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LZH develops method for repairing diamond-edged blades

The Laser Zentrum Hannover (LZH) and the Institut für Werkzeugforschung und Werkstoffe (IFW) in Remscheid have developed a mobile, laser-based process chain for gluing the cutting segments onto a diamond saw blade and removing them subsequently without causing damage.

The processing of natural stone such as marble or granite is usually done with saw blades with hard-wearing, diamond cutting segments. When these are damaged or worn, the cutting segments have to be replaced.

To do this, the LZH and IFW have created an alternative laser and gluing method. The laser radiation only exerts minimal thermal stress onto the saw blades, so that in the best case, the blades can be refitted without preloading or alignment. Ideally, the saw blade can be refitted as often as necessary.

Traditionally, the whole saw blade is then sent to a repair shop where the soldered cutting segments are thermally detached, the soldering partners prepared, and the new cutting segments are then soldered onto the saw blade. The soldering induces thermal effects such as warping and an undesirable distribution of stress in the saw blade. This causes the cutting quality to decrease, and cutting losses increase. Therefore, additional process steps are necessary to align and preload the saw blades. However, with the new process from LZH and IFW these affects can be avoided.

For demonstration purposes, the LZH has developed a mobile unit, with which refitting can be carried out directly at the user’s premises. Such a refitted saw blade has already been used to successfully cut granite.

The laser-based process for the first and consequent fittings of the saw blade consists of four steps: First, the surfaces of the segments and the saw blade are prepared by structuring them using a pulsed laser system.

The segments are then glued onto the saw blade using a one-component epoxy resin adhesive, which is thermally hardened using a continuous wave (CW) laser system. When the life span of the segments has been reached, they are detached from the saw blade using the CW laser system. A pulsed laser system is then used to remove glue residues and impurities from the gluing partners. Following this, the saw blade can be refitted.

In comparison to soldering, gluing has many advantages. Among these are a very low, respectively no thermal distortion, no heat tinting, a homogeneous distribution of stress in the joining zone, and a relatively high joining strength and high vibration dampening.

The IGF project under the number 17120 N of the Forschungsvereinigung Forschungsgemeinschaft Werkzeuge und Werkstoffe e.V. (FGW) [Research Association for Tools and Materials] has been funded within the framework of the programme for supporting industrial research of the German Federal Ministry for Economic Affairs and Energy (BMWi), based on a decision of the German Parliament.

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