LIQUID COATING

JOT INTERNATIONAL SURFACE TECHNOLOGY

Enhanced laboratory paint shop

Reproducible electrostatic painting in lab-scale Lab-scaled paint shops are established in coating manufacturing and OEM business to perform reproducible painting tests close to production line conditions. A new LabPainter series was designed to offer more control functions and an improved operation concept. Reproducible painting means to supply painting systems with a minimum control deviation. Only with minute deviations of the paining parameter control it is possible to test the quality of the paint material as well as the application process window. The application process must be as similar as possible to the production line conditions, especially regarding atomization of the paint. Both, a minimum parameter deviation and high similarity to production line conditions are necessary to detect problems regarding the paint material early in the production process. LacTec has designed 15 years ago the first concept of a compact laboratory painting system to provide a testing design for these requirements. Different atomizers can be operated using an atomizer quick change system. This

means that several production line conditions can be simulated easily with different atomizers. The design of the laboratory painting system called “LabPainter” was continuously upgraded during several machine series (QC 301, QC 501, QC 701 und QC 703). The abbreviation “QC” means “Quality Control” focusing on the main purpose of the LabPainter. The series QC 703 is well established at the market for more than four years. LabPainter users are paint manufacturers, paint component suppliers and OEMs especially in the automotive industry. Hereby, every branch has its own, specific requirements to the LabPainter. To cover these different requirements in future, new software was developed and implemented to the paint system. The software is based on a modular electromechanical design of the paint system, which was also revised completely.

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Electromechanical design

Control panel of a LabPainter (Type QC 705)

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The new electromechanical design of the LabPainter QC 705 picks up existing and expected trends in the coating industry regarding the future design of electrostatic high speed rotation atomizers. During the last years, the weight of the atomizers used in industrial production has increased significantly. The trend in atomizer design leads clearly to heavier atomizers. For instance, an EcoBell 1 atomizer has a weight of about 5.5 kg. An EcoBell 3 atomizer has a weight of about 11 kg due to the increased complexity of the atomizer functions (e.g. by additional valves

and distributers inside the atomizer). In addition, modern atomizers have a 60°-shape which is designed for 6-axis robots in production lines. With the 60°-shape, more complex geometries can be accessed by 6-axis robots (e.g. the inner surfaces of a car body) in contrast to straight atomizers (0°-shape). Straight atomizers are mainly used on older linearly moving paint equipment, e.g. side painting systems or roof painting systems. Therefore, recent atomizers are heavier and bigger. The increased installation space and weight was considered during the redesign of the LabPainter QC 705. Up to 31 different atomizers and atomizer-configurations can be implemented in one LabPainter . Using a new software, numerous atomizer control parameters of different atomizer types (EcoBell, Robobell, Picobell, Acculook, etc.) can be stored. This means, that for instance rotation speed and shaping airs reach in a very short time the required value at the LabPainter. The actual control parameters can be compared to stored reference control parameters in the LabPainter . If a shaping air ring is soiled or a sealing is defective, there will be a difference to the reference parameters. If a difference occurs, this is notified to the operator. Electrostatically supplied atomizers with exterior charge require an increased electrical current in comparison to contact charged atomizers. Currents of 350 µA with a voltage level of 70 kV at the high voltage power generator are common. To provide a power reserve, a new high voltage cascade

JOT International Surface Technology 2.2015

is used in the LabPainter QC 705. The cascade can provide up to 700 µA at 100 kV. The maximum values hereby depend on the permitted values given by the atomizer manufacturers and can be adjusted individually for each atomizer. To increase the safety level of the LabPainter, the high voltage supply is directly controlled by a Safety-PLC.

New Visualization

The most significant modification of the new LabPainter is the revised and redesigned visualization. A simplified and unified operation surface is based on a PC running with latest revisions of Windows operating systems. Nevertheless, the well-established way of operation was not changed in general but improved in detail. This means that experienced users of the LabPainter can use the new QC 705 without additional training. The operation of the visualization surface is done either by touchscreen or conventionally by mouse and keyboard. A detailed analysis of warnings and errors is possible due to the usage of a Safety-PLC. For instance, it is possible to identify a defective exhaust air monitoring line directly on the LabPainter screen. This leads to a faster troubleshooting and increases the production availability of the LabPainter. The PC is mounted separately from the display inside the operation rack. It is equipped with two hard drives mirroring the content of the operating hard drive in real time. In addition, an external backup drive for spray programs increases the data safety.

JOT International Surface Technology 2.2015

Three user levels

Based on customer feedback, the user management was completely reviewed. Different access levels lead now to detailed user permissions, especially regarding read-, write and modification permissions on existing paint spray programs. For instance, unexperienced operators should only load (read) spray programs. Experienced operators might additionally also change some parameters, but are not permitted to save these changes. Professionals have full access to the spray programs to create new spray programs or to modify existing spray programs. To help the administrator assigning the user permissions, three access levels “Gold“, “Silver“ and “Bronze” are available in pre-configuration. For unexperienced operators, the level “Bronze” should be used. Especially for this user group, a spray program quick access was implemented. By typing a number in an input field or by reading a barcode, the correct spray program is chosen automatically. This helps to avoid maloperations. Additional information can be stored for each spray program in a separate pdf-file. If a pdf-file exists for a chosen spray program it is shown to the operator automatically. The document contains process information (e.g. how to how to arrange and fix the substrate sheets on the substrate carrier). This increases the process transparency and avoids faults in the handling process. Therefore, this feature helps to increase the reproducibility of the complete process and is also necessary in process-

es of quality audit certification. The export of data into pdf- or Excel-file format is possible as well as printing with network printers or special label printers. Each successfully finished spray program is stored in a painting report. In this report, all relevant spray program parameters and additional information (e.g. temperature and humidity inside the spray booth) are saved. An offline spray programming tool enables the operator to do programming tasks aside the LabPainter on any Windows workstation. This increases the production availability of the LabPainter significantly. Production and standby durations are logged using a detailed production data acquisition system. A review of all data with respect to shift times is possible. In pdf- or Excel-file format all production related data can be exported for external analysis.

First commissioning successful

The first LabPainter of the QC 705 series was delivered to the paint manufacturer Hemmelrath in Klingenberg, Germany. Here, the LabPainter QC 705 replaces an older QC 501 system. Since air ventilation system and spray booth were already available on site, the LabPainter could be commissioned to be ready for production within one week. Dr. Felix Brinckmann [email protected] Rainer Prauser [email protected] LacTec GmbH, Rodgau, Germany Tel. +49 6106 8447-0

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