Prof. Dr. Techn Max Kurrein

(1878 - 1967)

After Schlesinger, Max Kurrein held the chair for machine tools and production plants. He is one of the most important industrial engineers of the Technical College in Berlin. His areas of research and teaching included industrial and military work, working and measuring tools, material testing and precision mechanics manufacturing . Max Kurrein, as an outstanding man of science, was - in much the same way as Georg Schlesinger - subject to national-socialist agitation even prior to their obtaining power in 1933. The NSDAP attempted to wield its influence as early as 1932 in the Prussian Ministry of Education and Cultural Affairs in order to oust Kurrein from his post at the Technical College. In mid 1933 the NSDAP raised an interpellation at the Prussian Parliament, in which the ”Jewish Professor Kurrein” was accused to have, as part of his duty as a consultant to the highest German court, the Reichsgericht, decided against his better judgement in favour of the American Gilette company. His sacking from the technical college followed in the summer of 1933. He successfully emigrated to the Palestine in 1934 after police had held him temporarily in ”protective custody”. His emigration was a result of the Hebrew Technion in Haifa appointing him to set up an industrial engineering faculty. The technical education which he accomplished at the new faculty is comparable to the achievements of Redtenbacher, Zeuner, Karmarsch, Bach, Riedler, Schlesinger and others at German colleges.

Max Kurrein was born on 29 April 1878 in Linz, Upper Austria. His academic parents, Adolf and Jessie Kurrein, belonged to the haute bourgeoisie. His mother, Jessie Kurrein (born 1849 in Broadstairs, England, deceased 1934 in Vienna), née Loewe, was the daughter of the orientalist and diplomat Dr. Louis Loewe (born 1809 in Suelz, deceased 1889 in London) . Loewe had studied in Vienna and Berlin prior to moving to London in 1833. He undertook many journeys to Egypt and dedicated himself to the deciphering of inscriptions in Theben, Alexandria and Cairo. At the same time he studied oriental languages, amongst them Persian, Turkish, Caucasian and Nubian as part of his archaeological numismatic investigations. As expert and translator he finally became personal secretary to Sir Moses Montefiori in Damascus . Louis Loewe held the post of director of the oriental department of the Duke of Sussex’ library from 1839 to 1856 and was vice-chancellor of the Jew’s College in London from 1856 to 1858 .

Max Kurrein’s father was the chief Rabbi of Linz, Dr. Phil. Adolf Kurrein, soon to become chief Rabbi of Teplitz. Adolf Kurrein (born 1848 in Trebitsch, Moravia, deceased 1919 in Teplitz), had studied history, indo-Germanic languages and mathematics at the University of Vienna and had the doctor’s degree conferred upon him in 1871. After he had attained his Rabbi diploma in 1872 he became Rabbi in St. Pölten. In the following year the family moved to Linz, where Max, the first of five children, was born . In 1881 they moved to Teplitz/Schönau. Adolf Kurrein published numerous papers on the Jewish situation, actively supported Theodor Herzl's plans and was delegate of the first Zionistic congress .

After their son Max completed his studies at the humanistic grammar school in Teplitz with distinction he went to the German technical college in Prague to study engineering science in 1896. At the young age of 22, in the year 1900, he became a fully fledged engineer. In addition to his assistantship at the University of Brünn, he completed his PhD at the University of Prague in 1904 to become a doctor of ”technical science” . The subject of his PhD, ”Structural Changes in Ingot Steel under Mechanical Stress” , was a precursor to one of his main research subjects later on: mechanical metallurgy and metallography. He lived in Birmingham, England, from 1905 to 1909, where he worked as technical and chief designer for W.T. Avery. In the following two years he worked in Düsseldorf as chief engineer in an experimental department for machine tools . In 1911 he moved to Berlin and became permanent assistant at the Technical College in Charlottenburg. In the academic year 1913/14 he was appointed engineer at the experimental chair for machine tools and factories and it was not before long that he became their chief engineer.

Max Kurrein’s name is closely linked with the history of experimenting with machine tools. This area experienced a specially active period prior to the first world war. In 1912 Schlesinger had the facilities improved and enhanced the technical equipment. Moreover, he had Kurrein working together with Otto Rambuschek, who had been chief construction engineer of the experimental department since 1906. Kurrein habilitated in 1913, which enabled him to become a lecturer from the following winter semester onward. Georg Schlesinger, whose assistant he was and whose colleague Kurrein would become, supervised his habilitation very closely. Kurrein's study of ”Areas of Usage of Measuring Devices in General Manufacturing” earned him his teaching license. In the academic year 1913/14 Kurrein held a one hour long lecture on ”Production and Testing of Measuring Equipment and Measuring Tools” .

