The concave deformation driven into the sheet becomes visible as a convex shape on the back of the sheet. The deformation is made easier by working on a flexible surface. Artisans such as goldsmiths and silversmiths use pitch or putty as a base, which offers sufficient resistance to the blows of the hammer and is smoothed again after the work by heating.
During artistic activity, indentations are made in the sheet metal to create a relief on the back .
Soft annealed sheet metal is often used for driving . Copper sheet hardens during processing by strain hardening and may have to be returned to its originally relaxed crystalline structure ( recrystallization ).
Already in ancient times this was art of metalworking known. According to previous knowledge , the beginnings lie in Mesopotamia , the first high culture in human history . In ancient Egyptian times, excellent works of driving technology were created from silver , gold and bronze , which have been preserved as grave goods .
In terms of work, a distinction is made between pulling up , deep drawing , bouncing , displacing and upsetting :
- Pulling is done by circular hammering from the center of the workpiece, working in a spiral towards the edge.
- Deep drawing is usually the industrial process for pressing down a hollow metal sheet at the bottom, whereby it is importantto prevent the material from folding in . Denting refers to the manual process of driving in a wooden hollow .
- Bouncing is used to narrow-necked containers by means of a special tool , a bounce iron say to form outwardly "auszudellen". Bouncing is an auxiliary method when normal external processing with hammers is no longer possible, even in conjunction with punches , especially when narrow-necked hollow objects such as vases , drinking vessels or other plastically deformed workpieces used as industrial prototypes are desired . When bouncing, the blows have an indirect effect. The prelle bar is made to vibrate by striking a light hammer, which causes the workpiece to be deformed at the rounded end of the bar.
- Displacement is often used both in driving and forging in order to reduce the material cross-section on a solid base (anvil).
- Compression is also called pulling in when forcing . The wrinkling or tearing of the materialmust betaken into account.
The sheet metal to be driven or solid material made of metal is processed on the later rear side using a driving hammer or forging hammer and expands in the process. If this happens on a solid base such as the anvil or driving anvil , a larger part of the sheet metal is deformed into a curvature. In contrast, significantly finer and more precise work is possible on a flexible substrate, comparable to deep drawing . To produce a relief , the sheet to be processed is placed on lead or putty for further driving out and, if necessary, later chiselling . Here, on the other hand, you work from the front . The processing takes place with the help of differently shaped hammer hammers and punches or with various driving sticks. An anchor is often used. A sack , a leather bag filled with sand or similar material, serves as a base for artistically free work . Finer work can be achieved by embedding the sheet metal in blowing putty and then driving or chasing using smaller tools.
The most suitable metals for handicrafts are copper and certain copper alloys, so-called wrought alloys , such as soft brass - (for example tombac ), silver - and (for reasons of cost rather seldom) gold alloys . Basically, aluminum and stainless steel are also suitable . The naturally harder and therefore more difficult to work bronze and iron sheets are of course also suitable for driving. The latter are more likely to be found in the architectural field. Only the technique of driving could in earlier times be used, for example, in the manufacture of vessels or antique helmets and many others. There were no other possibilities for spatial-artistic metalworking until the late modern or modern times , which of course also applied to everyday objects such as pots or large kettles. The known method of casting was generally avoided for reasons of cost.
During the driving process, the crystal structure of the metal is disturbed, as the deformation through manual or industrial processing ( deep drawing ) increases the dislocation density and the material is work hardened . The metal becomes increasingly harder and more brittle, this is referred to as solidification . Annealing the non-ferrous or alloyed precious metal and subsequent cooling in water between the individual phases of the work process restores the original plasticity . This allows repetitive driving until the final shape has been achieved. Sometimes, for example in the manufacture of vessels, the workpiece still has to be hammered after it has reached the desired shape in order to achieve a new and desired solidification for use.
Professions which today with the goings are related, read: metalsmith , blacksmith , coppersmith , goldsmith , silversmith , Spengler (also plumber called, which means nothing to the colloquial job title for the plumber gas / has to do), Gürtler , etc.
Earlier, now almost extinct job titles that are related to the metal and bustle: blacksmith , Pfannenschmiedsgasse , Boilermaker , armorer , armor smith , Plattner , tinsmith , Tinsmiths , Rotschmied , chain blacksmith , locksmith , tool smith etc.
Many of the requirements for the making of metal are now taken over by the blacksmith , who has almost become a universal genius in relation to the creativity of metalworking . The apprenticeship for "blacksmith", which was abolished in the 1980s, is now called "metal worker, specializing in design". In this profession, however, not all available basic knowledge of metalworking is imparted, as was customary, for example, in an earlier training as a (...) blacksmith.
Depending on the use, for example, a relief can arise during the drift . This type of metalworking was and is often used in handicrafts . In this way, high-quality and at the same time permanent ornaments or graphic representations can be created. Furthermore, unique bowls, vases (for example, pull and bounce technology), lamps, jewelry , or even portraits (here because of the level of detail in copper or precious metals) of art forging , or silver and goldsmiths made.
Especially for architecturally integrated art or unique pieces in the design area and small series, special pipeline construction or in the area of restoration, the driving of metal is still indispensable today.
After the automakers have to claim more and more, all depending manufactured models in the museum to show, even entire vehicle are increasingly bodywork reconstructed by driving. It is often specialists with decades of experience who carry out such work. Even a curved fender takes many thousands of hammer blows and is accordingly expensive. In earlier times, i.e. around 1920 to around 1950, there were so-called mechanical drifting hammers, among other things, for the production of rounded body parts for cars. These were machines that very quickly performed lighter blows on the thin (steel) sheet metal to be processed when cold and could only be operated by experienced masters .
A notable example of the use of solid material in relation to driving can be found in the history of the Tobias hammer in Thuringia . Until the collapse of the GDR in 1989, boilers and pans were used here by means of a historic waterwheel-driven tail hammer . a. Kettledrum produced from one piece , which set a benchmark in terms of sound to this day.
A much-seen example of chased metal today is the frame of the golden M in the McDonald's illuminated sign. It is driven from a straight L-shaped steel bar.
The Statue of Liberty in New York , which was driven from 2.57 mm copper, is likely to be even more popular . Or the quadriga made of 2 mm copper on the Brandenburg Gate in Berlin - created in 1793 by the coppersmith Emanuel Jury based on a design by Johann Gottfried Schadow .
In Berlin in particular , you can still admire many outstanding examples of figural drifting art, for example on the gables of the Gendarmenmarkt or at the Museum for Communication . Completely destroyed by the Second World War , the copper sculptures, up to six meters high, were faithfully reconstructed between the 1970s and 1990s by the Berlin blacksmith and metal sculptor Achim Kühn .
- Erhard Brepohl : Theory and Practice of the Goldsmith. 15th enlarged edition. Fachbuchverlag Leipzig in Hanser-Verlag, Munich et al. 2003, ISBN 3-446-22364-9 .
- Manfred Kluge (editing): metal technology. Metal construction and production technology, basic education (= European reference book series for metal professions. ). 9th, expanded edition. Verlag Europa-Lehrmittel, Haan-Gruiten 2007, ISBN 978-3-8085-1139-8 .
- German Copper Institute V. (Ed.): Driving copper and copper alloys. German Copper Institute V., Düsseldorf 1993, ISBN 3-921505-07-0 .
- Otto Schmirler : work and tools of the blacksmith. Wasmuth, Tübingen 1981, ISBN 3-8030-5040-5 (French / English / German).
- The silversmith. Instructional and manual. Rühle-Diebener, Stuttgart 1982.