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History of NDT-Instrumentation Prof.Dr.-Ing. Volker Deutsch, Wuppertal/Germany Contact

History of NDT-Instrumentation

For more than 50 years I am personally closely connected with Nondestructive Testing (NDT). During this period after World War II the emerging modern industry needed more and more testing equipment for the production of flawless components. Therefore, instruments for NDT were developed, produced in quantities and continuously improved. I met most of those persons working in this modern industrial field not only in Germany but also in other parts of the world. And I did not meet them only: I discussed, argued, cooperated and fought with many of them. Therefore I was asked by my students, collaborators, colleagues and friends to write down what I still remember.

I am aware of the fact that such a task can never be completed. Therefore I apologize to all those for excuse who are not mentioned or have quite different memories. In addition I want to point out that I name only those companies which have an considerable export and are not only working in one or few countries.

The first NDT-method coming into industrial application was the X-Ray Technique

X-Ray Technique

Already 1895 Wilhelm Conrad Röntgen discovered "An Unknown Kind of Radiation" which were named in all German speaking countries after him. In his first publication he described all effects including possible flaw detection. At that time industry did not yet need this invention but medicine did. So medical equipment was developed, used and produced in quantities. The only effect Röntgen could not foresee was that X-rays harm human health. Before radiation protection became introduced, many persons lost their life.

Early technical X-ray applications in Germany were realized by Richard Seifert around 1930. He improved medical equipment, cooperated with welding-institutes and built up the small company founded by his father to a world-wide respected name: Richard Seifert Hamburg 13. He got competition by Siemens and C.H.F. Müller, part of the Philips-organisation, who already worked in the medical field. Seifert died in 1969, but his company kept leadership in technical X-ray-application under the direction of his youngest daughter Elisabeth Samusch.

Radiation testing can also be carried out with radioactive isotopes. This was discovered by Mme. Curie. She, born as Maria Sklodowska in Warscaw received the Nobel-prize for physics in 1903 together with her husband Pierre Curie and Henri Becquerel. This was the second award after Röntgen's in 1901. Also radioactive isotopes were initially used for medical applications. In Germany Rudolf Berthold and Otto Vaupel applied them after 1933 to welded joints.

After World War II Arturo Gilardoni in Italy, Drenk and Andreasen in Denmark developed X-ray-equipment, Kurt Sauerwein portable isotope-containers in Germany.

Magnetic particle crack detection

Magnetic particle crack detection was executed even earlier than X-ray testing. The Englishman S.M. Saxby already in 1868 and the American William Hoke in 1917 tried to find cracks in gun barrels by magnetic indications. Real industrial application was made by Victor de Forest and Foster Doane after 1929. They formed 1934 a company with the name Magnaflux in 1934, famous world-wide until today.

The first European who built a magnetic particle crack detector was an Italian in 1932: Giraudi. His machine was named "Metalloscopio".

In Germany Berthold and Vaupel applied MP-technique to welded constructions. Their equipment was produced by Ernst Heubach. Bruno Suschyzki sold this equipment. He invented swinging field MP-testing.

In Berlin too E.A.W. Müller designed MP-testing machines for Siemens. In Prague the Seifert-representative Karasek began with similar production.

After World War II Wilhelm Tiede, a former Seifert-employee, started his own company in Southern Germany. Through the Seifert-organisation he had connections to Karasek who emigrated to Brazil in 1948 after the communistic revolution in Cechoslovakia. There he continued production of MP-machines.

Starting with dry-powder methods two more companies entered this market in the late Fifties: Karl Deutsch in Germany and CGM (Carlo Gianni Milano) in Italy.

Penetrant Testing

Penetrant Testing started also in second half of 19th century. The first people who applied the "Oil and Whiting"-process for crack detection to railway-components are unknown. The method was replaced by the upcoming MP-technique. Just before and during World War II the fast growing aircraft-industry used more and more nonmagnetic light metals, which could not be tested with MP. So independent of each other Magnaflux together with the brothers Switzer in USA, Brent Chemicals in GB, Adler (Blohm & Voss) and Klumpf (Junkers) in Germany started production of fluorescent and dye penetrants.

