Analysis
The subject of analysis in relation to general foundry practice has for some time occupied the attention of our foundry associations East and West, and called forth considerable comment from leading chemists and manufacturers all over. The writer's views upon the question are set forth in the following paper, composed by him, and read at a meeting of the Western Foundrymen's Association, held in Chicago, February 28, 1894: An article of mine of "Mixing Cast Iron," which appeared in the issues of March 24 and 31, 1892, of the American Machinist, and now constitutes the third chapter in my book, "The Iron Founder Supplement," was the natural outcome of experiences therein related. It was with some trepidation on my part that the article was presented, as at that early period of my experience in these matters I hardly felt able to adequately exhibit a subject which, to me at least, appeared in the light of a revelation.
The article met with a determined opposition from some quarters, both here and abroad; but I shall ever esteem the kindly criticism of Professor Torrey, who, while admitting that science must, for some time at least, get the lion's share of the benefits accruing from a system of chemical analysis in the foundry, thought the establishment of laboratories, and the installation of chemists in that department of the iron industries, would be a very good thing. He concludes a very instructive review of the subject as follows: "I have no intention of trying to instruct Mr. Bolland, or any other foundryman. I have simply called to mind a number of facts with which they are, presumably, as well acquainted as I am--better, perhaps, with one side. The only object in so doing is to put the question of chemistry in the foundry in its proper light with relation to existing facts. Perhaps the foundry at large, from a business point of view, would be benefited by the co-operation of the chemical laboratory; but I do not as yet believe it. . . . The foundry has not the great train of waste and by-products that many industries have, and the waste, such as it is, can be better controlled. The one place where it would seem that chemistry might come in would be in the mixing of irons, as Mr. Bolland suggests; but, as previously stated, it is by no means certain that anything definite or satisfactory would be accomplished." Since then, however, a gradual change has been taking place, and an eminent metallurgical chemist, Mr. Clemens Jones, emphatically states that "the foundryman is in a position to say to the pig-iron maker, 'I want such a quality of iron,' and the furnace manager is in a position to light his fires and make it." With such assurance from one so conspicuously qualified to pronounce an opinion on these themes, may we foundry-men not anticipate the time when, by reason of a superior education, we shall be able to exactly determine our requirements, and prove beyond question the validity of such an assertion? We who are not chemists naturally cling tenaciously to the only tangible support that, up to the present, has been vouchsafed us, viz.: the testing-machine; and I am persuaded that it will take some time to convert the large majority of founders to a belief in this (to them) new departure. My first acquaintance with this subject dates from the time when I was associated with Mr. Molin, metallurgical chemist, New York City. At that time I looked upon the faculty as a decided superfluity in a foundry; but it gives me pleasure to say that, while he noticed my self-assurance, he consistently acted, not only the scholar, but the gentleman. He also unmistakably demonstrated his ability to accomplish, by chemical analysis, what had before seemed impossible of accomplishment; and, while he may not have made a chemist out of such crude material, I am certainly a sound convert to the methods of which he is so able an exponent.
A careful perusal of Mr. Keep's able papers and other kindred works, as well as the exhaustive productions read before this and the Eastern Association by our foremost chemists, has established my belief beyond question. Mr. Henderson, in his address before the Foundrymen's Association, of Philadelphia, brings this whole subject out in bold relief when he says: "But what of permanent avail is accomplished by the application of physical tests to material the chemical composition of which is unknown? The very utmost that can be hoped from such tests is to establish the fact that a definite lot of material is either good or bad."
