Rotary die cutting equipment is an efficient production
tool. It increases productivity while it improves the tolerances of the
finished product. When production shops are gearing up to introduce additional
equipment, it’s easy to get caught up in the specifications of the new
machines, and forget that tolerances can be greatly affected by simple
maintenance. Cutting dies and anvil covers need to be handled properly in order
to achieve long life and accurate output.
Maintenance also affects the quality of the material support
as it moves through the equipment. For instance, anvil covers are commonly made
from urethane with a sheet of stainless steel for a backing. If this doesn’t
provide the correct amount of deflection when being struck by the die, or it
allows the material to slip during processing, misalignment is possible, and
the edges of the die-cut parts can be compromised.
Start With a Perfect Installation
Proper maintenance begins with proper installation and
setup. No matter how capable the machine, unless it’s installed properly, it
can’t possibly deliver the results you’re paying for. If you’re a business that
intends to make rotary die cutting equipment a centerpiece of your
manufacturing capability, you should consider bringing the machinery
manufacturer on board early in the factory floor design process in order to
ensure the best results. It can also avoid costly retrofits to work areas that
are intended to receive the die cutting machines. Makers of die cutting machines
like Baril
Corporation offer collaborative arrangements with both installation and
operational teams to make sure the equipment works perfectly on its first day
in service, and throughout its useful life.
One of the most common mistakes that occur during
installation of die cutting equipment is a less than flat and level floor. It’s
vital that machines that rely on spinning cylindrical parts to function are
firmly affixed to the floor, and that the machine is absolutely plumb and
level. Any variation in the orientation of the machine is likely to lead to
vibration. This can lead to less precisely cut parts, and also to much shorter
lives for important parts like bearings. You can use shims to level die cutting
machinery, but the more solidly the machine is in contact with the floor, the
more vibration-free it will be during operation.
A Reliable Electric Supply Is Important
Don’t overlook the quality of the power supply. Precision
machinery requires steady, reliable power without variations in voltage.
Voltage spikes and drops can wreak havoc with performance, and if the machine
labors due to low voltage, it can cause dies and anvils to bog down and sometimes
strike one another more forcefully than they would at speed.
Once the machine is in place and set up correctly make sure
that each and every setup of the die cylinder is done exactly the same way. The
number of mounting bolts for any particular cutting die will vary, but it’s
absolutely vital that all of the bolts be used. If the die cylinder has broken
bolts, you must tap out the holes and put in appropriately size inserts to
replace them. Then thoroughly clean the die cylinder to make sure that there is
no residue of dust that will cause a variation in height for the die that could
affect tolerances.
The dieboard, cutting rule, scrap ejector, and scoring rule
all need to be installed with the same eye for detail. No part of the machine
is less important than the others if tolerances are to be maintained, and
worker safety is to be safeguarded. Once again, use all the recommended
mounting bolts for every component.
Tighten all bolts by starting in the center and working out
from there. Never tighten any bolts without a torque wrench, whether you’re
using pneumatic tools or hand tools. This is important for two reasons. If the
bolts are tightened to different tolerances, it can deform the die. It’s also a
lot easier to shear off a bolt if you do not limit the torque that can be
applied.
Safety First
Don’t work on the anvil covers until you’ve removed the
cutting die. You can suffer a serious injury from the sharp edges of the
cutting die, and you can also damage it easily with the tools you’re using on
the anvil covers. Once again, clean the surfaces before mounting anything. One
trapped burr can affect an entire production run, and it can also make it more
difficult to install the dies and covers.
Make sure to use the bolts that were supplied with the
rotary die cutting equipment. If the actual bolts are not available, make sure
their replacements are identical in every way, especially in length. Bolts that
are too short won’t have enough threads in contacts with the machine, and they
may loosen under the stress of production. This can cause the parts to shift.
At first this shift can simply result in lower quality output. If not
addressed, continued loosening can have a catastrophic effect on moving parts.
Bolts that are too long are just as bad. The high spots they
produce will make the die cut parts inconsistent, and that will lead to the
operator to increase the force of the impression to make up for the problem.
That will lead to a much shorter life for the expensive dies and covers.
Regular Rotation Is Important
If you want to extend the useful life of the anvil cover,
it’s important to institute a program of regular cover rotation. Be careful not
to pry the cover off by inserting a tool between the cylinder and the cover.
This can permanently mark the cylinder and deform the cover. Covers come with a
removal tool that should be used at all times. Don’t rush the process. Compared
to the speed of the production runs, regular maintenance doesn’t take very
long, and should be performed with an eye towards being careful and exacting.
The amount of impressions that a given machine and die setup
can perform before requiring maintenance and rotation of the covers will vary
quite a bit depending on the material and other factors. As always, rely on
technical help from the manufacturer of the rotary die cutting equipment for
guidance in scheduling maintenance. If it’s difficult to estimate the total
number of impressions, a weekly or monthly rotation schedule is better than no
schedule at all.