Manufacturers use coordinate measuring machines (CMM) to check the dimensions of products and their components. The equipment offers an automated rendition of manual quality controls using traditional metrology tools.
One crucial part of a CMM is the probing system. When buying a CMM, a probe type is something you want to consider. Read on and discover the different types of probing systems and their uses.
What are CMM probes?
CMM probes convert physical measurement data into electrical signals through different measuring systems within the structure. They are a broad category of tools that rely on diverse technologies for comparative and direct measurements.
Different Probing Systems
There are many types of probes available today. However, developers categorize the most common into three types: contact, non-contact, and multi-sensor probes.
There are two common tactile or contact probes: touch trigger and analog scanning probes.
- Touch trigger probes
A touch trigger probe uses a stylus attached to a bearing plate. This plant is linked to pressure sensors within the system. It produces an electrical signal each time it touches the workpiece. Then, it sends the signal back to the CMM to generate measurement data.
One advantage of touch probes is that they offer versatility and flexibility. These probes also feature strain gauge technology. This tech ensures that the probes trigger with constant force regardless of the angle of contact. This feature provides a sub-micron level of accuracy.
- Analog scanning probes
Meanwhile, analog scanning probes are also stylus-based probes. However, manufacturers use them to measure contoured surfaces, such as sheet metal parts.
Unlike touch trigger probes which touch individual points, the analog probe keeps continual contact with the workpiece. It takes measurements as it is dragged across the component.
The procedure is beneficial for collecting data for complex contoured shapes, such as prosthetics, turbine engine blades, automobile bodies, and crankshafts.
Two types of continuous analog scanning (CAS) systems exist: closed- and open-loop systems.
Closed-loop systems automatically detect changes in the direction and surface of the workpiece. This probe adjusts itself accordingly to keep in contact with the component on the table.
Meanwhile, manufacturers drive probes with open-loop systems along a specific path using dimensional information. This system is helpful for high-speed data acquisition. It also works well on parts with geometry well-defined by computer-aided design (CAD) data.
A non-contact probe can measure any workpiece that might deform under the pressure of a contact probe. Manufacturers use them for complex and high-precision workpieces. A non-contact probe is either vision-based or laser-based.
- Vision-based probes
Manufacturers need vision-based probes to measure microprocessors and other small components. Rather than measuring the small parts themselves, manufacturers use a mold that will generate accurate dimensions for future pieces.
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Some probes use a high-definition camera capable of generating several measurement points in one frame. This feature allows users to measure components and compare them to the electronic model by counting pixels.
You need to calibrate a vision system only once. This feature is a massive advantage over other probes that require recalibration more often.
- Laser probes
A laser probe functions similarly to a CMM touch trigger probe. However, instead of a stylus, it uses a laser beam to take data. The light functions as an optical switch. When the laser touches the workpiece, a lens in the probe reads and records the dimensions.
The main advantage of a non-contact probe is it enables users to gather data from a larger surface faster than contact probes.
There are CMMS with multi-sensor probes. These tools feature more than one sensor on a single device. For example, one multi-sensor CMM can have touch and laser probes.
Choose the Right CMM Probe for Your Business
The type of probe you want to buy will depend on your manufacturing needs. There are many companies today that offer high-quality CMM with different probing systems. One of them is CMMXYZ. The firm provides a wide selection of new and used CMMs.
To end up with the right CMM, you must evaluate your measuring needs thoroughly. Doing so can help you identify what features you need in your equipment.