110 years keeping track of unbalances
On 1 October 1881, Carl Schenck founded the "Eisengießerei und Waagenfabrik", known today as Carl Schenck AG, in Darmstadt. Back in the year 1863, the "Commerzienrat Carl Heinrich Johann Schenck" co-founded the Mannheim-based company "Schenck, Mohr & Elsässer" at which the automobile pioneer Carl Benz was also employed as a technical employee.
In 1881, Carl Schenck left the company in Mannheim and established his own scales factory in Darmstadt. His prudence, international orientation and presences at world exhibitions ensured the company's success early on. And also for plenty of orders for the young business from Darmstadt. As a result of this dynamic development, the company began developing and manufacturing balancing machines in 1907.
Carl Schenck, who was intensely occupied with the topic of "balancing" concluded a license agreement with Lawaczeck in 1908, who was the first to develop a feasible solution for a "balancing machine". In 1915, Schenck took over the exclusive license for the entire world. The "Lawaczeck Principle" was to remain valid all the way into the 1940s.
During this period, a number of new optical and mechanical measuring methods were developed, whose measuring accuracy was quite remarkable. The "Lawaczeck model" was capable of achieving a balance quality equivalent to a centre of gravity displacement of 0.001 mm - a balance quality which would even today be perfectly adequate for many applications.
In 1935 a machine patented in the USA, featuring electrodynamic vibration sensors and stroboscopic determination of the unbalance angle pioneered a change-over to a new design.
1942 Schenck submitted the patent for a "Method and facility for dynamic balancing by determination of the angular position of unbalance by means of a periodic curve displayed on the screen of an oscillocope". Due to its high accuracy the system was used right through the second world war for balancing gyroscopic stabilizers for naval vessels.
The wattmeter method, the next step in the development, suppressed undesirable parasitic vibrations. With the basic components known at this time, i.e. wattmeter, vibration sensor and angle reference generator, it was possible to determine the position and magnitude of the unbalance in one measuring run. Unbalance values were displayed on two pointer instruments.
In 1953 the illuminated-spot vectormeter brought a further advance. The combination of both values in a single display unit and the "storage" of the measured values in the form of a light spot on a screen significantly simplified the balancing process - the unbalance was now visible. Even today, the vectormeter is an indispensable part of modern measuring instruments - a practice-proven method of showing the position and magnitude of the unbalance on modern measuring instruments with display screen.
In parallel to the development of what was then called "Workshop Machines" - nowadays referred to as Universal Balancing Machines - automation of the balancing process moved forward with great strides. "Balancing lines" for crankshafts determined the unbalance of crankshafts and the required drilling depth for its correction. Altogether, unbalance measurement, correction and check run for a crankshaft took around 2 minutes.
In the seventies, the mechanical foundations for balancing machines had basically established themselves. Electronics slowly made their appearance in balancing and diagnostic technology. In 1971 the electronic wattmeter measuring principle was introduced, the first computer-controlled balancing systems were introduced in 1974. The next major change came with the emergence of digital technology: At the beginning of the eighties, microprocessors started appearing in measuring systems and are still the decisive technology to this day.
The next major change came with the introduction of digital technology: At the beginning of the eighties, microprocessors started appearing in measuring systems and are still the decisive technology to this day. Having started with the CAB 690 and CAB 720, today's CAB 820 and CAB 920 are the 4th generation measurement technology.
In 1995, within the framework of the restructuring of Carl Schenck AG, the business units balancing and diagnosis technology were combined in an independent company – Schenck RoTec GmbH.
From a technical perspective, one of the most impressive highlights of this period was the realization of the world's largest geotechnical centrifuges for physical soil testing. New technological territory was entered with the CRYO spin-testing rig, with which the component of the rocket propulsion of Ariana 5 are further developed at temperatures close to absolute zero.
In the year 2000, the globally active technology group DÜRR AG based in Stuttgart acquired the majority stake in Carl Schenck AG.
Energy savings, noise reduction and efficiency increase were the prevailing themes of the first decade of the new millennium. In 2009 the test laboratory for balancing technology was officially accredited by the German accreditation body for technology "Deutsche Akkreditierungsstelle Technik" (DATech). For the very first time, users and service providers can certify their testing equipment and measuring technology – documented and traceable to international SI units.
