Plastic steel wire mesh, often referred to as PVC (Polyvinyl Chloride) coated welded wire mesh or vinyl-coated wire mesh, is a versatile material used in various applications, from fencing and animal enclosures to construction and landscaping. Its production combines the strength and durability of steel wire with the protective and aesthetic qualities of a plastic coating. The process typically involves several key stages, starting with the raw steel wire and culminating in the finished coated mesh.
1. Wire Preparation
The foundational material for plastic steel wire mesh is high-quality steel wire. This initial stage ensures the wire is suitable for mesh fabrication and subsequent coating.
- Material Selection: The core material is usually low-carbon steel wire (e.g., SAE 1008, 1010, 1012), stainless steel wire, or galvanized iron wire. The choice depends on the desired strength, corrosion resistance, and specific application of the final mesh. Galvanized wire, which has a zinc coating, provides an additional layer of corrosion protection underneath the plastic.
- Wire Drawing: If starting from a thicker metal rod, the material undergoes a drawing process where it is pulled through a series of progressively smaller dies. This reduces the wire diameter to the desired gauge, increasing its tensile strength and improving its surface finish.
- Cold Rolling (Optional but common): For some applications, particularly where precise dimensions and enhanced strength are required, the wire may undergo cold rolling. This process deforms the metal below its recrystallization temperature, increasing its yield strength and hardness by introducing defects into its crystal structure.
- Straightening and Cutting: The coiled wire is then fed into specialized machinery that straightens it and cuts it into precise lengths. This ensures uniformity and ease of handling during the mesh formation stage.
2. Mesh Formation: Welding or Weaving
The prepared steel wires are then formed into a mesh pattern, typically through welding or weaving. The choice of method depends on the desired mesh type, strength, and application.
a. Welded Wire Mesh Production
Welded wire mesh is characterized by its rigid structure, formed by electrically fusing intersecting wires. This is a common method for plastic-coated mesh used in fencing and security.
- Wire Arrangement: Parallel longitudinal wires are fed continuously through an automatic welding machine. Simultaneously, pre-cut transverse (cross) wires are automatically dropped perpendicularly on top of the longitudinal wires.
- Electric Resistance Welding: At each intersection point of the wires, an electric resistance welding head applies controlled pressure, intensity, and duration of electric current. This precise combination generates heat, fusing the wires together at their intersections. Modern machines are highly automated, ensuring consistent weld quality and precise grid dimensions.
- Mesh Advancement: As the welding occurs, the newly formed mesh is pulled forward, allowing the next set of cross wires to be positioned and welded.
- Cutting and Bending (if required): The continuous welded mesh can then be cut to desired panel or roll dimensions. For certain applications, such as reinforcement or specific structural components, the mesh may also undergo bending operations to achieve required shapes.
b. Woven Wire Mesh Production (less common for plastic-coated, but possible)
While more frequently associated with filtration and screening, some plastic-coated meshes, especially those with finer weaves or specific flexibility requirements, can be woven.
- Loom Setup: Similar to textile weaving, wires are loaded onto a loom. Longitudinal wires (warp wires) are strung parallel, and transverse wires (weft or shute wires) are interlaced.
- Weaving Process: The loom uses wire harnesses to lift alternate warp wires, allowing a shuttle to pass the weft wire perpendicularly. A reed then presses the weft wire tightly against the mesh. This over-and-under pattern creates the woven structure. Various weave patterns (plain, twill, Dutch) can be achieved.
- Crimping (for some woven mesh): For woven mesh with larger openings or where added stability is desired, wires may be crimped (deformed into a wavy pattern) before weaving. This helps lock the wires in place and enhances structural integrity.
3. Plastic Coating Application
Once the steel wire mesh is formed, it undergoes the critical step of applying the plastic coating, which provides corrosion resistance, durability, and aesthetic appeal.
- Cleaning and Pre-treatment: The steel mesh must be thoroughly cleaned to remove any oils, dirt, or rust. This ensures proper adhesion of the plastic coating. A pre-treatment process, such as phosphating, might also be applied to further enhance bonding.
- PVC Powder Application: The most common method for applying the plastic coating is using PVC powder. There are generally two primary techniques:
- Fluidized Bed Coating: The mesh is preheated to a temperature above the melting point of the PVC powder. It is then dipped into a fluidized bed of PVC powder. The hot mesh melts the powder upon contact, causing it to adhere and form a continuous coating.
- Electrostatic Spraying: PVC powder is electrostatically charged and sprayed onto the grounded mesh. The electrostatic attraction holds the powder in place.
- Curing/Baking: After the powder is applied, the mesh is moved into an oven where the PVC powder melts, flows, and cures, forming a smooth, uniform, and tightly bonded plastic layer. This heat process ensures a strong adhesive bond between the plastic and the galvanized or steel wire.
- Cooling: The coated mesh is then gradually cooled to solidify the plastic coating.
4. Quality Control and Finishing
The final stages involve inspection and packaging to ensure the product meets specifications.
- Inspection: The finished plastic steel wire mesh is inspected for uniformity of coating thickness, adhesion, absence of defects (e.g., bare spots, bubbles), weld integrity (for welded mesh), and adherence to specified dimensions (mesh size, wire gauge, overall panel/roll size).
- Packaging: The mesh is then typically rolled or cut into panels and prepared for shipment. Rolls might be wrapped in plastic film or kraft paper, and panels might be stacked and bundled.
This multi-step production process ensures that plastic steel wire mesh delivers a combination of mechanical strength, excellent corrosion resistance, and a visually appealing finish, making it a popular choice for a wide array of applications.
