Traditionally, product manufacturers take measurements visually using an optical comparator and other hand tools. But these machines have limited accuracy and do not usually offer quick results.
Meanwhile, a coordinate measuring machine (CMM) can assess the height, width, and depth of a product part using coordinate processing technology. With this machine, workers can measure components with high accuracy. Learn the different types of CMMs in this short guide.
A bridge CMM is one of the most common types of coordinate measuring tool. This type of CMM can be categorized into two subtypes: moveable-table and moveable-bridge.
It consists of three axes orthogonal to each other in a Cartesian coordinate system. Each axis features a sensor that monitors the probe’s position as it slowly moves along a component and detects points on its surface.
These points create a point cloud, highlighting the surface area manufacturers are interested in measuring.
A cantilever CMM is similar to bridge models because manufacturers can use them to measure small parts. But unlike bridge machines, this type of CMM has a measuring head attached to only one side of a rigid platform, which is open on three sides for easy operation.
The cantilever model provides users with greater access and features automatic loading and unloading of components that fit within the size restrictions.
A gantry coordinate measuring equipment can assess larger and heavier parts that bridge or cantilever models cannot. But for this type of CMM, the part to be measured must be mounted securely to the floor, meaning there is limited portability.
This machine is bigger than bridge models but has the same accuracy levels. Additionally, it removes the need to lift the component to be measured onto a table.
Gantry CMMs are usually used to assess very heavy or massive parts. Because of its size, the equipment must be mounted on a solid foundation or directly on the floor.
Horizontal Arm CMM
A horizontal arm CMM features a distinct design as its probes are mounted to horizontal arms instead of vertical ones. With this design, the tool’s probe can reach narrow or otherwise inaccessible areas of a component.
This model was developed to measure long and thin parts that vertical CMMs could not inspect, such as sheet metal. There are also two subtypes of this tool: runway-mounted and plate-mounted.
Portable Measuring Arm CMM
A portable measuring arm features a coordinate measurement system that can assess parts directly on shop floors. The mobility allows for quick results and real-time product analysis.
As opposed to manufacturers bringing parts to a laboratory to be measured, technicians use an articulated arm to measure components wherever required. The tool’s arm can have either a six- or seven-axis system.
A portable measuring arm CMM can be particularly useful to analyze parts even while they are still connected to their fixtures or assemblies.
An optical CMM is a portable, non-contact equipment. This model uses an arm-free system with optical triangulation processes to get three-dimensional measurements of objects.
Advancements in sophisticated image processing technology enable optical CMMs to provide manufacturers with ultra-fast and guaranteed metrology-grade accuracy.
That said, this type of CMM has a slightly lower accuracy level than other models. However, it can be accurate for a wide range of applications. This makes an optical CMM an excellent addition to traditional CMMs for manufacturers who want to free up production bottlenecks.
Workers use a conventional CMM to measure components that require a critical level of accuracy while using a more cost-effective optical model for other product parts.
These are the different types of coordinate-measuring technologies today. Before buying one, it is best to do thorough research so you will have a machine that will suit your company’s manufacturing needs. You can even find used CMM machines near you if you are looking for more affordable options.