for a particular product if the metal is kept at the incorrect temperature.Why does stickiness occur?* incorrect conditions in the annealing furnace:-any residual rolling oil left from the rolling process can polymerise and form weak bonds with the meta.What can you do about it?* monitor the annealing cycle closely and watch the:-heat up rate-soak time-temperature-cool down rate;* report any furnace problems-e.g. burner failure;* keep excess coolant carryover to a minimum.STICKY COILIT REQUIRES FORCE TO PULL THESINGLE SHEET FROM THE COIL FREE UNWIND COILTHE METAL SHEET EASILY FALLS AWAYFROM THE COIL UNDER ITS OWN WEIGHT0.1.1 Orange Peel EffectWhat is orange peel effect?Orange peel effect is a change in the surface of the metal. It becomes mottled, like the surface of an orange peel. This defect is always associated with high stickiness levels (see 0.1).When does orange peel effect occur?This defect mainly occurs on medium gauge coils (30 to 70 microns) and of a soft alloy and O Temper.Why does orange peel effect occur?* too much coolant left on the coil:-during annealing, the excess coolant between the foil layers forms a vapour.-the pressure from the vapour deforms the foil in localized pockets.What can you do about it?Minimize the amount of coolant left on the coil:* always use the splash guard when rolling the final. pass on No. 1 foil mill; * make sure the air wiper system is working properly;* check the amount of residual coolant on the metal when it is on the slitter -if the level is high, make a note of this on the lot ticket.0.1.2 Exploded AreasWhat are exploded areas?Exploded areas are small blister-like bubbles that occur between layers of light gauge foil after it has been annealed. You will find this defect mainly on annealed household foil coil.When do exploded areas occur?When light gauge foil is annealed.Why do exploded areas occur?* too much coolant left on the coil:-as the foil is annealed, the excess coolant between the foil layers forms a vapour-the foil is deformed by pressure from the vapour in localized pockets, this causes an exploded blistered effect.* incorrect anneal practice-too high an annealing temperature will also cause exploded areas.What can you do about them?* keep the amount of the coolant left on the coil to a minimum: -make sure the mill air wiper system is working properly,-check the amount of residual coolant on the metal when it is on the slitter.Make a note on the lot ticket if the level is high.* make sure the metal is annealed correctly and check:-heat up rate-soak time-temperature-cool down rate0.2 WettabilityWhat is wettability?Wettability is a measure of the amount of rolling lubricant left on the foil strip after annealing. If there is too much, it can interfere when plastics and inks are applied to the metal at the customers plant.When does wettability occur?When there is too much rolling lubricant left on the metal after it has been anneal.Why does wettability occur?* excess coolant carryover on the mill;* incorrect conditions in the annealing furnace.Why can you do about it?* monitor the annealing cycle closely and watch the:-heat up rate-soak time-temperature-cool down rate;* report any furnace problems-e.g. burner failure;* keep excess coolant carryover to a minimum.A GRADE WETTABILITYWHEN WATER IS APPLIED TO A SHEET OF FOILIT STAYS ON THE FOIL e.g. IT WETS THE SURFACEB BRADE WETTABILITYWHEN WATER IS APPLIED TO A SHEET OF FOILIT DOES NOT STAY ON THE FOIL SURFACE1.6.1 Hot SpotsWhat are hot spots?Hot spots are a continuous buckle (or belly) anywhere on the width of the exit strip. Provided the exit tension is not too high, hot spots are very easy to see when you are rolling. The buckled area is a lower gauge and longer than the rest of the strip. As a result it ‘puckers’.When do hot spots occur?When excess heat builds up in a section of a work roll or backup roll, the roll expands more in this area. The metal which comes into contact with this area is rolled to a lower gauge than the rest of the strip.Why do hot spots occur?Excess heat in a localized section of a work roll or backup roll is caused by: * foreign objects rubbing against the roll;* too mach wiper pressure in one area of the roll;* a blocked coolant spray;* coolant sprays which are not correctly aligned;* too much thermal crown;* local hard or soft spots on the roll;* disturbed oxide layer in the area of the buckle.What can you do about them?