1、Powder Coating Training,Metal Pretreatment for use with Powder Coatings 金属前处理,Metal Preparation 金属的处理,Pretreatment is a process intended to prevent the corrosion of the paintedmetal.前处理是一种提高耐腐蚀的工艺 Fe2 + O2 + H2O= RUST Iron reacts with oxygen and water in the atmosphere creating a powdery brownmess,
2、not very ornamental, and continuous until no solid metal remains.铁在空气中会与氧气和水反应生成褐色的物质,Metal Preparation 金属的处理,Why Pretreatment ?为什么要前处理？ Powder coatings are used to enhance the appearance of buildings, machines, furniture, appliances:粉末涂料用于改善建筑，机械设备，家具，以及其它器具的表面： Designers and architects are searchi
3、ng to give distinction in terms of colour and effects.设计师和建筑师提供了包括颜色和效果在内的标准等级 The problem is that all paints are porous：所有的涂料均不同程度的存在会渗水的小孔,Metal Preparation 金属的处理,Molecules of water and salt can penetrate through the paint film. When they reach the metal surface the effect is worse than if the met
4、al is uncoated. The answer = Pretreatment 水和盐分子可以渗透漆膜，一旦它们与金属表面接触，产生的影响甚至比没有喷涂还要糟糕。 要解决这个问题就需要前处理。,Pretreatment: 前处理： The chemical conversion of the metal surface before applying the powder coating. The metal then resists corrosion and the conversion permanently improves the adhesion of the coating.
5、 在使用粉末涂料以前用化学方法对金属表面进行处理，可以 改善耐腐蚀性和增加涂层的附着力。,The performance of the powder coating is only going to be as good as the metal preparation.We will cover two types of metal treatment systems粉末涂料的功能类似于金属处理，我们将介绍两种的金属处理方法Iron Phosphate for Steel用于铁系的磷酸铁Zinc Phosphate for Steel用于铁系的磷酸锌 Other systems can be
6、 used and information is available.当然还有其它处理方法,前处理方式,前处理依据工件形式,可有三种处理流程: 喷淋:一般用于平板,死角少,形状单纯的工件,或速度较快的喷涂线,如家电,天花板等 浸渍:一般用于形状复杂,管件,死角多的工件,如家具等游浸:此法为浸渍式的流水线作业方法,通常会搭配喷淋式共同使用,如运动器材,Metal Preparation Iron Phosphate 金属处理 磷酸铁,Metal pretreatment can be applied by spray or dipping.金属前处理可以借助喷淋或浸渍 In the case o
7、f iron phosphate the process could look like this:下面是磷酸铁的工艺流程,Stages 1, 2 and 3 can be either spray or dip 步骤1，2和3均可采用喷淋或浸渍,Metal Preparation Zinc Phosphate 金属处理 磷酸锌,Zinc Phosphate process for steel tends to be more complicated磷酸锌的工艺流程复杂一些,Metal Preparation 金属处理,Dwell Time :Each stage depends on:各阶段
8、所需的时间，受下面的因素控制 The amount of pretreatment chemical dissolved in water溶于水的前处理化学药品的浓度 The age of the chemical化学药品的有效时间 Regular checking is required to give consistent good results at least twice per shift.通常要经常检查前处理的状态一个班至少两次,Metal Pretreatment - BS 3189 Type 3,9 stage pretreatment九步法Degrease脱脂Rinse水洗
9、Rinse水洗Acid Etch (phosphoric acid)表调Rinse水洗Zinc Phosphate磷酸锌磷化Rinse水洗Rinse水洗De-ionised water去离子水水洗Dry 干燥 Quality Standard BS6497参考英国标准BS6497,Metal Pretreatment Quality Control 金属前处理 质量控制,Titration Checks:检测项目： 1. Cleaner 2. Rinses 3. Acid Concentration 4. Rinse 5. Phosphate Concentration and coating
10、 weight 6. Rinse 7. Observations Checked at regular intervals during normal production and before production commences以上项目应在生产过程中定时和生产前进行检验,Metal Pretreatment Dry 金属前处理干燥,To ensure metal surface is dry ready for powder coating. 在喷涂粉末涂料前必须保证金属工件已经完全干燥,不同前处理药剂比较,依据供应商提供资料定期监测药剂浓度,包含水的PH值 前处理外观应尽量做到颜色均
11、匀一致 前处理不要太厚,一般来说大致35um(磷酸锌),或膜重0.22g/m2(磷酸铁) 怀疑前处理有问题时,可用溶剂清洗工件作对比性测试 喷涂前确保工件干燥,Spraying and Application Of Powder Coatings 粉末涂料的喷涂与应用,Powder Application Systems 粉末涂料的应用系统,Powder Application Systems Feed Systems 粉末涂料应用系统供粉系统,Direct feed system from Drum to Gun.粉末涂料直接从粉桶送至喷枪 The system shown feeds 1
