What is a punch press? What can it do? What
canít it do? To put it as briefly as possible, it is a stamping plant in
itself. Set in a progressive die, and it will blank out metal parts and
But, such a press has its
limitations-because it has tool motion in only one direction it cannot,
in itself, make certain forms or bends. These have to be taken care of
by special cams and slides built into the die.
And thatís where the fourslide has the
advantage, combining the features of the punch press, cams, slides;
stock straightened and slide feed into one machine. A fourslide has all
this and more.
Even a press head is available for
fourslide, in 2 to 100 tons. The fourslides has four cams and slides,
set 90 degrees apart, and each can be timed at any point in 360 degree
of shaft rotation, with reference to the press head.
Yet the fourslide and its capabilities are
not as well known as those of the punch press. Many shop men define it
vaguely as one of those special machines that come tooled and ready to
work on special long run jobs. They cost plenty? Of fourslide? It has
something or other to do with forming wire or flat stock. Letís take a look at the fourslide and what it can do.
Take the slide feed, which can handle wire
as well as flat stock. Here, the adjustable gripping jaws pressure on
the material is positive and cam-controlled on the forward feed stroke,
and it releases on the return stroke. A separate, cam-controlled
adjustable stock checks jaw prevents the material from being dragged
back, or from drifting.
Stock straightened? The fourslide has a two
plane, 10 to 18-roll straightener that handles wire, as well as flat
stock. And the fourslide has a variable speed drive to handle many
And here is the ďand moreĒ: the fourslide
also has two adjustable cam-controlled motions from above; a form lifter
(for bending in the opposing plane, or for lifting the king-post form
tool), and the stripper. The latter, as its name implies, strips the
finished, formed stamping from the mandrel.
To round off the list of standard fourslide
equipment, the machine has another slide, the primary cutoff, which is
also cam-controlled and is laterally adjustable in either direction on
the bed area, so that it can part the stamping from its strip before
What do all these mechanisms accomplish?
Just this: no more building of cams and dies for certain formed
stampings Ė a job that involves a big dollar outlay for the press tools.
In addition to the standard equipment
listed, there are many optional accessories. For instance, there is a
secondary cutoff for notching, close control of length, and other
operations. A nail-pointing attachment points stock or cuts material
from above, instead of horizontally. Hoppers can be adapted for assembly
operations, and holes can be tapped with tapping attachments. Spot or
butt-welding can be done before, during, or after bending.
Does this mean you should sell your Punch
Presses and buy Fourslides? By no means. Actually, both the punch press
and fourslide are important in producing metal stampings. The fourslide,
however, can produce a large number of formed stampings at lower costs
with simpler tooling.
Fourslide tooling is designed and built to
go on each slide as separate tool blocks for bending or forming, as
required. For pushing off the formed stampings, a stripper is attached
at the king post, where mandrels are located.
After the slide feed pulls the strip
material off the stock reel and through the straightener, the material
automatically feeds into the press area for piercing, after which it
continues to the forming area, where it is cut off and formed to shape.
Just before final forming by the slides, the blank is held by the front
tool against forming mandrels.
The front tool finish forms the front
portion of the stamping, as well as partially bending its ends. At the
same time, the cut-off tool retracts, ready for the next cycle. The
right and left tools can simultaneously advance to impart another 90
degree bending of the ends inward around the mandrels. Then the back
tool advances to finish form the ends of the stamping around the
mandrels. At this point, the tool slides retract. The stripper rod is
attached to the stripper rod to push the formed stamping from the
mandrel through an opening in the bed of the machine into a container.
The same basic knowledge that the tool and
die maker and the tool designer have for tooling a punch press is
sufficient for tooling the fourslide. In fact, the problems of building
tooling are usually simple but perceptive skills are needed.
Our next installment will discuss why itís
better to make a music wire spring on a fourslide instead of using a
Many formed stampings, whether made of
strip or wire, whether completed parts or just components can be
produced by a fourslide as well as on a punch press. But if the job can
be made on either of the machines, it is necessary to know the
capabilities of each in order to choose which can do the job most
efficiently and economically.
Today, increasing competition and a
shortage of skilled labor have combined to put pressure on tool and die
makers, tool designers, and plant engineers to produce parts faster and
cheaper, and at the same time save on material.
And thatís where the fourslide comes in.