* check for foreign objects and remove any you find;* check the pressure on the wiper and alter it if uneven or too high;* unblocked any blocked coolant sprays;* make sure the coolant sprays are correctly aligned;* check the coolant pressure and increase it if necessary;* change the work rolls.Hot Spot \ Shape Defect Description1.9 Tension CutsWhat are tension cuts?Tension cuts are stretched bands of broken metal on the edges of the strip. They point towards the centre of the strip and spread out as they reach the edges. This defect is very easy to identify during rolling.When do tension cuts occur?When the strip wrinkles or folds over as it enters the mill bite.Why do tension cuts occur?* if the unwind tension is too low to hold the strip flat as it enters the work roll bite, the strip edges can wavy and wrinkle;* if the bridle is uneven or out of alignment, it may not hold the strip flat.What can you do about them?* increase the unwind tension until you can’t see any more fractures;* make sure the bridle is correctly aligned and the strip is flat as it enters the mill bite.2.1 Water stainsWhat are water stains?Water stains are a white or grey discolouration on the surface of the metal. Water reacts with the metal, causing surface oxidation and the formation of a metal oxide. This oxide stain is harder than the rest of the strip. When it passes through the mill bite, it can cause the strip to break.When do water stains occur?When the metal comes into contact with water.Why do water stains occur?* direct exposure to water;* condensation caused by rapid temperature changes in the metal:* when water is trapped between two closely packed metal surfaces there is no air circulating and the metal surface reacts with the water, this is known as surface oxidation.What can you do about them?* keep water away from the aluminium at all time- store away from roof leaks or keep the metal covered- keep the metal off the floor;* make the wooden boxes have low moisture content when you pack coils in them; * make sure the coils are cool before you pack them;* cover coils when transporting them from No. 1 to No. 2 mill on an overcast day.How to determine where the water staining occurredUsing a Scanning Electron Microscope, a good understanding of where the staining occurred can be achieved. With this type of microscope the stain can be studied, and other elements other than Aluminium can be detected. These will give you a rough estimate of the nature of the stain.* If Sodium or Chlorine are detected, then the stain is probably from sea water. * If Sulphur is detected, then the stain could be caused by acid rain.* If Calcium or Iron is detected, then the water source could possibly be unclean tap water.These generalizations can only be used as a rough guide when determining where the water staining has occurred..01 5.12 KeV Typical SEM Trace for a salt water caused “Waterstain”.2.2.1 HerringboneWhat is Herringbone?Herringbone is a surface marking along the strip which resembles a string of corpo ral’s stripes or the backbone of a fish.When does herringbone occur?There are a number of possible reasons:* the coolant may not be lubricating the strip well enough under the extreme pressure of the mill bite;* the strip may have a poor shape either from a previous pass or the present one; * the gauge reduction may be too great;* an earlier annealing treatment may have been missed* work roll finish may be incorrectly ground.What can you do about it?Herringbone is probably not the fault of your rolling technique, so you should follow or report on these matters:* check the composition of the coolant to ensure it has the correct levels of additives to give lubrication. The Rolling Superintendent or Foil Metallurgist keeps records of coolant additive levels;* check the previous rolling and annealing history of the coil from the Lot Ticket - report any ways in which this differs from the process schedule;* check the Roll Grind Requisition form, ensuring that the rolls have had the correct grinding performed on them.2.2.2 Lines of HolesWhat is lines of holes?Lines of holes are a continuous line of little holes in the metal. It varies in severity and can sometimes occur consistently throughout a coil. Lines of holes often cause strip break during the last single and the final doubling passes.When does lines of holes occur?This defect occurs when the metal has been scratched at any stage of processing or when a source of pick-up is introduced to the roll bite.Why do lines of holes occur?When the surface of the strip has been broken, by:* mechanical failure, for example- pulling the strip over a seized roll- a scratch on the work roll surface;* careless handling of the metal;* the work rolls have been ground with no relief on the ends. This results in small pieces of work roll surface breaking off and being forced through the bite.What can you do about it?Try to protect the metal throughout the process:* check and maintain a high level of cleanliness on the mill regularly;* when you detect lines of holes, the coil should be isolated and put on hold. The coil should not be processed any further;* check the work rolls for signs of spoiling.2.2.3 Roll HolesWhat are roll holes?Roll holes are small marks or holes that repeat at a regular interval along the metal strip. This defect is very difficult to see during rolling.When do roll holes occur?When a roll work become damaged and the damaged portion imprints a mark onto the metal surface.Why do roll holes occur?The work rolls can be damaged by a number of things:* grit;* dirt;* dust;* an inclusion in the strip.What can you do about them?