VOL. 4 September ISSUE YEAR 2003
in Vol. 4 - September Issue - Year 2003
Dedicated to Residual Stress Analysis!
Michael Brauss, President of Proto Mfg. Ltd.
iXRD Portable Residual Stress Analysis System
LXRD Laboratory Residual Stress Analysis
LXRD-GR Gantry Robot
iXRD MG40 Portable Residual Stress Analysis System
Interview with Michael Brauss, President of Proto Mfg. Ltd in Canada
MFN continues its interview series, this time with Michael Brauss, the President of Proto Mfg. Ltd.. This company is a world leader in the measurement of residual stress using XRD. Some examples of applications include stress measurements on suspension bridges, ships and submarines, natural gas pipelines, as well as automotive and aerospace components.
(?) MFN: Proto Manufacturing first appeared in our magazine in 2002, is Proto new to the peening world?
(!) M.B.: Peening is, in great part, a residual stress management technique and very early on in our residual stress analysis product and service development cycles we were asked to characterize the resultant surface and subsurface residual stresses from various peening, blasting and finishing processes. We’ve been providing systems and services in the characterization of residual stress for over 21 years now and every year we get a growing and significant volume of business involving the characterization of residual stress due to peening and grit blasting. I like to think that we’re keeping our approach to peening fresh by continuing to develop faster and better ways to characterize the residual stresses it leaves behind
(?) MFN: What roll do you see x-ray diffraction playing in the metal finishing world?
(!) M.B.: Well, based on just some of our instrument and application development work that we have accomplished in the last few years, x-ray diffraction is going to make a very exciting and perhaps significant contribution to the metal finishing world. In Aerospace for example: on the instrument level, we now have developed (Patents Pending) equipment that can quantitatively characterize residual stresses inside small diameter bores and other small stress concentration features such as are found on aerospace propulsion components. These are the very features that are typically peened. On the application side we now can quantitatively “fingerprint” the residual stress quality of a product at birth and track the LCF (Low Cycle Fatigue) life on that same component by monitoring the evolution in residual stress at key locations with cycles, removing it from service for reworking or retirement, before catastrophic failure can occur (Patents Granted). If you put both of these developments together it may become possible for OEMs and others to get LCF life “credit” for shot peening or some other surface modification based on residual stress. Today, credit is not given for shot peening, yet ironically some products would not achieve design LCF life without it. One of the main impediments has been the lack of quantitative residual stress characterization in these critical locations. Well, we can provide that information now. Other industries such as automotive, power generation, medical implants are also managing residual stress more and more and need the non-destructive, quantitative stress data that XRD can provide.
(?) MFN: Do you see x-ray diffraction replacing the Almen test strip?
(!) M.B.: No, not for some time as practices and standards are in place and besides they actually provide different information. The x-ray diffraction method is a fast and very direct method which measures the resultant residual stresses on the processed part at the exact location in question. We should also not forget that many parts already have some residual stress state in them as a result of the processing applied to them prior to peening. The residual stress history is additive to the resultant residual stress. As the suppliers of metal finishing and their respective customers learn of the capabilities of today’s x-ray diffraction equipment relative to the non-destructive quantitative characterization of residual stresses, the additional information will find uses in process optimization, avoidance of over processing and quality certification, thus reducing costs and adding value. What a great return on investment!
(?) MFN: How did Proto get involved with x-ray diffraction and residual stress?
(!) M.B.: Actually Proto Manufacturing has been in business since 1967. The primary product at that time and for many years thereafter was Automated Non-destructive Test systems for the automotive industry. These were typically based on a combination of eddy current, ultrasonic and dimensional measurement technologies. The company developed and honed the skills to design, fabricate, program, integrate and service complicated custom automation and testing systems. The discipline of designing these systems to run 24/7 with minimal downtime and the high output cycle times (typically 3-7 seconds) imposed by “Detroit” are still reflected in our design philosophy today. In 1981 I came to the realization that many of the problems that we were being asked to test and sort for, had at their origins, a direct or indirect association with residual stress. I thought that if I could measure residual stress there would be the possibility of intercepting these problems earlier in the processing stages before too much value had been added, thus saving the manufacturer a lot of money. So I began an investigation into all of the various methods which where then available to characterize residual stress. I was looking for a reliable technique that I could integrate into inline automated systems. The only technique that I found which offered even the slightest promise of a repeatable quantitative measurement as well as being a non-destructive measurement was x-ray diffraction. The equipment available at the time however was rather large, heavy, slow, complicated to operate and unfortunately not very robust. The residual stress measurements themselves were also subject to some questions as different results were often reported by different operators and different instruments. My vision became to address these problems and to bring residual stress characterization out of the laboratory and to the production process line and beyond. It seems that to a large extent, we have been successful in achieving that original vision.
(?) MFN: What differentiates Proto from other manufacturers of residual stress measurement equipment?
(!) M.B.: I would say that it is a number of things. Our vision was never limited to the status quo. For example, it was quite clear early on that the practice of measuring coupons cut from a structure or component was not in many cases providing very useful data while costing the value of the part. We wanted to measure the component or structure intact so that the value could be retained and the residual stress trends tracked. We have a holistic approach to residual stress characterization. This is reflected in our “turn key” product and accessories line which ranges from very portable to laboratory systems to large robotic systems to inline systems. In addition we have a very aggressive research and development program which has yielded a steady flow of very exciting innovations. I would also add that many of our developments have been the result of carefully listening to our customers’ needs and responding with solutions. Another interesting difference is that I believe we are the only firm that actually offers custom designed XRD systems in addition to our standard model line.
(?) MFN: You mentioned exciting innovations. Can you provide some examples?
(!) M.B.: Sure, I am particularly pleased with how our automated stress mapping has evolved. It has really generated a lot of extremely useful data for our customers that they find very easy to interpret and apply. Another one is our iXRD “Combo” TM residual stress analysis system, which has provided a unique level of versatility to our customers. We also recently developed a unique and very small x-ray tube for use in our goniometers opening up a host of additional access possibilities.
(?) MFN: X-ray diffraction residual stress characterization has been around for a long time. Why is it not used more?
(!) M.B.: Historically it was primarily in the laboratory domain where it was an esoteric instrument that required a lot of skill, patience and training to achieve results. Then there was the measurement time factor. Imagine perhaps achieving only two or three measurements a day. Combine this with an unsophisticated analysis and you have a very expensive and inconclusive measurement. For many people this is still what they think of when you mention residual stress measurement by x-rays. It has only been relatively recently that we have had instruments that could provide enough measurements where they were needed, fast enough with sufficiently high levels of confidence to really make an impact on problem solving. The cost of measurement has never been lower, the speed never faster and the integrity of the measurement never better.
(?) MFN: What is the future of x-ray diffraction residual stress analysis?
(!) M.B.: Well, who can say what the future holds? I think that because of the very elegant directness of the x-ray diffraction technique it will be with us for some time to come and we’re certainly not finished with our innovations. It is only now that XRD RS is really coming into its own. Perhaps I could sum it up this way with confidence, enthusiasm, and a little bravado. The future of x-ray diffraction residual stress analysis is Proto.
We at MFN would like to thank Mr. Michael Brauss for this interview.