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By Peter Jones and
Greg Rhoden, Phifer Inc.
Wire is woven in various mesh configurations
to meet customer specifications or industry standards from
fine wire that is drawn down from rod and prepared for weaving. |
Woven wire mesh is an integral component in
the design and production of many types of filters. While some filters
use wire mesh as the primary filtering medium, numerous pleated filters
are constructed from media that will not conform to a pleated configuration
or are subjected to pressure that the media will not tolerate. For
this reason, wire mesh is commonly used to provide strength, support
and separation for the filter media. High-speed pleating and related
filter manufacturing equipment are driving the demand for higher quality
and consistency in meshes supplied to the industry.
Today, steel, aluminum and stainless steel are
the most common metal mesh materials used in filter manufacturing.
The raw materials and processes that a top-tier mesh supplier uses
are critical factors in determining quality and reliability.
Raw Materials
There are two primary raw materials used in the production of wire
mesh for filters: the metal and a coating. Coatings are applied
to the wire mesh after it is woven to provide additional protection
and stability to the woven mesh. Epoxy-based coatings are widely
used with wire mesh for filtration, as well as acrylic-based and
polyester-based coatings.
Processes
Small-diameter wire (fine wire) for weaving is drawn down to weaving
size from larger diameter redraw rod or intermediate wire. Mesh
suppliers with in-house wire drawing and preparation capabilities
are better able to control mesh quality versus those who purchase
finished wire for weaving due to their control of the wire diameter,
roundness, tensile strength and other characteristics that impact
the quality of the woven mesh. Other advantages include better process
control, the ability to react quickly to special orders and faster
delivery of the finished product.
Finished wire is woven to customer's specifications
or to industry standards. High-quality input wire is paramount to
the weaving process to help control consistency in the mesh and
provide a reliable product for processing by the filter manufacturer.
For example, distortion in the mesh can cause consistency issues
when paying the wire mesh off into a pleating line.
After weaving, the mesh can be further processed
in a number of different ways depending on the end customer's needs.
The mesh could be shipped directly after weaving with no cleaning
or coating (referred to as "natural" or "mill finished").
It might be cleaned of drawing and weaving lubricants and shipped
as cleaned only, or it can be cleaned and coated according to customer
requirements. Prior to the coating process, it is sometimes necessary
for the mesh to be heat treated, or annealed. The annealing process
is critical for the wire mesh to be pleated. Aluminum, a softer
metal, often does not require annealing, while steel and stainless
steel mesh almost always require softening through the annealing
process to be pleated efficiently. Strict quality control of the
annealing process ensures that the wire mesh will remain consistent
and reliable in the filter manufacturer's pleating operation.
Wire mesh can be slit to custom widths
and is used in
multiple types of filters including air, oil, fuel, and hydraulic
fluid filters. |
Many filter manufacturers require custom slitting
of wire mesh. Precision slitting capability is paramount for a wire
mesh supplier to meet the exacting width tolerances required in
many filters. Another important and valuable factor for filter manufacturers
is the capability of supplying rolls of wire mesh in maximum lengths.
Longer input rolls require less frequent roll changes and increase
pleater input.
Product Selection
Filter manufacturers have a number of options when choosing a wire
mesh to add support and strength to their filters. Physical properties,
chemical properties and cost are factors to consider in selecting
the most suitable wire mesh for filtration applications.
Aluminum has a relatively high strength-to-weight
ratio, can be pleated easily with or without annealing and is generally
lower in cost per foot than most other metals. It is also not as
susceptible to rust and oxidation as ferrous metals and can be used
with or without a coating depending on the application.
Low carbon steel provides high strength to withstand
the cyclic pressure differentials present in many fluid filtration
systems, is easy to pleat when properly annealed and is a low cost
option in comparison to other metals offering similar physical properties.
In most cases, it should be coated to prevent rusting.
Stainless steel mesh, though a higher cost option,
offers still greater strength, high heat resistance, is more resistant
to corrosion, and can be used with or without a coating. It is generally
more suitable for applications with highly-acidic or caustic solutions
at elevated temperatures.
Wire mesh has long been a component of many
types of filters. The predominant use of wire mesh in filters is
as a support mechanism for various types of filter media. With advances
in filter media efficiency and development of high-speed filter
manufacturing technology, choosing the right mesh product and the
right supplier are critical to a filter manufacturer's success.
About the Authors:
Peter Jones, Metallurgist, Phifer
Inc.
Greg Rhoden, National Market Manager, Engineered Products,
Phifer Inc.
For more information
contact:
Phifer Inc.
Tel: 1-800-854-9473 | Fax:
1-205-750-4890
Email: greg.rhoden@phifer.com
Website: www.phifer.com
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