I have often been asked to provide some examples as to process improvement with the Acrolab thermal management system. Below is an article which was printed some years ago, however it does provide for real data and a definite impact in terms of how Acrolab engineered, manufactured and installed a thermal transfer system which heightened through-put, saved energy and improved quality of the product.

1. CASE STUDY -- Improving cycle time with heat transfer technology
I have often been asked to provide some examples as to process improvement with the Acrolab
thermal management system. Below is an article which was printed some years ago, however it does
provide for real data and a definite impact in terms of how Acrolab engineered, manufactured and
installed a thermal transfer system which heightened through-put, saved energy and improved quality of
the product. Questions? Comments? Please give me a call. 519 944 5900
Thanks and best regards,
Peter
Peter McCormack, BA, MA
Global Technical Sales Manager
Acrolab Ltd. Windsor, Ontario CANADA
Mold-heating technology raises thermoset molding
quality.
By Fallon, Michael Publication:
As printed in Plastics Technology
Date: Saturday, December 1, 1990
Mold-Heating Technology Raises Thermoset Molding Quality
Heat-transfer technology for thermoset molds has enabled a processor to eliminate a problem of uneven
mold heating and reduce cycle times by up to 23%. When Square's D's Columbia, Mo., injection molding
plant took delivery of its second 200-ton Bucher injection molding machine 18 months ago, molding
engineer Gary Emanuel had strong expectations that the new equipment would yield better cycle times
and less waste for the polyester BMC part he had been running on less sophisticated equipment.
However, early in the startup process, it became evident that the design of the mold Square D had been
using was creating problems that even the best of equipment and material couldn't overcome.
The Columbia plant molds and assembles circuit breakers for household electrical service lines. The mold
used for the breaker's plastic housing is both deep and complex in configuration. Production had been
plagued by excessively long cycle times, incomplete curing, and haze and blisters on part surfaces.
Through testing, Emanuel discovered a critical 50 [degrees] F differential between the heated mold base
and portions of the core face. Because the cavity was so deep, when the mold was heated to a set
temperature of 350 F, the reading on some mold surface registered only 300 F.
Process engineer Jeffrey Ison experimented with varying temperatures and preheating routines, with no
improvement. Says Isom, "The hotter the mold, the faster the material cures. If you get too hot, you can
damage the part, produce a hazy appearance, or, in the worst case, the mold will lock up on you." As
Emanuel and Ison ran out of ideas, their equipment supplier, Bucher, Inc., Buffalo Grove, III., called to
see how the new machine was performing. Emanuel recalls, "Bucher's response when it heard of our
mold heating problems was reassuring. They had experience with other complicated molds and found
solutions, including a new way to bring heat from the base to the face of the mold directly and
instantaneously."
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2. CASE STUDY -- Improving cycle time with heat transfer technology
HEAT PIPES DO THE TRICK
The solution Bucher offered to the mold-heating problem was a heat-transfer technology for thermoset
applications from Acrolab Instrument, Ltd., Windsor, Ontario. Acrolab's "Isobar" heat-transfer system
consists of inserting an array of heat-pipe thermal conductors within the cavity and core of the mold to
achieve high-speed heat transfer within the mold as well as thermal consistency of the mold faces. The
system also employs integrally heated sprue spreader and core pins, which permit active heating and
independent control of specific areas of the mold, such as bosses and sprues.
The Isobar system resides completely within the mold itself, and requires no additional external control
hardware, nor any special processing or handling considerations. The principal benefits of the system are
exceptional temperature uniformity of all molding surfaces and rapid mold-temperature recovery after
each clamp opening. Acrolab's Isobar heat-pipe system was custom engineered to suit Square D's mold.
In all, over 150 Isobar heat pipes of 13 different diameters were installed in holes drilled into the various
inserts that make up the cavity and core faces. Acrolab engineers calculated minimum hole depth,
location and wall thickness requirements to ensure that the inserts were structurally sound and that the
Isobar array would produce the most uniform temperatures at all molding faces. All the heat input for the
inserts was conducted by the heat pipes from a bank of cartridge heaters in the mold base.
Square D's mold was sent to Artag Plastics Corp., a Chicago mold builder, for preparatory machining and
Isobar installation. Holes had to be drilled, cleaned and dried for precision fitting of the heat pipes.
Acrolab's service manager flew to Chicago to inspect the mold and install the Isobar system, a service
extended to all Acrolab customers.
HOW IT PERFORMED
To evaluate the results of the newly installed heat-pipe system, Emanuel devised initial tests that would
eliminate all other variables and provide valid comparisons. He took a computer readout produced a year
earlier by the Bucher CNC press controller, and matched the parameters of that process exactly to run
the new tests. He selected the same material, stroke, injection profile and plasticating profile. He pre-
heated the mold to the specified temperature, and ran the process. The results were dramatic.
Not only was surface appearance improved, the system made it possible to reduce curing time by 13
sec. The reduction in total cycle time averaged 22-23% over the old mold design, exceeding Bucher's
own prediction of at least 15% improvement in cycle rates. And Emanuel says he is certain they can do
even better. Mold heating was totally stabilized through the entire depth of the mold. The face of the mold
now registered the same temperature as the mold base. As a result, Square D's team was able to reduce
set point temperature more than 40 [degrees] F, with a corresponding saving in energy costs.
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