Smart Tooling Takes Autonomous Machining By Force

by | Apr 26, 2023

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A REGO-FIX special guest blog featuring Pro-Micron

From handwheel controls through punched-tape toolpath programming to full CNC guidance, machining operations have evolved from manual activities toward fully autonomous systems. Each step in the progression has made machining faster and more efficient, more accurate and reliable, and less dependent on operator intervention. This ongoing transition from automatic to truly autonomous operation, however, requires gathering and processing vast amounts of operating data and translating it into the comprehensive knowledge needed for Artificial Intelligence (AI)-driven manufacturing.

Key to the accumulation of accurate machining data are today’s sensing technology that can provide measurements of forces acting on a cutter in real time. Such machining force measurement systems typically gather data indirectly by monitoring a spindle’s power consumption. As a cutting process progresses, power consumption changes, and system software applies force values per that changing data.

In contrast to that approach, sensor technology and software developer Pro-Micron offers Spike, a wireless force transducer system that transforms tool holders into smart tooling. The system directly measures bending moment, torque and axial forces at the tool holder, and it is this close proximity to the cutting edge that makes for extremely sensitive and accurate measurements. These measurements include loads on each single cutting edge, then displaying that edge condition in a graph format.

In an aerospace Inconel trochoidal milling operation using a 16 mm tool, the incorporation of Spike netted notable results. Prior to Spike, machining was performed at 0.1 mm radial engagement, and tool breakage occurred irregularly and unpredictably. This made it necessary to change tools at minimal intervals to avoid damaging the expensive component, resulting in excessive tooling costs.

Machining data gathered by the Spike system showed that the bending moment was much higher than expected, and analysis of the data indicated that changing the tool’s stepover by only 8 microns would double the tool’s reliable lifetime, resulting in a much more secure process and significant tool cost savings..

Similarly, precision force measurement enables a tool manufacturer to optimize cutting parameters when developing new products. Instead of lengthy trial-and-error experimentation, analysis of cutting force trends via Spike enables a toolmaker to significantly reduce development time by eliminating the need to repetitively run full tests. For one toolmaker, that translated to a six-time reduction in development work duration.

Spike data includes variables as precise as measurement of forces on a tool’s individual flutes, and geometry optimization graphs track how the sharpness and service lifetime of a tool changes during a cutting process. Using this real data, manufacturers can also benchmark their tools against competing products.

Beyond cutting tool manufacturing development, Spike technology allows individual machine shops to fine-tune their processes and test competing products in their own operations. Spike’s in-process monitoring, for instance, enables a manufacturer to anticipate the effects of cutting forces on part quality in production machining situations. Abnormal bending moment forces, for example, may produce degradation of surface quality and result in out-of-spec parts. Especially important in untended machining situations, this real-time force data provides immediate notice of unexpected force measurements and presents an opportunity to adjust process parameters so corrective actions can be taken before scrap parts are produced.

Spike transmits measurement data wirelessly from the toolholder to a receiving unit connected to a laptop equipped with processing and analysis software. Using the system is a plug-and-play application consisting of clamping the tool in the machine spindle, activating the Spike system and starting the cutting operation.

REGO-FIX is a Pro-Micron technical partner that provides its high-precision tool holders to which Pro-Micron adds its necessary strain gauge, electronic and battery components as well as containment parts for machining operation speeds up to 18,000 rpm. Higher speed capability and increased sensitivity for micromachining are currently under development as is new technology for measuring tool wear in 0.4 mm diameter drilling applications.

Since Spike cannot be retrofitted into existing tool holders and because it is used primarily for research and process development, it’s not necessary for a shop to replace its entire tool holder inventory with Spike-equipped holders. However, it should be noted that significantly longer or shorter holders may not perform similarly to Spike-equipped standard size holders used for development, and thus parameters for those other holders may be different. The main requirement for the potential Spike holder is that it have runout less than 5 µm.  REGO-FIX tool holder runout measures well under that requirement.

Autonomous machining on a wide scale involves smart tooling, smart software and application of AI algorithms. In addition to measuring and collecting cutting force data, true autonomous machining will require gathering and analyzing data from the machine tool control itself. Currently, Fusion software is capable of automated recording of machine data and synchronizing, sorting, processing and labeling the data. This enables manufacturers to custom tailor processes for specific machines, tooling, materials and parts.