the majority of cases, a press feed must meet three criteria to
be successful. First, it must be flexible in terms of set up.
Second, it must deliver the material with sufficient precision
into the tool, and third, it must feed at the correct time. In
addition, there are many other important considerations that will
ultimately determine just how effective the feed will be. Some
of those considerations are the amount of time and skill required
for job set up, the cost of energy to operate it, and how the
feed interfaces with the system as a whole.
The feed needs
to be flexible enough in its set up adjustment to accommodate
the full range of applications that will ever be run on the line.
It must allow adjustment to cover all set ups respective to feed
length, material width and gauge, feed and pilot release timing
as well as die heights. If the feed is for a dedicated system
these variables will be fairly limited but, more often than not,
it must address a wide range of applications.
requirement, that the feed must deliver the material with sufficient
precision into the tool, means that it must not only move the
desired amount of material into the tool, but it must place it
precisely in the die in terms of front to back, side to side,
and be square with the tool. Misalignment results in binding and
short feeds due to slippage and strip buckling. Short feeding
results in bad parts and broken dies. When they are new, nearly
any feed, if properly installed and set up, is capable of delivering
a level of length accuracy that is acceptable for most applications.
They will generally retain that accuracy if properly maintained,
but the amount of maintenance and set up time required will vary
dramatically from one type of feed to the next.
of the feed that is chosen, when installed it must be positioned
on center, square to the tool, and be rigidly mounted so that
no movement can take place between the tool and the feed, for
it to be able to deliver material correctly without binding and
mis-feeding. In addition to proper feed installation, the tooling
must be placed precisely on each set up as well. It is recommended
that some sort of registration device, such as positive stops
on the bolster, be used to insure consistent placement of the
tooling. Without good quality material, proper straightening,
and precise alignment there will be problems regardless of what
feed is ultimately selected.
requirement, that the feed deliver material at the proper time,
means that it must be capable of keeping up with the speed of
the operation. The time that a feed actually has to deliver material
is the result of the amount of time for one complete press or
shear cycle, minus the time that the tooling is engaged, minus
the time required to detect a mis-feed and stop the press. This
means that the longer the die engagement, or the faster the speed
of operation, the less time there is to feed.