Trouble is, even though this machine has been around for some 80 years,
few shops know how to use it effectively. Admittedly, there are a number
of knowledgeable job shops that use fourslides, but most other plants
donít seem to realize that they can produce complex parts on a fourslide
with simple tooling at low cost, and on a short lead time.
Over the years, the fourslide has become a
one-machine automated production line: raw stock is fed into it, and a
completed part emerges with each stroke. It has a certain edge over the
punch press in such operations as matching to bending, but that is not
to say that generally the punch press is just as efficient as the
fourslide when correctly tooled for a properly selected part.
Because of the fourslideís versatility, the
tooling designer is able to develop simple tooling for formed parts,
whether theyíre made of strip or of wire. Certainly, a music wire formed
part would be a tough job for a punch press. But itís a breeze for the
Letís put it another way: punch presses and
fourslides can work side by side, if each is doing the work to which it
is best suited.
Many job shops today have a wide range of
fourslides, so as to give them a choice that is dictated by the size of
the part to be made and the tonnage required.
In all fourslide models, however, basic
operations are the same: a slide feed pulls the material off a stock
reel, through a straightener, and into the press head area.
After the piece is punched, or goes through
other stamping operations, it travels into the fourslideís forming area,
where it is parted and formed into shape by developed tool blocks that
are arranged to suit conditions. And the positive feed is accurate in
most cases within +- 0.002 in. In some cases, tolerances can be held
with in +- 0.001 in. The tools in the four slides can be adjusted in any
direction, while the tools of a progressive die cannot be cross
adjusted. This also allows flexibility in any necessary deviations from
design specifications after the tools are made. Such corrections in a
die might be impossible.
Another quality and production
consideration is that buckling of stock can be a serious problem with
progressive dies. This can affect quality or cause undesirable machine
downtime. Because forming takes place after the stamping operations
buckling is reduced. Material cost, especially with strip stock, is
usually lower with the fourslide. Because of the operating
characteristics of the punch press, many times pilots are needed to
insure accurate feeding and this means extra stock for pilot holes. Or
again, added stock width might be necessary to prevent buckling. Then,
to allow for possible variations in feed lengths in the punch press,
material is provided between blanking in the strip. With the close
tolerance control on feeding in the fourslide and because feed length
usually equals blank length, less strip is consumed.
Some feel that the initial tooling cost for
the fourslide is higher than the cost for a progressive die for the same
part. NOT TRUE, fourslide tooling is significantly lower. Again, it is
good to remember that one big advantage of the fourslide is that it can
form complex shaped parts completely in one machine with out secondary
handling. As was mentioned earlier, the tool life usually is longer in
the fourslide, so the number of final parts required affects the tool
cost, too. Even if the fourslide tooling cost 24% more initially than a
progressive die. But the die life is half that of the fourslide tools.
Then the actual tool cost for the progressive die is 60% higher than the
Other economies are realized because of the
greater flexibility of the fourslide machines. Hourly production can be
doubled in some cases by manufacturing two parts simultaneously. Or,
complex parts can be partially formed at the same level as the die, then
stripped to a lower level where a second set of tooling completes the
forming operations. At other times, a third level and set of tools may
be used again to complete the form in one machine without secondary
operations. So many factors must be considered in determining which
process is best. The modern stamping plant uses both kinds of machines
for best results.
The fourslide have far more potential as a
cost saver than has been indicated so far in this series of articles.
Most people donít set up more than single level operations with a
combination of one or more of the four forming slides.
But this same machine can increase its
output substantially with multiples of four operations in the forming
section. Thus stampings requiring four, eight, or twelve forming steps
can be produced at no more cost than if the operation were limited to
four forming steps.
The trick here is to partially form the
stamped part at one level, than strip it down to a lower level, where
final forming is done with additional tools. This dual level tooling is
known as multiple block tool design.
Stacked tool blocks, for example, are
fastened together, and move together. The top tool performs part of the
initial forming sequence, whereas the lower tool is the finisher.
Multiple tool blocks, however, arenít necessary for each slide, because
tools are designed according to the requirements at each station.
Design and development of the tool blocks
is the key to success with a fourslide, whose tools can sometimes be
laid out completely by the tool engineer. In other cases, however, the
toolmaker must make alterations to suit the forming characteristics of
When tooled for the fourslide, a formed
sampling will generally require tools that are simpler and easier to
make than those for a punch press. As a result, design is both practical
and a better manufacturing method; and cost is low, because of simpler
Because of the variety of work that is
handled in many shops, these basic goals canít be achieved with a punch
press alone. This is especially true of some formed stampings and wire
parts. Therefore, an up to date stamping shop should have fourslides, as
well as punch presses, so itís possible to choose a better manufacturing
method, not just one that will make the part.
