Unique Pressure-Sensing Touch Probe for Machine Tools

Verifying the quality of machined parts is a challenge for manufacturing, particularly in the hyper-competitive aerospace component supply chain. Because errors can cost lots of time and large amounts of money to remedy, competitive shops actively measure the process signature to relieve time-consuming part inspections that can leave machines standing idle for hours or even days. On-machine measurement systems can diagnose erroneous feeds and speeds, NC program glitches, improper tool and work offsets, and other common machine tool problems within a process signature.

As part of the on-machine inspection system, a machine tool probe periodically measures the part being machined to monitor for process adjustments needed minimize the frequency and severity of these sorts of issues. An operator can also monitor tool wear by using the probe to measure selected part features as they are being machined to determine whether a particular tool needs to be adjusted or replaced. The process data generated from the probe can also be used to plan maintenance cycles – another big factor in aircraft component manufacturing.

Heidenhain Corporation (Schaumburg, IL) offers the latest technology in machine tool touch probes. Employing a pressure sensor, the unique TS 740 touch probe simultaneously maintains unusually high accuracy of < ±1 µm with a repeatability of 0.25 µm at a probing velocity of 0.25 m/min. With this accuracy and repeatability, machined part verification is no longer a challenge. The trigger pulse on the TS 740 is obtained through force analysis. The forces acting during probing are processed electronically. This method provides extremely consistent probe accuracy over 360 deg. With the unique TS 740, the deflection of the stylus is then measured by several pressure sensors that are arranged between the contact plate and the probe housing. When probing a workpiece, the stylus is deflected so that a force acts on the sensors. The signals generated are processed and the trigger signal is produced. The relatively low probing forces provide high probe accuracy and repeatability, while offering precise trigger characteristics in all directions!

The signals are transmitted via infrared, which is also ideal for use on machines with automatic tool changers. In spite of its low probing forces, the TS 740 is designed in such a way that it is well suited for use in machine tools with a fast tool changer. Rapid acceleration or deceleration does not cause uncontrolled trigger signals, as is common with those with low probing forces that are typically sensitive to mechanical disturbances. All of this makes the TS 740 the perfect choice for very demanding measuring tasks on machine tools used in aerospace manufacturing.

Heidenhain Corporation, 333 E. State Parkway, Schaumburg, IL 60173, 847-490-1191, www.heidenhain.us.