The above is preceded by a forcible plea for the recognition of chemistry as a factor in foundry practice on the following grounds: "That, whereas it is known that certain impurities in material produce certain characteristic effects upon the physical behavior of manufacture resulting from its employment; that certain combinations of impurities produce certain other effects, and that in the process of conversion, which is in every case a chemical one, these impurities may be eliminated, retained, or forced into combination with others according to fixed laws and conditions to which they are subjected." But he further affirms that in order to secure a proper adjustment of these proportions, so that the resultant casting shall meet all the requirements in the case, ability of the highest order must be employed, simply because the line is not so clearly defined, on either side of which an element may not enter into its composition without disaster. The same author, comparing the value of chemical against physical tests, affirms that, "A fact once established by chemical research remains fixed for all time. When it is known that a certain percentage of an element in a material under certain conditions produces a certain physical effect, every time these conditions are reached in this material having the same percentage of the element this identical physical effect is obtained and no other." Mr. Keep claims that "intelligent mixing of irons cannot be accomplished without the aid of chemistry, and conclusions must be reached by the united work of chemistry and physical experiment." That the time is not far distant when the chemist will be acknowledged as the supreme factor in foundry economics is significantly put by the same author, who on this phase of the subject says: "If a man with a thorough chemical education would learn to look at general tendencies and not hold so closely to four figures of decimals, and accept the results of late research, he could adapt himself to general foundry-work and be of great use. He would soon leave his laboratory and become the practical leader, and would only go back occasionally to solve some problem that needs new light. We cannot have too much respect for chemistry. Practical research could do nothing without it; but after general conclusions are reached, then to be of use the chemist must become the practical metallurgist."
On this head, Professor Torrey cogently informs us that "it takes the skilled metallurgical engineer to reason from the chemistry to the physics of iron; and the chemist must be a good one if the results are to be good for anything. It may be readily inferred from the preceding that the chemist's work in the foundry must be practical in all its bearings, and that a mere school knowledge of the science would be of little service there. Subjects like the porosity of castings, cast-iron and steel, would, under the supervision of a chemist, be subjected to a superior system of examination: even the ordinary crucible tests would receive his strict attention, with the positive assurance of their being made intelligently. Metal-mixing would be transferred from the ignorant mechanic, with his crude systems, to the more positive and scientific methods of chemical research--just where it should have been long ago. For the want of intelligent direction, the best systems of mechanical testing have always been more or less defective; and, as matters now stand, formulas of any kind are seldom understood and as seldom acted up to. The chemist would change all this with the greatest ease and dispatch. The business of steel-founding would have developed more rapidly if the chemist had been consulted with regard to the materials for forming the moulds as well as for the metal with which to fill them. Brass-founding is almost exclusively a branch of metallurgical chemistry; and it is safe to say that the few advances made in that art have emanated from the chemist's laboratory rather than the brass-shop.
There is nothing used in a foundry that does not require rigid inspection when purchased, such as an able chemist only can give; and it would be to the interest of every firm that not only can give; and it would be to the interest of every firm that not only the iron, but fuel, sand, fire-bricks, clays, and every material employed, should undergo close scrutiny. By this means all fraudulent impositions would be at once detected. Already we may observe that sands for foundry purposes are receiving some attention from the chemist. Analysis at once discovers just what may be used for the numerous classes of castings made. We may expect to be informed that in the great majority of cases we have been unnecessarily annoyed by the presence of elements unfavorable to the production of good castings, when, perhaps, a more suitable material has been overlooked that might have been employed with impunity at a much less cost. The percentage of iron oxide, alumina, organic and volatile matters present being made known, there will be no difficulty in making such selection as will meet every requirement absolutely. It is reasonable to presume that the advent of a chemist in the foundry will deter the artful agent from forcing material upon a firm that did not in every respect measure to the full what it was represented to be, and it is certain that the popularity of many favorite irons would go up with the smoke from the laboratory when a test in the latter sanctum had revealed its marked deficiencies.
Fracture will no longer be relied upon, as it is now a well-authenticated fact that analysis has shown that very many of the No. 1 irons are inferior to No. 2 of other brands which may be purchased for less money--saving, in many instances, from 50 cents to $1.50 per ton.
There can be no question as to how some of our foremost firms are producing castings for such low figures at this time. To my personal knowledge, analysis of the materials employed is at the bottom of it; for, by reason of the knowledge thus obtained, they have been enabled to purchase both pig-iron and scrap at ridiculously low figures, very much of which, under the old rule-of-thumb methods, would have been rejected as unfit for the purpose. In many instances this decided advantage has been further supplemented by the production of better castings.
