| Introduction
Probing
Probe systems require careful analysis to ensure that they will provide the necessary accuracy and are suitable for your application. |
In addition to a well
designed machine frame, powerful software, and a reliable
control system for DCC machines, a properly configured
probing system is also required. Basically, a probe head is mounted into the ram or arm of the CMM. In some cases the probe has the trigger mechanism built into the head and a stylus is mounted directly to the head or a stylus extension is used to extend the reach of the stylus. This type of system is used primarily on small CMM’s to get maximum measuring volume. Other probe heads require the selection of an electronic probe to be mounted into the probe head. An extension bar can be used to extend the reach along with a stylus or stylus extension. A stylus is then attached to the electronic probe and when the stylus makes contact with the part, the current location of the CMM is transferred to the computation system and multiple data hits are used to calculate a feature. Probe heads can be manually repositioned or motorized for automatic orientations. Electronic probes are selected based on the user requirement. Touch trigger probes, analog probes or piezo electric probes make physical contact with the part. Optical or laser probes are used where physical contact is not practical or possible. In addition to discrete point data collection for prismatic features, such as circles, arcs, lines, etc., there is also the capability to collect large quantities of data points where necessary. With the touch trigger type probing system this is accomplished using "peck" scanning commands. Some analog, laser and optical probes are also capable of constant contact scanning for even greater data density. This is particularly useful for free form surfaces, shapes and form deviation analysis. |
 Manual indexable probe head (commonly used on small, manual machines.) |
 Motorized probe head complete with touch probe. |
 Probe head with optional rack system offers a wide variety of probe configurations. |
| Some probe heads have optional RACK
systems, similar to a tool changer in an NC machine
center.These heads can make probe switches automatically
so that different stylus lengths and sizes can be
automatically built into a part program. These are used
primarily for DCC style coordinate measuring systems. The optimum probe system selection is determined by the type of parts to be measured and requires careful analysis to ensure that the probe system selected will provide the necessary accuracy and be ideally suited for your application. |
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