benefits molders derive from using Porcerax II are
primarily, but not limited to, the elimination of
trapped gas problems that occur in inadequately vented
areas within the mold. Frequently, it is difficult, if
not impossible, to provide adequate venting in these
hard to mold areas. Traditional methods of venting, such
as parting line vents, vent plugs, and pins often do not
provide sufficient surface area to accommodate the large
volumes of gases that can be generated. Porcerax II
provides a location-specific method of venting gas in a
targeted area. Since it is 25% air by volume, one-fourth
of the surface area becomes a vent. The larger the
surface area of the piece installed, the greater the
Burning is a condition
caused by compressed gases trapped by the flow of molten
resin in a cavity pocket. Using Porcerax II venting
steel, gases are permitted to evacuate through the steel
to the outside atmosphere, thus eliminating the burning
The enhanced venting capabilities of Porcerax II are
illustrated below. The illustration is taken from a
current production application:
scrap rate on this part prior to installation of the Porcerax
II insert was over 45%. Upon completion of the installation,
the documented scrap rate dropped to 9% and was unrelated to
the previous burning problem.
of Knit Lines
Minimizing or eliminating flow and
knit lines is an additional benefit for using Porcerax II.
Knit lines occur at points where resin flows converge after
molding around an obstruction, or protrusion within the mold,
usually away from the gate area. There are two primary reasons
for this occurrence:
failure of resin to sufficiently fuse due to the drop in
temperature after flowing over long distances.
presence of residual air at the resin flow convergence
point at the cavity obstruction, prohibiting the proper
fusion of the flows.
permeability of Porcerax II prevents defects arising from
residual gases normally trapped inside the mold cavity. Also,
using Porcerax II reduces back pressure and improves the flow
rate, allowing the resin flows to merge while still hot.
Trapped air bubbles between the
resin and mold steel surface can cause shrinkage or sink that
shows as a ripple in the otherwise straight plastic surface.
Using Porcerax II on the trapped air side of the cavity will
eliminate shrink in most cases.
Before using Porcerax II (click to enlarge)
After using Porcerax II (click to enlarge)
Webbed, ribbed, and other
difficult to fill thin-walled designs are greatly
enhanced and cosmetically defined using Porcerax II in
the mold. Molding these high-detailed, thin-walled, and
aesthetic parts is easily accomplished with the reduced
back pressure and added venting of Porcerax II.
Short shot is another
condition caused by too low of an injection pressure, or
trapped gases, in pocket areas of the cavity. This
results in the part not being completely filled out.
Porcerax II reduces back pressure, therefore, less
injection pressure is needed, and because it vents
trapped gases, both causes of short shots are
Automotive Speaker Grill
using Porcerax II as a cavity in an injection mold, the air
typically trapped between the cavity and the resin (causing a
gloss to show on the part) is allowed to escape through the
pores, thus leaving a dull matte finish. This often eliminates
the need for costly secondary spray painting operations.
Simplification and Cost Reduction
back pressures, injection pressures and cycle times are
lowered, fewer drops are needed to assure proper filling of
the cavity. Lowering the number of drops needed to fill a
cavity simplifies design while saving tool costs. In some
cases the entire hot runner manifold is eliminated.
in Part Ejection
In many situations, an air poppet
is needed to help eject the molded part from the cavity.
Inserting venting steel in the cavity with an air blow setup
accomplishes the same result. This helps break the vacuum seal
and aids the ejector pins in doing their job.
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All technical and engineering data and suggested procedures,
specifications and applications contained in this publication are for
general information only. Sintokogio, Ltd. International Mold Steel and/or
their distributors disclaim any and all express or implied warranties of
merchantability, suitability for any particular purpose or use, or freedom
from infringement of any patent, trademark or copyright. Porcerax II® is
a registered trademark of International Mold Steel, Inc. and Sintokogio,
Mold Steel, Inc. is a licensed distributor of Porcerax II, a
Mold Steel, Inc.
6796 Powerline Drive
Florence, KY 41042 USA
Tel: (859) 342-6000 or 1-800-625-6653
Fax: (859) 342-6006