White metal

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The term white metal is often used to summarize a group of alloys that either show lead as the main component and tin as an accompanying component , or there is an inverse ratio in which tin predominates and lead becomes a companion. Depending on the intended purpose, there are also other elements such as antimony , copper , bismuth and others.

The designation of an alloy as white metal remains unchanged, but is increasingly giving way to a metallurgically correct, standardized designation, which particularly takes into account the variety of solder alloys and the importance of the bearing metals, which or with a higher lead content (e.g. LgPbSn10) than lead bearing metal higher tin content (e.g. LgSn80) can be referred to as tin bearing metal.

grouping

According to a classification from the beginning of the 20th century, a distinction is made under the collective term white metals:

Solders and low-viscosity alloys ( Wood's metal and others)
In the 21st century, solders are still indispensable for certain joining techniques .
White bearing metals
In the age of machines and automobiles, the white bearing metals became the most economically and technically important part of the white metal alloy group.
Metal for writing and letters
Typeface metals have largely lost their importance in favor of modern printing technology; this also applies to the printing-related field of cliché production. Special cliché alloys (cliché metal ) received additions of antimony and bismuth to lower the melting point , or only bismuth and then up to 15%.
Britanniametall (crockery tin)
Britanniametall, known in the 19th and 20th centuries as tin for tableware, owed its appreciation to the fact that by adding antimony and copper to a tin base, a tin-like appearance could be combined with a hardness that broadened the range of uses. This made it a very stable raw material compared to tin and therefore particularly suitable for cutlery . Honorary prizes such as cups and plates are still made from it today.
Alloys for various uses
The alloys for various purposes include or included things as varied as the hard lead used by the military, but also tinsel, tinfoil capsules for bottle caps and pewter figures.

White bearing metals

Use and properties

As white metal bearings, later - to specify their use - called white metal plain bearings , alloys based on lead or tin have been used for plain bearings , for example in locomotives , agricultural machinery and machine tools , since the end of the 19th century . The bearings basically consist of a hard, often steel, support shell and a white metal spout. Because of the low melting temperatures between 180 ° and max. At 350 ° C, it was relatively easy to produce bearing spouts from blanks, which was beneficial for repairs. The poured bearing was then honed to such an extent that it worked with little friction. In operation, i.e. when power is transmitted to a shaft, the antimony content ensures the hardness, lead and tin, with the help of an additional permanent oil film, allow the bearing to work with low friction and thus avoid heating of the bearing as well as energy-saving.

By casting is that - predominantly that - parallel to the engine at ever increasing production speeds in automotive centrifugal casting used.

In terms of alloying technology, white bearing metals are also an object of research to improve their properties

White metal bearings of all sizes were traditionally used in steam turbines , as well as in hydropower plants with Pelton , Francis or Rohr or Kaplan turbines, because they are not only highly resilient, but also insensitive to temporary overloading and have good emergency running properties. The main areas of application for white metal are connecting rod and crankshaft bearings for automobiles.

The good recycling properties are advantageous , as the storage spout can be separated from its steel support shell with little energy consumption.

White metal alloys are still occasionally used in model making for foundries , the easily machinable alloys are also used for the production of medals of all kinds and are often coated with a visually enhancing bronze paint.

Individual evidence

  1. ↑ quoted from Paul Krais: Werkstoffe. Volume 2, Verlag Johann Ambrosius Barth, Leipzig 1921.
  2. ^ Paul Krais: Materials. Volume 2, 1921.
  3. ↑ Dießen am Ammersee is a place with a tradition of pewter foundry, not only pewter figures, like the classic tin soldiers, are made there in old family businesses, but also panoramas depicting historical events.
  4. ↑ Innovative white metal for highly stressed slide bearings. Press release on a patented, strength-increasing development that provides for the addition of tellurium . In: ERZMETALL. 65/2012, issue No. 5, p. 274.
  5. ^ Rolf Koring: Plain bearing technology in transition. Expert Verlag, 2012, ISBN 978-3-8169-3151-5 .

literature

  • ORDER METAL. Vintages?
  • Foundry - Lexicon. 17th edition. Verlag Schiele & Schön, Berlin 1997, ISBN 3-7949-0606-3 .
  • Paul Krais: Materials. Hand-held dictionary of technical goods and their components. Second volume, Verlag Johann Ambrosius Barth, Leipzig 1921, OCLC 634152069 . (Section alloys)

See also