Eddy Current Testing

Eddy Current Testing has old roots as well. The French Dominique Arago discovered the phenomenon during the first half of 19^th century. The principle was explained by and named after Leon Foucault. Many proposals for application were made until Friedrich Förster brought this method to industrial use. He worked since 1933 for the Kaiser-Wilhelm-Institute and there he developed instruments for measuring conductivity and to sort out mixed-up ferrous components. In 1948 he founded his own company in Reutlingen which grew up with eddy current testing (ET). Institut Dr. Förster became market-leader worldwide for many decades.

In Sweden Anders Arnelo started similar developments at Svenska Metalverken (SM). He solved the problem to test hot wires and invented the pre-magnetization for ET of ferritic bars.

Other companies followed later: Magnaflux, Hentschel, Law and Zetec in the USA, Rohmann and Prüftechnik Busch & Partner in Germany, Bergstrand in Sweden and Hocking in Britain.

Ultrasonic Testing

came latest into industrial use. The methods of exciting ultrasound were discovered already in 1847 by James Precott Joule and in 1880 by Pierre Curie and his brother Paul Jacques. Not earlier than 1912 a first application was proposed after the "Titanic" had sunk. The Englishman Richardson claimed the identification of icebergs by ultrasound in his patent applications. In France Chilowski and Langevin started their development to detect submarines by ultrasound during World War I.

In 1929 the Russian Sokolov proposed to use ultrasound for testing castings. In Berlin Pohlman realized in 1937 an image-cell to indicate the differences of ultrasound-energy similar to a X-ray image-screen.

The detection of laminations in plates and fine non-metallic inclusions in hot-rolled profiles became necessary during World War II. The already existing NDT-methods - X-rays, MP, PT and ET - were unable to solve these problems.

Industrial use of ultrasonic testing started simultaniously in three countries: USA, GB and Germany. The key-persons, Floyd Firestone, Donald O. Sproule and Adolf Trost had no knowledge of each other as they worked strictly in secret. Not even their patent-applications were published. Sproule and Trost used transmission-technique with seperate transmitter- and receiver-probes. Trost invented the so-called "Trost-Tonge". The 2 probes were contacted on opposite sides of a plate, held in same axis by a mechanical device - the tonge - and coupled to both surfaces by continuously flowing water. Sproule placed the 2 probes on the same side of the workpiece. So he invented double-crystal probes. But it has to be mentioned that he used this combination also with variing distance from each other. Firestone was the first to realize the reflection-technique. He modified a radar instrument and developed a transmitter with short pulses and an amplifier with short dead-zone.

Sproule and Firestone found industrial partners for their instruments: Kelvin-Hughes and Sperry Inc.

In Germany 1949 two persons received information about the Firestone-Sperry-Reflectoscope by publications in technical papers: Josef Krautkrämer in Cologne and Karl Deutsch in Wuppertal. Both started developments - without knowledge of each other. Josef Krautkrämer and his brother Herbert were physicists, working in the field of oscilloscopes. They could develop ultrasonic instruments alone. Karl Deutsch, a mechanical engineer needed a partner for the electronics and found him with Hans-Werner Branscheid who had got some technical experience in radar-technique during the war. Within only one year both young and tiny companies could present their UT-flaw-detectors, starting a competition still existing today.

Later on more UT-units came on the international markets: Siemens and Lehfeldt in Germany, Kretztechnik in Austria, Ultrasonique in France and Ultrasonoscope in Britain. They all stopped their production before the 70-ies, Kelvin-Hughes also stopped at the same time, Sperry was later renamed Automation Ind., around 1995.

Krautkrämer became world-wide market-leader in the early 60-ies and has kept this position until today. Besides Karl Deutsch new names came up: Nukem in Germany, Panametrics and Stavely (after Sonic and Harisonic) in USA, Sonatest and Sonomatic in GB, Gilardoni in Italy and Mitsubishi in Japan.

Today more than 50 companies are active in industrial NDT. They are still working under strong competition to the benefit of their customers on their way to improve the quality of industrially produced parts.

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