12、gun右图是只供一个喷枪的直接供粉系统,Powder Application Systems Feed Systems 粉末涂料应用系统供粉系统,Bulk feed system, powder is suppliedin a fibre bag.Weight of powder up to 1,000 kilosper bag.Used mainly on automatic plants where colour change is limited. 大型供粉系统，粉末涂料一般1吨一个包装，用于自动喷涂系统，限于换色较少的场合。,Powder Fluidisation Systems 粉末
13、涂料流化系统,The air must be dry and free from water and oil. 空气必须除水和油,Dry air passes through a membrane giving the powder liquid qualities. 干燥的空气通过微孔板，使粉末涂料象水一样流动。,Powder Delivery Systems 粉末涂料的传送系统,Powder Delivery Systems 粉末涂料的传送系统,Actual powder feed system Venturi feed from fluid bed. 右图是用文氏管从流化 床吸取粉末的送
14、粉系统,Forces at work on the Powder Particles,At any one time 4 forces are at work on the powder particle as it travels from the gun to the earthed work-piece. 粉末在离开喷枪到达工 件时受4种力的影响 -Air Resistance - Electrostatic Attraction -Weight (Gravity) - Aerodynamic Force,Powder Charging Systems,There are 2 major
15、 categories in charging of powder coating corona and tribo:粉末涂料主要有两种带电方法静电/摩擦,Corona Charging Systems 静电带电系统,In this method, a high voltage generator is used to charge an electrode at the tip which creates an electrostatic field (or corona) between the gun and the work-piece.利用高压电极使粉末带电，并在喷枪与工件间形成电场
16、,External Charging System/外充电系统,Corona Charging Systems 静电带电系统,Corona charging - manual system/手动枪 - automatic system/自动枪,Corona Charging Systems 静电带电系统,Internal Charging System 内充电系统,Corona Nozzle Systems 静电枪的喷嘴,The type of product to be coated will influence the nozzle to be used on the spray gun,
17、 two types are shown,Corona Nozzle Systems 静电枪的喷嘴,Conical Spray Nozzles used to give an evenly distributed film thickness over flat panels. 圆锥型的喷嘴一般用于喷涂平 面，并得到膜厚均匀的涂层。,Corona Charging Systems 静电带电法,The high voltage power supply charges the electrode高压发生器使喷枪电极带电The concentrated charge creates an elec
18、trostatic field带上电荷后形成静电场The electrostatic field causes the air to ionize and generate a corona静电场使空气电离形成电晕The corona emits electrons电晕放射出电子The electrons are picked up by oxygen molecules forming negative ions这些电子借助氧分子形成负离子,Corona Charging Systems 静电带电法,The ions follow the field lines负离子沿着电力线移动The p
19、owder particles distort the field around them粉末涂料粒子使周围的电力线产生扭曲The distorted field lines direct ions to the powder particles扭曲后的电力线引导离子被粉末涂料粒子吸附The ions bombard the powder particles and transfer the electrons giving the particles a negative charge吸附的离子轰击粉末粒子，并使其带上负电，形成负极,Tribo Charging Systems 摩擦带电法,
20、Tribo electricity is generated by the friction of one material on another.In Tribo charged spray guns, the powder rubs on a specially formulated and shaped surface which allows charge to transfer. 摩擦带电是通过不同物质摩擦形成的，摩擦枪可以使粉末与特殊设计并有特殊结构的表面摩擦而带电,Tribo Charging Systems 摩擦带电法,Tribo nozzles in different co
21、nfigurations. 不同结构的摩擦枪喷嘴,Electrostatic Fluid Bed Systems 静电流化床法,Powder Penetration 粉末的吸附,The picture shows the development of the corona (red dotted area).Articles passing through are charged with the negative ions(-).The charged powder particles are attracted to the earthed substrate. 右图显示了电场，电力线，粉
22、末的充电及被接地的工件吸附过程。,Powder Penetration 粉末的穿透,Achieving penetration into deep recesses in most important when applying powder coating. 粉末涂料能否到达死角这对粉末涂料的应用来说很重要,The most effective controls are the nozzle pattern and air assistance.有效的控制方法是选择合适外形的喷嘴及调整辅助空气 It is possible to overcome the “Faraday Cage Effe
23、ct”现在，克服“法拉第”效应已成为一种可能,Faraday Cage Effect,Powder Penetration 粉末的穿透,Reducing the “Faraday Cage” Effect减弱“法拉第”效应,To reduce the effect it is necessary To assist in the creation of charged air Particles inside the recess. This should be achieved by increasing the air stream.可以借助加大传送空气的压力来减弱“法拉第”效应,Fara