* make sure the mill is cleaned thoroughly- after a PM- after a strip break;* make sure the metal stays off the ground;* wear clean gloves when you handle the metal;* remove one wrap from the feed coil if it has been standing for a long time; * if the holes are repeating at an interval of about 1 metre when you measure them along the length of the strip, then the mark is caused by your work rolls - change the rolls;* if the holes are about 2 metres apart, they were caused before you received the coil- there is nothing you can do about them.2.2.4 ChatterWhat is chatter?Chatter is evenly spaced, two tone lines which run across the width of the strip. If you could see the edge of the strip magnified, it would look similar to the edge of a piece of corrugated iron. You will hear chatter occurring before see it.When does chatter occur?Chatter often occurs during mill acceleration and deceleration, for short periods only. Only when this occurs at longer periods of times does the defect become a problem.Why does it occur?Chatter is caused by machine resonance. Machine resonance can occur under the following condition:* the coolant is out of specification;* the feed strip is a hard alloy;* the pass line is incorrect;* the drive transfer box is worn;* the drive couplings are worn.What can you do about it?* if you want to finish the coil, try altering the mill speed and unwind tension,then stop rolling and look for the problem;* make sure the coolant is within specification at all times - if it is not, stop the mill until you can correct it;* change the product or program until someone alters the mill; * if the pass line is wrong, check the mill shims;* change the work rolls.THE LINES ON THE STRIP IF MAGNIFIEDWOULD SHOW VARIATIONS OF GAUGE WHICH WOULD GIVETHE CROSS SECTION A CORRUGATED EFFECT AS SHOWN ABOVE 2.2.5 Mill LinesWhat are mill lines?Mill lines are very narrow stripes which run along the strip in the rolling direction. To see them clearly, you need to straight down onto the strip.When do mill lines occur?When the work rolls or backup rolls are damaged.Why do mill lines occur?There are a number of reasons:* there is a scratch on the work roll;* the oxide layer on the work roll is uneven;* there are lines on the work roll caused by the damaged backup roll - the backup roll can be damaged by a worn wiper.What can you do about them?* if the defect is present in the following products, you must do a roll change - R No. 62715 Leigh Mardon .040mm x 592mm- R No. 62780 Leigh Mardon .040mm x 674mm- R No. 62576 Leigh Mardon .050mm x 675mm- R No. 62303 Leigh Mardon .040mm x 643mm* if there are lines on the backup roll, there is no point in changing the work rolls because the damaged backup roll will mark the new rolls- remove the mark from the backup roll with emery paper or a fine grinding wheel - if you can not remove the lines, change the backup roll;* if only the work roll is damaged, change the work rolls.2.2.6 Bruised CoilWhat is a bruised coil?A bruised coil is an area of discolouration which repeats along the metal strip at regular interval.When does a bruised coil occur?When a work roll has an impact placed upon it. The bruise can occur at any upstream process and can manifest itself upon further reductions as a discolouration on the metal or shape problems with the coil.Why does a bruised coil occur?* when the tail of a coil passes through the roll bite and damages the work rolls. This mark is then transferred onto the strip.- this occurs most often on heavier gauges and when you roll hard alloys (e.g.3003 and 3004 alloys).What can you do about it?* when you are rolling a breakdown pass, stop the mill before the tail of the strip passes through the mill bite;* cut the tail in an arc, reduce the load and pull the tail through;* when programming semi-rigid container metal on No. 1 Mill, always programme 8001 and other soft alloys before 3003 and 3004 alloys. The 3003 and 3004 alloys are harder than the 8001 alloy and are therefore less susceptible to the effect of bruising the work rolls.2.2.7 IndentsWhat are indents?Indents are small depressions that appear on the surface of the metal as the coil unwinds.When do indents occur?This defect mainly occurs on medium gauge coils (30 to 70 microns). It is most obvious on O-Temper metal.Why do indents occur?