Torch Brazing

Torch brazing is considered to be the most versatile method, since, its applications can be found in almost any industry, be it the vast fabrication or repair work. By burning gas combinations heat such as air and acetylene, oxygen and acetylene, oxygen and hydrogen and air and propane that the necessary heat is provided by ordinary gas welding equipment. Torch brazing has some essential applications which as well hold importance in the brazing sector. They are commonly applied for small assemblies and low-volume applications.

The Process of Applying Torch Flame
Depending upon the size of the torch, lowest flame temperature & less heat can be provided by air gas torches. As for brazing aluminum and other non ferrous alloys, oxy hydrogen torches are often used. In case of brazing, torch flames are played upon thoroughly cleaned parts by the operator. These flames are neutral or slightly reducing & are used to heat the heavier sections.

While heating, flux is applied to the joint area which prevents oxidation of the parts. Further, this flux prepares the surface for wetting by the filler metal once it cleans the joint area of oxides after it gets melted. The metal is later handfed to the joint area once these joints reaches a particular brazing temperature. Usually, instead of being handfed, the filler rods are preplaced to fit the joint contour in the form of a ring, washer, or insert. The most often used filler metals rather need a joint clearance (at brazing temperature) of 0.05 to 0.125 mm for capillary flow. Lap joints are usually preferred.

One can achieve uniform heating through the employment of multiflame torches. The torch can be directed more on the heavier members having greater thermal conductivity in order to bring all members of the assembly to brazing temperature simultaneously.

Equipment Required for Torch brazing
There are varied kinds of equipment required for torch brazing which makes the process quite convenient. These are basically :

• Oxygen cylinder with pressure regulator
• Fuel gas cylinder with pressure regulator
• Gas cylinders with trolleys for transportation
• Welding torch
• Red fuel gas hose
• Blue oxygen hose

Advantages
Torch brazing have their own set of advantages which needs to be taken into consideration, helping further to prove the worth of brazing over welding. These are widely categorized into the following pointers :

• Brazing & brass welding help in changing the crystalline structure or induce the thermal stresses through their low temperature without distorting the work piece. In case of large iron castings crack, welding is not preferred for repairing. Rather, torch brazing is the perfect repairing solution in a case when there is a large casting crack in an industrial setting & heat soaking for welding is an absolute no-no. In such a case, these castings only require to be water tight or take mild mechanical stress.
  
  
• In case of brazing vs welding related low temperature, it can increase the joining speed while reducing the fuel gas consumption.
  
  
• Welding procedure is a tougher technique to learn for beginners when compared to torch brazing.
  
  
• Torch brazing results in a less burn-through in case of thin workpieces (such as sheet metal or thin-walled pipe).
  
  
• Torch brazing is considered quite an effective technique apart from being cheap for mass production. The components are actually assembled with preformed plugs of filler material which are positioned at joints. Once heated in a furnace, these are passed through heating stations on an assembly line & then flows into the joints by capillary action.
  
  
• There are smooth & attractive beads in braze-welded joints which do not require additional grinding or finishing. With gold being the most often used filler material color, there are instances when appearance becomes a more vital aspect & fillers closely matching the base material color are used as well.
  
  

Torch brazing requires a very small investment especially when the joint quality is largely dependent on operator skill having a consistency issue.