Eliminating chatter through vibration analysis

Aug 6, 2021 | Springs & shock absorbers

Vibration is all around us. In fact, to the untrained ear, vibration might seem to be part and parcel of the manufacturing environment. To some extent, that’s true – vibration is a common by-product of the rotating tools used in milling – but to machine specialists, vibration can lead to chatter and be the cause of poor-quality parts and excessive cycle times.

In order to avoid chatter and eliminate its impacts on performance, including increased tool wear and poor surface quality on components, machine operators spend a significant proportion of their time determining the ideal setup of individual jobs. This approach often centres around trial and error tactics – from reducing speed and adjusting feed rates through to varying axial and radial depths of cut.
This process takes time, but it has always been worth the investment, with the ultimate goal to extend the life of tools and produce more high-quality parts in less time.
In milling environments, more vibration generally means more problems – and the greater the need for adjustment in speed and feed in order to protect parts and setups from failure. Key to overcoming this challenge is vibration analysis – the process of gathering information about vibration which informs the selection of optimal, stable speeds and feeds when machining parts.
Monitoring machine and tool condition
By monitoring the vibration of tooling and machinery setups, manufacturers can avoid unexpected machining trouble and improve accuracy and output quality.
To achieve this, vibration analysis has four key principles – time domain, frequency domain, joint domain and modal analysis – each of which provides specific information on the working conditions and features of the vibrating part.
Time domain, for instance, measures the amplitude of a vibration signal. Alone, this can make it difficult to identify where the amplitudes happen and, subsequently, isolate and calibrate machines appropriately.
That’s where frequency domain comes in, looking at each of these signals – or waves – at set points to understand how its amplitude changes at distinct frequencies. As many vibration-related challenges occur at specific frequencies, its cause can be better identified based on variations in amplitude at certain frequencies, making these two principles of vibration analysis essential – both of which are paired through the third principle, joint domain.
Finally, modal analysis takes into account the natural frequencies of vibration based on the structural materials of the setup, the machine and the workpiece. In practice, this creates a baseline against which the vibration analysis can accurately identify when, and to what extent, a tool setup and machine are outside of the desired calibration for a specific job.
By carrying out a vibration analysis, machine operators are able to identify the optimum speed for a particular job, using a specific setup on a specific machine.
Now, with MSC MillMax – the milling parameter selection tool from MSC – it is possible to measure vibration frequencies and optimise setups in a matter of minutes. By equipping operators with accurate insight, setup and cycle times can be reduced, efficiency enhanced and quality of output heightened.
MSC MillMax® measures the frequency of each tool and, in almost real-time, displays the results on a digital dashboard which calculates the precise, stable speed, feed rate and width and depth of cut to maximise performance. Alongside this, the system determines the best speeds for surface finish and accuracy.
To discover the full benefits of MSC MillMax, visit: https://www.mscdirect.co.uk/MSCMillMax/


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