During a visit to a cement customer in the United States, our local Integra™ services team was asked to provide a solution to combat wear on the classifier louvres/blades situated within a Vertical Roller Mill (VRM) at the plant. This 6-roller VRM is used to grind raw material at the plant, making it a critical piece of production equipment. As with all critical equipment, downtime and maintenance can amount to a substantial cost and a loss of production. The more frequent the downtime, the higher the cost.
Situated in the upper section of the VRM, Classifiers are difficult and time-consuming to replace, repair or remove, increasing cost, downtime and production loss. It is therefore a huge advantage if these pieces of equipment are protected against wear, using advanced materials to directly reduce the need for maintenance and lowering the Total Cost of Ownership (TCO).
By the time Welding Alloys visited the plant, competitors had already implemented improvements on the OEM design, but the wear life was still unacceptable and had to be improved. The OEM design utilises 8mm thick 400 Brinell Quenched and Tempered Steel (400 Q&T). This was replaced by 8mm thick 500 Brinell Quenched and Tempered Steel (500 Q&T) as well as standard chromium carbide materials. Despite these changes, the Louvres still experienced detrimental wear in less than 6 months.
Welding Alloys Integra™ was able to analyse the wear patterns on the existing Louvres. Based on the findings, our engineers implemented some design changes making it possible to utilise our ultra-thin Hardlite™ (2+2) material in a back-to-back configuration ensuring advanced wear protection on both sides of the Louvre. Experience has proven that only a change in the materials is often not the best solution. At Welding Alloys, we utilise years of industry-specific knowledge to derive the best possible solution in terms of design, materials and installation.
The Hardlite™ (2+2) sheets were cut to the new design, welded in a back-to-back configuration and installed inside the Classifier. Periodic inspections revealed no signs of wear. The classifier has currently done 24 months without the need for Louvre replacement or even repairs and there are still no signs of wear.
Hardlite™ (2+2) is a chromium carbide (CrC) welded overlay product manufactured by The Welding Alloys Group, consisting of a 2mm low carbon steel backing material and a 2mm CrC layer. Utilising refined welding procedures, automated equipment and dedicated consumables, dilution is kept to an absolute minimum while carbide formation and distribution are uniform and finely dispersed throughout the thickness of the overlay material, making it an excellent choice for advanced wear protection in light-weight and rotary equipment applications such as fans, fan casings and classifiers.
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