* small particles of dust, dirt and grit get trapped between the metal layers as the coil is slit- the problem gets worse when the metal is annealed because the metal is softer and more prone to mark.What can you do about them?* clean the slitter thoroughly before you use it- this is especially important if the slitter has not been used for a while; * keep the metal off the floor;* handle the metal with clean gloves;* when slitting metal on the 755 slitter always use rotary blades, as razer blades tend to produce a larger amount of swarf which then deposits on the metal strip.2.2.8 SplitsWhat are splits?Splits are very thin creases which have been rolled into the metal. These creases weaken the metal and will easily break apart during rolling. When you are rolling, a split looks like a continuous black line, usually on the centre of the rewinding coil, but sometimes on other side. Take care you don’t confuse this defect with mill lines which look very similar.When do splits occur?When you roll a fold or crease into the strip.Why do splits occur?There are a number of reasons:* incorrect pass line- if the pass line is wrong, the strip will not be level when it enters the mill bite;* the unwind tension is too high, cause a crease in the unwinding strip - this occurs mainly in light gauge strips;* the entry bridle is not correctly aligned.* the backup roll has recently been changed and the work roll camber has not been change to accommodate this change.* the work roll finish may be incorrectly ground.What can you do about them?* carry out a pass line check whenever you change the top backup roll;* make sure the pass line is correct;* make sure the unwind tension is correct;* make sure the correct shims are inserted at every work roll change;* check that the entry bridle is correctly aligned.* ensure that the correct work roll camber is used after the backup rolls have been change.2.5.1 DrossWhat is dross?Dross is a mark or hole in the strip. In very severe cases, it ban lead to web break.When does dross occur?True dross is very rare. It occurs when the metal has not been sufficiently drossed off during casting. Many other defects are mistakenly reported as dross.Why does dross occur?* oxidational impurities form in the metal during casting and hard oxide particlesbecome embedded in the aluminium;* during rolling the oxide particles do not deform as readily as the aluminium and can damage the work rolls;* this leads to marks and holes in the strip and finer gauge strips may disintegrate.What can you do about it?* there is nothing you can do about true dross because the defect is already in the metal before you receive it;* by keeping the metal clean, you can avoid defects which show similar characteristics, but are not in reality dross.2.5.2 StainingWhat is staining?Staining is a black or brown mark which appears or the coil after annealing.When does staining occur?When there are organic compounds left on the strip during annealing, they burn on and cause staining.Why does staining occur?Staining can occur on different parts of the coil:* on the side- if the staining compound was deposited during rolling;* on the side, but only near a join- if the compound was left when the coil was being joined or welded;* on the outside wraps- if the compound came into contact with the metal inside the furnace;* if there is ‘wet lube’ on the furna ce tree when it enters the furnace, the lube evaporates, concentrates and burns on the coil- this could come from a side arm tree that has had container coils on it.What can you do about it?* make sure the coils do not have excess coolant left on them- use the splash guards during the final pass on No. 1 foil mill;* make sure the side arm trees do not have any wet lube on them before you place a coil on them for annealing;* make sure the mill air wiper system is working properly;* check that there is no tape or other foreign matter on the coil before you anneal it.* always ensure that furnace exhaust vents are working properly.2.6.1 Chicken trackingWhat is chicken tracking?Chicken tracking is a slit defect that looks like lines on the edge of a slit coil which radiate from the centre to the outside.When does chicken tracking occur?This defect is a result of slitter blade flutter.Why does chicken tracking occur?Slitter blade flutter can be caused by following:* a damaged female knife roll:* a loose knife;* badly shaped feed metal.What can you do about it?