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1. How Are Mill Rolls Used in Industry to Shape Metal
Mill rolls are used to alter the form of metals either with heat and pressure or pressure alone in cold mills in order to create a number for metal forms used in various manufacturing industries. Metal forms such as plate, sheet, foil and more complex shapes such as curved and angled forms produced by sectional rolls.
Molten metal alloys are forged in furnaces and poured at extremely high temperature into moulds to produce tubular metal cylinders or mill rolls. Once the metal has been machined and cooled then the roll shafts are fitted and they are ready to be used to shape other metals. Typically mill rolls are placed vertically above each other, with one pushing against the metal which needs to be re-shaped and rolled, the most common of these for example are metal tubes, bars, sheets and wire.
Historically this type of machinery was used in steel mills to shape the forged steel into forms which can be sold for particular uses. These machines are now used in light and heavy industrial processes. These range from the large scale process of manufacturing parts for aircraft and space vehicles to the small scale manufacture of jewellery. Regardless of the scale, a high level of accuracy is crucial.
When mill rolls are manufactured they need to conform to the exact specifications required by the process they will be used for. Amongst the tests that take place on mill rolls as they are manufactured, ultrasound is used to check for any flaws which may exist in the rolls and the tensile strength and hardness is extensively tested to provide a guarantee of the stresses they can withstand during operation.
There are two main categories for processes involving mill rolls. Hot rolling is normally used at an early stage of metal production which shapes heated metal into general forms which can then be used in cold rolling mills. Cold rolling allows metal to be very accurately formed into shapes which can then be used for specific tasks. Cold rolling mills can be found in foundries but they are also used in other factories where there is a need to shape metals into specific forms before it is made into an end product.
2. What Are the Most Common Shapes Produced by Mill Rolls?
Mill rolls are used to create a number of different shapes from metal bar which are required by all sectors of the market from motor manufacturing and aerospace to the electronics and chemical processing industry. The most common shapes required however are as follows:
Metal Sheet is used in construction, transport and aerospace. After being further refined, these sheets could be used anything from aircraft components to joists for construction.
Metal Plate is generally thinner than the sheet form but used in similar applications. Most notably this form is extensively used in the automotive industry.
Metal Foil is extremely thin and flexible making it ideal for use in packaging. The electronics sector also uses this form for shielding. It is also used in printing for foil stamping.
Section Mill Rolls
Foundries and other factories then take these general forms and convert them into more bespoke forms with section rolls. The reason these processes take place after the metal is cast as opposed to casting the metal straight into the final form is the existence of ‘blow holes’. These gases trapped in steel and iron ingots make their properties inconsistent. As they normally occur at the head of the ingot this section is removed before undergoing hot rolling. This ensures a level of consistency throughout the metal once it has cooled.
Mill rolls are also incorporated into more complex systems that also bend and cut the metal. This is known as roll forming. As metal is fed into these machines it passes through several stages of processing. The resulting product is rolled, bent and cut to specification.