Using a flame, brazing permanently connects two metals. Most metals can be brazed together using a propane torch. Propane torches are frequently accessible at local hardware stores, plumbing supply stores, and metalsmith and jewelry supply stores.
Is it possible to braze with a Bernzomatic torch?
Brazing is a similar process to soldering, however it takes place at a higher temperature. Use the appropriate brazing rod material for the metal you’re working with. The brazing rod should be melted by the heat of the metals being connected, rather than by coming into direct contact with the torch flame.
For brazing steel, what kind of rod is used?
SSF-6 56 percent silver solder makes brazing steel to a range of metals simple. SSF-6 is a flux-coated brazing rod that flows at only 1150F in all positions. Its high silver content results in some of the strongest bonding in the maintenance welding industry, with a 70,000 psi binding strength. SSF-6 is a cadmium-free product that may be used in both restaurants and hospitals without fear of contamination.
In this video, we braze a piece of brass tubing to a small piece of square steel to demonstrate SSF-6’s improved flow. Due to the small size of the parent metal components, propane was used for this application. Brazing larger or thicker metals will necessitate the use of a torch capable of raising the base metal temperature to 1150F (MAPP or oxyacetylene is recommended for large/thick items).
To begin, preheat the base metal with the torch until it turns a dull red, indicating the suitable working temperature. It’s time to apply the flux from the brazing rod by slowly heating it until it melts into the joint when you observe this transformation. Continue moving the torch to prevent the base metals from melting or overheating, and to allow the flux to flow completely into the steel joint. Make sure the heat is directed at the larger/thicker piece.
Apply a tiny amount of silver brazing rod to the joint and flow it around it using the heat of the torch. With no pinholes or porosity, 1 inch of silver solder will flow up to 18 inches. A wire brush and warm water are used to remove excess flux; no chemicals are required.
The flux in SSF-6 wets the steel and brass, and no finishing is necessary because this brazing rod has an excellent finish. SSF-6 brazing rod creates leak-tight junctions that are electrically conductive, corrosion-resistant, and leak-proof. Steel, cast iron, copper, silver, bronze, brass, stainless, and other metals can all be joined using this method.
When brazing, what kind of flame is used?
When the proportion of oxygen and acetylene in a flame is equal, it is called a neutral flame.
The name “Neutral Flame” comes from the fact that it has no chemical reaction with the molten metal.
A distinct Cone Flame at the base of a long feather flame are key elements of a Neutral Flame.
A Neutral flame should generate no more than a soft hiss if the suitable nozzle size is utilized.
The most common form of flame is a Neutral Oxy Acetylene Flame, which is used for welding, brazing, and silver soldering most metals.
Cutting using Oxy Acetylene also requires the use of a Neutral Flame.
What sort of brazing torch do you need?
The fuel gas (acetylene, propane, or natural gas) can be burned with air, compressed air, or oxygen, depending on the temperature required for your assembly. Torches with several points or flames can be employed by shifting the flame constantly to diffuse the heat uniformly throughout the assembly and avoid localized overheating, which can damage the joint’s strength. Depending on the assembly that needs to be welded, these are the various equipment procedures.
- You’ll want to utilize torches with the lowest heat and flame temperature for brazing small components and thin sections. The air-natural gas and air-acetylene torches are employed for these applications.
- Oxygen with natural gas, or other gases such as propane or butane, produce good results in many brazing applications. Although these provide a greater flame temperature, for best results, brazing should be done with a slightly decreased or neutral flame.
- Because it operates at a lower temperature, the oxyhydrogen torch should be used to braze aluminum and nonferrous alloys (metals that do not contain significant amounts of iron).
- Flux-covered or cored filler metal rods are required for torch heating to fill in joints of your assembly. The moderate flame temperature of natural gas is ideal for this approach because it decreases the risk of scorching the joint and metal filler. Only copper-phosphorus fillers, which are employed in brazing in the absence of flux, are self-fluxing. Fluxes, on the other hand, are required for all other filler metals. As the joint is prepared for brazing, the filler metal can be preplaced or face-fed into the joint. Remember that torch brazing procedures for oxyfuel gas welding differ from those for oxyfuel gas welding.
- Without automation, manual torch brazing is a basic method. This method is generally used for assemblies with sections that are not all the same size. Only the braze joint is visible, because it is the only part of the body that receives direct heat. The torch in question features a single tip, which is commonly used to control single or multiple flames. If you need to make a large number of assemblies, a mechanical option can be set up to move the assembly components, the torches, or both during the brazing process.
Is it possible to braze with propane and oxygen?
Propane is the most accessible fuel gas alternative to acetylene, and it is typically delivered in cylinders on a deposit basis rather than rented (as is usually the case with Acetylene).
