Advances in machine accuracy, on-machine touch probing technology, and non-contact tool setting provide powerful tools for automating and speeding machining.
Drives to faster, leaner, more flexible manufacturing are shifting industry focus away from traditional post-process quality control. The most expensive, non-value-added process in most shops is part inspection. Inspecting good parts – that meet all print specifications – is a waste of time, money, and manpower.
Rather than back-end detection, attention is shifting to front-end prevention. To move to defect-prevention you must be able to document your process capability and the accuracy of your machine tools.
Today’s standard machine tools can deliver accuracy and repeatability approaching levels formerly available only on CMMs. This enables the machine tool itself to be used for probing checks of workpieces during critical stages of the machining process. Once a machine tool’s performance as a measuring instrument has been established, the touch probe becomes the operator’s CNC gauge.
Probing routines can be programmed as part of the machining process, and automatically run at various points to check feature dimensions and locations, and apply necessary compensations. Probing on the machine should be a standard part of the process – a powerful process improvement tool for making parts right the first time in the shortest throughput time. It can be used to locate the part automatically and establish a work co-ordinate system. Probing cuts set-up time, increases spindle availability, lowers fixture costs, and eliminates non-productive machining passes.
When starting with a casting or forging, probing can determine workpiece shape to avoid wasted time in air-cutting, and help determine best tool approach angle. A touch probe can be programmed to check actual machined results at various stages against the programme, and automatically apply cutter compensations – particularly after rough machining or semi-finish machining. Such a closed-loop process control can allow a machining centre to achieve accuracies comparable to boring mills and other high-precision machines.
Inspecting on the machine is particularly beneficial with large, expensive workpieces, such as mould or dies, which can be especially difficult and time-consuming to move. Laser tool setters provide a fast, automated means to verify tool dimensions, especially critical in checking for wear during the long machining runs in mould making. A cost-effective solution to high-speed, high-precision tool setting and broken tool detection, laser tool setters rapidly measure tool length and diameter on the fly, while the tool is indexing through the laser beam and rotating at normal speeds. Laser checking at working spindle speeds identifies errors caused by clamping inconsistencies and radial run-out of the spindle, tool, and tool holders. But this is not feasible with static tool setting systems. These laser systems can accurately measure tools as small as 0.2mm diameter anywhere in the beam.
Advanced electronics and simplified design makes non-contact tool setting an affordable alternative to contact systems. Perhaps it’s time you gave it a try!