Geometrics and dimensions are very crucial when it comes to producing prototypes or final components. Every part should be manufactured identically to ensure high functionality. To achieve this, manufacturers should avoid any errors to acquire the right part measurement. However, irregularities during the production process may result in inconsistency of the manufactured part’s dimension. When there are dimensional errors, the whole manufacturing process can be greatly affected. Produced parts may fail to function correctly as well.
Traditionally, manufacturing businesses have professional quality assurance teams to check the final product using calipers and gages. Although these professionals are experts in quality assurance measurement, the procedure is still susceptible to errors and is time-consuming.
A high-precision measuring machine called CMM was developed to address the said issues. The goal of this article is to help you understand what really is a CMM machine. You will also learn its different types, applications, benefits, components, disadvantages, features, and how it works. As you go through this article, you can have a deep understanding of this machine.
What are you waiting for? Scroll down and keep reading!
What is a CMM Machine?
CMM is the abbreviation of a coordinate measuring machine. These machines are designed with coordinate processing technology. Therefore, it can measure a component’s dimension including depth, width, and height accurately.
There are several types of CMM machines. However, all types share the same working principles. These devices can capture the coordinates of the object’s features and surfaces using ruby styli tipped or non-contact probes such as lasers.
The machine also precisely indicates the probe’s location from the starting point to the 3-dimensional coordinate system. It can also precisely capture 3D measurements, store the collected data, and discern intricate geometric dimensioning/tolerancing.
The Role of CMM Machine in the Manufacturing Process
Measuring components using traditional methods have limitations. The traditional method requires professionals with expertise and skills to check every machined part. If not well executed, this can lead to irregular part dimensions.
Due to technological sophistication and advancement, machined parts are manufactured with more complex geometries. A CMM machine is ideal to use for more accurate measurements.
Unlike conventional methods, CMM can precisely measure part dimension at a higher speed. Therefore, manufacturers can increase their productivity. It also helps in reducing the risks of human error. Fabricators can surely save their money, time, and labor costs.
Working Principle
There are two methods used by the CMM machine to measure a component. The first method is called the contact mechanism. It uses touch probes to measure the components. The second method is called the non-contact mechanism. It uses lasers or cameras to measure the parts. These machines can measure machined parts with different sizes. There are CMM machines that can measure components of 10mm size or larger such as automotive models.
The CMM machine is designed with a plate made from rigid and dense material. This provides the necessary stability required to hold the machined parts to be measured. Therefore, allowing the machine to measure and analyze accurately. The component should be placed first on the plate or the work table.
At the top of the plate is where a gantry is located. The gantry of the machine controls the vertical mechanical probe. Thus, it can measure the machined part along the three-dimensional coordinates.
After that, the machine will ensure that the parts have the right design. Then, it will analyze the collected data. After the information is analyzed, the machine will store the data and end the process.
Different Types of CMM Machine
These machines are less rigid compared to the bridge type and gantry type since they are supported only at one point. It can move quickly when measuring low-weight components due to their single-point support, allowing it to obtain higher accuracy.
However, cantilever CMM can only be used for measuring master parts, gauges, and other small machined components.
As its name implies, these CMMs have a horizontally mounted scanning probe. Due to that, horizontal arm CMM is capable of measuring large machined parts with hard-to-reach and complex features.
It is perfect for measuring sheet metal parts with thin walls. However, it is important to take note that these kinds of CMM have low accuracy.Different Components of a CMM Machine
It is the most commonly used type of this machine. The bridge type comes with a moveable bridge or moveable table. You can also choose from portable or fixed units of this machine.
These are designed with an extremely stable measuring apparatus anchor. Therefore, it can measure machined parts with the tightest tolerance and highest accuracy requirements.
However, bridge-type CMM is only best for measuring machined parts with small or mid-size that can be lifted on to the table easily. The bridge’s upright anchor of this machine is holding the x-axis. Therefore, you may face difficulties when accessing the parts to be measured.
Gantry-type CMM has similarity with the bridge-type. However, they slightly differ when it comes to their capabilities and designs.
In contrast to the bridge style, gantry CMM is positioned directly on the floor. Its bridge is elevated on pillars. Therefore, the gantry type is capable of accommodating or reaching machined components with large volumes and intricate geometries.
The typical measuring range of gantry type in a 3D coordinate system ranges from 1mm x 2mm x 1mm up to 5mm x 9mm x 3mm.
Different Components of a CMM Machine
It is the primary component of the CMM machine. It is a measuring tool that’s responsible for measuring the machined part placed on the plate. Its tip is usually made from rigid material. It should also be resistant to temperature. Thus, its size will not alter when the temperature changes. The probe’s tip can be needle-like or spherical made from zirconia and ruby.
There are also CMM machines that use lasers, cameras, and optical light rather than a mechanical probe.
The CMM machine’s table is also an important component. This is where the machined parts to be measured are placed. The table is usually made from granite. It should also be temperature resistant and has a low wear and tear rate. The stability of the granite table is important to ensure highly accurate measurement.
Fixtures are also a component of CMM machine that provides support and stability in different manufacturing processes. They are used to fix the parts making sure they are in the right place. It is an essential component to reduce measurement errors due to moving parts. Fixtures include different tools such as magnets, clamps, and more.
These are important, especially for gantry-type or standard bridge-type coordinate measuring machines.
Though it is not part of the physical component, software is very important for a CMM machine to analyze a component’s sensitivity, including the probes.
Advantages of Using a CMM Machine
Quick Manufacturing Process
After the machined parts are placed on the CMM plate, the probe will automatically detect the point clouds. Then, it will start to measure the component’s coordinates and will analyze the dimension. Therefore, shortening the production process of each component without compromising the accuracy. This will also speed up the production process of the machined parts with the most complex geometries. Allowing business owners to save time and costs.
Versatility and Compatibility
CMM can be used with different probes. Therefore, you can assure its versatility. It is also compatible with various components and tools. The machine can also measure a wide range of machined parts regardless of their complexity.
Reduce Human Error
Most of these machines are controlled by a computer, reducing the interference of human operators. This will significantly reduce human error that may result in production failure.
Enhanced Quality Assurance
CMM machine can provide more reliability in measuring parts dimension compared to traditional method. This machine is capable of measuring and analyzing components digitally. It can also offer reverse engineering, tool certification, CAD comparison, and other services needed for quality assurance.
Easy to Upgrade
The hardware of CMM machine does not require frequent upgrades. On the other hand, its software is also easy to upgrade to enhance performance and accuracy. You can update the CMM software without compromising its reliability.
Limitations
The Probe Should Touch the Part’s Surface
The CMM probe should touch the surface of the machined component. It is not a big deal for durable and hard components. However, it can be challenging when measuring fragile components. Consecutive probes touching the delicate parts may result in damage.
Cause Damage to Soft Components
Soft parts made from materials such as elastomers and rubbers can get damaged due to constant probe touching.
Manufacturers Should Choose the Right Probe
Selecting the right probe for a specific type of application can be challenging since there are different types of probes available. The right probe will depend on its capability, required design, and dimension.
Conclusion
CMM machines are surely a great tool to increase the productivity of manufacturing processes. It helps speed up the measuring process of each part, allowing manufacturers to have accurate quality checking while saving time and costs. We’ve delved into their diverse types, operating principles, and benefits. CMM machines are indeed the forefront of dimensional metrology and quality control processes.