Part of the exhibits on the NCMT stand will be a photo-activated adhesive system from the US, Blue Photon, for which NCMT is sole European agent.
The method is ideal for securing awkwardly shaped parts to allow maximum access to tools for tight-tolerance machining or inspection.
The process involves applying an adhesive that is cured by ultraviolet light via an LED spot curing system. After machining is complete, the adhesive contact points can be sheared to free the workpiece by rotating the gripper pins in the fixture plate with a spanner. The residual adhesive can subsequently be removed by application of hot water.
Use of the technique is predicted to grow due to its ability to hold components securely with a shear resistance of up to 200kg per gripper point, while allowing cutters excellent all-round access for machining on five sides. Unlike magnetic clamping systems, it can be used to secure non-ferrous metallic parts including ceramics and composites.
Blue Photon is ideal, for example, for clamping a turbine blade to enable the fir-tree and wedge face on the root as well as the shroud end features to be machined in one hit without tolerance build-up.
Traditionally, due to clamp interference, multiple operations are required. A novel turbine blade fixture incorporating four gripper inserts has been designed by NCMT that, once adhesive has been applied and cured, holds a blade securely by one side of the aerofoil.
Tests have shown that the clamping force produced by the fixture can easily withstand the rigours of machining. Material removal rate actually exceeded that achieved when the blade was mechanically clamped, as in the latter case the pressure had to be limited to avoid component distortion and marking.
Other advantages of Blue Photon clamping are good damping properties to suppress chatter, reduced cost of fixtures for holding complex parts and elimination of locating lugs on castings.
Hall 19, Stands 120, 130