Modern CNC lathes and tooling permit high cutting speeds and feeds, leading to increased machine efficiency and productivity. To ensure operator safety, however, European Norm EN 1550 states that the gripping force of chucks should be checked regularly — hence Kitagawa’s introduction of its KGFM series of wireless grip-force meters.
Available from UK agent 1st Machine Tool Accessories Ltd, Salisbury
(www.1mta.com), this Japanese-built unit is designed to measure holding force quickly and accurately; it can perform either a static test, or a dynamic test with the spindle running (in this case, the instrument records the rotational speed of the chuck as well the force that it applies to the billet or casting).
The sensor is available in two standard sizes with measuring diameters of 72 and 125mm respectively. By installing rest pads in the appropriate locations, both types can be used on two- and three-jaw chucks; the larger model can also be used on four-jaw chucks.
In addition to ensuring safety by avoiding the risk of a workpiece flying out of the chuck, the units maximise lathe productivity by ensuring that full gripping force is being applied, allowing high rotational speeds and feed rates to be programmed into machining cycles. The dynamic grip-force meter uses a standard 9V battery and comes as a kit including wireless force sensor, rev/min magnetic ‘wand’, standard rest pads, display and padded carrying case. Stop rings are available for controlling insertion depth, as
are ‘custom’ sensors for measuring the gripping force and rev/min of larger chucks.