This book has been written with the object of placing before die-makers, tool-makers and tool draftsmen, certain definite information not heretofore available as a whole, although some of the material here published is necessarily of a fundamental character with which all mechanics must familiarize themselves in their progress toward a reasonably complete knowledge of the subject of press tools and their construction.

Practically ninety per cent of the material in these pages has been gathered and prepared expressly for this volume and is here published for the first time. The remainder has been selected from current articles originally published by the author and by other contributors to the technical press. For information taken from the latter sources full credit is given under the list of references at the back of the volume.

In gathering photographs, drawings and data for the preparation of this book the author has been accorded free access to the methods and practice of many of the leading plants of America where he has received the hearty cooperation and assistance of numerous shop executives, tool room foremen, press room foremen, die-makers and others, and full appreciation of this invaluable aid is herewith expressed. In this connection especial thanks are due the following firms and individuals:

-    PRESS TOOLS IN GENERAL
-    BLANKING DIES
-    PIERCING TOOLS BLANKING AND PIERCING DIES
-    COMPOUND DIES FOR BLANKING AND PIERCING
-    CUTTING OFF DIES OR PARTING TOOLS
-    SHAVING DIES AND THEIR APPLICATIONS
-    TRIMMING DIES TRIMMING AND SHAVING
-    DRAWING DIES AND THEIR ACTION UPON MATERIALS
-    COMBINATION AND COMPOUND DIES FOR BLANKING, DRAWING, FORMING AND PIERCING
-    BENDING AND FORMING TOOLS
-    BENDING, FORMING AND OTHER DIES APPLIED TO SPECIFIC LINES OF WORK
-    DIES FOR EMBOSSING, MARKING, RIVETING, SWAGING
-    INDEXING AND TRANSFER DIES
-    THE SUB PRESS AND ITS DIES
-    PUNCH AND DIE STANDARDS
-    FINDING THE SIZE OF BLANKS FOR SHELLS AND OTHER DRAWN AND FORMED WORK
-    LAYING OUT AND MAKING TEMPLETS AND DIES
-    LOCATING HOLES ACCURATELY IN DIE WORK
-    MAKING A SET OF SHAVING DIES
-    SOME HARDENING PRINCIPLES APPLIED TO DIES

PRESS TOOLS IN GENERAL

The class of shop equipment commonly known as press tools or punches and dies, is becoming extended into so many lines of manufacture and in those lines assuming such constantly increasing aspects of importance, that no one responsible for factory output or in any way connected with design, manufacture, or tool department activities can afford at the present time to remain uninformed in respect to the details of construction and application of these tools if the product of the plant is of such character as to admit of the utilization of sheet metal working apparatus. And, it may be added, there are to-day very few lines of metal manufacture where such tools cannot be employed to advantage, even though in many instances their complete possibilities are not recognized and appreciated until a detailed study has been made of existing methods in the plant, and a comparative analysis drawn up to determine what parts may be converted with economy into press manufactured material.

More and more it has come to be the practice to produce, by some form of stamping process, work that formerly was almost invariably manufactured from the solid bar, from forgings, or from some other class of solid material. So, in addition to a widely diversified line of products that have always been recognized as press work pure and simple, there have developed numerous other classes of metal parts whose manufacture has been transformed from the conventional operations of, say, turning, drilling, and so on, to the processes available under press working methods. It therefore is quite within the truth to state that the time is already here when no progressive individual connected with metal parts production, whether in drawing office or shop departments, can consistently refrain from persistent investigation of current practice in press working operations, which, though often fundamental in character, display in details of application distinct advance over the methods of the past, with corresponding progress as measured by quality and volume of output.

Where formerly it was the occasional or the specialized shop that made use of press working methods, at the present time it is the exception to find a well organized plant engaged in small or medium parts production that does not find it necessary to utilize metal working presses to a considerable extent. Even where very large articles are produced from sheet metal an important percentage of the work and frequently the whole of it is accomplished by the blanking, drawing, forming, and other processes of the press department.

As a natural consequence, the rather unusual occupation of the die maker of early times is to-day followed by a great number of tool makers who have entered upon this highly skilled branch of shop work and whose handicraft is to be noted in tool rooms innumerable throughout the country. Similarly, the tool designers over the drawing boards in our plants are devoting more and more attention to the consideration of progressive methods of handling sheet metal through dies of various classes, and these men, like those in the tool room, exhibit an increasing degree of interest in the general subject of press tools.