* make sure the knives are firm;* make sure the female knife roll is in good condition.2.7 Broken MatteWhat is broken matte?Broken matte are shiny spots scattered over the dull, matte side of the metal.When does broken matte occur?Broken matte occurs when you are doubling strips and the two strips weld together in spots. As the strips are separated, the welded areas break leaving shiny spots.Why does broken matte occur?There are a number of possible reasons:* not enough inter lap solvent used;* too much speed when rolling;* uneven roll grind;* the two entry strips have different surface textures;* in some alloys, broken matte can occur if the inter lap solvent has a higher lubrication capability than the coolant (e.g. alloy 1145).What can you about it?* make sure you use enough inter lap solvent;* make sure the mill speed is correct;* change the work rolls if you suspect the roll grind is mismatched.2.7.1 Streaky MatteWhat is streaky matte?Streaky matte is also known as no matte and is exactly as the name suggests, a section of the metal strip on the matte surface where there is no matte.When does streaky matte occur?When you are doubling two strips and the solvent application is not consistent you get varied lubrication characteristics in different areas of the strip.Why does streaky matte occur?* there is not adequate inter lap solvent being deposited across the whole strip of foil.What can you do about it?* use plenty of inter lap solvent;* ensure that none of the inter lap sprays have become blocked;* if you increase the mill speed during doubling, then ensure that the inter lap sprays are accordingly adjusted to a greater outflow.6.3 Step OutsWhat are step outs?Step outs are uneven wraps in the coil that have deviated from the normally smooth end face of the coil.When do step outs occur?When you alter variables such as steering or tension during rolling or slitting.Why do step outs occur?* when you alter variables such as steering or tension during rolling or slitting. What can you do about them?* if you need to change any variables when the metal is either being slit or rolled, then do so gradually and smoothly. Any quick changes could result in step outs.6.4 TelescopingWhat is telescoping?The wraps of the coil slip out sideways and result in a telescoped effect.When does telescoping occur?Telescoping generally occurs when there are steerage problems on the slitter or mill.Why does telescoping occur?* incorrect steerage on the slitter- because of badly shaped feed metal;* insufficient tension during rolling/slitting can result in a loose coil, that may slip to one side during coil handling.What can you do about it?* increase the ironing roll pressure on the side of the coil that the telescoping is steering away from;* increase the unwind tension on the side of the coil that the telescoping is steering towards.LATERAL MOVEMENT OF FOIL LAYERS RELATIVE TOEACH OTHER HAS CAUSED THE COIL TO GELESCOPE6.5 Out of RoundWhat is out of round?This term describes a coil which is not perfectly round. To measure the extent of the defect, find the maximum distance between the core and the outside diameter (shown by the bottom arrow in the diagram) and from this, take the minimum distance (shown by the top arrow in the diagram).maximum distance – minimum distance = extent of defectNote: this diagram has been exaggeratedNORMAL SLIT COILTELESCOPING OF SLIT COILWhen does out of round occur?Out of round generally occurs on insulation coils and wide flexible packaging coils.Why does out of round occur?* the bulk of the metal sags to the bottom of the coil during annealing - the cool down rate is particularly important, if the cooldown rate is too high it creates a thermal gradient in the coil. This defect is minised by using 152mm cores.What can you do about it?* make sure the cool down rate is within specification.6.7.1 Edge CracksWhat are edge cracks?Edge cracks are cracks or small splits along the edge of the strip. They are generally 0.2 to 0.3 mm long. Edge cracks are particularly a problem in hard alloys and can make it difficult, Sometimes impossible to roll the final pass.When do edge cracks occur?When the coolant composition, the pass schedule or the condition of the strip are out of specification.Why do edge cracks occur?There are a number of reasons:* too much friction during rolling;* the gauge reduction may be too great;* the edges of the strip may be shorter than the body of the strip, putting more tension on the edges.What can you do about them?* bend the edges of the coil, to do this:- turn positive bending off- increase negative bending to -2- increase the load;。

