Views: 0 Author: Site Editor Publish Time: 2025-09-05 Origin: Site
Scraper plates—water blades, baffles, cut-off plates and oil scrapers—play a quietly critical role on rolling mills. They control water and oil on the strip, protect downstream equipment, and help preserve product surface quality. Choosing the right base material for these components affects performance, lifetime and the cost of ownership.
This article focuses on two economical and commonly available laminates used by suppliers and fabricators: cotton fabric laminate (fabric-reinforced phenolic-style sheet) and epoxy laminate (glass-fiber reinforced epoxy sheet). It explains how they behave in different mill environments, recommends practical design and finishing choices, and gives action-ready guidance for manufacturers and end users.
Cotton fabric laminate: A layered laminate using woven cotton (or cellulose-based) fabric impregnated with a thermosetting resin and pressed into a board. It is often chosen for low-cost structural parts where extreme stiffness isn’t required.
Epoxy laminate: A fiber-reinforced board using glass cloth (fiberglass) and epoxy resin. It delivers higher stiffness, better dimensional stability and improved resistance to moisture and oils compared with fabric-based laminates.
Scraper plates see diverse conditions depending on where they are installed:
Hot-rolling lines: elevated temperatures, abrasive oxide scales and particulate matter in cooling sections.
Cold-rolling and precision finishing: lower temperatures but strict surface-quality demands and sensitivity to scratches or indentations.
Lubrication/degassing or oil-coating stages: exposure to oils and solvents; a blade’s tendency to soak or swell becomes critical.
High speed / high tension lines: dynamic loads, vibration and higher incident forces at the blade edge.
When evaluating materials, consider: thermal exposure, abrasive contamination, fluid chemistry (water chemistry and oil type), mechanical load (clamping and impact), and whether the plate will be in direct contact with the strip or act as a nearby guide or baffle.
Stiffness & dimensional control: Epoxy laminate is significantly stiffer and holds precise flatness under load. Cotton fabric laminate tends to flex more and can show permanent deformation over long spans or under concentrated loads.
Fastening and machining: Both materials are machinable, but epoxy takes cleaner threads and holds tolerances better; cotton-based boards may crush or fuzz at edges during aggressive machining.
Smoothness: Epoxy laminate accepts finer finishing and can be polished or coated to low-friction finishes. Cotton laminate typically produces a slightly textured surface unless sealed or coated.
Risk of marking: For critical cold-rolling or finishing operations, epoxy-based assemblies fitted with a soft contact insert reduce the risk of marking when compared to untreated cotton laminates.
Water and humidity: Epoxy laminate resists moisture uptake if properly cured and edged-sealed. Cotton laminates will absorb fluids more readily unless the faces and exposed edges are protected by coatings or sealants.
Oils and solvents: Epoxy is chemically more inert and less prone to swelling or staining. Cotton-based boards can trap oil and contaminants in fiber voids, degrading performance over time.
Short exposures: Neither board is suitable for repeated direct contact with red-hot strip. For elevated but non-contact zones, epoxy tolerates higher service temperatures than cotton laminates.
Long-term heat cycles: Epoxy resins formulated for higher Tg (glass transition temperature) are preferred if the installation approaches the upper limits for polymer components.
Abrasive particulates: Both will wear when in direct contact with oxide scale and grit. Epoxy’s higher hardness and ability to accept sacrificial inserts (e.g., UHMWPE strips or ceramic tiles) make it superior in abrasive zones.
High-abrasion, high-temperature zones (hot-rolling cooling beds and descaling areas)
Avoid relying on either laminate as the primary wear surface. Use steel or ceramic/metal composite facing for abrasion resistance. If a laminate is required for mounting or insulation, choose epoxy board as a structural substrate and fit replaceable wear strips.
Cold-rolling and finishing lines (surface-sensitive)
Use epoxy laminate as the structural plate because it offers flatness and stable mounting. Fit the contact edge with a soft, low-friction insert (PTFE, UHMWPE, or PU) to protect strip surface and allow controlled contact pressure.
Water and oil control applications (cut-off plates, oil scrapers, baffles)
Epoxy laminate is the safer default: low absorption, easy-to-clean surfaces and long-term dimensional stability. Where cost is the primary driver and the environment is dry and non-critical, a sealed cotton laminate can suffice when fully finished and regularly inspected.
