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IT MAY reasonably be asked “why should metalworking lubricants be considered as a class on their own?” Apart from convenience of classification, there are at least three good reasons for doing so:

FOREWORD COMMUNICATION OF IDEAS and data leads to dross‐pollination in research, which can be as important as the bench work itself. Channels of communication are now highly developed and the growth of specialized symposia and conferences points to the continuing development of this important aspect of research. Those who move about meetings regularly can acquire a balanced understanding of what is going on in the many corners where research is being prosecuted. Those who make a habit of combing, methodically, the technical press can also arrive at some idea of the direction and speed of the currents flowing through a particular subject. There are, however, many technical men who find themselves too busy in their management sphere to keep abreast with either meetings or the scientific journals.

CUTTING FLUIDS FACILITATE MACHINING OPERATIONS by virtue of their cooling, lubricating and other properties, and the fluid selected for a particular operation should have the best possible combination of properties to suit that case. In addition, the fluid must be correctly applied to enable its properties to be utilised fully.

WHEN WE turn from oil‐based to aqueous cutting fluids, we meet additional problems and require many more tests. Before dealing with these it should be remarked that they often apply to fluids used in other operations, notably rolling and drawing, so that the following section is not restricted to cutting fluids only.

“For a number of years there have been some machine shops in which a water‐base fluid has been used to the exclusion of all other aqueous cutting fluids. The advantages of such a practice are most attractive; nevertheless, immense quantities of soluble oils continue to be sold”. Why is this? It is hoped that this article will stimulate discussion on this question.

Sendzimir mills have already been referred to as notable examples of cluster mills (p. 142 and Fig. 9). They exploit the advantages of well‐supported small diameter work rolls, making heavy reductions possible and producing very accurate cold rolled strip. The work rolls can be finished to produce the sheet surface quality required, can be very rapidly changed in service, and can be made of special very hard material such as tungsten carbide when minimum flattening is needed. Accordingly these mills are used for a great variety of materials — not only all types of steel (including stainless), copper and its alloys, and aluminium and its alloys, but titanium, tantalum, zirconium and even rarer or more intractable metals.

The attraction of shorter and less expensive methods of performance testing of cutting fluids, as just indicated with respect to broaching operations, applies to all operations in some degree. Even established drilling or turning tests can soon involve expenditure of some thousands of pounds, and this may be difficult to justify where, as is often the case at present, any improvement may only give a modest commercial return.

DRAWING of metals occurs in innumerable ways, both hot and cold. Here, however, we are concerned only with the cold drawing operations used to form vast tonnages of steel, and large quantities of non‐ferrous metals, as tube and wire, and for the forming of sheet metals (especially by deep drawing).

AFTER cutting oils, rolling oils probably constitute the next largest overall offtake of metalworking oils although the proportions for any individual supplier may be very different, since much of the business is in the hands of specialists and some of the largest companies may do little.

CUTTING FLUIDS function by providing lubrication and cooling, and naturally where the latter is the predominant requirement cutting fluids based on water are used. Soluble oil emulsions are the most common type, but in recent years there has been a revival of interest in aqueous solutions as alternatives, and sufficient experience in their use has been accumulated to warrant a review of their present status.