24、day Cage Effect “法拉第”效应,A Faraday cage can technically be defined as an area within which there is noelectrostatic field. In finishing, this term is applied more loosely, and generally refers to an areasuch as inside corners or cavities that are difficult to coat. The reason why these areas are diff
25、icult to coat is that the adjacent surfacesto the inside of the corner attract the electrostatic filed, therefore deflecting the powder from penetrating into the recessed areas. At the same time , this recessed area is difficult for the aerodynamic forces topenetrate into without blowing powder off
26、already coated areas. 法拉第区域可以被认为是静电屏蔽区。实际应用中定义更宽松，通常是指死角和洞等难喷涂区域。难喷涂的原因是这些区域的外围吸引了电荷，这样粉末就不能被吸附。另外，从空气动力学来讲，输送空气将粉末吹至这些区域也很难。,Back Ionisation 反弹效应,A = powder attracted to the earthed component B = build up to correct film thickness C = ionised air within the powder film repels oncoming particlesA =
27、粉末吸附在接地工件B = 形成合适的膜厚C = 在涂层上的离子云抵制吸附带有同类电荷的粉末,Powder Recovery Integrated System 粉末回收系统,Integrated Spray / Recovery Booth System完整的喷涂/回收系统,Powder Recovery Systems 粉末回收系统,Typical cartridge back- Pulse cleaning design. Used in cartridge Recovery systems. 典型脉冲自清理设计， 通常适用于桶状回收系统,Powder Recovery Systems 粉
28、末回收系统,Cyclone Recovery System,The cyclone is used to separate the powder particles from the air. The air is driven round the sides of the cyclone, reducing in velocity and releasing the powder to be collected at the base. Fine powder is usually transported out of the cyclone on the air flow. 旋风分离器根据
29、粒径分离粉末，空气沿着旋风分离器壁做圆周运动，速度渐渐降低，并释放被收集的粉末至底部。细粉通常会随流动空气离开旋风分离器。,Powder Recovery Systems 粉末回收系统,Fine powder is collected on a filter system in the “after filters”. The pneumatic air pulse ensures air flow is consistent and the fine powder collected for disposal. 细粉通过滤芯滤层被收集。有力的气体脉冲保证了空气流动的连续性及需被分离的细粉收集
30、。,Powder Recovery Systems 粉末回收系统,A motor generates the air flow.Ensuring the correct air volume and velocity is maintained. 电机提供流动空气，并保证气体流量和速度。,Powder in-line Sieving Systems 粉末过筛系统,Rotary In-Line Sieve 旋转筛,Powder Vibrating Sieving Systems 震动筛,Vibrating sieves are designed to work either: - Free st
31、anding - In-line 震动筛适用于： - 独立区域 - 流水线,Powder Reciprocator Cycle 粉末喷涂的往复机构,Cycle Rate =No. Of Guns x Pitch of Guns x 60 Conveyor Speed(mm/min) 往复速度= 喷枪数量x喷枪位置x60传送链速度（毫米/分钟）This will ensure striations do not occur on the components being coated. 在喷涂中要保证不要形成带状涂层。,Stoving and Curing of Powder Coatings
32、固化炉及粉末涂料的固化,Types of Oven 固化炉的类型,Convection energy is transmitted by air circulation to heat the components对流 热量通过空气流动传送，加热工件Radiation energy is transmitted directly onto the parts without heating air between the parts and the radiation source辐射 热量直接从辐射源被传送至工件而无需空气作媒体Induction energy is transmitted
33、through inducing electrical eddy currents that generate heat in the metal parts感应 热量借助电流来传送来加热金属工件,The Baking Process 固化过程,The baking stage, during which the powder coating melts, flows, gels and finally chemically reacts (crosslinking) and cures. It is critical to the performance of the coating tha
34、t the temperature and time at temperature are maintained. Most baking ovens are designed to take the substrate through a pre-programmed time temperature profile. 固化过程包括粉末的熔融，流平，凝胶最后发生化学反应形成涂层。固化温度极其所占时间是非常重要的，大多数固化炉借助预先设置固化时间（温度曲线）来设,Powder Application Radiation Stoving 粉末的辐射固化,Gas fires Infra-Red o
