limits the quality of thick cuts.
What are the advantages of LBC?
•Narrow kerf widths
•High cutting speeds
•High quality edge surfaces
•Low heat input/minimum distortion
•Cuts most materials
•Easily automated
•Repeatable, precision dimensions
•Multiple layers of material may be cut at the same time
What are the drawbacks to LBC?
•Equipment is expensive.
•Replacement lens’ and consumables are expensive.
See Figure 2–33.
Figure 2–33Schematic of a LBC
It is possible to fly without motors, but notwithout knowledge and skill.
Wilbur Wright
Introduction
Soldering has been used for thousands of years, but a solid theoretical understanding has come only in the last one hundred. Brazing is similar to soldering but performed at higher temperatures. It has come into use more recently as higher temperature torches became available. Although soldering and brazing do not make joints as strong as welded ones, they are widely used in making and repairing a wide range of products from airplanes to computers to household plumbing to jewelry. Soldering and brazing processes can be as simple as using a soldering iron, a propane torch or as complex as using radio frequency energy in a vacuum to join parts. We will discuss the theory, materials, fluxes, and common industrial processes. These processes have some advantages over welding and we will present them. There are safety issues too. Because soldering copper water pipe is so useful and something every welder should know how to do, we cover step-by-step instructions in Chapter 15.
Process Names
What is the AWS designation for brazing?
The AWS designation for brazing is B.
What common names are sometimes used for brazing?
Silver soldering, silfloss, and hard soldering are non-preferred names for brazing. Silver brazing filler metals are not solders; they have melting points above 840°F (450°C).
How are brazing processes classified and what are the commercially significant ones?
Brazing processes are classified by heat-source type. Commercially important ones are:
•Dip Brazing (DB)
•Furnace Brazing (FB)
•Induction Brazing (IB)
•Infrared Brazing (IB)
•Resistance Brazing (RB)
•Torch Brazing (TB)
What is the AWS designation for soldering?
The AWS designation for soldering is S.
What are the commercially important soldering processes?
•Dip Soldering (DS)
•Furnace Soldering (FS)
•Induction Soldering (IS)
•Infrared Soldering (IRS)
•Iron Soldering (INS)
•Resistance Soldering (RS)
•Torch Soldering (TS)
•Wave Soldering (WS)
Note that with the exception of iron soldering and wave soldering both brazing and soldering share most common processes.
Process
In general terms how does the brazing process work?
Brazing joins materials that have been heated to the brazing temperature followed by adding a brazing filler metal having a melting point above 840°F (450°C). This temperature will be below the melting point of the base metals joined by this joining process. The non-ferrous filler metal is drawn into and fills the closely fitted mating or faying surfaces of the joint by capillary attraction. The filler material, usually aided by fluxes, wets the base metal surfaces allowing the brazing material to flow or capillary more readily through and between the two surfaces. When the filler metal cools and solidifies, the base materials are joined. See Figure 3–1.
Figure 3–1Capillary forces draw molten filler metal into brazed joint
How does soldering differ from brazing?
Brazing takes place above 840°F (450°C) and soldering below 840°F (450°C), otherwise, the processes are quite similar. They both depend on capillary attraction to draw filler metal or solder into the joint. In general brazed joints are stronger than soldered ones because of the strength of the alloys used.
What is the difference between brazing and braze welding?
Brazing depends on capillary attraction to draw the filler metal into the mating joint, while in braze welding the filler metal is deposited in grooves or fillets at the points where needed for joint strength. Capillary attraction is not a factor in distributing the filler metal, as the joints are open to the welder. Braze welding is not a brazing process, but welding with brazing filler metal. Braze welding is frequently used to repair cracked or broken cast iron parts. Joint design is similar to those for OAW: V-groove butt joints, lap joints, T-joints, fillets, and plug joints.
What advantage does braze welding have over welding?
Because braze welding does not melt the base metal and is performed at a lower temperature than welding, there is less distortion of the part. Also, the process of braze welding is performed only on a small area of the part, so the entire part does not need to be brought up to braze temperature all at once.