轧制振纹缺陷产生原理及影响因素分析摘要：本文通过对铝箔轧制过程振纹产生的机理进行研究，以及对影响振纹的相关因素进行分析验证，得出引起铝板带及铝箔产品产生振纹关键影响因素，为解决振纹问题提供改进依据和改进方向。

关键词：轧制；振纹；润滑振纹是铝板带箔产品常见的缺陷。

产品表面有振纹，不仅影响美观，还会影响铝箔的连续生产（轧制是容易断带），影响后工序涂覆的正常使用（振纹明显时涂层无法掩盖该缺陷）。

目前轧制的所有铝板带箔产品都有可能出现振纹的现象。

振纹的产生不分合金、厚度和材料的硬化状态，当轧制油品润滑条件不满足，道次设计不合理，轧辊粗糙度不合适，设备振动等，都有可能产生振纹缺陷。

以下图1、2是常见的振纹缺陷。

图1 图21. 轧制振纹缺陷产品原因及影响因素振纹是在板带材及铝箔表面周期性或连续地出现垂直于轧制方向的条纹。

该条纹单条间平行分布，一般贯通带材整个宽度。

产生于轧机、矫直机、压光机等设备在生产过程中高频振动。

振纹产生的因素主要有以下几点，如下表1：2. 振纹影响因素分析2.1. 轧机工作辊的影响轧辊质量是影响振纹的主要因素之一，轧辊的影响主要包括轧辊磨削粗糙度的影响，轧辊使用周期的影响。

2.1.1轧辊粗糙度的影响在相同的轧制工艺（道次加工率）和相同的油品指标下，磨削的轧辊粗糙度越低，越容易出现打滑形成振纹。

打滑形成振纹的机理：由于打滑形成的振纹，产生于轧制过程中油膜不连续形成振动引起，周期为5~10mm，通常产生在一个速度区间。

以下是某铝箔生产厂在相同的轧制工艺（道次加工率）和相同的油品指标下，对轧辊粗糙度与振纹产生的验证情况。

以轧制1235合金1300mm宽度，0.065-0.032mm三道次为例，生产过程中在恒定的速度区间内，通过调整张力和轧制力，尽量保持稳定连续轧制，验证产生振纹的粗糙度临界参数。

如下表2表1因此，在该生产工艺条件下，轧辊粗糙度应控制在0.1um以上，才可较好避免振纹缺陷。

最佳轧辊粗糙度为0.11-0.12um，随着粗糙度加大，轧制需要的润滑要求提高，如果润滑条件得不到同步改善，容易衍生出其他质量问题。

铝箔的主要缺陷有：（1）针孔。

针孔是铝箔材的主要缺陷。

原料中，轧辊上，轧制油中，甚至空气中的尘埃尺寸达到6μm左右进入辊缝均会引起针孔，所以6μm铝箔没有针孔是不可能的，只能用多少和大小评价它。

由于铝箔轧制条件的改善，特别是防尘与轧制油有效地过滤和方便的换辊系统的设置，铝箔针孔数目愈来愈依赖于原料的冶金质量和加工缺陷，由于针孔往往是原料缺陷的脱落，很难找到与原缺陷的对应关系。

