t e s t i n g y e s t e r d a y the krautkrämer story krautkramer story.pdf · the krautkrämer...

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T E S T I N G Y E S T E R D A Y

The way it all began.

The Krautkrämer Story

The legendary garageThe history of Krautkrämer begins – asso often in those days - in a garage. It’sthe year 1946: The university of Co-logne, where Dr. Josef Krautkrämer islecturer and Herber t Krautkrämer astudent, is in ruins. The two brotherswant to try and earn some money un-til the university reopens – naturallywith something they know how to dobest: physics. So they hire a garage,set up a laboratory in it, and nail asign beside the door: Dr. Josef andHerber t Krautkrämer, Company forElectrophysics. They hope to get afew orders for the repair or develop-ment of all types of physical measur-ing instruments.

The challengeOne day they are faced with problemsof a different type from industry: theKrupp-WIDIA company is looking for anondestructive test method thatwould help reduce the reject rate oftheir products. This concerns wiredrawing dies made of metal carbidewhich in many cases show blowholesand pores just underneath the materi-al sur face. As these defects are notrevealed till the grinding process, thework done here is quite uneconomicinvolving a lot of wasted time. How isit possible to detect such materialflaws before any further processing ofthe components? X-rays are not suit-able anyhow, they’re no use for de-

tecting even the largest accumulationof pores.

Clearly, this is a challenge for passion-ate physicists like the two Krautkrämerbrothers. Their answer: the develop-ment of an ultrasonic instrument thatoperates according to the through-transmission method - a principlewhich, though already described inscientific publications, had not yetbeen applied successfully in field con-ditions. However it works, but is notthe thing needed because the teststake by far too long. It’s only a sort of”warm-up round” in ultrasonics, thereal breakthrough is yet to come.

1949: the first ”real”Krautkrämer instrumentWe’re in 1949. The Krautkrämerbrothers have discovered the fasci-nating world of echoes as they havefurther developed their idea and builtan ultrasonic flaw detector in whichthe ultrasonic signals transmitted intothe component are displayed on anoscilloscope. It’s true that this instru-ment does not solve the actual prob-lem because, due to unsufficient res-olution, it cannot deliver proof of thedetected porosity just below the sur-face. It’s also true that the disap-pointed customer therefore shelvesthis new development. It’s likewisetrue that this took a good bit of windout of Josef and Herbert Krautkrämer’s

sails since they had used the advancemoney paid but not carried out the or-der. But they did develop an instrumentable to do something else, viz. to non-destructively detect material flaws incomponents made of steel. Nobody atthat time had the slightest idea of thepossibilities opened up by this ”blackbox”.

Not even the Krautkrämer brothersthemselves, although they are con-vinced of their own development. InAugust 1949, a meeting of the VereinDeutscher Eisenhüttenleute - Associa-tion of German Ironworkers – takesplace in Düsseldorf, on which occasionthey aim to present their meanwhile ad-vanced ultrasonic flaw detector – thefirst German instrument of this type,and already a typical ”Krautkrämerproduct” with all the bits and pieces,that means with all the features point-ing the way ahead for the later develop-ment: highly sensitive, high resolution,display of flaws measuring only onemillimeter at a depth of less than tenmillimeters (radio-frequency displaywith a 50-millimeter range), pulse rep-etition frequency up to 1000 Hertz,and portable with its weight of around20 kilograms.

This makes 1949 the year when the ultra-sonic flaw detectors from Krautkrämerwere born.

The beginning of a wonderful(business) friendshipA few hundred people are present atthe meeting in Düsseldor f when JosefKrautkrämer begins to read his papertitled Nondestructive Ultrasonic Test-ing. Herbert Krautkrämer operatesthe projector. When the lights areswitched on again after the per for-mance, only three members of thewhole audience are left. One of themis the head of quality assurance atthe Federal German Railways.

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The people at the German Rail are in-terested. They have a few problemswith their surviving cars and enginesafter 1945. The readiness for serviceis not guaranteed, axle breakage andrail failures are to be expected. X-raydevices, whose introduction has beenpromoted by the German Rail itself, arenot available. In addition, this newmethod presented by Josef and HerbertKrautkrämer involves other promisingpossibilities for easy field application.The German Rail is very soon to beone of the first and, all through theKrautkrämer history, one of the com-pany’s most important customers.

