Presentation on theme: "Air Carbon Arc Cutting and Gouging NCCER WELDING LEVEL ONE- UNIT 4."— Presentation transcript:
Air Carbon Arc Cutting and Gouging NCCER WELDING LEVEL ONE- UNIT 4
Intro Carbon arc-cutting (CAC-A) is an arc cutting and _________ process. The base metal is melted with an ______________ formed between a carbon electrode and the base metal. A jet of __________________ passes through the electrode holder and its head blows the molten metal away. This process can be used in _____________________ on any type of metal that will conduct electricity. It is primarily used to gouge welds, gouge out defective welds, and to prepare ____________ for welding.
CAC-A Process CAC-A process uses a high current electric arc between the base metal and the end of a carbon graphite electrode to melt away the base metal. The currents used with CAC-A electrodes are ______________ than those required for same size SMAW electrodes. The size of the groove to be cut can be controlled by electrode size, amps, travel angle, electrode movement, and air pressure.
CAC-A Power Supply Either AC or DC constant power sources can be used but ___________________ is preferred. Type of current used depends on the type of base metal to be cut.
Air supply A CAC-A torch requires _______________________ to blow the molten metal away from the cut. Compressed air is supplied to the torch through a hose attached to a fitting on the end of the torch cable. The pressure on the torch regulator should always be set for the _____________________ that will reliably do the job. Because the molten metal tends to splatter, make sure that ________________________________ or screens are set up to protect any equipment or personnel near the work area.
CAC-A Electrodes Electrodes used for cutting and gouging are composed of a blend of carbon and graphite with a binder material, which is baked to produce a uniform structure. There are three basic types: ◦Plain, Copper coated for DC current, and Copper coated for AC current
Electrodes Plain- Do not have a copper coating and run at ____________ surface temps Copper coated for DC current- most common, carry more current, and operate at cooler temps. Copper coated for AC current- contain rare earth metals that help stabilize the arc. Used to cut _______________
Electrodes Electrodes are also manufactured in several styles, each with a range of sizes… These types are: ◦Round, Round jointed, and special shapes _____________________ electrodes are designed to make special shaped grooves or cuts. Special shapes include flat and half round. Flat electrodes are designed for close tolerance metal removal. _________ electrodes are specified by the widths of their widest side.
Safety Remember that CAC-A work generates ___________________ and heavy smoke and fumes. Always take the proper safety precautions to ensure that nobody is harmed during this type of welding. Make sure that proper ___________________ is available before starting.
CAC-A Equipment CAC-A equipment consists of the arc torch and its attached cable. The torch cable must be attached to a welding machine and a compressed air source. The connecting cable on a CAC-A contains both an ______________________ and a compressed air hose. Always be sure to position the _________________________ where the welding currents will not pass through seals, bearings, or other parts that could be damaged from arcing.
Washing ________________ is the process of cutting objects or projections (Such as bolts or rivet heads, old welds, and other unwanted materials) from the surface of a base metal to leave a flush surface. Typically use a _____ degree push angle to ensure a good wash. Any notches left in the base metal also have a tendency to trap slag during welding. Dross or carbon deposits left on a surface to be welded will combine with the base metal to form _____________________ and porosity in the weld zone.
Gouging ___________________ is a process of cutting a groove into a surface, usually to prepare it for welding. When gouging, the electrode size determines the minimum groove width. Special shaped electrodes can be used to cut special shaped grooves. To create a shallow gouge, you should advance the electrode __________________.