Oxyacetylene welding

“ It has been rightly stated that oxy-acetylene welding is yet in its infancy. The torches, regulators and in fact all parts of the apparatus are constantly being improved. The process of cutting cast iron must still be solved, so it will again be stated that it behooves those who are interested in this work to apply themselves to the great future in store for them. ”

“ There were so few men familiar with the oxy-acetylene process that it at once took measures to establish its own schools where men could be trained, a thing that the commercial world had been THINKING of doing for some years. As the demand for operators continues to increase, it behooves a man, even though he is not a metal worker, to think and apply himself, in order that he may “carry on,” to the best advantage when opportunity knocks. ”

“ At the present time only such metals as steel and wrought iron can be successfully cut. When it comes to cast iron no method has yet been discovered to cut it with any degree of success by the oxy-acetylene flame, on account of the high melting-point of the oxide and various other matters. The day is looked forward to, however, when after sufficient time and study has been devoted to this subject, that cast iron can be as successfully cut as any other metal, by introducing another gas or agent to destroy some of the reactions which retard its application at the present time. ”

“ Acetylene gives a light which is nearest to sunlight of any artificial illuminant. But for the fact that this gas light gives a little more green and less blue in its composition, it would be the same in quality and practically the same in intensity. This light from the gas is almost absent during welding, being lost with the addition of the extra oxygen needed to produce the welding heat. The light that is dangerous comes from the molten metal which flows under the torch at a bright white heat. ”

“ However, as soon as there is heat introduced into the water-jacket and not into the cylinder wall, there are certain to be strains set up which, if sufficient, will distort the cylinder and make it useless unless it is rebored. The sooner welders realize that work of this nature must be preheated throughout, to a point as near melting as they can approach without causing the metal to scale, before any welding is attempted, the better success will be obtained in these lines. It is quite necessary to line up the work well, so that it will not sag when heated. ”

“ To assist the welder in executing welds on large steel castings, the pieces are generally preheated, so that the work will take less time, be more successful, and save both oxygen and acetylene. When working on preheated jobs, in order to get the desired angle on the filler-rod so the welder may use it without discomfort, a light heat is played on the filler-rod, a matter of six or eight inches from the end being fused and then bent to an angle of 90 degrees, so that the operator may hold the rod at some distance from his work and still introduce it in the manner he desires. ”

“ The one great advantage of the oxy-acetylene method in comparison with other methods of welding is the fact that in some cases of very thin sheet, the weld can be made somewhat sooner than is possible otherwise. ”

“ The flame must be much larger than for the same thickness of steel and neutral in character. A slight excess of acetylene would be preferable to an excess of oxygen, and in all cases the molten metal should be kept enveloped with the flame. The welding rod is of copper which contains phosphorus; and a flux, also containing phosphorus, should be spread for about an inch each side of the joint. These assist in preventing oxidation, which is sure to occur with heated copper. ”

“ None of the melted metal is allowed to precede the flame, and at all times the operator can see whether the edges to be fused are at the right heat. As soon as the bottom is reached, the weld can again be gone over if it is not thought strong enough, and reinforced as much as desired. As soon as the operator is familiar with this method, he will find that much more speed can be developed, less filler-rod lost and less lapping done than by building up from the bottom. ”

“ A good bronze for welding purposes should work easily under the influence of the oxy-acetylene flame and have sufficient alloys present to take care of those destroyed by the action of the flame. It is not thought advisable to work over welds of bronze, for fear of making them porous, unless more filler-rod is added whenever the flame is brought in contact with the weld.
(139) Welds of malleable iron can be made which will be even stronger than the surrounding metal, and at times they can be reinforced by adding small strips of steel. ”

“ The theory of this reaction is that the heavy aluminum oxide is the only thing which prevents the metal flowing together when heated, and as soon as the flux is introduced this oxide will be destroyed along the line of weld and a fusion of the metal effected. This actually takes place, providing enough heat has been introduced to permit this reaction to penetrate the depth of the weld. The flux contains the chemicals necessary to cause this reaction if the metal is in the right condition. There are many welders who do not use sufficient heat and blame the faulty results upon the flux. ”

“ On account of this exceedingly rapid oxidation, it will be found to the operator’s advantage to complete his aluminum welds as quickly as possible in order that he will have less of this oxide to combat. It will be found in using the puddle system that greater haste can be made by using the torch in the left hand, leaving the right free to do the puddling and to add whatever metal is necessary. In this method most of the success depends upon the operator’s skill in handling his puddle stick and puddling in additional metal. Generally the right hand can do this more rapidly than the left. ”

“ This light is dangerous to observe at close range without colored glasses. The burning of the metal can be maintained for hours, without any other source of heat except that caused by the combustion of the iron. The oxy-acetylene cutting process is based upon this principle, in that a neutral flame is applied in order to heat the part being cut to the desired temperature. Once the melting-point is reached, pure oxygen under pressure is applied to maintain oxidation and force out the burned portion. ”

“ It is singular indeed that a school manual, devoted exclusively to the instruction of the beginner, which will serve as an aid to the instructor as well as to the student, has not yet been put forth. It cannot be said that there is not a demand for such. Recently there seems to have been a mushroom growth of welding classes. The majority of the vocational schools, colleges, night schools, and automobile schools have all entered the instruction in oxy-acetylene welding on their rolls and each is attempting to instruct in an entirely different manner from the other. ”