Starting offFor the time being, however, theKrautkrämer brothers are unceasinglytraveling around everywhere in order todemonstrate the usefulness of their de-velopment on site. And it works: it ispossible to use ultrasonics to demon-strate whether there are materialflaws inside a component or not. Ev-ery time a component is identified asdefective using ultrasonics, the de-fect becomes a fact when the work-piece is subsequently cut open. It isthen that another step towards con-vincing people has been taken. Some-times there are discussions as towhether an expensive componentshould really be destroyed in order toconfirm the defect, sometimes ittakes hours until the componentbreaks apart; but the tests are alwayssuccessful.

The ultrasonic instruments are beingcontinuously improved along with theexperiences gathered in the field; or-ders also star t to come in slowly butcontinuously. From January 1951 on-ward, all engines belonging to GermanRail are tested using Krautkrämerequipment; a number of more or lessimportant cracks are detected in theaxles in this connection. Express trainservices can now be continued with-out risks thanks to ultrasonic testing.

A truly portable USIP

left: Axle testing atthe Federal German Railways

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From the garageon tour around the worldThe feeling of starting off changesinto euphoria. Since the university ofCologne has reopened, Dr. JosefKrautkrämer continues his teachingactivities, and Herbert Krautkrämercompletes his studies of physics.They commute between the universityand the garage which is still the com-pany’s headquarters. In the mean-time, this place has become a well-known meeting point for students ofphysics who are infected by the enthusi-asm and become both cheap and effec-tive helpers. At the same time, the com-pany’s activities expand. In 1952, thepoint is reached when the first two em-ployees are hired: Dr. Ludwig Niklasand Dr. Werner Grabendörfer, both ofthem likewise physicists and formKrautkrämer’s first department ”Re-search and Development”. Not thatwe could speak here of any specializedjobs: everybody is still doing every-thing. The first foreign representatives’

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offices of the young company are like-wise already founded in Belgium andFrance in the early 50’s. Representa-tives in almost all European countriesand in numerous countries outsideEurope are added to this during theyears that follow. The triumphal marchof Krautkrämer test equipment aroundthe world cannot be stopped. ”You thinkyou’re the driving force, and it’s youwho are driven by the continuouslygrowing demand from all corners ofthe world” – that’s how Dr. Josef andDr. Herber t Krautkrämer put it 20years later.

Another trade mark:the transfer of know-howWith all the worldwide activities, salesfigures shooting up, growing numberof employees and building activitiesstarting from the mid fifties: from thevery beginning, Krautkrämer is notonly interested in products and in theimplementation of the technically fea-sible. The inspector or test operatorand his experience as well as theknowledge acquired in the field are al-ways incorporated into the work.Looking at it the other way round, it’salso par t of the company’s philoso-phy to impart company know-how tothe inspector. The fact is that the firstmajor successes of ultrasonic tech-nology established that in his workthe user profits from his knowledge ofthe theory of test methods and of theway to handle the equipment. Conse-quently, the first of the monthly trainingcourses titled Introduction to UltrasonicTest Methods is held in the new build-ing on the Luxemburger Strasse in Co-logne’s city quarter Klettenberg as ear-ly as in 1955. Many thousand will fol-low. The participants come from all eco-nomic sectors. Starting from 1956, thecustomer magazine the echo is pub-lished, a forum that has always been,and still is, aimed at presenting sub-stantiated information from the ultra-sonic world. Moreover, a forum thathas accompanied us – also as athank-you to our customers - through50 years of Krautkrämer history.

Up to this very day.

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Reminiscenses of the early yearswith KrautkrämerC. D. Wells, Wells Krautkramer, Great BritainI first became involved with ultrasonictesting in 1952, using Krautkrämerequipment (an USIP 9) about 1954/55.My association with the Krautkrämercompany started in 1957 and so I wasvery much involved in those early pio-neering days. It was pioneering in thesense that it was a completely newtechnology, relatively unknown in in-dustry and often referred to as a“black ar t”. We were all very busy atthat time speaking at seminars, con-ferences and running training coursesas part of the process - “to spreadthe word”.