Because the fourslide machine has a press
head (ram), or can have a press attachment, as well as the four slides,
plus stripper and vertical form, the part can be completed in one
machine. Two types enhance versatility and flexibility of the
fourslides: first, a wire machine, and second, a flat stock or strip
The wire machine handles
material up to Ĺ in. in diameter and feed lengths to 36in. Four shafts
surround its horizontal bed with power transmitted through miter gears
from the variable speed motor. The machine incorporates its own roll
straightened, feed mechanism, stock check, cut off, four cam actuated
slides operating at 90 degrees apart, a stripping mechanism to eject the
finished part, and, when required, a vertical form lifter.
The cut off unit can be
removed and a light press attachment substituted for use in light flat
stock jobs. Cutting off is then accomplished with the press attachment
or front tool. A standard secondary cut off attachment can be used for
cutting the right hand end of wire or ribbon stock for extreme accuracy
in length. The device also is used to cut an irregular contour on the
end of the stock different from that made by the primary cut off, or to
perform operations on the fight hand end of the stock.
The feed is accomplished
in 180 degree of the cycle. It is accurate in most cases to within +-
0.002 in. and in some cases to +- 0.001 in. Special feeding can be
accomplished in 90 degrees, allowing 270 degrees for forming. While the
feed stroke, the stock check grips the stock positively to eliminate
slippage. The cut off mechanism has adjustable timing and is cam
actuated. Cams also actuate the fourslide. Camming is made to suit each
job, but standard cams are used in many cases.
Then, the fourslide flat
stock machine has all the features just mentioned, plus a crank or cam
actuated ram located between the check and cut off. This provides a
horizontal press head or ram, so the stock rests vertically on edge.
Design of dies is the same as for progressive dies. Pilots can be
employed and vertical ram actuated holders hold strip against the wear
strip in the die, which is made in sections. If additional piercing is
required, the press attachment ca is used in place of the cut off
There are some models of
the fourslide that have two rams where the stroke of the first die is 35
degrees of the second. Although the tonnage of each ram might be 12
tons, machine rigidity is required only for 12 tons instead of 24. This
out of phase operation of the stock lengthwise, in an operation such as
coining, without affecting piercing, trimming or drawing in the second
die set 35 degrees later. With the stock coming through the fourslide in
a vertical position, slugs from the stamping operation are pushed out
the back. The completed parts are made from stock up to 4 in. wide and
feed lengths to 15 in.
It is important to select
the right size fourslide machine for the wire or strip job. Fourslides
are rated for thickness and width, or diameter, length of feed, and
tonnage required for the press operations. Feed rates for simple jobs
approximate 100fpm/ Actual speed is determined by strokes of cams, feed
length and intricacy of the tooling involved.
By forming on two levels,
as described in Part 3, a large number of operations can be performed on
one fourslide machine. Therefore, there is a strong chance that a rather
completed piece can be completed on one machine, rather than requiring
The two or three level
capability of the fourslide should also be kept in mind. And to extend
the usefulness of the fourslide, try to think in terms of making two
parts at once, and splitting them apart.
It is this sort of
versatility and resourcefulness that keeps a stamping shop competitive.
The company that has capable tool designers, toolmakers and methods
engineers can come up with economies that supply the essential ďedgeĒ in
obtaining new work. With both presses and fourslides in several sizes on
hand, the capable production man can decide which will give the best
efficiency and delivery on a job.
Final cost and delivery
depend heavily on the time it takes to design, make, and set up tooling.
By having both presses and fourslides in the shop, the advantages of
each can be obtained in respect to tooling and production. But to show
where the fourslide fits in, we must explain an example.
The job is a formed
stamping that is required in large quantities and, as usual, at low
production costs. First, the choice must be made between the punch press
and the fourslide. Since this part is complex, tooling costs mount in
unrealistic proportion with the punch press to produce this part
economically. But an acquaintance with the versatility of the fourslide
is needed to see how to double production.
The obvious approach with
the fourslide is to think of producing one part at each machine cycle.
