Brazing
Complete alloy and flux solutions for industrial brazing
The Brazing Division of Pietro Galliani specializes in the production of brazing alloys and fluxes for a wide range of industrial applications. With over 30 years of experience in the field and more than 100 alloys, we offer a comprehensive portfolio of products, including silver-base alloys, copper-phosphorus alloys, brass, aluminum, and tin-based alloys. Our products are available in various formats (rods, wires, foils, rings), alongside powder and liquid fluxes for both manual and automated brazing processes.
Our alloys are engineered to meet the highest standards of joint quality, reliability, mechanical strength, and ease of application. Thanks to our in-house foundry and proprietary Nanotech technology, we ensure full control over the production process and provide solutions that comply with international regulations.
Main application sectors:
We also offer integrated services such as sample testing, technical consulting, metallographic analysis, and co-development of new alloys in partnership with our customers’ R&D departments.
What is Brazing
Brazing is a process by which two metal parts are stably joined by the use of a filler material which is brought to fusion through the application of heat, this filler material penetrates in a capillary way between the joints to be united, connecting them definitively.
Brazing, unlike welding, does not unite the two metal parts by melting them, but instead unites them by melting the filler material, which by capillarity penetrates the two metal parts to join them in a stable and permanent way. The filler material must always have a lower melting temperature than the parts to be joined. One of the main advantages of
brazing is the ability to join together homogeneous and heterogeneous materials. In particular, heterogeneous materials, due to their diverse nature, have different mechanical characteristics, which do not allow the use of fusion by welding, welding which would jeopardise the stability of the joint over time.
The brazing technique is also used in those cases where it is important to maintain the shape and the aesthetic aspect, which is better obtained by not welding the joints to be united.
In the world of brazing it is possible to identify two types of brazing, soft brazing and hard brazing. In soft brazing the brazing temperature is below 450°C and in any case always below the melting point of the materials to be joined. In hard brazing, the brazing
temperature is above 450°C but maintained always below the melting point of the materials to be united.
How to choose the alloy for brazing
The alloy for the brazing (the so-called “brazing alloy”) has to be chosen considering various aspects, including the characteristics of the materials to be joined and their melting point. In fact, the alloy must melt at a lower temperature than the base metals,
to avoid deterioration of the other materials involved in the operation. The field of application of the finished product is also important, in fact, there are alloys that have a higher resistance to environments particularly subject to corrosion, or alloys that are more suitable for jewellery because of the aesthetic result required.
How is the joint heated
The heating method of the joint varies according to the melting temperature of the filler metal. Brazing can be carried out by using a torch, a means similar to that used for typical welding, fueled by acetylene, propane, oxygen, hydrogen or natural gas, or by electric induction or resistance heating (a method used for electronic applications), or in a vacuum oven or in a controlled atmosphere (for higher quality joints).
The application of the flux
The flux plays a fundamental role in the brazing process because by preventing the formation of oxides, it greatly helps the wettability of the molten alloy, allowing it to flow more smoothly. An indispensable operation before proceeding with brazing is the cleaning of the surfaces to be joined, they must be cleaned of grease and oil using specific solvents or hot water. Furthermore, it is important that in the vicinity of the joint, the pieces do not have any imperfections or burrs (resulting from cutting or previous processes) as these imperfections affect the heating of the piece itself, heating which must be evenly carried out.
The surface oxides are then removed by mechanical brushing, considering that the choice of flux is as important as that of the alloy. The working temperature of the flux has to be inside a range that enables its action to be maintained throughout the brazing cycle so as to prevent the formation of new oxides.
At the end of the brazing, the flux residues are normally eliminated by cooling the piece in water.