Brazing Best Practice

practiceBrazing Best Practice
 
Topics related to brazing to aid with learning and understanding the technical aspects of brazing, how brazing works, why it works, along with useful hints and tips. Copper alloy brazing can be performed in both vacuum and atmospheric furnaces, and can be used to braze many different metals. Copper brazing alloys can be used to improve ductility and electrical conductivity. Our nickel alloy brazing is performed in high temperature furnaces using vacuum or atmospheric brazing techniques. As with other brazing services, nickel alloy brazing reduces the need for post-assembly finishing and can be used to join two similar or dissimilar metals.S-Bond Technology and its personnel have extensive experience in materials joining and can assist you in your applications.  You are buying 5 rods (approximately 1.4+ ounces, oz) of EutecRod 1601 Low Temperature Silver Brazing Soldering/Welding Rod. X 14in.L Lincoln Electric Flux Coated Brazing Rods are an excellent choice for brazing automobiles, pipes, tanks and more. Use for brazing copper-to-copper air conditioning refrigerant lines, also, repair, maintenance and joining of copper-to-copper alloys. Fluxed Low Fuming Bronze Brazing Rod is high quality low fuming bronze brazing rod with flux. Fluxed low fuming bronze brazing rod is a high quality, low fuming bronze brazing rod with flux. These brazing filler metals are primarily used to join copper to copper, copper to brass, and brass to brass.Harris 0® is a low cost alloy suitable for most copper to copper or brass joints where good fit-up exists, and the assemblies are not subject to excessive vibration nor movement. I am planning on doing just straight brass to brass, brass/copper to steel and brass to copper. I have found that for putting together dissimilar metals, not much beats tig brazing with a silicon bronze rod. Because the tig process uses an inert gas sheild, it will work with all kinds of metals that would otherwise be very tough to deal with. I have used silicon bronze tig brazing to put together virtually any copper based alloy, even some with high lead or zinc contents, with steel, stainless, and cast iron.Elcon specializes in joining ceramic to metal and metal to metal assemblies by brazing.  It can be used to repair most cast irons, it will work on most exotic nickel and other high tech alloys, and it works well with alloys where the melting points are vastly dissimilar- say, brass to stainless. I am from the old school of using a torch for my metal work and been doing it since 1972. The propane tips do not get the heat pinpointed, especially on gas welding sheet metal.We receive many questions about the difference between soldering and brazing.  I would like to know if the same process as you described above would be applicable to my situation. The trick to successful solder to stainless steel is primarily, cleanliness - the metal must be chemically clean and free of oxides. You need to be able to heat the stainless quickly and also to overcome the conductive losses in the copper. The fluoride salt in it is the only thing that cleans the nickel and chromium oxides off the heated stainless to allow complete wetting of the joint by the filler.
 
Generally, I use flux coated bronze rods and I shave about 2/3 of the flux off with a box knife if the metal is clean. I`m trying to tig weld032 in copper sheet to 1/8 inch ss square rod using silicon bronze filler rod. I`m having trouble get the rod to melt without burning through the copper sheet. I have found that in DC mode, I have no problems blending (Bonding) mild steel filler rod right into copper. I have not tried it yet, but am pretty sure I could also bond brass to copper, brass to mild steel and so on. I believe (if not structural) bonding materials (if enough material is available to do so) is a great way to sidestep brazing.The issue with copper and certain fuel gases has to do with the formation of acetylides , potentially explosive oxides of acetylene. The primary source of problems was people piping pure acetylene through copper pipe in manifold delivery systems. In those cases acetylides formed on the inside of the copper pipe as the acetylene was in constant contact with it. When soldering or brazing with MAPP gas, the copper is realy only exposed to the heat from the flame - the acetylene in the mix has been burned by then. We typically work with active metal braze, copper, gold, and silver-based alloys.Even if you flooded raw, unburned MAPP gas onto copper in open air you probably couldn`t develop any acetylides in a short period of time. Braze alloy is generally available as rod, ribbon, powder, paste, cream, wire and preforms (such as stamped washers). Depending on the application, the filler material can be pre-placed at the desired location or applied during the heating cycle. For manual brazing, wire and rod forms are generally used, as they are the easiest to apply while heating.In the case of furnace brazing, alloy is usually placed beforehand since the process is usually highly automated. Request a quote on copper alloy brazing wires, copper alloy brazing rod, or other filler materials. If you experience difficulties producing sound strong joints re-examine your techniques to adhere to the basic principles of the process. A brazed joint is identified by the temperature of the filer metal, not by the composition of the rod in the hand. BS EN 13133 Brazing Practice suggests that the joint length should be 3 - 4x the thickness of the thinner component. Longer joints run the risk of flux entrapment or incomplete penetration and potential weakness.The strength of a joint simply depends on the load being transferred from one component to the other across the filler metal and relies on the tremendously strong inter-atomic strength between the silver solder and the parent materials. Hold components together with soft wire that will expand with the components preventing distortion. Any clamping arrangemment should be as light as possible to avoid it becoming a heat sink and slowing the heating process. It is, however, immaterial as to the cleanliness at room temperature, it is the state at soldering or brazing temperature that is all important. Before soft soldering, the parts should be degreased or scoured with wire wool.
 
If appropriate de-grease using warm soapy water, solvent, wire wool or a stiff wire brush. These can leave deposits behind that the flux cannot remove leading to porous joints. The detergent aids mixing, helps the flux to stick to the components and allows remixing with a little extra water if it dries out. Sound joints made with relatively short heating times, using a low melting or medium temperature silver solder eg 455, 445 and 438 can normally be achieved with EF flux.Use Staybrite Flux or Stainbrite Aluminium when soldering stainless steel or aluminium respectively. Ater brazing, the flux residues (some of which are corrosive) must be removed from the components. With EF flux this is readily done by a soft brush under running water or immersion in a bath of dilute sulphuric acid or the safer, more environmentally friendly citric acid. HT5 residues are best removed mechanically with a stiff wire brush or immersion in a 10% solution of caustic soda. However when working on larger copper components eg boilers propane alone may be insufficient.There are many on the market and it can be difficult to assess their true value when it comes to brazing and soldering. The basic premise is to have a torch that produces a focused flame capable of generating sufficient heat, quickly enough to achieve metal flow into the joint. Capillary flow increases with increasing surface tension, decreasing viscosity and reduced contact angle of the filler metal with the parent material. The flux melting, becoming a clear liquid is a good indicator that the joint is approaching the brazing temperature.When brazing in a confined space eg in a firebox the burner uses all the available air and the flame extinguishes. In these cases use the propane as a background heat to get the joint area hot and expand, Use the oxy-acetylene to lift the temperature locally to brazing temperature. Placing a ring or cropped piece of rod internally and heating externally to draw the metal through is an ideal scenario. The alloys are all made to ISO 17672, the International Standard for brazing materials.It stops the wire moving about in the draught of the flame and keeps the fingers away from the heat. Brazing and soldering are known for their ability to produce strong joints in a wide range of material combinations. HTG manufacturing processes allow the brazing of dissimilar metals with very thin thicknesses or thick to thin materials. We produce brazed honeycomb components from stainless steel and titanium alloys, as well as, nickel-based super alloys. Furnace brazing in accordance with MIL-B-7883 Type II and other widely recognized and accepted procedures.