We have a CMM Machine, but what exactly is it?
A CMM (or Co-ordinate Measuring Machine) is a device that measures the size and shape of a physical object (in our case the bespoke component parts manufactured) through the use of a probe which touches the surface of the object or, on some more complex machines, uses lasers and sensors.
The probes or sensors can be manually positioned by an operator, who uses a control pad to move the probe to the desired point on the part; or the CMM can be pre-programmed to automatically detect the component on the bed.
This then maps out the co-ordinates to create a 3D model of the component, with dimensional accuracy, which can be directly compared to the original 2D or 3D CAD drawings.
On some CMM machines, like on our model, you can load the CAD model into the program, so that once mapped out, the CMM will automatically tell you if the part being tested is within tolerance to the drawing.
Advantages of using a CMM
- Reduces human error – Although we would all like to think otherwise, humans can make mistakes. Compared to using calipers and verniers, which involve a person physically taking the measurement by hand, the advanced technology increases the accuracy and reliability.
- Increases checking speed – A CMM, when compared to checking each individual measurement by hand, is a lot quicker so can be a more efficient way in passing off component parts.
- CAD Analysis – The CMM can be loaded with the CAD model of the part – the probe can compare the physical parts on the machine directly to the CAD model and automatically analyse whether the part conform to the drawing.
- Future proof – The hardware itself, if maintained and looked after correctly, is guaranteed to last a number of years. On top of this, the machine can be upgraded through software updates, rather than having to buy a new machine every time.
Disadvantages of using a CMM
- Initial setup costs – The price of the machine itself, plus the required initial programming and setup, leads to a high initial outlay on cost
- Limited standardization – There are hundreds of manufacturers and models of the machines, and likewise various pieces of software that can be used to program them. It is difficult to interchange between different machines as the models are not always cross-compatible.
- Maneuverability – Due to the size and weight of the machines, it is often difficult for them to be moved once in-situ as most models require compressors and ventilation to also be installed. If you were to relocate offices, or just wanted to move around the machines on your shop floor; it would be difficult to do so.