When it comes to injection mold materials, nothing
speeds production like copper alloys. Copper's thermal conductivity
is three- to nine-times greater than stainless steel and tool steel,
so it offers faster, more uniform heat dissipation. That means 16-20%
shorter cycle times, and up to four times less warpage of parts.
But speed isn't the only benefit of copper alloys. Mold life is very
important, too.
Copper alloy cores exceed most production requirements. And for extreme
conditions, copper alloy cores thinly coated with hard chromium last
as long or longer than P-20 steel cores.
The high thermal conductivity of copper alloys makes them ideal for
the injection mold sprue bushing and runner bars. Several beryllium-copper
and NiSiCr copper alloys have six- to nine-times greater heat transfer
rates than conventional mold steels, as indicated by their thermal
conductivity ratings.
Properly designed molds with copper alloys (usually in the core) reduce
injection molding cooling cycles by 20 to 50%. The mold core is responsible
for removing 65-75% of the heat from the plastic molding due to the
material shrinking around the standing features of the mold.
Copper alloys enhance performance, reduce cycle time and cost, and
improve the quality of parts in injection molding applications. The
advantages of mold materials with high-thermal conductivity copper
include reduced cooling times in the molding process and enhanced
dimensional control (e.g., lower tolerance deviation, less part warpage,
fewer molded-in stresses, and reduced number of sink marks).
The thermal conductivity of copper alloys, along with their high density
and tensile strength, make them ideal for core materials. |
