Brass and silver plating of components for lighting and furnishings;
Building and montaje of particular for the illumination and the amoblamiento;
Construction brackets for car body work.
Main applications of welding
The main characteristic of welding is to create monolithic structures, ie structures that do not exhibit discontinuity of features in the presence of joints. This particularity of welding is of great importance either when a uniform mechanical strength is required, or when uniform resistance to external aggression (eg corrosion) is required. Given these characteristics, welding has remarkable applications in several engineering fields:
- Mechanical engineering: construction of complex mechanical structures and subject to significant efforts
- Civil engineering: construction of metal structures supporting buildings or bridges
- Chemical engineering: construction of containers (under pressure or not), pumps, valves and piping networks
- Nuclear engineering: pressure vessels for reactors, piping, security structures and containment
- Transportation engineering: construction of land and naval vehicles
- Aeronautical engineering: aircraft carrier structures.
Vi sono comunque dei casi particolari in cui la saldatura viene utilizzata per unioni “parzialmente” continue come nel caso della “puntatura”.
The welding process
Each type of welding takes place through different processes and specific machining. However, it is possible to describe a generic process that shares the different welding processes.
In order to realize a two-part welding, it is necessary first to prepare the two flaps of the joint by means of the one which is defined as cracking. Then the joint is heated to different temperatures depending on the process used.
When the joint is heated up to melt, joining the flaps with the material of the joint itself or with the help of a homogeneous intake material it is referred to as autogenous welding. If, on the other hand, when the joint is heated below the melting temperature, a heterogeneous filler material is melted thereon and with a lower melting point it is referred to as heterogeneous soldering or brazing.
The heat required to implement the process is achieved by several systems:
- A flame produced by combustion of a gas with air or oxygen.
- An electric arc that is formed between two electrodes (one of them may be the same piece).
- Electrical resistance obtained by Joule effect when passing a current through the pieces to be welded.
- High power laser or other non-flammable energy delivery systems.
To obtain a strong, technically good and impermeable solder, the melting zone must be protected by oxidation phenomena and molten metal must be cleaned from slag. In order to avoid oxidation, the welding must be as free as possible in the atmosphere as oxygen (inert): for this purpose substances such as gas, borate, silicates and carbonates must be added in the area close to the welding, creating a “protective cloud “Near the melting bath and allowing debris expulsion. In the oxyacetylene welding, a reducing atmosphere is produced while arc welding is carried out in the atmosphere produced by the burning of the electrode coating or under gas flow.
The input metal can be in the form of bars or continuous wire, which are brought closer to the blending zone (flame welding and welding TIG, tungsten inert gas) or to form the real electrode that blends due to ‘ Electric arc that it itself causes.
A brazed exchanger is a particular type of plate heat exchanger in which the plates are welded together. As with all plate heat exchangers, this is a thermal machine used in the transfer of thermal energy (heat) between two fluids (heat transfer fluids) that lick the opposing surfaces of the plates in the exchange pack.
The heat transfer is used to heat or cool fluids used in industrial processes, for example to provide for thermoregulation and cooling of machinery and equipment such as endothermic motors, lubrication circuits and compressors, or to exploit waste heat produced in numerous production processes , With significant benefits in terms of energy consumption and energy efficiency. This is a case of heat recovery applications that are not dissipated in the environment but can be reused for various purposes, such as heating water for sanitary use, heating and pre-heating of process fluids, or even heating or Cooling of environments and premises without primary energy consumption.