Propane is less expensive for most users, especially those who use Oxygen + Fuel kits infrequently. The only disadvantage of utilizing Oxy/Propane is that it cannot be used for welding. Kits that run on oxygen or propane, on the other hand, are suitable for silver soldering, brazing, cutting, and heating. So, if you don’t want to weld, Oxygen and Propane is a perfect alternative! A flame temperature of roughly 18000C is produced by combining oxygen and propane.
Is MAPP gas sufficiently hot to braze?
Because of its high flame temperature of 2925 C (5300 F) in oxygen, genuine MAPP gas can be used in conjunction with oxygen for heating, soldering, brazing, and even welding. Although acetylene has a higher flame temperature (3160 C, 5720 F), MAPP has the advantage of requiring no dilution or special container fillers during transportation, allowing a larger amount of fuel gas to be transported at the same weight, and it is considerably safer in use.
Due to the high concentration of hydrogen in the flame (greater than acetylene, but lower than any of the other petroleum fuel gases), a MAPP/oxygen flame is not totally suitable for welding steel. The hydrogen corrodes the welds by infusing itself into the molten steel. This is not a severe concern for small-scale MAPP welding because the hydrogen escapes rapidly, and MAPP/oxygen can be utilized to weld small steel pieces in practice.
Underwater cutting, which necessitates high gas pressures, MAPP/oxygen was shown to be beneficial (under such pressures acetylene can decompose explosively, making it dangerous to use). Underwater oxy/fuel gas cutting of any kind, on the other hand, has mostly been supplanted by exothermic cutting, which is faster and safer.
MAPP gas is also utilized in air combustion for brazing and soldering, where its higher combustion temperature of 2,020 C (3,670 F) in air gives it a modest edge over rival propane fuel.
The most significant disadvantage of MAPP gas is its high cost, which is typically one-and-a-half times that of propane at the refinery and up to four times that of propane at the consumer level. It is no longer widely used in large-scale industries. for consumers on a broader scale When high flame temperatures are required, acetylene/oxygen is more cost-effective than MAPP/oxygen, while propane/air is more cost-effective when large amounts of overall heating are required.
A MAPP/oxygen flame, on the other hand, is still extremely desired for small-scale users, as it has higher flame temperatures and energy densities than any other flame other than acetylene/oxygen, but without the hazards and hassles of acetylene/oxygen. It comes in handy for jewelers, glass bead makers, and a variety of other craftspeople. The high heat capacity of the MAPP/air flame is particularly valued by plumbers, refrigeration and HVAC experts, and other craftsmen; MAPP was frequently utilized until recently, and was provided in small to medium size containers.
Blowtorches are used to brown and sear food cooked sous-vide at low temperatures. MAPP gases should be used instead of cheaper butane or propane, according to Myhrvold’s Modernist cuisine: the art and science of cooking, since they create greater temperatures with less chance of giving the dish a gas flavor, which can occur with incompletely combusted gas.
Is it possible to braze using a blowtorch?
Blowtorches were made to cut metal rather than to glue it together. In some braze welding and soldering applications, blowtorches can still be employed.
Even if it is possible to accomplish, it is an inefficient choice for more exotic metals like aluminum.
Regardless, blowtorches have been and continue to be effective in a variety of welding applications.
What metals are ineligible for brazing?
You can braze practically any metal you want if you’re careful. However, there are a few factors to consider when selecting whether or not to braze a given metal.
It takes a lot of accuracy to heat metals like silver or gold to such high temperatures. Soldering rather than brazing is more frequent for these metals.
Gold and silver can withstand lower temperatures better, and soldering can still provide a solid bond.
What is the procedure for brazing?
Brazing distributes molten filler metal between the surfaces of the base metals through capillary action. Maintain a space between the base metals when brazing to allow capillary action to work most efficiently. Almost always, this entails a tight clearance. For most filler metals, the ideal clearance or joint gap is 0.0015 inch, but typical clearances range from 0.001 to 0.005 inch.
To create a sufficiently robust joint in daily brazing, clearances do not need to be too accurate. Capillary action works over a wide range of clearances, so you have some flexibility. In common shop practice, an easy slip fit between two tubular components will usually result in a satisfactory brazed junction. Keep in mind that when clearance increases, joint strength typically declines. Around 0.012 in, capillary activity ceases. You can rest one flat part on top of the other while combining two flat sections. Because the ordinary mill finish of metals offers enough surface roughness to produce capillary pathways for the flow of molten filler metal, the metal-to-metal contact is usually all the clearance you’ll need. Highly polished surfaces, on the other hand, have a tendency to obstruct the flow of filler metal.
Remember that brazed joints are created at brazing temperatures, not room temperature, when planning joint clearances. Consider the coefficient of thermal expansion of the metals being bonded, especially in tubular assemblies that contain different metals.