Chip off the Hard Block

A new laser machining center laser ablates 3-D profiles in superhard cutting tools.

Courtesy of All images: Wendt

The working environment of the Spectra laser machining center features modular clamping and a 3-D measuring probe for positioning the workpiece.

The machining of 3-D profiles, such as chipbreaker geometries, into PCD, PCBN, carbide and ceramic cutting tools presents unique processing challenges. These challenges have created limitations to the profitability of the process and to the profile’s dimensional accuracy.

Electrical discharge machining is probably the most common machining process for generating 3-D profiles in superhard cutting tools, but it also has tool wear limitations, long cycle times and is suitable only for conductive materials.

Laser ablation offers an attractive alternative to EDMing. Eliminating the need to compensate for tool wear while increasing material-removal rates make laser ablation appropriate for creating 3-D profiles. Additionally, the workpiece does not need to be conductive and therefore laser ablation offers the potential for machining ceramics and other nonconductive materials. It creates chipbreakers in superhard cutting tools, profiles in punch dies and toolholder locating and locking geometries in inserts.

Removing Material

A laser removes material either by burning or vaporizing it from the surface. A laser beam burns a continuous path on a workpiece surface, a typical technique for engraving or cutting. However, a pulsing laser will vaporize material at a specific point, thereby leaving a small cavity. It does this with each pulse of light.

The cavity size is a function of the size of the laser and the light’s focus diameter. A higher wattage laser creates a larger cavity than one with less wattage, and a larger cavity means a higher mrr.

The Spectra 820 laser machining center from Wendt uses a stationary diode-pumped, solid-state laser and oscillates the workpiece to the light source to achieve material-removal rates and impart surface finishes similar to finish grinding. Unlike grinding, where parameters such as wheel diameter or wheel speed are continually changing and interacting with each other, Wendt says the laser machine’s parameters are predictable and do not interact with each other.