Metalúrgica

El proveedor optimiza la limpieza de piezas para requisitos variables

La combinación de sistema y contenedor lo permite

Con una gama de alrededor de 1.000 piezas diferentes, no es fácil cumplir, de manera confiable, las crecientes demandas de limpieza técnica de la superficie. Para superar este desafío, el fabricante de piezas de precisión Allweier, no solo invirtió en dos nuevos sistemas de limpieza con equipos a medida, sino también en contenedores de limpieza flexibles, fáciles de limpiar y de utilizar. Con esta combinación, el subcontratista cumple con los valores de limpieza de cara a un futuro y limpia, evidentemente, de forma más rentable.

En el campo de la tecnología de propulsión, Allweier Systeme GmbH, ha estado trabajando con sus propios progresos durante aproximadamente diez años. Hace más de 40 años, Allweier Präzisionsteile GmbH, se estableció como proveedor y como socio en la industria de sistemas y de desarrollo para la eliminación de virutas. Las competencias centrales de esta empresa familiar con sede en Überlingen (Alemania), a orillas del lago Constanza, son los servicios de torneado, fresado y lijado CNC, así como en el ensamblaje de módulos y componentes. La empresa cuenta con una amplia maquinaria de vanguardia para el tratamiento de piezas de aluminio, inclusive aluminio fundido; acero; fundición gris y acero fundido; titanio y materiales especiales. Actualmente, la gama incluye alrededor de 1.000 piezas diferentes de ingeniería mecánica; instalaciones industriales; construcción de vehículos; manejo de material y robótica; sector naval y extraterritorial; óptica y tecnología médica; así como sector ferroviario y otros sectores. En total, Allweier, procesa alrededor de 20 millones de piezas por año.

"La limpieza de las piezas mecanizadas representa un gran desafío debido, por un lado, a los diferentes materiales y a las diferentes geometrías y dimensiones de las piezas. Por otro lado, los requisitos para la limpieza técnica de las superficies, han aumentado significativamente en los últimos años. Las especificaciones tales como no partículas de más de 600 μm son usuales hoy en día y la protección óptima contra la corrosión es indispensable para las piezas de acero", explica Thomas Schmidt, diseñador tecnológico para la rotación en la Allweier Präzisionsteile GmbH. Con el fin de lograr, de forma fiable, los valores de limpieza especificados y, al mismo tiempo, hacer que el acabado sea más eficiente, la empresa invirtió en dos sistemas de limpieza Universal 81W de Ecoclean GmbH y en contenedores de limpieza diseñados y fabricados por Metallform Wächter GmbH.

Tecnología del sistema a medida para mayor eficiencia

"Hablamos con cuatro fabricantes de equipos y realizamos pruebas de limpieza. Ecoclean no solo nos dio excelentes consejos, sino que también nos ofreció el mejor concepto de sistema para el trabajo que debíamos realizar", informa Thomas Schmidt. El Universal 81W tiene una cámara de trabajo hermética al vacío en la que se realizan las operaciones de limpieza, enjuague y secado. Los dos sistemas solicitados están diseñados para un tamaño de cesta de 670 x 480 x 300 mm (LxWxH) y un peso máximo de carga de 150 kg. Para garantizar una limpieza fiable de partículas adherentes y virutas, así como los residuos de los medios de procesamiento, la cámara de trabajo está equipada con dispositivos de lavado hidrocinético y de limpieza por ultrasonidos de alto rendimiento con una capacidad de 10 vatios por litro . Las piezas se secan mediante una combinación de aire caliente y de secado al vacío. "También tenemos piezas de extracción que, a través del curso del sistema anterior, a menudo salían húmedas. Gracias al secado al vacío, estas piezas, ahora salen del sistema completamente secas ", dice Thomas Schmidt.

The different requirements on cleaning aluminium and steel parts are addressed by tailor-made configuration of the new cleaning systems. Thus, the system for steel parts and steel castings has four flood tanks. This makes it possible to adapt the fluid used in the cleaning step to the given part (i.e., steel or casting). The third and fourth flood tanks hold the rinsing and preservation fluids, respectively. The Universal 81W on the aluminium cleaning line is equipped with three flood tanks. It comprises an additional treatment system for the demineralized rinsing water. The quality of this water is monitored continuously. „With aluminium parts, it is very important to rinse with demineralized water and to ensure quick and complete drying. This ensures that the parts will remain free of stains and discolorations“, the Technology Planner explains.

