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Another
significant advantage of RIM is that lead times average approximately half
to two-thirds those of injection molding, with, again, the greater
disparity for larger parts. The benefit to Molecular Dynamics, as the
company's senior mechanical engineer, Iain Hueton explains, is that “RIM
is an excellent process choice for moderate volume products requiring
medium to large structural parts. Rimnetics proved to be a capable and
accommodating shop that understands the strengths of the RIM process and
facilitates its use in the oppressive schedules of the instrumentation
market.”
In Reaction Injection Molding,
manufacturers have found a way to liberate design from many of the
limitations of conventional structural foam and sheet metal. The RIM
process enables designers of equipment enclosures to develop complex
shapes with mechanical functionality including molded in ribs, bosses and
inserts. Lighter enclosures that are both corrosion and impact resistant
with a wide range of other physical properties are common accomplishments.
RIM truly brings both Style and Economics to equipment enclosures.
Rimnetics, Inc., using “Reaction
Injection Molding” (RIM), will form your enclosure to your exact
specifications. Used in thousands of applications, RIM is a very cost
effective process for high quality enclosures in moderate volume. For the
first time, medium to large complex enclosures can be molded in a single
step at high product rates on low-cost equipment with low cost tooling,
using relatively little energy. RIM'd polyurethane has replaced many
materials and processes in the electronics, medical equipment, and
business machine industries.
Molecular Dynamics wanted an extremely
durable product with a low tooling cost and with structural rigidity.
Rimnetics was able to develop the enclosure of the Personal Densitometer
with consistent dimensions from top to bottom, within their moderate
volume. Because RIM materials start as low-viscosity liquids, the process
can fill complex molds and dependably produce parts even of unusual
thickness or varying cross-sections without inducing the flow-generated
internal stresses that result in sink marks or “read-through” of
reinforcing ribs. Part shrinkage is minimized by low mold temperatures of
130o - 160o F, and internal mold pressure of less
than 100 psi allow for a variety of mold materials and significant
reductions in mold costs, especially as part size increases.
Benefits of the RIM Process
The RIM process provides designers with a great deal of flexibility and
selection, including:
- Complex Shapes
- Mechanical Functionality
- Molded in Ribs, Bosses, and Inserts
- Moderate Volume
- Lower Weight
- Thermal and Acoustical Properties
- Wide Range of Physical Properties
- No Sink Marks
If you are a design engineer seeking a
manufacturing technology that can fulfill your design without compromise,
even with a short or medium production run, RIM will be found to be a very
attractive process and very economical in terms of tooling cost and short
lead time.
RIM'd Polyurethane Structural Foam
combines the strength-to-weight benefits inherent in structural foams with
the economies and design freedom of the RIM process. Enclosures produced
from RIM'd Structural Foam continue to benefit from the classic properties
for polyurethane, including:
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