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Flame Cutting Principles

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Presentation on theme: "Flame Cutting Principles"— Presentation transcript:

1 Flame Cutting Principles
Chapter 6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 Objectives Describe oxy-fuel cutting principles.
Identify oxy-fuel cutting equipment. Explain the safety issues of oxy-fuel cutting. Describe various support equipment for oxy-fuel cutting. Identify various cutting techniques. Describe the oxygen lance cutting process.

3 Oxy-Fuel Gas Cutting Torch
Become universal tool Used widely for straight-line shape cutting Used as means of scrapping obsolete metal structures Used to fabricate metal structures from heavy rolled steel © EdDegginger Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

4 Oxyacetylene and Other Fuel Gas Cutting
Limited to cutting ferrous materials Ferrous materials have affinity for oxygen Rusting process is slow form of oxygen cutting Chemical cutting process Arc or water jet process Stainless steel, manganese steels and nonferrous materials Mechanical method of cutting

5 Oxygen Cutting Requires that the part to be cut be raised to a temperature of 1,500-1,600ºF Stream of pure oxygen directed onto hot metal causing it to burn rapidly Burning steel gives off iron oxide as a product of combustion Iron oxide solid at room temperature Melting point below melting point of steel so iron oxide runs off as molten slag, exposing more iron to jet

6 Properties of Common Fuel Gases
Methylacetylene- propadiene (MPS) Propane Natural Gas Acetylene Propylene Chemical formula C2H2 C8H8 C3H C3H4 CH4 Neutral flame Fº 5, , , ,200 4,600 Primary flame heat emission Btu/ft Secondary flame Btu/ft , , , Look for the rest in Table 6.1 from text

7 Oxy-fuel Gas Cutting Equipment
Single-purpose cutting torch, or welding torch to which adaptable cutting head is attached Flint lighter Oxygen regulator Acetylene regulator Oxygen welding hose with couplings attached to each end Acetylene welding hose with couplings attached to each end Flame arresters and check valves

8 Cutting Torch A high pressure oxygen valve operated by a lever controls the oxygen. Connecting Tubes Oxygen furnished to the preheating flame is regulated by a preheat valve on the side of handle. Cutting Head Handle Adaptable Cutting Head A needle valve in the acetylene inlet connection controls the supply. Hose Connection for Oxygen Acetylene Thermadyne Industries, Inc The cutting torch mixes oxygen and acetylene or other fuel gases in the proportions necessary for cutting. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

9 Internal Construction of a Standard Cutting Torch
Take a closer look at the cutting end of the torch! Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

10 Internal Construction of a Standard Cutting Torch
Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

11 Internal Construction of a Standard Cutting Torch
Now a closer look at the handle end of the torch! Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

12 Internal Construction of a Standard Cutting Torch
Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

13 Thermadyne Industries, Inc
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

14 Standard Adaptable Cutting Attachment
Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

15 Cutting Tips Around this center hole are a number of preheating flame holes. Thermadyne Industries, Inc Cutting tips may be obtained in various shapes and sizes. The thicker the metal that is to be cut, the larger the size of the center hole must be. The cutting tip has a central hole through which the high pressure oxygen flows. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

16 Cutting tips are designated as standard or high speed.
Standard Cutting Tips Cutting tips are designated as standard or high speed. The standard tip has a straight bore cutting oxygen port and is typically used with oxygen pressures in the 30 to 60 p.s.i. range. American Welding Society, Welding Handbook, Vol. 2, 8th ed.,Fig. 14.5, p. 457 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

17 High Speed Cutting Tips
The high speed tips have a diverging cutting oxygen port that flares out toward the opening. This flaring out allows much higher oxygen pressure (60–100 p.s.i.), while maintaining a uniform oxygen jet at supersonic velocities. These high speed tips are typically used only for machine cutting and will yield an increase in travel speed of 20 percent over standard tips. American Welding Society, Welding Handbook, Vol. 2, 8th ed., Fig p.457 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

18 Orifice Size Cutting Oxygen orifice size not usually affected by type of fuel gas used Preheat orifices need to be of appropriate design for type of fuel gas being used. Various fuel gases require different volumes of oxygen and fuel Tips used for acetylene usually one piece, while other fuel cases may be one-or two-piece tips

19 Flame Tips Acetylene tips are usually one piece and flat on the flame end. Close quarters cutting attachment 1 Long cutting tip 2 Rivet-cutting tip 3 Tips for methylacetylene-propadiene (MPS) have a flat surface on the flame end. Straight gouging tips 4 Most propylene tips have a slight recess, and natural gas and propane tips usually have a deeper recess or cupped end. Tips may be obtained for flame machining, gouging, scarfing, and rivet cutting. Bent gouging tip 6 Rivet-burning tips 5 Sheet metal cutting tip 7 Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

20 Lighters The cutting torch should be lighted with a friction lighter.
The flints of friction lighters can be easily replaced at small cost when worn out. Matches should never be used because the thermal cutter’s hand has to be too close to the torch tip and may be burned when the gases ignite. There is also the danger that the supply of matches that the thermal cutter may be carrying in his or her pockets will ignite and cause severe burns. Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

