Gripping with light

The process involves applying an adhesive that is cured by ultraviolet light via an LED spot curing system. 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 the application of hot water or steam.

Use of the technique is predicted to grow rapidly due to its ability to hold components securely with a shear resistance of up to 200kg per gripper point, yet allow cutters excellent all-round access for machining on five sides. Unlike magnetic clamping systems, it can be used to secure not only ferrous metals but also non-ferrous metallic parts as well as ceramics and composites, including delicate materials.

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 at the tip to be machined in one hit. Traditionally, due to clamp interference, multiple operations are required. The novel turbine blade fixture incorporates four gripper inserts that, once adhesive has been applied and cured, hold the blade securely by one side of the aerofoil.

Tests have shown that the clamping force produced by the fixture can easily withstand the requirements of machining. Material removal rate actually exceeded that achieved when the blade was mechanically clamped, as the pressure had to be limited to avoid component distortion and marking.

Other advantages of Blue Photon clamping are an absence of workpiece distortion, good damping properties to suppress chatter, reduced cost of fixtures for holding complex parts and elimination of locating lugs on castings. A recent innovation is the introduction of smaller diameter grippers for smaller workpieces and lighter duty machining applications.

NCMT www.ncmt.co.uk Stand: H19-640 www.bit.ly/MACH2018