The
choice between compression molding over other molding processes has been a
point of contention for many manufacturers. All of these manufacturing
processes have their advantages and disadvantages and choosing the right fit
will depend on the product requirements.
To
know why compression molding is reigning supreme over the rest means that we
have to take a deep dive into what compression molding is all about.
An
In-Depth Look at Compression Molding
The
compression molding process features the use of a heated
mold treated with pressure. Just like in the other molding process, it also
uses the same materials, typically a polymer or plastic and a mold cavity. When
the material hardens, the product will be removed from the cavity. What makes
it unique is it uses both the capabilities of pressure and heat. When both of
these variables are added to the production process, it alters the properties
of the molded material.
The
compression molding process begins with heating the material and the mold
cavity. When the desired temperature is achieved, the material will be
introduced into the mold. Using heat alone can cause the heated material to
expand. The use of pressure in compression molding makes it an effective
process.
To
apply the pressure, the molded cavity with the molten material will be properly
sealed with a plug. The pressure is then exerted so that the material fills all
the smallest crevices in the mold. In some processes, the pressure can reach up
to 2,000 pounds per square inch or PSI. When this pressure combines with heat,
the pressure will push the materials throughout the cavity.
When
the materials cooled down, the final product will then be removed from the
cavity. While other molding processes are the same, the pressure makes all the
difference in compression molding.
The
Advantages of Compression Molding
Compression
molding is ideal when creating durable products. Here are the rest of the
benefits of using this molding process.
1.
Seamless Design - The compression
molding technique can make products with different wall thicknesses. It can
vary from 1.3 millimeters to one inch.
2.
Lower Costs – When used in
low-pressure molds, producing multiple cavities incur lower costs.
3.
Varied Options for Materials – In
compression molding, you can use materials that stay pliable after the cooling
process. Some of the most common materials used are natural rubber, silicone,
and EPDM.
4.
Seamless Design – The final product
in compression molding is seamless without knitting or flows. Some of the
products it can produce is a gasket that has a cohesive characteristic and with
a good surface finish.
5. Fit
for High Volume Manufacturing – Compression molding has longer production
time, but it’s a low-pressure mold, so it has inexpensive tooling costs.
Drawbacks
from Compression Molding
Here
are the disadvantages of using compression molding:
1. Slower Turnaround Time – The time it
takes to complete a compression molding cycle is much slower than other molding
processes.
2.
Higher Labour Cost – In compression
molding, it is necessary to remove flash, which translates to additional
manpower requirements.
3.
Lower Productivity – Removing the
flash lowers down the productivity because it slows down the production.
4. Production of Simple Parts – This
technique is best for parts with simple geometry.
Conclusion
Compression
molding has its benefits and drawbacks that companies should consider before
going into production. The manufacturer has to select a technique that best
suits their requirements.
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