THERMOFORMING: Top Ten Tips to Becoming More Efficient in Thermoforming
As today’s heavy gauge thermoforming market is
growing and becoming more competitive, companies
are looking for better ways to gain efficiencies.
A large portion of a company’s success comes from the
efficiencies they have or the efficiencies they create.
Through years of working with thermoformers, we
often work with companies that we can help gain
major efficiencies. Although engineering firms, suppliers
and consultants are not necessarily needed to
implement improvements, they all have the continual
opportunity to work with thousands of thermoformers
and thousands of different applications. From a
general viewpoint, here are 10 tips to be more efficient,
or areas where improvements can be implemented.
With the proper knowledge, companies
should assess their strengths and weaknesses and
begin preparing for future plans to address their
1. Outdated Equipment
As thermoforming is not a new process, thermoforming
equipment has been around for over 50 years. This does
not mean you should keep your machines for 50 years!
Begin putting together long-term plans to replace or
upgrade them. Old inefficient machines are the single
largest item that restricts manufacturers’ ability to run at
their most efficient. Older machines also tend to have limited
capabilities and offer no real competitive advantage. The
term, “it paid for it self already” does not make you efficient.
A large portion of a company’s success comes from the
equipment they utilize. If you never investigate the latest
technology or do not have plans to invest in the latest technology,
this may be the single largest mistake you can
make. With all of the technological advancements available
in today’s new machinery, older machines cannot be compared
and certainly cannot compete in terms of performance,
cycle time, material distribution, energy use, repeatability,
change-over time, flexibility and even maintenance.
One of the most limiting factors leading to running efficient
stems from poor mold designs and, even worse, the
type of material chosen to construct the mold. Regardless
of your machinery being new or old, a bad mold will dictate
your ability to be efficient.
Although the volume of products produced or the design
of the finished product may dictate what can be used, too
many formers start with looking for the least expensive
way to get a mold and start producing products the fastest.
A badly designed mold or molds that are not water cooled
aluminum will allow competitors to redesign and improve
cycle times lowering overall manufacturing costs. Patching
up poorly designed molds may help, but will only allow you
to run your product at what the mold design allows for. Too
often formers are running high volume jobs, in some cases
several shifts, with multiple non-water cooled molds; when
one good aluminum water cooled mold can be utilized to
produce parts up to three times faster. Production cycle
times should never be based upon how long it takes your
mold to cool off between shots unless the volume is very
low or you are prototyping.
3. Cycle Times
As there are many ways to improve cycle times, we far too
often see products running too slow. Thermoformers need
to take the time to improve, determine the bottle neck and
implement a way to correct it. If the problem is heating
times, make plans to improve your ovens or spend more
time setting them up and tweaking them. If the issue is
forming and cooling times, look to replace tooling with better
molds or investigate alternative cooling options. If secondary
operations are much more time consuming, look for
more options and capabilities to speed up the process or be
open to jobbing the work out to someone who may be more
efficient in that portion of the process.
4. Sheet Size
Use smaller sheets: far too many
thermoformers are using too much
material. Look for ways to reduce your
material costs and implement a new
standard. Look at your clamp frames;
are you clamping more than 1/2”? Do
not try to get 50 years out of a piece
of clamp frame, you will easily spend
the money in material costs in the
long run due to sheets pulling out,
oversizing the sheet and increased
scrap rates. Replace damaged or bent
frames: utilize frames that require less
than 1 inch in the clamp.
Work on utilizing thinner gauge
sheets too. This can be achieved with
more oven control, better oven
designs and the use of different forming
techniques. Material gauges can
be greatly reduced and still meet your
finished parts’ minimum thickness
Ovens and Oven Controls
Older ovens need attention.
Maintain them to get the most out of
your machines. Costly retrofits are
one option, but typically only help in
one area of your machine. For 30% to 40% of a new
machine cost, oven retrofits are typically seen as a
short term solution to gain efficiencies.
Get more oven control, or at least some control.
Machines with no “Zones” should not be used unless
you have no competition and are a non-profit organization.