But, without any increase in tooling costs, there is a method of
producing two identical piece parts at each cycle to double the output.
For the job with the machine operating at 190 strokes per minute. 380
parts are produced.
After the piercing
operations, the double piece part is formed on the upper. Then it is
transferred to the lower level for final forming and parting of the
final form into two stampings.
All holes, notching and
blanking are handled in the built in press head section of the fourslide
ahead of the forming area. The developed double length blank is fed into
the forming area. Here the cut off tool parts the blank. At this
instant, the front tool is holding the double length blank against the
forming mandrel. Form this point, the front tool continues forward, to
bend the four legs of the blank. The cut off tool is retracted and ready
for the next cycle.
Next the left and right
tools advance to form the double blank. The back tool, advances to
complete forming the four legs on the upper level. As all tools retract,
the stripper pushes the finished double form from the upper to the lower
As the front tool starts
a new cycle at the upper level, the tool on it lower level serves as a
pressure pad to hold the preformed stamping. This lower level front tool
presents a slitting die section, to receive the slitting punch on the
back tool, lower level.
A secondary cut off
attachment provides the tooling action, under the front tools, to make
the final form on both parts of the double form. Then the back tool,
advances to cut out the center divider between the two parts. Thus, two
identical stampings are completed. The two side tools were not used on
the lower level.
In addition to the
production advantages of getting two finished parts at a time on the
fourslide, material cost are less than they would be with the punch
press. Savings in material can be substantial. Also, handling of
excessive scrap is eliminated.
Then, too, the simplicity
of the form tools is seen. The separate tool blocks for each bend or
form are not complex nor are they confined to one area as in the die
shoe of a punch press. Also, they use the built-in fourslide cam system,
so that no special cam slides are required.
There are many other jobs
where a decision as to which method to use is determined by the
versatility of the fourslide process and simplicity of tooling. Example:
one wire form, with a center bend and a bend on each end, is produced by
the thousands in eighteen different sizes. All bends are identical, but
the length in the two legs varies. The final tool design enables the
production of all sizes with one set of tools impossible by any method
other than the fourslide. Simple spacers for each length are inserted
into the front tool as needed. Then the stock feed and the strokes of
the left and right tools are adjusted as required with each new size.
If the modern stamping
plant has fourslides, many jobs can be accepted that formerly were
turned away. For instance, a part is wanted in large volumes, and is to
be produced from 0.125 in. brass tubing 3ľ in. long before forming. A
hole is to be pierced in one wall, one end is to be swaged watertight
and the tubing formed into an eye. Without the fourslideís versatility,
the job probably would not otherwise come out of the shop.
Some thinking precedes
turning up a solution. In the cited case one must decide to take the
tubing off a coil or use stock cut to length. The latter is the right
answer. However, this means a new type of feed. And here a simply
designed gravity magazine feed is the answer. Since the primary cut off
isnít needed with stock cut to length, the secondary cut off attachment
replaces the primary and is used to hold the magazine feed. Then a
feeding finger is designed to push the tubing lengths from the magazine
over a grooved guide rail that is attached to the secondary cut off. All
the operator must do is to keep the magazines filled on three machines,
remove filled tote pans. Our records show that he can turn out 345,000
pieces per eight-hour shift.
At other times, the
fourslide can eliminate special machines. One such job requires dual
coils on the ends of No. 10 round wire, with different lengths between
the coils which always require the same 2 ľ turns. In this case, the
long feed length of the fourslide comes in handy because the lengths run
to 26 in.
One must not forget that
various types of treatments can be put on wire. In addition to a square
cut off, chamfered ends can be obtained. Then simple swaging operations
can provide parts swaged on the ends, swaged in the middle or items with
swaged ears. Other wire parts may require swaging, piercing the swaged
section and trimming.
Further flexibility of
the fourslide process will be described in Part 5. A detailed account
will be given of how a fourslide machine can handle both wire and strip
at the same time. The strip is punched, the wire is inserted into holes
in the strip, and both parts are formed into one completed partÖall in
one machine cycle.
Stampings costs come down
when you can eliminate a second operation. And especially so, if you
keep the tools simple. But these truisms are annoying when you are
confronted with a part that consists of a wire form assembled to a flat
stamping. However, if you have a fourslide, it is frequently possible to
do the whole job in one operation.
