The Art of Welding. William Galvery

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       Auto-darkening Faceplates

      An electronic faceplate or lens is one of the most recent and important safety devices developed in the welding industry. These devices are designed to be clear, or nearly clear, then darken the instant arc is established; when purchasing be aware of the time the lens takes to darken 1/25.000 of a second or faster is recommended. Advantages of auto-darkening faceplates include:

      •The welder does not need to raise and lower his helmet when performing a series of welds: he can always see where he is with the helmet down.

      •The beginner does not have to master holding his electrode steady when he drops his helmet. This permits beginners to perform better welds earlier in their training.

      •Electronic faceplates offer continuous eye protection from infrared radiation coming off red-hot metal even when they are not in the darkened mode. It is just easier on the eyes and the welder is less likely to incur eye injury from inadvertent arc strikes.

      Figure 2-15 Auto-darkening faceplates darken almost immediately as soon as the arc is established

       Photo courtesy of Hobart Welders.

       OXYACETYLENE WELDING

      Oxygen and acetylene gases when combined, in the proper proportions in the torch handle’s mixing chamber, produce an approximately 5,600°F (3,100°C) flame at the torch tip. This flame melts the edges of the base metals to be joined into a common pool. Sometimes additional filler metal is added to the molten pool from a welding rod. When this common pool cools and the metal freezes solid, the joined metals are fused together and the weld complete. Other fuel gasses can be used in place of acetylene—and often are for soldering or brazing—but their maximum heat potential is below the heat output required for welding steel. The American Welding Federation (AWF) uses the abbreviation OAW for oxyacetylene welding.

      WHAT ARE THE APPLICATIONS THAT OAW IS BEST SUITED FOR?

      WHAT METALS CAN THE OAW PROCESS READILY WELD?

      WHAT ARE SOME BASIC SAFETY PROCEDURES?

      WHAT TYPES OF EQUIPMENT ARE NEEDED?

      HOW DO YOU SELECT FILLER METAL (WELDING ROD)?

      HOW IS THE EQUIPMENT SET UP?

      WHAT ARE THE SPECIAL PREPARATIONS FOR WELDING?

      HOW ARE WELD RESULTS ACCESSED?

      WEST COAST CUSTOMS WELDING TIPS

      OXYACETYLENE WELDING TIPS FROM WEST COAST CUSTOMS

      Figure 3-2 OAW does not require electrical power, so it is extremely portable.

What are the applications that OAW is best suited for?

      If you have many different types of projects or repairs, OAW processes work well, particularly if you are not near an electrical power source. Unlike other welding processes, OAW does not require electrical power. Use it for welding thin sheet, tubing, and small-diameter pipe.

       Pros and Cons of OAW Process

       Advantages

      •Low cost

      •Readily portable

      •Excellent control of heat input and puddle viscosity

      •No external power required

      •Good control of bead size and shape

      •Fuel mixture is hot enough to melt steel

       Disadvantages

      •Not economical to weld thick pieces of metal compared with other processes

      •Slowest of the welding processes

What metals can the OAW process readily weld?

      •Copper

      •Low alloy steels

      •Bronze

      •Wrought СКАЧАТЬ