The war brought about a break in Kurrein’s career. During the entire period of the war Otto Rambuschek remained chief construction engineer in the experimental department. Max Kurrein, on the other hand, soon received his military call up . Following his voluntary enlistment as a so called ”Non-server” , he was assigned to the Austro-Hungarian army . As first lieutenant and engineer he ran the canon factory of the Vienna arsenal until Christmas 1918 . It was only in the beginning of 1919 that he went back to his work as a chief engineer and once again took up his teaching duties. During the war he had been substituted by Eugen Rehner and from the summer semester 1917 onwards by Eugen Simon . In 1921 Rambuschek left the chair for machine tools and factories. Kurrein became his successor as chief construction engineer and was to run, having been given the title of reader in 1922, the experimental field until his removal by the National Socialists in 1933.

In 1918 Max Kurrein married Charlotte Blau (born 1894), who belonged to a respectable merchant family from Berlin, which also prided itself on having a number of famous medical specialists in its midst. Her father was the privy councillor Dr. Louis Blau, who had studied, amongst others, under Du Bois, Reichert and Virchow. Blau was a consultant and an ear specialist and edited the ”Ontological Review” from 1910 until his death in 1919. Charlotte studied mathematics and physics at the University of Berlin. One of her tutors was Max Planck . Of Max’ and Charlotte’s two children the first, Fritz Georg, called Fred, was born in the same year that they married, namely 1918. Their daughter Ina was born in 1922. In 1924 Kurrein became an honorary member of the Prague Society in Support of Israeli engineers .

Prior to the first world war, Max Kurrein’s inclusion on the Technical College staff meant a widening of the scope of subjects. Kurrein took over ”Exercises in the Experimental Field” in the academic year 1912/1913, which was new in the syllabus. Moreover, he held his one hour lecture on ”Production and Testing of Measuring Equipment and Measuring Tools” in the academic year 1913/1914. Following his return to teaching in 1918 he continued giving these lectures in a nearly unaltered form until 1920/1921, not receiving any remuneration for his work. From 1919/1920 he expanded his teaching repertoire with another one hour lecture on ”Tools for Machine Fabrication”. Both lectures were known under the heading ”Working and Measuring Tools” until 1922/23 and were combined thereafter, which resulted in a two hour weekly lecture known as ”Working and Measuring Tools for Machine Production, Their Production and Testing”.

Max Kurrein’s doctoral candidates while he held the chair for machine tools and factories.

Max Kurrein’s name last appeared in the university calendar of 1932/33. Until then he gave the ”Working and Measuring Tools” lecture series during the winter semesters, the ”Operational Studies” lectures during the summer semesters and the ”Fine-Mechanical Production” series of lectures including the three hourly practical sessions throughout. Unlike Schlesinger’s lectures, Kurrein’s were struck off the university calendar from 1933/34 onwards without being replaced (figure 12-03).

During the academic years from 1924/25 until 1928/29 Kurrein limited his ”Working and Measuring Tools” lectures to winter semesters only and replaced these with ”Operational Studies” lectures of equal length (2 hours per week) in the summer semesters. In the academic year 1926/27 he took on another series of lectures (again, two hours per week) on ”Fine-Mechanical Production”. It is clear from correspondence between the faculty for machine tools and the ministry of science, art and education, that the faculty decided to include these lectures in their syllabus on 14th April 1926 in order to better meet the requirements the precision engineering industry made on its workforce . It appears that Kurrein held these lectures, which were extended by a further three hours of practical exercises, of his own free will. Various requests to furnish him with a teaching assignment (22.3.1928), a lectureship (30.6.1928) or even to create a permanent professorship for precision engineering (1929) were declined.

In their report, drafted in 1924, Kurrein and Schlesinger summarised the improvements made to the facilities to the experimental machine tool department at the Technical College from 1912 onwards. They stated, that the facilities had been systematically enhanced to make a complete industrial engineering examination of the following areas possible:

§Machine tools in both fiscal as well as operational contexts

§Work and measuring tools in terms of quality of work, material, exactness, in both normal and stressful conditions with or without control measurements

§Working materials such as belts, lubricants, coolants, hardeners, etc.