35、ven used for industrial components. 左图为用于固化工业用品 的瓦斯红外炉,I-R emitters inside the oven cure the powder film when in direct line, as radiation energy. 右图为通过炉内红外发生器（热源）固化粉末涂料,I-R is often used to boost the curing in front of a conventional air circulating oven. 红外热常常被用于传统的利用空气循环的固化炉的前段, 喷枪应定期检修,更换零件 定期检测
36、炉温,建议半年一次 炉子须定期清理,依据使用的产品,燃料及频率而定,建议每月 一次 注意喷涂环境清洁,回收风量不宜太小,造成逸散影响喷涂环境 与质量 定期清理吊具,以免影响带电性,或因生锈造成异物掉落, 滤芯式回收系统,注意逆洗,以免破坏滤芯或回收 风量不足;定期清理浮动槽(一星期至少一次) 在每个过程中,最好都有品检人员:- 进入前处理前:工件是否有生锈- 进入喷房前:工件是否处理干净,是否有药剂残留- 进入烤炉前:喷涂是否均匀,是否太薄或太厚- 工件下料:外观,基本机械性能, 理想喷涂环境- 1826oC- 相对湿度4060% 空压机出来的压缩空气的露点,不要超过5oC,较不含有油气 或水
37、气,若因高压空气的油水产生凹陷,则管路可能残留,应清 理或更换 回收粉应有效地被管理,Quality Control in Powder Coatings 粉末涂料的质量控制,Sample preparation 制样,Powder is applied using a corona charged hand spray gun左图为手动静电枪在喷涂粉 末涂料It is important to ensure all the equipment is clean and free from any contamination保证所有设备清理干净无污 染是非常重要的,Manual sprayin
38、g,Film thickness 膜厚,After stoving at the recommended time and temperature采用推荐的温度和时间固化后Stated as Object Temp.规定工件温度The film thickness is checked to ensure it is in the specified tolerance检查膜厚是否在标准的范围内Records are made of film thickness when testing is carried out在测量膜厚时应记录结果,Gloss meter 光泽计,Maximum and
39、 Minimum gloss values are checked and recorded according to ASTM D523 (60 Angle)按ASTM D523（ 60 角）检查和记录光泽的最大和最小值 Some industries may use 85 angle and 20 angle 一些工业可能使用85 角和20 角,Color Difference 色差,Colour checked by /颜色的检测利用Eye/眼睛Computer/计算机 Color differences are quoted in terms of:颜色的不同通过下面几项反映 Ligh
40、tness黑白DL Red/Green红绿Da Yellow/Blue黄蓝Db Chroma (color strength)彩度Dc Hue Angle (shade)灰度Dh An overall color difference is calculated: DE将所有的颜色差别计算表示为：DE,Particle Size Analysis 粒度分析,Powder particles are passed through a laser light source粉末经过激光照射区The distribution of size is measured very accurately粒径分
41、布被非常准确的测量出来The distribution is checked against theproduct specification and recorded 粒径分布与产品的标准进行比较并作记录Particle distribution is critical for goodcontrol in powder application 粒径分布对粉末涂料的质量控制非常重要,Mechanical Performance 粉末涂料机械性能,Test carried out to BS3900 Part 3 or ASTM D2794依据BS3900 Part 3 或ASTM D2794
42、 A measure of the coatings performance under rapid deformation是测试涂层快速变形性能的方法Performance is measured in terms of cracking or disbondment of the coating测涂层的裂纹或剥离程度A test for completeness of cure是一种涂层完全固化后的测试,Impact Test,Mechanical Performance 粉末涂料机械性能,Test carried out to BS3900 Part E6 or ASTM D3359依据
43、BS3900 Part E6 或ASTM D3359 A measure of the coatings adhesion to the substrate是测试涂层附着力的一种方法Performance is measured in terms loss of adhesion following a tape pull-off测能被胶带粘离的涂层的比率Measured in % removal of film表达单位为%,Tap Adhesion Test,Mechanical Performance 粉末涂料机械性能,Test carried out to ASTM D3363依据AST
44、M D3363 A measure of the coatings surface hardness测试涂层表面硬度的一种方法Performance is measured as the hardest pencil lead to give no rupture to the film测能破坏涂层的铅笔硬度Measured in B or H pencil.表达的单位用铅笔的硬度来表示（B或H 等）,Pencil HardnessTest,Mechanical Performance 粉末涂料机械性能,Test carried out to ASTM D4061依据ASTM D4061 A
45、measure of the coatings abrasion resistance测试涂料耐磨损的一种方法 Performance is measured as the weight loss after a given number of cycles测经过规定次数的旋转摩擦后的重量 损失Measured in grams表达单位为克,Teber AbrasionTest,Test carried out to ASTM D522/A 依据ASTMD522/A A measure of the coatings flexibility 测试涂料韧性的一种方法Performance is measured as the minimum diameter of bend no cracking is seen 测不产生裂纹的最小直径Measured in mm 表达的单位为毫米,Thanks!,
