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The environments
in which equipment must often operate—oil, water, ozone,
corrosion, and temperature extremes—are as critical to
designing materials and assemblies that isolate shock and vibration
as factors such as space limitations, shock loading capability,
weight, radiation, and surface friction.
As a result of its interlocking
loop construction—which
couples resiliency with high damping characteristics and nonlinear
spring rates—Metal Textiles knitted wire mesh offers unique
properties for absorbing shock and vibration. It also provides
dramatically
improved performance in hostile environments. Each loop acts
as a small spring when subjected to compressive loads, and
will immediately resume 90% of its original shape when the
load is removed.
Knitted wire mesh, in a compressed form, can handle shock loadings as
high as the yield strength of the material itself. In fact, it is not uncommon
for a one-inch-thick disc to absorb up to 100,000 pounds of loading—a level
not obtainable with any other fabricated material. Loadings may be in any
direction. Knitted wire mesh is also versatile: additional resilience, as well as
reduction of surface friction, can be obtained by knitting plastic fiber in
parallel with metal, in which case the metal wire acts as a structural support
and binder for the plastic.
Proven performance in shock and vibration damping
Knitted mesh has a distinct advantage in its ability to withstand hostile
environments over other materials such as rubber, plastic, cork, and felt. By
proper selection of the material or combination of materials, it is possible to
provide vibration or shock control in corrosive atmospheres or at ultrahigh or
cryogenic temperatures, as well as radioactive, dirty, oily, and other extreme
conditions.
Knitted mesh also offers other environmental advantages. Since the knit
contracts within itself to take up the expansion of the metal, the coefficient
of thermal expansion is not a factor—the resiliency of the knit allows for
expansion and contraction without the subsequent danger of the support
separating from, or pinching, the equipment it protects.
Knitted Wire Mesh-Providing High Temperature Dampers for the World's Most
Demanding Industrial Environments
Not only does knitted wire mesh provide superior performance-with an extra
measure of protection against shock and vibration-but it can be fabricated from
any material that can be drawn into a wire form. The most common knitted
materials are stainless steel, copper, aluminum, and Inconel.
An assortment of fibers, plastics, and other materials can also be combined
with metals to provide specific, desired damping or environmental characteristics.
In addition, bulk material may be flattened, calendared, corrugated, wound, or
compressed to enhance its properties for specific applications. The density of the
knit may also be controlled from 10 to 70%-permitting constructions of widely
varying compression characteristics.
The versatility in selection of materials and their fabrication make knitted
wire mesh an ideal solution for an extremely wide range of demanding industrial
applications.
Advantages
Metal Textiles knitted wire mesh products provide a number of significant advantages over other shock
and vibration damping materials:
- High temperature dampers offer variations of
alignment, flame resistance, expansion and
contraction, and corrosion control.
- Offers more durability with less effect from
the environment.
- Wide range of materials can be used to
control not only acoustical properties, but
aging processes.
- High temperature isolators can withstand more
weight and maintain its resiliency without
deterioration.
- Will reduce wear and tear on critical piping
or delicate tubing on aircraft, marine, or
other transit equipment when used as
clamps for retainers.
- As bumper pads, can add extended life to
pneumatic tube carriages, plus reduce
impact noise.
Applications
Applications for Metal Textiles knitted wire mesh include vibration and shock control for:
- Engine mounts—cars, trucks, boats, recreation
vehicles (camper trailers), electric
motors, auxiliary motors, and aircraft
- Vibration pads—Machinery, floating slabs
and pipes
- Mounts—Electronics, tubing, hydraulics, aircraft,
and marine
- Bumper pads—Pneumatic tube systems,
coin machines for bank, ball screws, and
steering columns
- Clamps—Tubing, tongs and furnace clamps
(fingers)
- Exhaust Systems—Catalytic monolith
supports
- AUTOMOTIVE
Challenge: In the early 1970s, the automotive industry needed a mechanical support for the
brittle ceramic honeycomb substrate used in exhaust system catalytic converters.
- The support was used to fill a gap of approximately 4 mm between the ceramic monolith
substrate and the metal shell in which it was housed. However, since the rates of expansion
and contraction of the metal shell and ceramic element are different, the clearance space
changed whenever the engine ran or was shut off.
- The mechanical support had to compensate for this changing clearance space while protecting
the substrate from road shock. It also had to withstand temperatures as high as 650° C
(1200ºF), wide temperature differentials and corrosive exhaust gas emissions.The ceramic
felts and other fiberglass materials previously employed lost their resiliency and became
permanently compacted well before the service life required of the converter. As a result,
they lost their supportive power or broke up, causing destruction of the substrate.
Solution: To solve this problem Metal Textiles developed a knitted wire catalyst substrate support,
from resilient, knitted metal.The knitted metal not only supports the monolith and compensates
for the thermal expansion of the assembly, but also protects the ceramic honeycomb
from mechanical shock during normal and abnormal driving.To date, over 25 million of these
mounts have been manufactured by Metal Textiles Corporation.
- AIRCRAFT
Challenge: The aircraft industry required tubing and harness clamps which could effectively
dampen the high-frequency engine vibrations experienced during taxi, takeoff and in-flight
operations-yet prevent them from affecting fuel, hydraulic, and electrical lines.
It was also important that the clamps have low surface friction so any linear movement
would not cause wear at the holding point-which could lead to in-flight failures.
Solution: Metal Textiles solved the problem by developing a knitted metal pad that is spot-welded to
the inside of the clamp. Due to high temperature differentials-and the potential of attack from
ozone, hydraulic fluid, and jet fuel-stainless steel and Inconel were specified. Since the surface
friction of the knitted metal is relatively low, it allowed for lateral motion of the assembly with
full protection from the wear and vibrational stresses.The use of knitted metal also allowed a
degree of electrical grounding through the all-metal mount.
- MARINE
Challenge: Electronic equipment mounted aboard ships or moving vehicles requires mounting
devices that are lightweight and can provide protection from high levels of vibration and shock
over extended periods.
Solution: A series of Metal Textiles-developed shock mounts now provide a resilient cushion to
protect sensitive equipment The high damping qualities of the knitted metal cushions also
allow faster reduction of vibration without severe rebound.
Exposure to oil, saltwater spray, solvents, dust, dirt, or temperature extremes cause no
degradation of the unit's performance.
- POWER GENERATION
Challenge: In nuclear power plants, pipes suspended in pipe hangers must be protected from
vibration.
Solution: Many utilities have solved the problem by using a flat pad of knitted metal, designed
by Metal Textiles.The 150 mm wide by 230 mm long by 12 mm thick pads are placed inside the
hanger. Pipes as large as 765 mm in diameter have been protected in contaminated areas.
The knitted metal has been impervious to radiation degradation.
PRODUCT BENEFITS
- Resistance to corrosion and high temperature
- Wear resistant
- Excellent strength
- Resistant to melting
- High degree of resiliency- product maintains shape over a long period of time
The interlocking loop construction of knitted mesh provides the resiliency and thermal durability required for high temperature damping
Automotive exhaust air-gap pipe ring-the inherent resiliency and high-damping characteristics of knitted wire mesh provide superior performance
Engine clamp-geometry and diversity are not limited to round, square or rectangular
cross sections
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