Page 49 - Plastics News July 2020

PRESS RELEASE

How to increase productivity in plastics production by 25%
There are many ways production lines can be achieved with AMPCOLOY® alloys. This means that
optimized to achieve higher productivity. In plastics productivity can be increased by at least 25 percent,
production, there is special potential for an upgrade with some users in the automobile headlight production
that manufacturers underestimate at their own peril. industry reporting up to a 500 percent production
It concerns injection molds and the materials they are increase simply because a reduced cycle time means
made of. more components can be made per shift.”
Manufacturers know that there are certain time losses in But gains in productivity can not only be also achieved
production that have to be accepted and cannot be due to their conductivity. The excellent polishing ability
eliminated. In plastics production, a specific time loss of AMPCOLOY® alloys has been proven when used in
occurs when the molten plastic cools down inside the contact lens packaging manufacture, which requires the
mold. Water runs through the mold to accelerate the packaging to be transparent so the lenses can be
process, and it seems that is all that can be done to checked through the packaging. Such high quality plastic
reduce this downtime. However, manufacturers in the packaging is achieved with high conductivity copper
plastics industry should direct their attention to alloy inserts that are highly polished. The polishing time
something they may not have thought hard enough about of such inserts has proven to be four times faster than
until now: the material the injection mold is made of. steel inserts, and the cycle time to be reduced by 57
percent.
Different materials have different properties that make
them well-suited for injection molds. If plastic is to be Reduced warpage
cooled down, a key metric to watch out for is thermal Part warpage can be greatly reduced as, with the
conductivity. The more thermally conductive a material improved cooling, the molded component spends less
is, the quicker it can be heated and cooled and the time at an elevated temperature, thus the number and
quicker the production of parts can be completed. If, for severity of “hot spots” within the mold are reduced and
instance, you use an injection mold made of iron, the
part quality is greatly improved. This means for the
best thermal conductivity you can expect is somewhere producer more constant part quality, shot after shot.
around 60 W/m K, which is not much compared to what
other materials can achieve. Heat removal
In the field of plastic injection molds, producers are very Due to the superior thermal transfer characteristics of
careful when it is time to decide which basic material high conductivity copper alloys, (typically five to 10
should be used for their molds. Up to now, some times better than steel), heat can be moved away from
companies still use conventional tool steels, but if this sensitive areas of the mold at such a rate that the need
material is less expensive for the buyers' side, it still for complex cooling channels in the immediate location
presents a lot of inconveniences compared to high of the molded component is reduced, or eliminated
conductivity copper alloys. altogether. Because the number of cooling channels
required in the tool is less, the machining costs of the
The best possible choice when it comes to injection mold
molds can be greatly reduced—up to four times less than
materials is copper base alloys. The average thermal that of a comparable cooling rate on a steel mold.
conductivity of copper is about 399 W/m K, which is 60 %
better than aluminum and 3000 % better than stainless Diffusivity
steel. Copper is second only to silver in this regard, High quality copper alloys absorb the heat wave in a
which as a precious metal is not a sensible choice for mold when a plastic part is injected. The initial
manufacturers. Combining copper with materials like absorption of the heat wave is a key factor. Heat removal
beryllium or nickel, silicone and chrome results in alloys in the backstage with the cooling system leaves plenty of
that offer an optimal combination of hardness, wear time to do it. This is where AMPCOLOY® alloys really
resistance, thermal fatigue and thermal conductivity. stand for—absorbing the first heat wave, shot after shot.
Mr. Luis J. Bento, Chairman of AMPCO METAL, explains: Coating
“Cycle time can be reduced by at least 20 percent, and
some users report reductions of up to 80 percent, In order to increase wear resistance, the high quality
copper alloys can be very easily coated with electroless
resulting from the significantly faster cooling rates
nickel, hard chrome or even PVD (physical vapor

July 2020 49 Plastics News