TQC VF2255 / VF2256 / VF2257 Wet Film Thickness Gauge Wheel
| Brand | TQC |
|---|---|
| Construction | Stainless Steel & Anodized Aluminum Body |
| Bearing Type | Precision Ball Bearing |
| Measurement Principle | Eccentric Rolling Wheel (ISO 2808 Compliant) |
| Scale Range | VF2255 (1–100 µm), VF2256 (5–250 µm), VF2257 (10–500 µm) |
| Graduation Accuracy | ±2 µm (per ISO 2808 Annex B) |
| Wheel Diameter | 42 mm |
| Compliance | ISO 2808, ASTM D1212, JIS K 5600-1-4 |
Overview
The TQC VF2255 / VF2256 / VF2257 Wet Film Thickness Gauge Wheel is a precision mechanical instrument engineered for rapid, non-destructive measurement of wet film thickness on flat or slightly curved substrates during coating, printing, and laminating processes—particularly in flexible packaging, paper converting, and corrugated board production. Based on the eccentric rolling wheel principle defined in ISO 2808:2016 (Annex B), the gauge operates by rolling a calibrated, offset-circumference wheel across a freshly applied wet coating. As the wheel rotates, its eccentric rim contacts the substrate at two fixed points while the highest point of the rim simultaneously engages the wet film surface. The resulting gap between the substrate and film corresponds directly to one of the engraved scale increments on the wheel’s perimeter—providing an immediate, analog readout without electronics, batteries, or calibration drift. This passive, first-principle method ensures long-term metrological stability and eliminates dependence on operator interpretation of digital displays or probe alignment.
Key Features
- Three interchangeable models (VF2255, VF2256, VF2257) covering overlapping thickness ranges from 1 µm to 500 µm—optimized for aqueous coatings, solvent-based inks, UV-curable varnishes, and adhesive layers common in packaging gravure, flexo, and coating lines.
- Machined stainless steel hub and hard-anodized aluminum body ensure corrosion resistance against aggressive solvents (e.g., ethyl acetate, ethanol, toluene) and mechanical durability under repeated industrial handling.
- High-precision ball bearing assembly minimizes rolling friction and hysteresis, enabling consistent, low-torque traversal across high-viscosity or tacky films—including hot-melt adhesives and water-based acrylic dispersions.
- Eccentric wheel geometry conforms to ISO 2808 geometric tolerances (±0.5° runout, ≤0.01 mm radial deviation), guaranteeing traceable measurement uncertainty within ±2 µm across the full scale range.
- No zero adjustment or recalibration required; each unit is factory-certified with individual metrology report traceable to NIM (China National Institute of Metrology) standards.
Sample Compatibility & Compliance
The gauge is validated for use on smooth, non-porous substrates including coated paperboard, PET film, aluminum foil, and chrome-plated gravure cylinders. It accommodates moderate surface roughness (Ra < 3.2 µm) and tolerates ambient temperature variations from 10 °C to 40 °C without thermal expansion-induced error. All models comply with ISO 2808:2016 (Method A – Eccentric Wheel), ASTM D1212 – 19 (Standard Test Methods for Measurement of Wet Film Thickness of Organic Coatings), and JIS K 5600-1-4:2016. Documentation includes conformity statement per ISO/IEC 17025:2017 requirements for measurement equipment used in GLP-compliant QC laboratories.
Software & Data Management
As a purely mechanical, analog measurement device, the TQC Wet Film Thickness Gauge Wheel requires no firmware, drivers, or software integration. However, its output is fully compatible with structured quality documentation workflows: recorded values may be entered directly into LIMS (Laboratory Information Management Systems), MES (Manufacturing Execution Systems), or paper-based batch records compliant with ISO 9001:2015 clause 8.5.2 (Identification and traceability) and FDA 21 CFR Part 11 (when paired with electronic signature-enabled data capture). Each instrument bears a unique serial number laser-engraved on the hub for audit trail linkage.
Applications
- Inline verification of wet film build prior to drying/curing in flexographic and gravure printing units—ensuring color density consistency and minimizing over-coating waste.
- Process validation of water-based barrier coatings (e.g., PVDC, acrylic dispersions) on food-grade paperboard for moisture vapor transmission rate (MVTR) control.
- Adhesive transfer monitoring in cold-seal and heat-activated laminating lines—critical for peel strength reproducibility in pouch manufacturing.
- QC release testing of UV-curable overprint varnishes on metallized films, where excessive wet thickness leads to incomplete cure and surface tack.
- Supplier qualification audits requiring physical evidence of coating uniformity across web width (measured at multiple lateral positions per ISO 2808 sampling protocol).
FAQ
How often does the gauge require recalibration?
No recalibration is required during normal use. The eccentric geometry is mechanically invariant; only periodic visual inspection for wheel edge wear or bearing play is recommended per ISO 2808 maintenance guidelines.
Can it measure on textured or embossed substrates?
It is not suitable for substrates with relief patterns exceeding 10 µm depth or surface roughness Ra > 3.2 µm, as local topography interferes with consistent wheel-substrate contact.
Is the scale readable under low-light production conditions?
Yes—the engraved scale features deep, matte-finish markings with high-contrast white paint fill, optimized for readability under standard factory lighting (≥300 lux) and compatible with portable LED inspection lamps.
Does it meet FDA or EU food-contact compliance requirements?
The materials (304 stainless steel, 6061-T6 anodized aluminum) are inherently inert and compliant with FDA 21 CFR §175.300 (resinous and polymeric coatings) and EU Regulation (EC) No 1935/2004 for indirect food contact applications.