§Working processes on raw materials and intermediate stages

Articles published by Kurrein between 1914 and 1917 give a rough overview of research done during the war. Amongst others they dealt with ”Production of Rifle Ammunition”, ”Typical Products of Rifle Production” and ”Modern Machine Tools and the War Effort” . Apart from their obvious contribution to weapon and ammunition production, these articles prove the teamwork between the institute and its members and the military planning bureaus in general and the Spandauer Rifle Factory in particular. Kurrein’s efforts in this field would have been virtually impossible to achieve without Schlesinger’s consent and support. This in turn suggests that Schlesinger did not only put himself, but the whole institute, including its competencies, logistics and infrastructure at the disposal of the war effort. In the same period Max Kurrein, together with Schlesinger, published the essay ”Research and Factory. Lubricant Testing within the Company” (Werkstattstechnik 1916, Vol. 10) and put to print a number of articles, which document the need for special research projects during war and clearly reflect his interest in measuring techniques - a subject which was to become the main focus of his later research .

Out of the 572 articles published in the ”Werkstattstechnik” by Schlesinger and his colleagues during 1918 and 1933, circa 170 were penned by Kurrein. This means that he was as productive as Schlesinger himself. Between 1918 and 1924 Schlesinger and Kurrein published four monographs along with numerous articles in ”Werkstattstechnik” about production techniques and machine tools.

In 1920 Schlesinger and Kurrein published results from tests on replacement belts made in the experimental department, which built on initial examinations dating back to 1918 . Aim of this research was to establish criteria enabling the setting of quality standards for the various replacement belts, which appeared on the market during the war . Research was continued after 1920 in order to ”assess the number of inconsistencies made apparent by previous tests, and to establish the impact of stress prior to and during operation ”. The sixth booklet with reports by the experimental department for machine tools appeared in 1924 with the title ”Replacement Materials” (”After Effects of War”). It contains articles by Schlesinger, Kurrein and Simon on their tests of replacement belts, drilling oils and low grade copper zinc alloys for use in bearings .

Questions relating to standardisation and measuring techniques were closely interlinked, and dealt with mainly by Max Kurrein. Measuring techniques were his main focus up to 1924 and he published nearly 20 articles as well as a volume in the Werkstattbücher series in 1921, the second edition of which appeared in 1923. Schlesinger himself only published two articles on this subject, both in 1920.

 Amongst the numerous articles about new measuring tools, Kurrein published a special edition in the ”Werkstattstechnik” series in 1919 about ”Measuring Tools and Techniques” . He pointed out that prior to the war Germany had been one of the world leaders in the area of measuring techniques and stressed the close connection to standardisation. The results of the ”enormous workload absolved during the years of the war” were the foundation for the effectiveness of the various standardisation committees. Only ”the sheer abundance of accumulated material” made it possible to do some groundwork on fitting systems, thread measurements, gauges and types at a given temperature. Standardisation on the basis of advanced measuring techniques was, according to Kurrein, a prerequisite for ”functional production”:

That the soul of an orderly and modern factory is a skilful and in every aspect properly functioning tool fabrication process and that this is therefore the area one has to look at most and foremost if one aims to achieve a true and enduring factory improvement, is common knowledge among bigger and well run plants and factories, but mostly ignored by many smaller companies (...) Perhaps the most important aspect of tool fabrication is the measuring and quality control of the tools during fabrication prior to their storage; if suitable storage is possible, one can expect properly functioning tools from the tool makers. Moreover, if faults in the production process can be identified prior to delivery to the factory, one can take responsibility for the skilful production of tools .

In 1921 Kurrein’s article entitled ”Measuring Techniques” appeared as second booklet in the Werkstattbücher series, edited by Eugen Simon. Already in 1913 the Julius Springer publishing house created the Werkstattbücher series from existing factory handbooks. However, these were only published by Simon as an improved version after the war . The book on measuring techniques dealt with ”the necessary in a clear and detailed manner” . It described in detail the most important measuring tools and techniques, which the relevant industries had poured onto the market. This list of all available products was supposed to assist specialists in the machine tool field in making informed decisions. In addition some newly developed tools were presented,

”... which were partly designed according to the factory’s own needs, but already existing designs were also adapted and developed further in accordance with in-house requirements. The author considered it proper to include such designs and techniques in the booklet, as they represent likely developments when normal tools are not available or do not meet requirements .”

Shortly before and during the period mentioned above, Max Kurrein published some short articles about special turning tools in ”Werkstattstechnik”, which may have been inspired by his supervising Klopstock’s PhD. The longest of these articles deals with thread cutting on a lathe. In it he discusses systematically and in context the required prerequisites for using a lathe for cutting threads, the adjustment of tools, the cutting of multiple and conical threads etc. Kurrein did not fail to mention the necessary measuring tool, a micrometer for measuring threads .