In those early years a demonstrationof the equipment at a potential cus-tomer, had to start with an explana-tion of ultrasound, piezoelectricityand the two axes of an oscilloscope,before showing its capacity on somefaulty specimens. Those were the ear-ly days of television and to see asmall CRT on a factory floor invariablydrew a small crowd and some wise-crack such as “What won the 3’0clock race today?”!!!

Covering the whole spread of industrywith site work and representation forKrautkrämer, raised many testing andoften fundamental questions and Iwas a frequent visitor to Köln. I foundit a great strength to be able to go tothis “fount of ultrasonic knowledge”with my problems. Having dealt withthe commercial business at the offic-es in the Luxemburger Straße we invari-ably visited “Works II” fur ther downthe road, the restaurant Unkelbach,and there together with one of the DrsKrautkrämer, or Niklas or Grabendörferwould try to solve the latest technicalproblem, leaving all our technical se-crets scribbled on the paper tableserviette!!

In December 1959 I went with JosefKrautkrämer to the institute of Phys-ics in London, where he gave the firstrepresentation of his paper on the DGS(AVG) diagrams for the variation of am-plitude with distance from disc shapedreflectors. The amplitude was mea-sured for the first time in Decibels andthis was also the introduction of the cal-ibrated attenuator to ultrasonic testing.This original work took the “black art”out of echo amplitude and gave ultra-sonic testing a clear amplitude refer-ence unit which was adopted immedi-ately by all the workers in this field. Ibelieve that this was the most impor-tant milestone we have seen in the his-tory of ultrasonic testing.

Those were the days, as the oldieswould say, they cer tainly have givenme many happy memories, lifelongfriends, and I feel privileged to havebeen a part of that “historical” periodof ultrasonic testing, which was syn-onymous with the name Krautkrämer.

The Krautkrämer staff in 1969 with C. D. Wells (first row, the sixth from the right).At the far right, Dr. Josef and Dr. Herbert Krautkrämer.

Yoji Kobayashi, Krautkramer Japan

My first contact with Krautkrämer hap-pened in 1963. At that time I wasworking with a German trading firm inJapan and responsible for importedNDT-products. X-Ray and Eddy Currentinstruments were well known even atthat time, but Ultrasonics was a less-er known factor. Of course, I did notknow anything about this method -and was sent to Germany to gettrained at this company. I remember

Dr. Herbert Krautkrämer being dis-pleased with my non-professionalquestions....

All parties had to learn from each oth-er. Krautkrämer had to learn that thevoltage in Japan was 100 Volt - not115 Volt as in America, or 220 Volt asin Germany - and I had to learn, whatultrasonic testing of materials was allabout.

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Back in Japan I was sent to carry outdemonstrations with the heavy,mains-operated best seller USIP 10.Once I had five of these instrumentsin the boot of my car, when somebodyhit the rear and seriously damaged mycar. The outcome of this story wasthat I had to demonstrate and give in-formation to the police at their head-quarters in Tokyo. Needless to say, upuntil now we have not received any in-strument orders from them...

In 1971 I founded my own company,Krautkrämer Japan Ltd., thanks to thekind understanding and support of

many people at Krautkrämer. Thiscompany now exists for also almost30 years - so as you can see this is apartnership which has been goingsteady for quite some time!

Now I am preparing to join the“Krautkrämer old boys club”. I trustthat the younger generation will fur-ther develop the next half century ofKrautkrämer’s successful history.

Manfred Müller, Krautkramer Forster Española, Spain

The first time I had contact withKrautkrämer was in 1963 – I was incharge of destructive and nondestruc-tive testing at Siaisa in Madrid at thattime. Having demonstrated Krautkrämerinstruments at several customers forsome years, I received the offer to set upa Spanish branch office for Krautkrämerin 1966. That’s the way KrautkramerEspañola was established in the mid-dle of the year 1966.