The additional utility costs for operating the
entire oven when smaller sheets are used is not efficient
and costs too much with today’s utility prices. You
need oven zones to shut off areas that are not heating
the sheet, zones also allow you to gain more control
over the process to decrease heating times and even
decrease starting sheet gauges. Having zones in your
oven also eliminates the need to physically screen an
oven or block heat transferring into the sheet. Physical
screening is both time consuming and an inefficient
use of energy.
6. Over Heating the Sheet
Stop overheating the sheet. Many thermoformers
are overheating the sheet as they do not know what
temperature the sheet is. The days of visually detecting
sag or touching the sheet to measure temperature are
gone. Photo eyes and infrared pyrometers are used for
detecting sheet sag or sheet temperature. Some of
these devices can be purchased for less than $100. If
you overheat the sheet, forming and cooling times are
extended, making cycle times much longer than necessary.
Not to mention the additional wear and tear on
your machine, your mold, the extra costs you pay for
labor and the added utility cost used to overheat the
PLC’s and Quick Set Ups
Updating machines from manual timers to PLC controls
is a step forward but PLC’s programmed by nonindustry
professionals will most likely limit the
machines capabilities and only allow a slight increase
in efficiencies. Again, this should be looked at as a
short term fix. Thermoforming machine manufacturers
who build these controllers can at least guarantee flexibility,
full functioning and support.
Companies must fully investigate the control systems
and all features that will benefit their operation. The latest
controllers allow you to memorize all functions of
the machine for each job you run. This means all the
time it takes to manually program a machine is reduced
to the touch of a button the second time the machine is
set up. The possibility of damaging the machine or producing
scrap is greatly reduced, and the ease of continually
tweaking specific applications is simplified.
The thermoforming process may begin with heating
the sheet but acquiring the fastest cycle times is not
solely based on how fast you can heat the sheet. In
order to establish faster cycles with materials that have
longer cooling characteristics (than heating characteristics),
you must accommodate the cooling process.
Whether you need additional cooling fans, a directional
blower, spray mist or even air conditioned cooling,
there are numerous ways to incorporate these.
Precise location and positioning of these cooling systems
will also lead to faster cooling times. Automated
in-machine post cooling may be needed for heavy
gauge products in order to run the machine based on
heating times rather than cooling times. Depending on
part specifications and tolerances, post cooling can be
the key to gaining more parts per hour.
Too often thermoforming machine cycle times are
extended to match the trimming process time. Again,
companies who investigate in the newest methods of
trimming and trimming speeds may find ways to speed
up the parts trimmed per hour. With newer equipment
with faster speeds, some applications can see a 300%
increase in parts per hour. A little more time spent on
tightening up the programming can now result in parts
per hour increases as high as 500%.
Insufficient volume, recovery time and insufficient
pressure are often the cause for deficient processing
causing part variation and increasing scrap rates.
Determine the amount of work to be done in cubic feet
or cubic inches. Items needed to calculate amount of
work are: process (possible predraw box), sag, tool and
tool cavity. Large tool cavities are back-filled with polyethylene
balls to reduce the amount of cubic feet needed.
Determining the flow in cubic feet per minute will
result in the amount of time at a specific pressure (hg)
to evacuate the needed cubic feet of work. Items needed
to calculate are: tool port size, distance from tool
port to vacuum valve, vacuum valve flow in cfm, starting
pressure and tank volume. By adding pump starting
pressure and cfm capacity, the recovery time may be
Although this is all easier said than done, companies
who are in it for the long run will continually look for
ways to improve and gain efficiencies. Whether you
develop short or long term plans, or implement temporary
fixes to help gain efficiencies, you must start
preparing to stay ahead of the market.
Written by Michael P. Alongi, Sales Director for
MAAC Machinery Corp., manufacturers of a wide
range of cut-sheet thermoforming machinery.
For more information, contact MAAC Machinery
Corp., 590 Tower Blvd., Carol Stream, IL 60188,
630-665-1700, Fax: 630-665-7799, E-mail: sales@