“ High carbon steels are very difficult to handle. It is claimed that a drop or two of copper added to the weld will assist the flow, but will also harden the work. An excess of oxygen reduces the amount of carbon and softens the steel, while an excess of acetylene increases the proportion of carbon and hardens the metal. High speed steels may sometimes be welded if first coated with semi-steel before welding. ”

“ Now, if there is a fracture and a foreign metal, which under no circumstances can be expected to take the same hardening as the rest of the spring, is introduced into the weld, it can easily be seen why a fusion of this kind is not to be relied upon. If it were possible to diagnose or take an analysis of the metal in the spring and use a filler-rod which, after being acted upon by the flame, would come out the same as the metal in the spring, then some success might be expected, but until that time, welding of springs will not be encouraged. ”

“ The application of heat always causes expansion. There are no exceptions to this rule, likewise upon cooling the metal there will be a contraction. Outside of the actual welding, that is, the fusing of the metal into a homogeneous mass, perhaps the greatest problem that the welder has to confront is the expansion and contraction of his metals. Whenever the ends of two pieces of metal which are to be welded are free to move, or even one end, there will be no difficulty encountered with contraction and expansion, but if these ends are confined, it is an entirely different problem. ”

“ A flux is not used, as many suppose, to cement the filler-rod to the metal. It is used purely as a cleansing agent and may be likened to the acid used in soldering. It does not act on the metal until the latter has reached the melting-point, but then it starts to break up the oxides and clean the surface. This action permits the metal to flow together more readily. A cast-iron flux is always used in welding cast iron, to break up the oxide, because the cast iron itself will melt before the oxide and no matter how hot the metal is it will not flow together as long as this oxide is present. ”

“ The electric arc will melt metal in a weld for less than the same metal can be melted by the use of the oxy-acetylene torch, and, on account of the fact that the heat can be applied exactly where it is required and in the amount required, the arc can in almost all cases supply welding heat for less cost than a forge fire or heating furnace. ”

“ Undoubtedly it will assist some operators in solving the trouble that has been occasioned by the ordinary hose clamps, especially when doing cutting or heavy welding work where the gas pressure is considerably higher than usual. The wire used should be large enough to prevent cutting the fabric in the hose.
(53) An injured hose which may leak should never be used after the leak is noticed unless some means are taken to repair it. The use of tape in trying to repair hose on an oxy-acetylene welding outfit should never be permitted. ”

“ The cast iron in the rods is of a very good grade and generally much better than the piece to be worked upon. To permit the ready flow of the rod and eliminate oxidation, as much as possible, three per cent of silica is generally used in the casting of filler-rods for cast iron welding. Piston rings and other scrap iron should not be used for filler-rods, as they contain many impurities such as core-sand, dirt, grease, etc., which will ruin the weld. It is disheartening to see some operators attempt to economize on the filler-rod. ”

“ In welding over head there is a tendency on the part of most welders to avoid the use of enough heat to bring their metal to a molten state, for fear that it will drop upon them. It must be remembered that lack of heat means poor welds and that the metal must be in a molten condition whenever the weld is to be made. As soon as a little practice is given to this kind of work, the welder will see that the melted metal can assume some proportions without dropping off, despite its weight. ”

“ If, while welding, a spot appears which does not unite with the weld, it may be handled by heating all around it to a white heat and then immediately welding the bad place.
Never stop in the middle of a weld, as it is extremely difficult to continue smoothly when resuming work.
The Flame.--The welding flame must have exactly the right proportions of each gas. If there is too much oxygen, the metal will be burned or oxidized; the presence of too much acetylene carbonizes the metal; that is to say, it adds carbon and makes the work harder. ”

“ It cannot be expected, however, that a steel with the same cross-section as the original will possess the same properties and be as strong, for a weld is only a casting unless treated otherwise and the steel or wrought iron used in the specimens is of rolled stock. If too much metal has been added and dressing down is necessary, the student will find that by using a slightly oxidizing flame the surplus metal can be burnt away very rapidly and a very good-looking job can be executed much more rapidly than if a neutral flame were used. ”

“ It is well to learn how to make a successful weld from one side of the metal only, and while this will apply to all metals, it is especially advantageous in working aluminum. Where a small layer of metal has been added to one side of an aluminum job, such as a crank case, and it does not penetrate the entire thickness of the metal, when the other side is turned, and the flame applied to it, a difference in temperature and the loss of strength in this metal when heated will cause the first side welded to crack unless the operator is extremely cautious. ”

“ In welding cast steel the same procedure takes place as previously described for steel, and it should present no real difficulties after that process is understood. There may be more sand, oxide and other impurities present on account of the nature of the metal, but these can all be worked out if plenty of heat is applied. At times, when working in steel, it will be found that there may be a small hole develop in the center of the weld and as the torch is worked into this hole it is found that it goes down a short distance and seemingly refuses to be worked out. ”

“ As often as it is necessary to clean up the metal and break up the oxides. All fluxes should be kept in airtight containers when not in use, to keep their chemical contents in the very best condition and it is best to use only a small quantity of flux on the welding table at one time. ”

“ It is probably safe to say that the principal cause of hard spots in steel welds is due to lack of heat. This, if given careful thought and consideration, will be brought home forcibly to the welder as he proceeds in his work, for the lapping of metals, trapping of oxides, “craters,” too rapid cooling, etc., may all be directly attributed to a lack of sufficient heat. If the metal is in a molten state, all impurities will be brought to the surface, for they are bound to be displaced by the weight of the metal, the same as corks in a barrel will float to the top if water is introduced. ”