一般认为，针孔主要与含气量、夹杂、化合物及成分偏析有关。

采取有效的铝液净化、过滤、晶粒细化均有助于减少针孔。

当然采用合金化等手段改善材料的硬化特性也有助于减少针孔。

优质的热轧材轧制的6μm铝箔针孔可在100个/㎡以下。

铸轧材当净化较好时，6μm铝箔针孔在200个/㎡以下。

在铝箔轧制过程中，其他造成针孔的因素也很多，甚至是灾难性的，每平方米数以千计的针孔并不稀奇。

轧制油的有效过滤，轧辊短期更换及防尘措施均是减少铝箔针孔所必备的条件，而采用大轧制力，小张力轧制也会对减少针孔有所帮助。

（2）辊印、辊眼、光泽不均。

它主要是轧辊引起的铝箔缺陷，分为点、线、面三种。

最显著的特点三周期出现。

造成这种缺陷的主要原因为：轧辊不正确的磨削；外来物损伤轧辊：来料缺陷印伤轧辊；轧辊疲劳；辊间撞击、打滑等。

所有可以造成轧辊表面损伤的因素，均可对铝箔轧制形成危害。

因为铝箔轧制辊面光洁度很高，轻微的光泽不均匀也会影响其表面状态。

定期的清理轧机，保持轧机的清洁，保证清辊器的正常工作，定期换辊，合理磨削，均是保证铝箔轧后表面均匀一致的基本条件。

（3）起皱。

由于板形严重不良，在铝箔卷取或展开时会形成皱折，其本质为张力不足以使箔面拉平。

对于张力维20MPa的装置，箔面的板形不得大于30I，当大于30I时，必然起皱。

由于轧制时铝箔往往承受比后续加工更大的张力，一些在轧制时仅仅表现为板形不良，包括轧辊磨削不正确，辊型不对，来料板形不良及调整板形不正确。

（4）亮点、亮痕、亮斑。

收稿日期:2003-10-30 作者简介:王艳波(1969-),男,河北邢台人,工程师。

铝箔成品轧制中亮点缺陷的成因与对策Preventive Methods and G eneration C auses of Broken MatteDefects during Aluminium Foil Finish P ass R olling王艳波WANG Y an -bo(渤海铝业有限公司,河北秦皇岛066001)摘要:介绍了铝箔成品轧制中亮点的表现形式和产生机理,对其影响因素进行了分析。

为了防止亮点,必须严格控制轧制油中添加剂的含量,制定合理的轧制工艺参数,在轧制过程中细心操作,加强成品前一道次双张箔厚度的控制,保证双合油的清洁度,使用低粘度、低闪点的双合油,对轧制油的粘度进行控制,对轧辊良好磨削、尽量减小上下辊径差值,及时更换工作辊,及时更换老化的轧制油,对铝箔来料中的夹杂等缺陷严格控制。

关键词:铝箔;亮点;添加剂;偶极;碳链;双合油中图分类号:TG 339 文献标识码:B 文章编号:1007-7235(2004)02-0031-02 为了满足客户的要求,铝箔在一定厚度以下需要进行双合轧制。

在双合轧制过程中,由于各种因素的影响,在铝箔的暗面有时会出现亮点缺陷,它不但影响产品的美观,而且亮点会导致铝箔力学性能大幅度下降,使铝箔在深加工时容易断裂破碎。

因此,研究亮点的产生机理和预防措施,对于铝箔生产和使用具有重要意义。

1　亮点缺陷的特征亮点一般分布在双合轧制铝箔的暗面上,呈椭圆形,个别呈长条形,弥散分布,有时在整个铝箔面上都有,有时在局部出现。

双合的上下两张铝箔暗面上有明显上下一一位置对应关系。

亮点的颜色比铝基体颜色深且发亮,在较严重的情况下亮面的相应位置有可见痕迹,特别严重时形成针孔。

2　亮点缺陷产生的机理2.1　亮点产生过程分析铝箔从0.05mm 厚再往薄轧制一般属于无辊缝轧制。

在正常轧制过程中,轧辊表面与铝箔表面是不直接接触的,轧制力是通过轧制油膜进行传递的。