The work on drills was part of the systematic research in the field of necessary machine tools and production, all of which were part of the overall research of the experimental department. Their aim was to optimise construction and precision under factory conditions. Schlesinger’s monograph about ”The Drill, its Construction and Use” from 1925 summarised the results of the previous years. Kurrein’s articles on screw taps stemmed from this work and appeared in the same year in the ”Werkstattstechnik”. They were supposed to give an insight into the exactness of measurement achieved during drilling . The differences observed between threads worked by normal screw taps and those which worked without fault – in exactly the same conditions – could only ”be accounted for by the screw tap construction. They became much more obvious when typical and differences in construction of the drill come into force” .

Customary screw tap quality control was therefore of no significance when it came to ”the work itself”. Customary ¾”-Whitworth screw tap sets as well as ¾” female screw taps were used in the tests. Four sets produced by ”the best German companies” were used on ingot steel, cast iron, two kinds of brass and two different aluminium alloys from both Germany and America.

During the material convention in Berlin in 1927, both Kurrein and Schlesinger, as part of the ”Material Working Group”, held talks on this subject, which, together with contributions by other members of the group – Vogelsang, Peter and Kühner – were to be published in volume 21 of ”Werkstattstechnik”. Schlesinger lectured on ”Working of Materials. Interaction between Material and Tool” and provided an insight into the workings of the experimental department .

Max Kurrein, taking up where Schlesinger had left off, went into the subject in more detail in his study entitled ”Working of Metals in Connection with Strength Testing” and suggested a law of deformation taking into account results of material testing and forces set free during cutting:

Deformation taking place during cutting is defined by processes between cutting blade or bit and the material, namely cutting pressure and the facings. The former determines calculations relating to the whole process, the cut material represents the factory intended deformation and the subsequent increase in value. It is therefore imperative, that, after having stated the working process, the strength of the material to be worked, the working conditions and the form of the tool, one can determine the magnitude of the necessary forces.

All technical strength calculations, according to Kurrein, were subject to two prerequisites, namely the theoretical stress formula and the stress value of the material to be used. The ”strict application of the theoretical formula to the actual stress” applied to a component – ”in praxis an impossibility” – was adjusted by a ”degree of security”. The estimate of the ”degree of security” was subject to mere experience. The negative impact of this method showed up especially during the production or purchase of the machine tools and just as often during the pricing for such a method of production. These figures, called ”material constants”, were, as a rule ”very questionable” and subject to great variations, in order to ”cover our ignorance of deformation theory in its practical application” .

Kurrein, based on Nicolson’s research and supported by microscopic observations, put forward the thesis that one law should govern all kinds of cutting – planing, turning, drilling and milling. This law could be formulated once the mechanical laws between yield point and breaking point of metals were sufficiently known. For the time being one was reduced to the deductive method of determining such forces by measuring them under known conditions for different materials and different tools etc. and thus postulate a possible relationship between material strength and cutting forces. Only practical examinations and measuring equipment of the experimental department at the Technical College Berlin made it possible to measure such forces ”exactly and properly” and thus determine the parameters needed to define the governing law for these forces. Klopstock was the first to establish the relationship in relation to turning, but it was Kurrein, who expanded it to drilling and grinding and made exemplary calculations:

Following these results, which have to be verified during further tests on different materials, the validity of a common law, which can be applied to mechanical production and which governs the relationship between material strength and cutting forces for all cutting procedures, can be said to have been almost achieved .

In 1928 Kurrein published his test results on grinders . The tests were understood to be a continuation of the work on the measurement of grinding forces dating back to 1925 , which served the development of grinders and are related to the production side of the relationship between material workability and material testing. The aim was to achieve a dependable numerical value of the hardness of the disk by way of objective criteria. As a result five different disks with the same grain size, but with different hardness values were chosen. Siemens-Martin steel of 65kg/mm2 of the same dimension as during the first test was used for grinding. The disks’ make-up was, apart from the raw materials used, defined by hardness and grain size. While the latter was a value which, through the production process and careful riddling, could be depended upon, the former was subject to great variations due to a lack of standardisation.

Kurrein deduced from the test results that a classification of the disks according to their hardness would be possible, which would be ”devoid of individual guesswork and therefore much more accurate than has been possible with current techniques” . He suggested to put up tables for standardised steels or, alternatively, to determine a standard steel as testing material.

In 1929 Kurrein conducted experiments with milling processes in a similar vain. His aim was to prove the laws which he set up for other working processes for the mill. During his experiments Kurrein formulated a number of construction principles for the production of mills .

He determined a number of basic principles and described the necessary machinery and processes to make accurate and successful testing possible. The tests were thus comprised of the following