The Evolution of Sensors and their Migration to the Multi-Sensor CMM
The Role of Sensors in Metrology
In the world of metrology, precision is paramount. The accuracy of measurements directly impacts the quality and performance of manufactured components, making metrology a cornerstone of manufacturing industry. Over the years, advancements in sensor technology have significantly transformed the landscape of metrology, enabling higher precision, speed, and flexibility in measurement processes. Among the most notable developments in recent decades is the migration of sensors into multi-sensor coordinate measuring machines (CMMs). These highly advanced systems have revolutionized industrial measurement, offering manufacturers an all-in-one solution for complex, multi-dimensional quality control.
In this article we explors the evolution of sensor technology in metrology and how these innovations have facilitated the transition to multi-sensor CMMs, providing manufacturers with versatile, powerful tools for inspecting increasingly intricate parts in today’s advanced manufacturing environments and negating the requirement to move manufactured parts between various measuring equipment devices to obtain a full dimensional analysis.
The Early Days of Sensors in Metrology
Metrology has long relied on simple yet effective mechanical devices for measurement. Early coordinate measuring machines (CMMs) were based on touch probes that mechanically contacted the surface of a workpiece to determine its geometry. These initial CMMs were manual or semi-automatic, relying on human operators to guide the probe and take measurements. The precision of these systems, though impressive for the time, was limited by the resolution and accuracy of the probes and the inherent limitations of mechanical systems.
The 1980s and 1990s saw the introduction of computer numerical control (CNC) to CMMs, greatly improving automation and precision. During this period, sensors began to evolve from purely mechanical devices to more sophisticated systems incorporating electronics, lasers, and optics. However, early CMMs were still primarily limited to tactile probing, which, while highly accurate, were slow and unsuitable for certain types of materials and geometries, particularly delicate or flexible parts.
Rise of Non-Contact SensorsE xpanding Measurement Capabilities
The need for faster, more flexible measurement solutions led to the development of non-contact sensors, which marked a significant leap forward in metrology. Unlike tactile probes, non-contact sensors do not physically touch the part being measured, making them ideal for inspecting delicate, soft, or highly detailed surfaces. The two major types of non-contact sensors that began to emerge in the 1990s were optical sensors and laser-based systems.
Optical Sensors: Optical systems, including vision sensors and cameras, use light to capture the geometry of a part. These sensors work by projecting light onto a workpiece and capturing the reflected light with a camera, allowing for the measurement of part geometry without physical contact. Optical sensors provided a much faster alternative to tactile probing, making them ideal for high-speed production environments. They also opened the door to more detailed inspections of small features that were difficult to access with traditional probes.
Laser Sensors: Laser triangulation sensors use a laser beam to scan the surface of a part, with the reflected light being measured by a detector. By analyzing the time it takes for the laser to return, the system can precisely map the surface geometry. Laser sensors are highly effective for measuring complex freeform surfaces, making them valuable in industries like aerospace, automotive, and medical devices, where high-precision parts with intricate geometries are common.
Both optical and laser sensors significantly enhanced the speed and flexibility of CMMs. However, they were still largely used as separate systems, with tactile probes remaining the dominant tool for high-precision measurements. This led to the need for a more integrated approach, where multiple sensor types could be used in tandem to offer the best of both worlds: the precision of tactile probes and the speed and versatility of non-contact sensors.
Multi-Sensor CMM: The Integration of Multiple Technologies
The next major advancement in the evolution of metrology sensors was the development of multi-sensor coordinate measuring machines (CMMs). A multi-sensor CMM integrates various types of sensors—such as tactile probes, optical sensors, and laser scanners—into a single system, allowing for a more comprehensive and flexible approach to measurement.
The integration of multiple sensors within a single CMM platform offers several key benefits:
Versatility: Multi-sensor CMMs are capable of measuring a wide variety of parts with different geometries, materials, and surface finishes. For example, a part may require tactile probing for precise measurement of hard-to-reach features and high-precision dimensions, while laser scanning or optical sensors might be used to quickly measure larger, freeform surfaces.
