BASIC MEANINGS
1. Part Drawing
To begin our study of the various components that make
up a complete die, let us consider the drawing of the link
illustrated in Figure 1.1. This part is to be blanked from steel
strip and a die is to be designed for producing it in quantity. The
first step in designing any die is to make a careful study of the
part print because the information given on it provides many
clues for solving the design problem.
Figure 1.1 A typical part drawing.
2. Die Drawing
Figure 1.2 is a complete die drawing ready to be printed in blueprint form. To the uninitiated it might appear
to be just a confusing maze of lines. Actually, however, each line represents important information that the
die makers must have to build the die successfully. In illustrations to follow, we will remove the individual
parts from this assem- bly and see how they appear both as three- and as two-view drawings, and as pictorial
views, to help you to visualize their shapes. As you study further, keep coming back to this illustration to see
how each component fits in. When you are through, you should have a good idea of how the various parts go
together to make up a complete die.
Figure 1.2 A complete die drawing.
3. Blueprints
After a die has been designed on tracing paper using traditional
techniques or AutoCAD, blue- prints are produced for use in
the die shop where the dies are actually built by die makers.
This is how a blueprint of a die drawing appears. From such
prints, die makers build the die exactly as the designer
designed it. The drawing must be complete with all required
views, dimensions, notes, and specifications. If the die maker is
obliged to ask numerous questions, the drawing was poorly
done. Figure 1.3 shows a typical blueprint.
Figure 1.3 A typical blueprint.
4. Bill of Material
The bill of material (Figure 1.4) is filled in last. This gives
required information and specifications for ordering standard
parts and for cutting steel to the correct dimensions. This material
is cut and assembled in the stock room, then placed in a pan, along
with a print of the die drawing. When filled, the pan must contain
everything the die maker will require for building the die, including
all fasteners and the die set.
5. Die Assembly
Figure 1.5 is a pictorial view of the entire die as shown in
Figure 1.2. The die pierces two holes at the first station, and then
the part is blanked out at the second station. The material from
which the blanks are removed is a cold-rolled steel strip. Coldrolled steel is smooth, medium-hard steel, and it gets its name
from the process by which it is produced. It is rolled, cold,
between rollers under high pressure to provide a smooth surface.
The strip A is shown entering the die at the right.
Figure 1.4 A typical bill of material.
Figure 1.5 A pictorial view of an entire die.
6. Scrap Strip
A scrap strip (Figure 1.6) is designed as a guide for laying out the views of the actual die. Figure 1.6a
shows a typical scrap strip. This illustration shows the material strip as it will appear after holes have been
pierced and the blank has been removed from it. We would first consider running the blank the wide way as
shown at A. When blanks are positioned in this manner, the widest possible strip is employed and more blanks
can be removed from each length of strip. In addition, the distance between blanks is short and little time is
consumed in moving the strip from station to station. However, for this particular blank there is a seri- ous
disadvantage in this method of positioning. Because the grain in a metal strip runs along its length, the grain in
each blank would run across the short width; the blanks would be weak and lacking in rigidity. This defect is
important enough for the method to be discarded. Instead, the blanks should be positioned the long way in
the strip as shown at B. The grain will then run along the length of each blank for maximum stiffness and
strength.
Three views of the material strip are shown in Figure 1.6b exactly as they appear in the die drawing in
Figure 1.2. In addition, a pictorial view is supplied at the upper right corner to help in visualizing the strip. In
other words, this is the way you would imagine the strip if you were to draw it in three views. The top or plan
view shows the strip outline, as well as all openings. This would be made actual size on the drawing. The holes
are represented by circles at the first station, and the blanked opening is shown at the second station. At the
lower left, a side view of the strip is drawn. It is shown exactly as it would appear at the bottom of the press
stroke, with the pierced slugs pushed out of the strip at the first station and the blank pushed out of the strip
at the second station. The narrow end view at the lower right corner is shown as a section through the
blanking station, and the blank is shown pushed out of the strip. The strip in many instances is often drawn
shaded to differentiate it from the numerous lines that will represent die members. In the upper plan view,
shading lines would appear on the surface of the metal. In the two lower views, the lines are shown in solid
black to further differentiate the strip from the die members.
(A)
(B)
Figure 1.6 Scrap strips: (A) Typical scrap strip layouts and (B) Three views of the scrap strip.
7. Stampings
Stampings are parts cut and formed from sheet material. Look around you! Wherever you may be, you
will find stampings. Many are worn on your own person; the ring on your finger is probably a stamping. Most
of the parts in old- fashioned wrist watches are stampings, including the wristband. Your belt buckle, the
metal grommets through which your shoe laces pass, eyeglass frame, the clip on your ball point pen, and
zipper all these are stampings.
Look around the room, any room, and you will find products of the pressed-metal industry. Most of the
parts in the lighting fixture are stampings; so are threaded portions of light bulbs, door knobs, and the radiator
cover. The list is a long one indeed. In the home we find stampings by the score: pots and pans, knives, forks,
and spoons, coffee pot, canister set, pie plates and muffin pans, cabinet handles, kettle, can opener, and
more.
The refrigerator is almost entirely made of stampings. So are the stove, toaster, and other appliances.
And each single part in all these requires an average of three to six dies to produce.
Every automobile contains hundreds of stampings. The largest are the roofs, hoods, quarter- panels,
doors, etc. Even the wheels are stampings. There are hundreds of smaller parts, many of which are covered
and seldom seen. For example, even the points require very complex dies with multiple stations each, costing
thousands of dollars to build, in addition to assembly dies for join- ing the components.
Office machines and computers provide another big stamping field. So do adding machines,
calculators, and dictating machines. We could go on and on; the list is almost endless. Radio and television
components require thousands of dies. So do stream- lined trains, aircraft, and missiles. All of these are
improved from year to year, so an enormous number of new dies is constantly required.
The foregoing should give you some idea of the great size and importance of the pressed-metal
industry.
8. Punch Press
Figure 1.7 is a photograph of a typical mecha- nical
punch press in which dies are operated to produce stampings.
The bolster plate A is a thick steel plate fastened to the press
frame. The complete die is clamped securely on this bol- ster
plate. The upper portion of the die is clamped in ram B, which is
reciprocated up and down by a crank. As the material strip is run
through the die, the upper punches, which are fastened to the
moving ram B of the press, remove blanks from it.
9. Exploded Drawing of the Die
Figure 1.8 is an exploded drawing of the die shown in
Figure 1.5 with the names of various die components listed.
These names should be memorized because we will refer to
them many times in future work.
Figure 1.7 A typical punch press.
10. Die Set
Figure 1.9 shows a die set, and all parts the die assembly comprises
are built within it. Die sets are made by several manufacturers and
they may be purchased in a great variety of shapes and sizes. The
“center posts” A are called “punch shanks” in the die set
manufacturers’ jargon. And, no, they cannot be used for clamping
the punch holder, but they can be used for aligning the die in the
press. Ram mounting holes must be provided in the punch holder
for mounting. In operation, the upper part of the die set B, called
the “punch holder,” moves up and down with the ram. Bushings C,
pressed into the punch holder, slide on guide posts D to main- tain
precise alignment of cutting members of the die. The die holder E is
clamped to the bolster plate of the press by bolts passing through
slots F.
Figure 1.9 A typical die set.
Figure 1.8 An exploded view of the die shown in Figure 1.5.