Ball manufacturing
Today, ball production is an industrial branch of production for the production of prefabricated parts that are used for the manufacture of machine parts , especially bearings .
History of ball making
There was a need for balls even before industrial production . The examples are diverse and range from turned wooden balls for bowling to balls in goldsmithing to cannon balls made of stone or iron.
Pre-industrial series production of ammunition takes place in the scrap tower , for example , stone balls were ground in ball mills - today's ball production no longer includes the term bullet production .
The industrial production of balls in ball factories using machines based on the flow production principle began around 1900. At that time, the first industrial ball manufacturers such as Friedrich Fischer , who dealt with the mass production of steel balls ( rolling elements , roller bearings ), established themselves . A whole region ( Schweinfurt , Lower Franconia) as far as the neighboring Hesse developed as the center of rolling bearing manufacture with its suppliers. Also Fulda was and is a major center of the sphere of production.
During the Second World War , German ball production was classified as essential to the war effort, as the balls were needed for ball bearings for the manufacture of fighter planes, tanks and other armaments. The Reich Ministry of Armaments and Ammunition promoted this through special allocations of raw materials and labor. Because of its central importance for the armaments industry, the German ball bearing industry has repeatedly been the target of heavy Allied air strikes. B. as part of Operation Double Strike . In order to avoid these attacks, production was decentralized in the last years of the war and outsourced to mining tunnels. After the end of the war, production only partially returned to its original location.
Manufacturing methods and technology
Cylinders are cut from the wire ( steel , aluminum , non-ferrous metals ) , which are inserted into the dome in a ball press by means of dies , and shaped into balls , as illustrated in the adjacent photo.
With larger ball diameters, the balls are also forged . In the next work step ( rolling ) the balls are freed from their pressing edge ( burr ) between two rotating tools . Depending on the material , balls can be brought to the desired degree of hardness in the heat treatment . The precision of the balls is increased step by step through several successive grinding or lapping processes. Depending on the desired quality , the balls are manufactured to a more or less precise dimension (ball diameter accurate to 1 µm is possible). In a final production step, the balls are polished in order to achieve a surface that is as closed and shiny as possible. Finally, final optical and mechanical tests are carried out on the balls in order to guarantee specified values for the basic parameters of size, shape and surface roughness . Balls can be made from a wide variety of materials (steel, plastic , aluminum, ceramics , glass and non-ferrous metals), whereby the respective manufacturing methods must be adapted to the requirements of accuracy and material.
Areas of application and standards
In the 19th and early 20th centuries, balls were mainly used in the bicycle industry , while today the areas of application are far more important (automotive industry, linear technology, balls in valves or pumps in the pharmaceutical and cosmetics industry, mechanical engineering, wind turbines , etc.). Shotguns made of various non-ferrous materials are still in use today.
Balls made of special materials
In most cases, the medium and the application determine the material from which the balls are to be made. Balls made of special materials have to do their job over long periods of time in various media such as water, acid, alkali, alcohol, gasoline and gases of various compositions. Depending on the requirements, non-ferrous materials such as brass , bronze , copper , titanium , gold and aluminum are also used. Vehicle construction, measurement technology, goldsmithing and fittings are examples of possible applications for these materials.
A special program enables the production of drilled balls or the attachment of surfaces to the balls as well as the production of switching balls (e.g. ball valve ) and ball holders.
In addition to standardized standard dimensions, all desired ball diameters can be continuously produced. A manufacturer from Hessen / Germany has z. B. a production program between 1 and 320 mm in diameter in various materials. A steel ball with a diameter of 320 mm has a mass of around 135 kg.
Important standards for ball production include DIN 5401 and ISO 3290 .
Web links
Individual evidence
- ^ Schramm, Wolfgang: Armaments madness - air war against ball bearings / a film by Wolfgang Schramm. - [Munich]: BR. - 2005. - 1 DVD video (44 min.): Mostly b / w, partly in color; 12 cm; (ger / dt.) Film report, Germany 2005. - Also cited and d. T .: Armaments mania - underground ball bearing production 1944/1945