The first years were very much charac-terized by travelling; we were constantlyaway on business dealing with ultrason-ics. One week ”on the road” at the cus-tomers, one week in Madrid to do thework there – that was the rhythm of ourlife. Free weekends? A rarity.

Nevertheless, we were successful inour operations. The business devel-oped continuously, and in 1971, we

took over representations of other Ger-man companies – for example, of theinstitute Dr. Förster in Reutlingen andthe Tiede GmbH in Aalen. In the courseof this, the name of our company wasalso changed to Krautkramer ForsterEspañola. The staff also grew along. Atthe beginning, the team consisted ofthree persons - a service electronician,a secretary and myself; in 1997, wehad come so far that our staff num-bered 20 persons.

We managed to achieve this boomthanks to our consistent customer-ori-ented work: individual problem solu-tions and a good after-sales service forour customers were always in the cen-tre of our attention. We have achieved inour country that the name Krautkrämeror Krautkramer Forster Española cameto be identified with the term ultrasonictesting (just as stock-cubes and Maggiwere at that time...). What more couldone wish for the image of a company?

Stand at a fair in Madrid in 1967:Manfred Müller (center) talking with theMinister of Industry, Mr. Lopez Bravo.

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Rudolf Brutsaert, the Brutsaert company, BelgiumThe companies Brutsaert andKrautkrämer are united by a really longhistory. It must have been in 1951 whenmy father heard of Krautkrämer for thefirst time – to be more precise, the occa-sion was a contact with a German manu-facturer of medical instruments: thismanufacturer had just received an orderfrom Dr. Josef Krautkrämer to make aseries of printed circuit boards for an ”in-dustrial ultrasonic instrument”. I remem-ber that my father talked about it athome and that he thought about possi-bly accepting the representation of thisinstrument – whatever it might exactlybe - in Belgium. A little later, all uncer-tainties as to the type and significanceof this ultrasonic instrument were dis-pelled; and as early as in 1952, the offi-cial cooperation between Brutsaert andKrautkrämer started.

This decision turned out to be just theright one soon enough. The break-through with the new method was al-ready achieved with one of the first cus-tomers – the Kuhlmann chemicalworks. All of a sudden, it was possibleto measure wall thicknesses on sulphu-ric acid cisterns nondestructively andquickly! As this news very soon reachedthe customer‘s headquarters in Paris,the future of Brutsaert was sealed: allother activities were stopped, ultrason-ic testing was immediately in the centreof attention. And so it came that a lot ofpioneer work was done in Belgium andFrance in the years that followed.

This shows that Brutsaert was ”oneof the party” to make the ultrasonicmethod known and to disseminate itin Europe almost right from the begin-ning - and thus likewise looks back onalmost 50 years of company history.

left: Rudolf Brutsaertin the fall of 1960 on theSeverin bridge in Cologne.

below: Rudolf Brutsaert,this time without hair,approx. 1970,at Krautkr mer inCologne-Klettenberg

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All safe and (ultra)sound,play it safe with ultrasoundThe past and present of ultrasonic test applications.

The history of materials and qualitytesting has always been a quite ”in-conspicuous” one. It’s in the natureof these things. However, if we con-sider that in many respects materialtesting is the very thing that makeslife safe, it should have deserved abit more attention. Sad enough, it’smostly not talked about unless it hasnot been carried out - or not been car-ried out properly - and damages oreven accidents could not be prevent-ed. The result that documents noflaws is seldom worth mentioning.We would therefore like to seize thisopportunity and for once do some-thing for it in order to devote to ultra-sonic testing – largely unnoticed inpublic – the space due to it. A few ap-plication examples are meant toserve this purpose, chosen from thegreat variety of field applications. In thisregard, the history of Krautkrämer is in-separably connected with the ever in-creasing possibilities of solving testproblems over the course of the past50 years.

