LESSON #1 – AIR CARBON – ARC CUTTING (A.C.C.)
TOPIC: INTRODUCTION
INTRODUCTION: A simple process used for the removal of unwanted metal. “Arc Gouging.” “Back Gouging” “Arc Cutting” “Arc-Air”.
LESSON POINTS: The equipment consists of four (4) primary components:
POWER SOURCE – AC/DC, CC/CV.
ELECTRODE HOLDER – directs air to the arc.
COMPRESSED AIR – shop air 80-100 psi.
CARBON ELECTRODE
HOW DOES IT WORK?
A stream of compressed air, directed at a pool of molten metal. Created by an electric arc, blows molten metal away, leaving a crater or gouge in the metal.
WHERE IS IT USED?
Used to remove defective welds, metal cutting, bevelling plates, and back gouging etc.
ADVANTAGES:
Special care must be taken against fire hazards.
The shaded lens should be at least a shade 12-14.
Non-flammable clothing is recommended.
All hoses, welding cables, flammable materials, gas cylinders and tools must be removed from the path of the molten metal stream.
Good ventilation is required.
Respirator should be worn. There is a possibility of toxic fumes from the copper coated carbon electrodes.
Ear protection should be worn.
Remove the carbon electrode from the holder.
Cheaper to operate, less space, a cleaner process of metal removal than oxy/fuel.
SAFETY: Safety in welding and cutting are applicable to the Air Carbon – Arc Cutting and Gouging processes. In addition:
LESSON #2 – AIR CARBON – ARC CUTTING (A.C.C.)
TOPIC: EQUIPMENT
INTRODUCTION: There are a few different types of torch models to choose from.
The most common of which is “Arc Air”. We use a “Pro Fax”.
LESSON POINTS:
POWER SOURCES: AC/CD. CC/CV type.
AMP rating of machine a 100% duty cycle.
Cycle must not be lower than maximum current capacity of electrode.
Single phase DC is not recommended.
Average power level not high enough.
Min O.C.V. On a CC machine is 75 V (stick).
Min O.C.V. On a CV machine is 65 V.
Arc voltage ranges from 27-55 V depending on electrode diameter.
HOLDERS: Three (3) basic classifications
Manual, semi-automatic, and fully – automatic.
Manual electrode holders most commonly used in welding industry.
They have a rotatable head, with air passages.
Minimum and maximum diameter capacities.
It is important that the electrode holder is the proper size and rating for carbon electrode to be used.
CARBON ROD: Three (3) types.
DC Copper Coated.
DC plain.
DC Copper coated most popular. They have a longer arc life, better arc stability and good groove dimensions.
Available in diameters from 5/32” to 1”.
Designed to operate with DCEP.
LESSON #3 – AIR CARBON – ARC CUTTING (A.C.C.)
TOPIC: USES
INTRODUCTION: The air Carbon – Arc cutting and Gouging is used for severed things.
LESSON POINTS: A.C.C. Can be used for preparing plates for welding such as; cutting and bevelling.
It can also be used for back gouging.
Removing unwanted welds and metal.
Repairing cracked welds (gouge welds and re-welds).
Types of metal it can be used on:
Carbon steel.
Low-Alloy steel.
Gray-Cast steel.
Malleable iron.
Ductile iron.
Copper alloys.
Nickel alloys, etc.
Stainless steel.
Carbon electrode sublime when they reach their melting point of 6, 740 degrees F.
Define Sublime: To change from solid state to the gaseous state without the intermediate liquid state.
Air and hose: Min. Hose ID 3/8” air pressure 80-100 psi (MINIMUM).
LESSON # 4 – AIR CARBON – ARC CUTTING (A.C.C.)
TOPIC: EQUIPMENT PREPARATION AND BASIC USE PREPARATIONS PREPARATIONS
INTRODUCTION: If the Air Carbon Arc process equipment isn't set up and connected correctly the process cannot funtion the way it should. The basic considerations presented in the following paragraphs will help you get started on the right track! We are assuming that the power sound is connected to primary electrical power and that a source of compressed air is available.
LESSON POINTS: EQUIPMENT PREPARATION
Connect electrode and work welding cables to the power souce output terminals. Tighten connections firmly.
Connect the welding electrode power cable to the ACC electrode holder cable assembly. Connect the cable to the base metal.
Connect the air pressure hose to the AAC electrode holder assembly.
Insulate the ACC cable and hose connections with the insulation “boot” supplied with the ACC unit.
Connect the air pressure hose to a source of 80-100 psi air pressure an air pressure gage and regulator is recommended to regulate the flow pressure. A water vapour trap in the air supply line would be advisable.
Select the correct diameter and type carbon electrode (3 types).
