Tool monitors optimize machine tool operating conditions based on feedback from sensors or probes. They include monitoring sensors and instrumentation for the predictive maintenance of industrial equipment and processes. There are many different types of tool monitors. Some products are used to determine whether a machine tool is dull, broken, or properly mounted in a machine. Others sense whether the workpiece is positioned properly. Many tool setting monitors are used to detect clamping errors, thermal shifts and broken tooling during rapid traverse. Crash avoidance systems detect imminent collisions and turn off motion control circuitry before damage can occur. Tool monitors are also used to check conditions or parameters such as temperature, corrosion, oil condition, wear, vibration (flaw detection and growth), speed and pressure.
Tool monitors are used with machine tools such as machining centers, lathes, turning centers, rotary indexing tables, grinding machines and Swiss screw machines. Machining centers are computer numerically controlled (CNC) devices that are designed to repeat operations automatically. Lathes and turning centers cut a rotating part with a stationary cutting tool. They move parallel and perpendicular to the workpiece axis to provide the desired finished shape. Rotary indexing tables have a round table that can be accurately indexed at angled increments for machining, assembly, and other operations. Grinding machines remove metal and provided a fine surface finish. Swiss screw machines or automatics are turning machines with a sliding headstock and cross tools that can produce very small parts with consistently excellent surface finishes.
Communication standards for tool monitors include RS232, RS485, PROFIBUS®, and Ethernet. RS232 is a popular serial communication standard that provides asynchronous communication capabilities with hardware flow control, software flow control, and parity checking. RS485 supports multipoint connections whereas RS232 supports only point-to-point connections. The process fieldbus (PROFIBUS) is a communication standard used in factory automation, process automation, motion control, and safety applications. PROFIBUS is standardized by IEC 71158 and IEC 61784 and is suitable for both fast, time-critical applications and complex communication tasks. PROFIBUS is a registered trademark of PROFIBUS International.
Selecting Tool Monitors
Selecting tool monitors requires an analysis of product features. Some products include adaptive controls, diagnostics, or wear compensation. Others provide data logging or remote data retrieval features. Self-teaching tool monitors can “learn” to adjust to changes in tool cutter dimensions and conditions. Tool monitors with a time-delay trip are also available.