What is CMM?
The CMM specifies the status of the probe in reference to its displacement from the reference point in a 3D Cartesian coordinate system.
In CMM, the test plays an important role because it is the one who feels the discrete points and detects the geometric characteristics of the object.
The status of the investigation can be control manually or with the help of a computer.
Or We can say:-
CMM can be a “coordinate machine”, a computer control test device that determines the point of points or points set on an object, x, y and z offset from the data set.
It is use to observe precisely mechanise or raw parts for dimensional accuracy
While all CMM performs similar functions, each type of machine is manufacture and designe differently.
When selecting CMM, an industrial buyer should consider its various specifications, the design of equipment and its underlying characteristics.
The specifications of the machine are important to properly adjust a workpiece and to meet the necessary measurement capabilities.
- Measuring length is the total distance, which can be a test to measure in x, y, or z-direction.
- The maximum size of the capacity object or work-piece is that the machine can adjust. CMM should have a capacity that is enough to fit the size of objects measure by the user.
- Resolution is the smallest increment which the device can also measure. A high resolution indicates a more specific measurement.
- Measurement speed is the rate on which one can read the CMM positions and take measurements.
It can refer to the probe’s imaging speed, or overall measurement process, which is also a function of control type (CNC is faster than manual control).
- Weight capacity is the maximum or standard weight of the work-piece, which the machine can adjust. A CMM should have a weight capacity that is enough to keep the weight of objects measure by the user.
CMM can be design to perform various types of measurements. These Contains:
- Dimensional measurements are shaping the measurements made in x, y and z directions.
- Profiles are measure to gain information about the appearance or profile of an object. Depending on the capabilities of the machine, these measurements can be either 2D or 3D.
- An angle or orientation is measure to capture the information of the angle between points on an object.
- Depth mapping is construct by measuring the difference between two stereo images. Stereo pictures are gradual images of the same scene taken on slightly different angles.
The distant objects will move from one image to the other at a relatively low speed, while the objects coming closer to the viewer will move from a greater degree.
A depth map is formed, resulting in different intensities to represent different depths using a single image.
- Digitization or imaging provides a digital format or image to visually capture the workpiece geometry from the measurements made by CMM.
- Shaft measurements are application-specific designations for measurements made by CMM specially designe to inspect the shaft.
The tool design includes a control system of CMM systems, a method of operation, mounting style and testing type.
The CMM probe is designe to control itself or through CNC. Selection is largely an act of quantity, complexity, and cost of the part.
• CNC (Computer Numerical Control), or DCC (Direct Computer Control), a control system create to control the probe movement in CMM.
CNC CMMs are most suitable for production environments that require measurements in larger quantities, and also in applications requiring complex and small measurements with fine features.
They are more expensive than manually control machines.
- An operator is require for manual or operator-control equipment, which proceeds with the axis to create physical contact and record measurements.
Manual CMM usually costs less than CNC CMM of the same size and is better suit for prototype shops with smaller amounts of measurement.
Operation describes the method or measure of CMM, which usually depends on the design or orientation of the investigation branch.
- Bridge-style machines include a hand vertically suspend with a horizontal beam, support by two vertical positions in a bridge system.
The machine moves the X-axis, which spreads to measure the object. Bridge guide rail (machine y-axis) supports the bearings and z-axis bar of the machine. They are consider to be the most popular type of machine style.
- Gantry-style machines have a frame structure that is raised on side support so that the object can be measure or scan. Gantry machines are similar in the construction of bridge-style designs.
- Horizontal hand machines include a hand that supports check, horizontally cantilever with floating vertical support. They are known for strong construction and low power consumption.
They are capable of measuring large envelopes on acceptable accuracy and are mainly used for large workpieces such as auto body parts and welds.
- Articulated arm machine includes an articulate or multi-axis arm. It allows keeping the probe in many different directions. This design is very common for portable machines.
- The cantilever-style machines include a vertical arm which is support by a cantilever support structure.
Sometimes a CMM requires a specific mounting style when joining in a system or mode of operation. These mounting options include:
- Benchtop machines are mount on benchtop or desk. This is the typical feature of most CMM.
- Freestanding machines can support themselves and they do not need to grow.
- Portable machines are devices that can be transfer independently and are not design to be place in bolt or hardware. Handmade machines are a subset of portable devices, which are design to be hand-operated.