Nothing done by halveswith semifinished productsMetal sheets or plates, tubes, rods orbars, billets – a great variety of fabricat-ed materials are ultrasonically testedbefore being further processed or fin-ished; this often enables optimizing themanufacturing process itself. The first”case” of the Krautkrämer brothers –blowholes or pores lying close belowthe material surface in wire drawingdies made of metal carbide – alreadyinvolved the task of reducing the rejectrates within the manufacturing process,that means of detecting material flawsas early as possible during the workingprocess. It turned out very soon thatthe testing of semifinished productswould be a domain of the automatictesting because it deals with largepiece numbers having identical geome-tries and with the integration into the

production process. So it came that anautomation project for plate testing in arolling mill was already worked on in the50’s. The idea developed at Krautkrämerof coupling via free water jets inthrough-transmission technique in or-

der to avoid probe wear contributed tothe construction of the first heavyplate testing machine. As early as in1960, a tube testing machine usingrotating probes was developed, thefirst of its type.

top: Mechanized weld testing using USIPbelow: Heavy plate testing using free water jets

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Automatic testing machines have al-ways been and will always be designedin close cooperation with the end user.A recent example includes the technicalprogress on the one hand, but on theother hand, it also shows that the prin-ciple hasn’t changed: this system per-forms a 100 % volume test on a wirehaving a maximum temperature of1000 °C, and it does it at rollingspeeds ranging from 10 to 45 m/s.Both internal flaws and surface flawsare detected and evaluated ultrasoni-cally – in this case using so-called rodwaves which are excited electrodynami-cally in the test material, that meanswithout any couplant.

Smooth transition:weld testingIn the early 50’s, the inspection ofwelds was already a matter of greatinterest to the industry. Welds alwayswere and still are something thatcause problems, for example in theindividual components of chemicaland power plants, and also in tankconstruction, shipbuilding and bridgeconstruction. Inspection of welds wasalready prescribed in those days dueto the obvious safety relevance. Thenewly appeared ultrasonic methodstepped beside the previously usedradiographic method and comple-mented it as it could be carried outfaster and without expenditure for rayprotection.

For the Krautkrämer brothers as pio-neers in the field of ultrasonic testing,weld testing was of course somethingthey took up at once: in 1952, aUSIP 5 was already used for testingthe large-diameter, longitudinallywelded pressure pipes of the Schluch-see power plant in the Black Forest.

At this stage, the position of eachflaw had to be determined by measur-ing and calculating; location aids werestill unknown. A true evaluation offlaws with reference to their position,type and size – essential factors interms of any possible impairment ofthe weld – wasn’t possible tillDr. Josef Krautkrämer developed theDGS diagram in 1958. In modern in-struments, such as the USLT 2000 orthe USM 25, DGS diagrams and trigo-nometric functions (display of soundpath, projection distance and flawdepth) for flaw evaluation are integrat-ed into the instrument by means ofsoftware.

The way is clearfor the German RailThe first truly usable ultrasonic flaw de-tector in Germany, which the Krautkrämerbrothers had developed in 1949, wassuitable for detecting material flawsin components made of steel. One ofthe first beneficiaries of the newmethod was the Federal German Rail-ways who had big problems after

1945 with the axle breakage on ex-press engines due to war damage.Par t of the wheelset axles showedmore or less large cracks that couldnot be recognized from the outside. Itwas possible for the first time to usethe ultrasonic method to nondestruc-tively detect the par tly extensive fa-tigue fractures in the wheelset axles.The extent of the cracks could be esti-mated with astonishing accuracy onthe basis of the flaw echo sequence.A systematic test of all locomotive en-gine wheelsets was carried out, onwhich occasion a lot of engines had tobe put out of service. This was theonly way to ensure that the train ser-vice could be safely continued.

The guaranteed safe operation ofmeans of communication and trans-por tation is still one of the most im-por tant tasks of ultrasonic testing to-day. Even if manufacturing technologyhas advanced fur ther and further –there’s always a risk left due to mate-rial defects, unrecognized errors andflaws produced during the manufac-

top:Weld testing

left:Ultrasonic testing of anaxle shaft

right:DGS scale as of 1967;developed on the basis ofthe General DGS Diagramfrom 1958

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turing process, unforeseeable stress-es, or a combination of several caus-es which cannot be fully excluded bythe usual safety precautions. Shaftsand axles of trains and trams orstreetcars must continue to be sys-tematically checked for any fatiguecracks at regular intervals.