21 Goggles The thermal cutter must wear protective goggles to prevent harm to his or her eyes from sparks, hot particles of metal, and glare. Thermadyne Industries, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

22 Gloves Heat is very intense Shower of sparks and hot material
Best gloves should be of non-burnable material Common practice to wear ordinary canvas glove with cuff which can be purchases at very small cost Gloves should be kept free from grease and oil because of the danger involved in contact with oxygen. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

23 Magnetic Burning Square
Contour Sales Corp. The magnetic burning square makes it possible to cut straight lines with a high  degree of accuracy. It can be used for structural burning and layout work in general. The tool is inscribed with a 90° protractor in 1° increments, allowing a swing of 180° with the blade or tool. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

24 Magnetic Burning Square
© Centour Sales Corp. The base of the tool is a perfect square, with two strong, cast-in magnets for holding the tool in the overhead, vertical, angular, and horizontal positions.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

25 Magnetic Burning Square
© Centour Sales Corp. The top part of the tool is cast with an 18-inch blade in 1/8-inch increments, and it has a large knob for setting and holding the blade in the desired degree position. With the exception of the magnets, the tool is made of aluminum. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

26 Oxy-Fuel Gas Cutting Machines
These machines have device to hold cutting torch and guide in along the work at a uniform rate of speed. Work is of higher quality and faster than with the hand cutting torch. They may be used for cutting straight lines, bevels, circles, and other cuts of varied shape. Small machines used with only one torch. ESAB Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

27 Multiple Cutting Torches
Automatic control Multiple torches ESAB Large permanent installations can make use of several cutting torches to make a number of similar shapes at the same time. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

28 Automatic Control ESAB Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

29 Multiple Cutting Torches
A number of cutting torches are mounted on the machine so that a number of parts of the same shape can be cut simultaneously. These machines can be used for straight-line or circle cutting. They can be guided by hand or a template. Metal Fabricating Institute Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

30 Tracing Devices Cutting machines may be guided by various types of tracing devices. One type follows a pattern line of tracer ink and electrically controls the movement of the torch by means of a servomechanism. Some units make use of a tracer roller, which is magnetized and kept in contact with a steel pattern. The tracer follows the exact outer contour of the pattern and causes the cutting tools to produce a cut in exactly the same shape. ESAB Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

31 Stack Cutting Cuts made through several thicknesses at same time
Plates in stack must be clean and flat with edges in alignment Tight contact with minimum of air space between Need to clamp them together American Welding Society (AWS) Welding Handbook Committee, 2001, Welding Science and Technology, Volume 1 of Welding Handbook, 9th ed. Miami: American Welding Society, Fig , p. 468 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

32 Stack Cutting Stack cutting is particularly suitable for cutting thin sheets. A sheet 1/8 in. thick or less warps, and the edge is rough with slag if cut singly. If stack cut, the edges are straight and smooth and free from slag. Plates may be up to ½ in. thick. American Welding Society (AWS) Welding Handbook Committee, 2001, Welding Science and Technology, Volume 1 of Welding Handbook, 9th ed. Miami: American Welding Society, Fig , p. 468 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

33 Beam Cutter The beam rail is positioned across the flanges.
BUG-O The beam cutter is a portable structural fabricating tool. The operator can trim, bevel, and cope beams, channels and angles. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

34 Beam Cutter Two permanent magnets lock and square rail in position.
Variable speed power units used on both horizontal and vertical drives Squaring gauge enables operator to adjust tip quickly from bevel to straight trim cuts Weighs only 60 pounds so one operator setup times is minimal Clean, accurate cuts done in minimum time

35 Oxygen pressure used is 75 to 100 p.s.i.
Oxygen Lance Cutting Oxygen pressure used is 75 to 100 p.s.i. The lance is length of black iron pipe. The pipe size may vary from 1/4 to 3/8 in. American Welding Society, Welding Handbook, Vol. 2, 8th ed., Fig , p. 479 Oxygen lance cutting (OLC) is a method of cutting heavy sections of steel that would be very difficult by any other means. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

36 Oxygen Lance Cutting American Welding Society, Welding Handbook, Vol. 2, 8th ed., Fig , p. 479 In order to start the cut, it is necessary to preheat the cutting end of the pipe (lance) to a cherry red with an oxy-fuel cutting or welding torch. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

37 Oxygen Lance Cutting American Welding Society, Welding Handbook, Vol. 2, 8th ed., Fig , p. 479 Once it is cherry red the oxygen flow is started. The steel pipe burns in a self-sustaining, exothermic reaction, and the heating torch is removed. When the burning end of the lance is brought close to the workpiece, the work is melted by the heat of the flame. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

38 Oxygen Lance Cutting The lance is slowly consumed during the operation and must be replaced from time to time. The oxygen lance is useful for piercing holes in heavy thicknesses of steel, cutting off large risers in the foundry, and opening holes in steelmaking equipment which have become plugged with solidified metal. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

39 Oxygen Lance Cutting The lance is slowly consumed during the operation and must be replaced from time to time. The oxygen lance is useful for piercing holes in heavy thicknesses of steel, cutting off large risers in the foundry, and opening holes in steelmaking equipment which have become plugged with solidified metal. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.


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