Our case study, was a
flat stamping with a wire form assembled through its legs. This assembly
can be produced on a fourslide by feeding the strip and the wire from
opposite directions. The standard stock straightener and feed mechanism
built into the fourslide will handle the strip. And, an inexpensive, air
operated slide feed is added on the right side of the machine to draw
the wire through a set of roll straighteners. A Nilson S1-F fourslide
provides the die space for the piercing or punching operation in the
Production rate for the
complete assembly is 165 units per minute, using the tooling setup.
Because the strip must be pierced and formed first, the wire is fed
through the punched holes, at a second, or lower level of the tool.
Additionally the cut off
quill and cut off tool for the wire are mounted in the standard
secondary cut off attachment that finds so many good applications in
After the holes are
punched in the flat stock at the press head area, the developed blank is
fed into the forming area. Here, the primary cut off tool parts the
blank. At the moment of cut off the front tool clamps the blank against
the king post tool on the upper level. Then, the front tool continues to
advance to form the first portion of the stamping into a double
The left and right side
tools now advance to finish form the stamping. (Note that the back tool
is not used on the upper level.) After this, the tools retract and the
stripper transfers the formed stamping to the lower level of the king
post tool. At this second level, the developed length of the wire is
inserted through the slot in the king post tool.
While the upper level
tools start a new cycle, the secondary cut off attachment on the lower
levels cuts the developed length of wire. Now, the front tool (lower
level) acts as a pressure pad on the wire, and also presents a forming
area for the wire to be shaped.
At this point in the
cycle, the back tool advances to finish form the wire as a two-piece
assembled part. As the cycle repeats, the first level form strips off
the completed assembly when it is pushed into position on the second
level. Again, it is to be noted that the side tools on the second level
are not used. If more complicated forms were needed on the wire, these
tools would be available.
All stock fed into the
fourslide forming tools should be as free as possible of bends, kinks,
spirals or twists. But the wire, unless straightened, will have coil
curvature, and may have additional spiral twist or cast, especially if
it is high tensile or music wire. Uniform straightness is essential of
accomplished by bending the wire past its elastic limit in two planes,
so that it lays flat. For this purpose, one uses a standard wire roll
straightener. This device has the usual two banks of slide-able tools
mounted in antifriction bearings. The two banks operate at 90 degrees to
each other to straighten in two planes. Each bank shown has five rolls,
three above and two below the wire line. The roll positions are
Screws all on the rolls
to be moved against the wire line. All rolls have grooves to guide the
To set a wire
straightener for a new stock size, the rolls are backed off so a
hand-straightened length easily passes through the rolls. Now you set
the rolls against the straight length. As the wire extends from the
first plane, the furthermost roll to the right is moved toward the wire
line to turn the wire from A to X. The opposite occurs to move from B to
X. When these movements do not rectify the wire, so it points straight
out to X, adjustments must be made on other rolls. This is true in both
planes. After adjustments are made on the test wire, production wire can
be inserted through the rolls to start the coil. For heavy gage wire of
ľ in. diameter or larger, a quick release type straightener is used for
starting new coils.
During the last decade,
miniaturization has required closer tolerances for straightness of small
gage wires in various alloy materials. This occasionally calls for the
use of rotary straighteners, wherein grooved blocks rotate around the
wire. The blocks must straighten the wire without spiral scratches or
With some types of small
diameter wire, a counter rotating straightener might be required. In
this unit, two heads turn in opposite directions at up to 12,000 rpm, so
that wire down to 0.004 inches in diameter can be safely straightened.
As has been said
repeatedly in this series, the fourslide is as important as the power
press in the manufacture of metal parts at high production rates yet it
seems that few press room have both types of equipment.
It stands to reason that
any shop, which possesses both kinds of machines, is more flexible, and
can handle a greater variety of jobs than a shop with just one type.
And the fourslide and the
power press need not be competitive there are many instances when they
With such a combination
of machines, a shopís versatility is greatly increased, secondary
operations can be eliminated, and handling and assembly costs reduced.
Tooling flexibility on
fourslide machines is maintained without a complex, sophisticated
approach. In the production of formed stampings, one of the big
advantages of the fourslide process is the simplicity of the form tools
used in conjunction with a separate die area for stamping operations.
And, when comparing this process with the punch press, the avoidance of
intricate camming, as in a progressive die, is an attractive advantage.
Moreover, the many different approaches in fourslide tooling make it
possible to select a simple one.