Efficiency: By combining multiple sensors in one system, manufacturers can perform a wider range of measurements without the need to switch between different machines or systems. This reduces setup times, minimizes handling, and accelerates the overall inspection process.
Improved Accuracy: In some cases, combining data from different types of sensors can lead to improved measurement accuracy. For example, a tactile probe might be used to establish precise reference points, while a laser scanner can capture detailed surface data. This hybrid approach allows for better measurement accuracy and consistency across complex geometries.
Key Drivers of Multi-Sensor CMMs
Several key technologies have driven the evolution of multi-sensor CMMs, enabling greater measurement capabilities and expanding the range of applications for these advanced systems.
Probe Technology: Modern tactile probes have become more sophisticated, with advancements such as high-precision scanning probes that can continuously measure complex surfaces. These probes use advanced electronics to sense deflections in multiple axes, allowing for more accurate and detailed measurements of freeform surfaces compared to earlier single-point contact probes.
Vision Systems: Vision sensors have seen significant improvements in resolution and processing power, allowing for the capture of more detailed images and faster processing times. Modern vision systems can capture millions of data points in seconds, making them ideal for high-speed production environments where rapid inspections are necessary.
Laser Scanning: Laser scanners have evolved to offer higher accuracy, faster data capture, and improved resolution. Today’s laser scanners can quickly measure complex surfaces with high precision, making them a key component of multi-sensor CMMs.
Software Integration: One of the key enablers of multi-sensor CMMs is advanced metrology software that can integrate data from different sensors and produce a unified, coherent measurement result. Modern CMM software allows operators to switch between different sensor types seamlessly during inspection, and it can process large amounts of data from multiple sources. This software-driven integration ensures that manufacturers can leverage the strengths of each sensor type to obtain the most accurate and efficient measurements.
Automatic Sensor Changing: Today’s multi-sensor CMMs are equipped with automatic sensor changing technology, which allows the machine to change between tactile, optical, and laser sensors during the same measurement cycle without manual intervention. This capability is a game-changer in terms of efficiency and automation, as it eliminates downtime associated with changing measurement tools and ensures that the optimal sensor is used for each feature of the part.
Applications of Multi-Sensor CMMs in Advanced Manufacturing
The migration of sensors to multi-sensor CMMs has opened new possibilities for manufacturers in a wide range of industries, from aerospace and automotive to medical devices and electronics.
Aerospace: In aerospace manufacturing, components often feature complex geometries, such as turbine blades or fuselage panels, that require high-precision measurement. Multi-sensor CMMs are ideally suited to this environment, as they can use tactile probes to measure critical dimensions and laser scanners to capture detailed surface data, ensuring that components meet strict quality standards.
Automotive: The automotive industry has long relied on CMMs for quality control of critical components such as engine parts, gears, and transmission systems. Multi-sensor CMMs allow for faster inspections and greater flexibility, particularly when measuring a mix of machined, cast, and plastic components.
Medical Devices: Precision is critical in medical device manufacturing, where components must meet stringent regulatory standards. Multi-sensor CMMs are used to measure small, intricate parts such as surgical instruments, implants, and prosthetics. The non-contact nature of optical and laser sensors makes them ideal for measuring delicate and highly detailed components without the risk of damage.
Electronics: As electronic devices become smaller and more complex, manufacturers need highly precise measurement tools. Multi-sensor CMMs are widely used in the electronics industry to inspect components such as printed circuit boards (PCBs), connectors, and microchips.
The Future of Precision Measurement
The evolution of sensors and their migration to multi-sensor CMMs has transformed metrology, providing manufacturers with powerful tools for precision measurement in increasingly complex production. Looking ahead, the continued miniaturization of sensors, advances in AI and machine learning, and improvements in automation will further enhance the capabilities of multi-sensor CMMs. AI-driven algorithms may soon be able to automatically select the best sensor or combination of sensors for each feature of a part, further streamlining the inspection process and improving measurement accuracy.
Author: Gerald Jones Editorial Assistant