It is certain that those who buy on analysis, knowing what they want, monopolize every opportunity for grabbing whatever offers cheap, as the chances for future disappointment are reduced to a minimum by the substitution for the old unsafe method of one that is not only cheap, but sure. There is practically no difficulty in producing steel of any desired quality, owing to the fact that the different elements are now so well known and may, by chemical test, be regulated in such proportions as will result in the quality of steel required. To accomplish this without loss and inconvenience, all the material is tested before purchase is made, and the user knows exactly what he has bought, and can, without fear of mistake, proceed to the manufacture of his product, knowing from the beginning what the end will be. Surely castings, pig-iron and scrap, can be analyzed with as great nicety so that when fault is found with the resultant castings, the true cause of the trouble may be located, the mixture changed to the requisite proportions, and thus control the business as effectually as it is now done for steel. In framing mixtures for cast iron, it must naturally occur to the least observant that if a certain proportion of the elements contained in the iron produce certain chemical effects, which, in turn, are productive of certain physical properties which may be altered according to the proportions employed, we are forced to the conclusion that chemical analysis will reveal whatever is lacking, and will also suggest a remedy.
A defect in some pump-castings resulted in an analysis of the iron being made by Mr. Molin, who found that it was too high in graphitic and correspondingly low in combined carbon, which caused a soft, porous iron that would dissolve rapidly in the water from the mine. This discovery led to an immediate change in the mixture--an additional quantity of combined carbon effecting at once what under the old regime would not have been satisfactorily accomplished until the offending stock had been all used up and a change brought about, perhaps, by a new consignment. The latter alternative is, unfortunately, the only means of escape possible for numbers of foundries to-day almost everywhere. Desiring to learn more in reference to the above, I waited upon the superintendent of the firm, who informed me that an elaborate system of physical tests were the order of the day, and that unremitting attention was paid to this department; but he was now firmly persuaded that, unless this was accompanied by chemical analysis, they would always be subject to a like experience.
Personally, I may state that since I became satisfied in reference to the wonderful property of silicon to change white and intermediate grades of iron more or less high in combined carbon, into graphitic iron, I have experienced no difficulty whatever in arranging my mixtures, simply because a physical test informs me of its strength, and, if the shrinkage is found too high, it is evidence of hardness, which latter condition I now know may be lessened by an increase of silicon, the shrinkage always decreasing in proportion as the iron becomes more graphitic.
It is not supposed that the common run of small found dries will employ a chemist, but if it be found in the long run that the system of analysis pays, there is no question but that they too will contrive some means for obtaining these valuable aids. For instance, proprietors' sons who have hitherto been satisfied with the regular routine of office-work will now have their ordinary course of education supplemented by a course in metallurgical chemistry, and thus qualify themselves for the position of chemist as well as clerk. A chemist lately said that the reason of foundrymen remaining in the blindfold state in which they are is simply their ignorance of the fine elements which determine the quality of their castings; and, furthermore, that this knowledge can be easily obtained by any intelligent clerk, who may then with an outfit, costing about $ 200, proceed to make tests for these elements as satisfactorily as any chemist.
One thing, however, is certain--our young men are gradually awakening to the advantages open for students in the technical schools; and, as chemistry is taught at most of them, we may expect in the near future to see our benevolent employers rendering substantial aid to their apprentices, in order that they may be qualified for the important duty of making an analysis. Why is it that our technical schools stand aloof from this all-important question? Is this, like everything else pertaining to the foundry, to be tabooed also? Have moulders and founders no rights that these institutions feel bound to respect? Surely the day is now past when a foundryman is to be spurned because of the apparent griminess of his business. I think the advent of chemistry in the foundry will mark a new era in the history of foundrymen. Hitherto the faculty have shunned them on account of their surroundings, but the rays of science have penetrated the dark moulding-shop at last, and her votaries hasten to undo the errors of the past, because, discerning the numerous problems that remain as yet unsolved, they have finally cast prejudice aside, and are now walking hand in hand, the more practical moulder being guided by the scientist in paths that harmonize with physical law. Your true man of science now acknowledges freely that the foundryman is deserving of more than ordinary credit in that so much has hitherto been accomplished by men who were shrouded in such a dark panoply of ignorance. It is to the truly great among these men of science that the future founder must look for enfranchisement. Let furnaces and the necessary equipment for the smelting of ores, metals, alloys, etc., be at once erected in our technical schools, where our aspiring youth may be taught experimentally how to eliminate the objectionable elements from metals; also to determine by analysis of materials, including fuel, slags, ores, fluxes, etc., what their natures consist of, and thus qualify themselves for the very excellent change in their position, which to me seems inevitable in the near future.