Not a bad move:NDT on all routesUltrasonic testing plays a part in safetyand reliability in many different wayswithin the automotive industry - andagain, it’s almost unnoticeable in thebackground. Who could really claim thathe knows that valves, pistons, cylinders,crankshafts and many other items arenot used unless they have passed amaterial test? Dreaded breaking of ax-les and cardan shafts, spring and valvefractures of the past are long gone andonly very seldom happen today.

A particularly high safety relevancemakes ultrasonic testing indispensablein the aircraft industry as well. Rivetedjoints and bondings, for example at crit-ical transition points between fuselageand wing, or at the wing edges, landinggears, turbine blades, vital parts of en-gines – these are all objects liable to besubjected to the most thorough ultra-sonic inspection.

Though laid on thick: justthe remaining wall thicknessesThe first ultrasonic gauge, exclusivelymeant for measuring wall thicknesses,was developed by Krautkrämer in1967. The wall thickness measure-ment became especially important – forexample on pipelines operated by refin-eries – in terms of safeguarding envi-ronmental protection. A reduction of thewall thicknesses, for example due tocorrosion, can lead to disastrous dam-ages and accidents here. The ultrason-ic method has the special advantage ofallowing the wall thickness measure-ment to be carried out on objects whichare only accessible from one side. Wallthicknesses which are too low can bedetected in good time using systematicultrasonic checks. In addition, down-times and consequently also cost andtime expenditure can be reduced.

Thickness measurements are carriedout on various test objects subject towear: pressure vessels, gas cylinders,

storage tanks, receptacles for chemi-cal processes, material handling sys-tems and pumps, facilities in ship-building and structural steelwork.When the D-Meter thickness gauge,no bigger than a camera, was intro-duced by Krautkrämer in 1971, it sig-nified a spectacular improvement. Itwas spectacular because it was impor-tant in connection with plant supervi-sion tasks, for example within thechemical industry, that small and light-weight equipment be available for the”comprehensive climbing exercises”.The latest Krautkrämer thickness gaug-es only weigh around 250 grams, andthey offer even more advantages. Forexample, they enable precision wallthickness measurements even throughcoatings, without having to remove thecoating first.

Tales of layersCoatings are not only important in wallthickness measurements. In manybranches of industry, the assessmentof the coatings themselves is an inte-gral part of quality assurance. What’sat stake here is also the exact controland monitoring of coating materialquantities, which in the end aims atmaterial saving and cost reduction. Themeasurement of coatings is requiredfor example at automobile-body worksfor the paint coating layers on metalsheet base material, or within the woodworking industry for sealing varnish orprotecting lacquer layers on woodenbase material. These applications arenowadays also part of ultrasonic testrepertoire, and the innovative technolo-gy from Krautkrämer is decisive here. Inthis regard, it was possible to imple-ment an ultrasonic measurement reso-lution – in the micrometer range - whichwas previously unattained.

Play it safe with ultrasoundIn the course of the 50 years ever since1949, during which time Krautkrämerhas been active in ultrasonics, manythings have changed. An ever increas-ing number of test problems could besolved, more and more new require-ments from the field could be met.There were quantum leaps in technolo-gy, such as digital technology or theminiaturization in electronics, whichhas led to the present-day systemswhich are ultrasonic instrument and PCin one and fit into a laptop. Somethinghas never theless also stayed as ithas always been: material flaws can-not be excluded, the risks due tothem still exist, for example fatiguefractures due to cracks are nowadaysjust as topical as they were in 1949when the Krautkrämer brothers start-ed to deal with this problem. The an-swer to the question concerning apossible solution for all these prob-lems referring to materials testingand quality assurance is today thesame as it was yesterday: play it safewith ultrasound.

The application examples mentioned weretaken from specialized literature, e. g: KlausEgelkraut; Werner Grabendörfer: Ultraschall-Prüfung in Deutschland. Erinnerungen an dieAnfänge (Ultrasonic testing in Germany. Rem-iniscences of how it all began). Minden 1993

Wall thickness measurement:two are better than one.

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