Frequently asked questions
Wondering something about quality control or stress testing? Check first here below or elsewhere on these pages if your question is already answered. If not send us your question, e.g. by Contact form , and we are happy to answer you here or privately.
We have no grinding burn?
If you have hardened parts that you grind, you can make grinding burns. Maybe you need not to control the grinding burns if your parts are not primary important for you or for your customer.
What do I need to begin the Barkhausen measurements?
Minimum instrumentation you need is a Rollscan and a sensor. We recommended to invest for ViewScan Data Acquisition software and a simple component handling fixture or a stand. They improve the repeatability of measurements and make the measurement cycle easy.
How often should I measure?
The frequency of measurements depends on your need. You can make a few measurements in the laboratory or you can measure all the parts of your production. You can measure a single part, every fifth part ... or every part. You can measure all the surfaces of the part, every fifth part, in the beginning of you process ..., etc.
How long is the measuring time?
It can vary from 0.2 s up to 10 minutes. The time depends on your needs and the shape of your part.
How can I set the rejection limits?
Rejection limits are determined experimentally.
How can I compare the results?
In the beginning it is good to use the Barkhausen method together with X-ray diffraction. Barkhausen sensor can be used to scan quickly large areas. The biggest changes can be measured by XSTRESS 3000. It gives value of residual stress and FWHM (Full width half maximum) that correlate to the hardness on the part surface. Nital etching is a comparable method as well.
Is the Barkhausen method better than the Nital etching method?
Both methods are excellent for finding grinding burns. Results measured with the Barkhausen method can be saved and printed for later use. The Barkhausen method is sensitive for residual stresses. The Barkhausen method does not use unhealthy chemicals.
Do we need other methods if we begin to use the Barkhausen method?
Yes - The Barkhausen method is like a hardness tester. Both methods add to your knowledge of your product but neither is able to tell you everything about your parts.
Can we find the cracks by Barkhausen method?
The Barkhausen method is not a crack detection method. The Barkhausen method does see residual stress changes that are common near a crack.
Can we correlate the Barkhausen unit to test the residual stress or hardness?
At the moment our Rollscan units do not support this feature. If it is important to you, contact our sales persons for the development status.
How can I get the first experience of the Barkhausen method?
You can contact Stresstech Group companies or Stresstech Group representatives. You can find their names in the page Representatives under Contact Us.
Can somebody make the Barkhausen and X-ray measurements for us?
All the Stresstech Group companies can make measurements for you by Barkhausen or X-ray method. Contact the companies for a measurement service quote.
Do you have patents for the Barkhausen and X-ray equipment?
Where can I use the Barkhausen method?
You can use the method in the laboratory or on the shop floor. We manufacture sensors for single measurements up to fully automated inline systems.
How can I separate stress and hardness?
You cannot separate from Rollscan signal if it is caused from stress only, from hardness loss only or from both. For grinding burn detection this does not matter at all! In a grinding burn, always microstructure changes go together with stress changes. Rollscan will pick up these changes and display a signal increase. Grinding quality can be monitored very easily this way.
What type of parts can you measure?
Mainly we can measure all the same parts that you can grind.