Low-speed, low-cost or temporary installations
Cotton fabric laminate can be chosen for economic reasons, but it must be fully impregnated, edge-sealed, and used with sacrificial soft contact strips and a planned replacement cadence.
Edge treatment: Always break and radius edges at the contact face (recommendation: R ≥ 1.5 mm for sensitive strip surfaces). Sharp edges cause scratches and accelerate laminate damage.
Seal exposed faces and edges: For cotton laminates, apply a compatible epoxy or polyurethane edge seal to prevent fluid ingress. For epoxy boards, a thin topcoat or PTFE film increases cleanability.
Modular, replaceable inserts: Design the plate so the part that contacts strip or fluid can be replaced independently (bolted insert strips or dovetail holders). This extends service life and simplifies maintenance.
Fastening details: Use backing plates or countersunk clamps to avoid protrusions above the contacting face. For brittle laminates, distribute clamps over a larger area to prevent crushing.
Surface finish: For epoxy plates used near product surfaces, specify a smooth finish (low Ra) and, where appropriate, a low-friction coating or bonded UHMWPE/PTFE layer.
Drainage and recovery features: Integrate channels and shallow gutters behind water and oil scraper edges to capture and redirect fluids away from the product and machinery.
Routine checks: Inspect edges for wear, delamination, oil saturation or fiber fuzzing. Replace inserts or blades at the first sign of damage that could transfer to the strip.
Cleaning: Use non-aggressive cleaners compatible with the laminate. Avoid prolonged exposure to strong solvents on cotton laminates.
Record keeping: Track lifespan of each replaceable insert and the mounting board so you can correlate wear to operating conditions and refine material choices.
Spare strategy: Keep spare inserts sized to standard bolt patterns and at least one full spare board per major line, reducing downtime.
If you build scraper plates and boards for mills, consider these options:
Offer epoxy laminate plates as a standard product with pre-drilled universal mounting patterns, edge radii and pre-machined slots for replaceable inserts.
Provide sealed cotton laminate panels as a budget alternative but include mandatory edge sealing and a recommended replacement interval in documentation.
Supply a family of replaceable contact strips (UHMWPE, PTFE-coated, PU) that fit the same mounting geometry so operators can choose the right contact material without replacing the whole panel.
Provide testing & acceptance checks: flatness tolerance, porosity/absorption test for cotton laminates, and a simple solvent exposure check for epoxy boards.
Is the application surface-critical (cold/precision rolling)? → Prefer epoxy laminate + soft insert.
Is the environment hot and abrasive (hot-rolling descaling)? → Avoid laminate contact; use metal/ceramic faces and epoxy for structure only.
Is cost the dominant driver and risk acceptable? → Consider sealed cotton laminate with planned maintenance.
Is oil/water exposure continuous and fluid chemistry aggressive? → Epoxy laminate is more reliable.
Panel size: custom to strip width; typical modules 800–2000 mm wide, lengths as required.
Structural thickness: epoxy base 8–15 mm typical; cotton laminate 10–20 mm depending on stiffness needed.
Contact insert thickness: UHMWPE/PTFE 4–12 mm replaceable strips.
Edge radius: minimum 1.5 mm; 3 mm preferred for sensitive strips.
Mounting holes: countersunk M8 standard or specified to match customer bolt pattern.
Finish: epoxy board — machined and sanded to Ra ≤ 0.6 µm when required; cotton board — sealed topcoat recommended.
(Adapt sizes and tolerances to each mill’s drawing and operating speeds.)
For most modern rolling operations where surface quality and long-term stability matter, epoxy laminate is the more reliable and lower-risk choice as the structural base for scraper plates and baffles. Cotton fabric laminate remains useful where budget limits prevail and operating conditions are benign — provided the board is fully sealed, edges protected and the design allows sacrificial, replaceable contact strips.
Being pragmatic pays off: specify high temperature resistant laminate materials for the zone of service rather than applying a single material everywhere. Wherever laminate comes into direct contact with strip or abrasive particulates, plan for replaceable wear parts and a documented inspection cycle. That approach keeps costs predictable while protecting the product surface your customers care about.