Around 80 per cent of all parts are cleaned in defined position. Parts are supplied by an automatic feeding system comprising buffer sections at the entry and exit. Appropriate cleaning programs are stored in the system controllers. The part-specific program for each load is selected either by a basket identification system using sensors, or manually by the operator. After the cleaning process the parts pass through a cooling zone from which they emerge ready for immediate packaging.

The fluids from all flood tanks are subjected to full-flow filtration in the supply and return lines alike. While the cleaning fluids are run through bag filters, cartridge filters are used for the rinsing and anti-corrosion fluids. This system yields a highly effective removal of particulate contaminants. Film-type contaminants such as emulsions are removed first by the oil separator and then, for additional cleanliness, by the Aquaclean system. The latter evaporates the fluid from the flood tanks and returns the condensed liquid into the process circuit while collecting the dirt residue in the Aquaclean tank. This fluid treatment method increases bath life while also reducing the equipment outage times necessitated by bath changes.

Versatile tanks, purpose-designed for the cleaning process

In order to realize the full potential of their new systems, Allweier invested in a set of new cleaning tanks at the same time. These allow all parts to be variously arranged inside for maximum cleaning and drying performance. The requirement spelled out by the company to its four candidate suppliers was that all parts had to be protected as effectively as possible in the tank, apart from being arranged and secured so as to withstand rotation. After all, the baskets are swung and turned through up to 360 degrees in the cleaning cycle. Moreover, each tank needed to hold a maximum number of parts without restricting fluid or ultrasound access to the product and hence, impairing the system's cleaning action. Ease of handling was likewise high on the priority list. „In the first phase we were looking at tanks for ten different parts. With that objective in mind, all companies received the same documentation from us. Metallform stood out among the other vendors as early as in this bidding phase. For instance, they supplied 3D design drawings of the tanks with product arranged inside, so I was able to imagine at once how the part would be placed and fixed in the basket. Their consulting service, too, was and continues to be excellent. All this is backed by plenty of competence and in-depth analysis", Thomas Schmidt explains his company's decision in favour of Metallform Wächter GmbH.

In addition to a range of rigid, part-specific product carriers for fast-selling parts, a variety of different semi-flexible and fully flexible solutions were implemented. These are designed to be used for different components or component families at the same time and to be quickly and easily adaptable to another part by the operator while production continues. „Metallform is showing us optimum support in reducing the necessary number of part carriers by providing flexible technology. We derive benefit from this not merely by saving investment cost but also through reduced space demand on the shop floor“, the Technology Planner explains. For instance, the range comprises a part carrier for aluminium annular housings measuring between 240 and 320 mm in diameter and between 20 and 100 mm in length. Relocatable prism-type rake supports inserted into the basic carrier allow different parts to be reliably accommodated and secured. At the same time, the part fixtures can be arranged such as to be in contact with the parts at uncritical points only. For disc-shaped parts of diverse diameters, Metallform developed a fully variable system. It consists of two different inserts of which one defines the number of shelf rows while the other defines their depth. It is thus possible to create a part-holding structure in no time, whether in a MEFO box or in the basic rack. Locking is by means of spring-loaded snap engagement bolts.

All part carriers and cleaning baskets are made of round stainless steel wire with an electropolished surface finish. The round wire makes for good all-round fluid and ultrasound access to the parts. In addition, optimum draining properties are ensured while dirt and fluid carryover is minimized. Moreover, the round wire provides a reduced contact surface area. Local sheathing in clip-on Teflon tube sections for additional part protection is an option.

Superior quality and higher cost-efficiency

This combination of new cleaning systems and tanks enables Allweier to not only reach, but in fact outperform technical cleanliness standards for all parts in a reliable manner. „We carry out periodic laboratory analyses, and these have shown that we are achieving a much better cleaning result. Unlike our previous continuous cleaning line the system requires no compressed air for drying. Moreover, the cleaning process is so effective now that the parts made in three shifts can be cleaned in just around two. So it goes without saying that we are working more efficiently as well“, Thomas Schmidt concludes.

Author: Doris Schulz

Mr. Rainer Straub

Phone: +49 (0) 711 7006-0
Email: rainer.straub(at)ecoclean-group.net

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