Owing to the fact that punch press operations are peculiar to themselves, and the tools of this branch quite incomparable with other special apparatus about the shop, any book treating upon the general subject forming the title of the present volume must necessarily deal to a certain extent with some few details of a fundamental character; details possibly of common knowledge to such tool makers and draftsmen as have long specialized upon work of this nature, but none the less important however to men who, with perhaps many years of experience in other skilled branches of the machine industry, have had limited opportunity for following the advance gained in the punch and die makers' art. Still, from their ranks must come many of the die makers of the immediate future and therefore in this book, along with examples of what leading mechanics consider their best practice in press tool work, a little space will be devoted to certain elementary considerations.


GENERAL CLASSES OF DIES

First, when we speak of diet, we mean just as when we refer to press tools, both punches and dies. Often we mention a set of dies, meaning usually, as before, a punch and a die. While ordinarily the die is secured to the bed of the press or to the bolster thereon, and the punch carried above by the traveling ram or slide of the press, this arrangement is by no means universal, for in many instances marked advantages of operation are derived by inverting the usual order and placing the punch below and mounting the die upon the slide above. And in compound dies, as they are called, we have before us a common example of a set of press tools in which the die proper carries also a punch: while the opposite tool, the punch proper, carries a die inside. So in neither case of upper or lower tool in the set, considered as a whole, can one be distinguished entirely as a die and the other as a punch for each half combines the functions of both punch and die.

However, no matter what the relative positions of the punch and die maybe or how the two tools may be arranged, we may safely define the die as the tool that establishes the external form of the work or of the opening in a pierced piece, and the punch as the corresponding internal member.

In considering press tools as a whole it is of value to note how they fall into certain classes as distinguished by the character of their action upon the metal which is manipulated in their operation. It should be understood here that although reference is distinctly made to metal, numerous other materials are worked by identically the same processes as the various sheet metals such as iron, steel, brass, copper, aluminum, german silver, tin, zinc, etc. These other materials would include such as hard fiber, rubber, card board, leather, paper, mica, fabrics, and so on. Not but what special modifications must be made in many instances where press tools are applied to manufacture of parts from these substances, but in their principal characteristics the tools used are identical with or quite similar to those employed on sheet metal operations.


HOW TOOLS MAY BE CLASSIFIED

If now we group the various forms of press tools according to their action upon materials, we shall find that in general they may be classified under four heads as follows:

I. Tools that operate by cutting or "shearing" the metal, for example, blanking dies (Figs. 2 and 3), shearing or cutoff dies, notching dies, etc.

II. Tools that shape the article by drawing the material, causing it to "flow" under tension as in the instances of cupping dies, drawing dies, bulging dies, and so on.

III. Tools that manipulate the stock or the blank already cut out, by some form of bending process. In this class come simple and compound bending dies, forming dies, and the like.

IV. Tools that by compressing, squeezing, or forcing the material cause it to "flow" into the desired form as when acted upon by swaging dies, extruding dies, coining dies, etc.

In Class I may be included the following tools: Blanking, Piercing, Shaving, Notching, Shearing, and Trimming Dies. Also Hollow Cutting or "Dinking" dies, so called, belong in this general class, although made not for working metal, but rather for cutting out leather, card board, fabrics, and other materials either by hand or machine processes.

Class II includes Cupping, Drawing, Redrawing, Bulging, and Reducing Dies. Strictly speaking the latter tools do not draw or "stretch" the metal, but rather act in an opposite manner to close or taper a shell, say, already drawn out to required length and body size. Their operation is thus so closely allied to that of drawing and their design so similar that they may be grouped in the same class as the usual drawing die.

Class III, which covers various forms of Bending and Forming Dies, may also include, under certain circumstances, Curling and Wiring Dies. That is, when the operations of curling, or of curling and wiring combined, are applied in the manufacture of flat parts whose ends or edges are curled or rolled up, the process is one closely akin to forming as conducted with dies having side closing members which catch the edges of the blank and turn or curl it over as desired.

Where Curling or Wiring operations are applied to such articles as are drawn up to cylindrical or conical form, as in the cases of cups, utensils, or other objects requiring curling around the open end, the Curling and Wiring tools come within Class II as the processes are those involving stretching and drawing over of the annular surface about the mouth of the work. Then there are miscellaneous tools that according to individual circumstances may or may not be grouped under someone or other of the above heads: These include Flattening or Straightening Dies, Marking or Numbering Dies, Staking Dies, Crimping Dies, Burnishing or Sizing Dies, Assembling Dies, etc.