Method and algorithms therefore for monitoring the performance of a tool and modifying the feed rate thereof

A method of monitoring the performance of a tool which moves relative to a workpiece through a cycle and controlling the feed rate between the tool and workpiece in response to the monitored performance of the tool comprising the steps of:

• dividing said cycle into a plurality of increments:
• sensing a function of the force applied to said tool during said increments;
• determining a mathematically smoothed function of force for said sensed function of force for each sensed individual increment of said cycle;
• establishing a reference for the mathematically smoothed function of force for each of said sensed increments;
• comparing said determined mathematically smoothed function of force for a particular sensed increment with said established reference for that particular increment;
• generating a first signal if said actual determined mathematically smoothed function of force for a particular increment deviates from the established reference for that particular increment;
• and
• modifying the feed rate between the tool and workpiece in dependence on said first signal;
• wherein said step of determining a mathematically smoothed function of force for the sensed function of force includes the steps of determining the cumulative percentage deviation for the sensed function of force for each sensed individual increment of said cycle;
• and determining a cumulative percentage deviation data point for each sensed individual increment.