FAQ Center

Single layer: one MD+CD yarn set, best drainage (500-800 CFM), lowest FSI (50-80). Best for low-speed heavy grades. Double layer: two CD yarn sets, FSI 80-120, CFM 400-650. Workhorse for medium-speed packaging/kraft. Triple layer: separate top (fine) and bottom (wear-resistant) weaves, FSI 130-200+, CFM 250-500, longest life 60-150 days. SSB is premium variant with integral binder yarns — required for high-speed (>800 m/min) and quality-critical grades.

Tissue/lightweight (<40 gsm) → 70-95 th/cm. Fine/cultural paper (40-120 gsm) → 50-70 th/cm. Packaging (80-200 gsm) → 35-55 th/cm. Heavy packaging/kraft (200-400+ gsm) → 25-40 th/cm. Higher mesh = better fiber support but lower drainage. The correct mesh is the finest that still provides adequate drainage for your target speed.

FSI quantifies support points per unit area on the sheet side. Each warp-weft intersection = fiber anchoring point. Higher FSI = more uniform fiber mat = better retention + fewer defects. Ranges: single 50-80, double 80-120, triple 130-170, SSB 150-200+. FSI >150 recommended for fine paper/tissue. Upgrading fabric (e.g., double→SSB) typically improves first-pass retention 5-15%.

Replace when: (1) CFM increased >30% from baseline, (2) caliper loss >25%, (3) tensile strength <75% of original, (4) sheet quality degrading (wire marks, formation), (5) visible wear stripes at vacuum slots or seam wear >50%, (6) economic life reached. Track fabric life in BOTH days and tons produced.

Causes in order of likelihood: (1) Binder knuckle protrusion — most common on standard triple layer. Upgrade to SSB. (2) Fabric tension too low — increase within 4-8 kN/m. (3) Mesh too coarse for basis weight. (4) Excessive vacuum — reduce to minimum needed. (5) Stock freeness too high — adjust refining.

YES for machines >600 m/min or quality-critical grades. SSB delivers: 30-50% longer life, 5-15% better FPR, 50-80% fewer wire mark defects. Most mills report $3-7 savings per $1 extra fabric cost. Standard triple layer may suffice for slow machines (<500 m/min) on non-demanding grades.

PET: primary material, excellent stability, good hydrolysis resistance (HR-PET), lower cost. PA: 3-4× better abrasion resistance, used strategically in bottom CD positions where wear concentrates. PAPTEX hybrid PET/PA design delivers 20-35% longer life on abrasive furnishes at 5-10% cost increase.

Starting ranges: tissue 250-400, fine paper 300-450, packaging 400-650, kraft 450-700, recycled board 500-800 CFM. Principle: higher speed/higher basis weight → higher CFM. Optimal CFM is the lowest value providing adequate drainage at max target speed.

Recycled fiber reduces life 30-50% vs virgin at same speed. Causes: higher ash (10-25% vs 2-5%), contaminants (stickies, plastics), shorter fibers. Mitigation: PA yarns in wear zones, higher shower pressure (25-40 bar), SSB construction, more frequent inspection.

Yes — Voith, Valmet, Andritz, Toscotec, A.Celli, all Chinese manufacturers, and more. Fabrics custom-engineered to your machine dimensions (width 12m+), speed (2200 m/min), and grades. We maintain machine profiles for 200+ mills in 30+ countries.

Flat yarn: 60-75% contact area, better stability, longer life (45-150 days), preferred for packaging/cultural/kraft. Spiral: easier threading, anti-static options, preferred for tissue and complex threading paths. Flat yarn costs 20-40% more but typically 40-60% longer life = lower cost/day.

Packaging: 500-800, fine paper: 400-650, kraft: 450-700, tissue: 300-500 (spiral), recycled board: 600-1000 CFM. Higher CFM = better ventilation but lower contact. Seam CFM must match body CFM ±10%.

Pin seam: standard for flat yarn, good strength, easy install. Spiral seam: highest strength for wide machines (>6m). Clipper/hook: lightweight fabrics, frequent changes. PAPTEX seams are factory-installed — no field seaming required.

Check: (1) Even tension across width. (2) Laser-align all rolls annually. (3) Gradual heat-up (10-15°C/30min) to prevent width shrinkage. (4) Inspect guide palm/roll monthly. PAPTEX dryer fabrics: <0.5% width shrinkage at 180°C.

Standard PET: continuous 150°C, peak 180°C. HR-PET: continuous 160°C, peak 190°C — PAPTEX standard. PPS: continuous 190°C, peak 220°C for specialty. PA: continuous 140°C (less common in dryers). PAPTEX HR-PET covers 95% of applications.

Strongly recommended for: tissue, lightweight grades (<60 gsm), high-speed (>1000 m/min), low-humidity environments. Anti-static prevents dust attraction, sheet sticking, and operator hazards. PAPTEX uses carbon-filled PA yarns woven into fabric — permanent dissipation, not surface coating.

Flat yarn: 60-150 days (packaging/cultural), 90-180 days (fine paper). Spiral: 50-100 days (tissue), 45-90 days (kraft/recycled). Longer than forming fabrics due to lower mechanical stress, no abrasive filler contact, lower moisture. Primary limiters: seam wear, edge wear, heat degradation.

Yes — single-tier, double-tier, multi-cylinder, Yankee. Widths 12m+, CFM 200-1000+. Custom-engineered to your dryer section diagram (cylinders, felt run, threading path, temperature).

3-6 hours (machine stop to restart) for experienced crew on standard Fourdrinier. Factors: machine complexity, crew experience, auxiliary maintenance. PAPTEX provides free installation supervision for first-time customers.

Over-tensioning. Reduces fabric life 20-40%, increases power consumption, accelerates bearing wear, increases seam failure risk. ALWAYS follow manufacturer spec (4-8 kN/m forming, 2-5 kN/m dryer, 30-40% of operating for press felts initially). Use calibrated gauge — never tension by feel.

Temperature 10-30°C, humidity 40-70% RH, UV protection (opaque packaging), horizontal storage (never on edge), max 3 rolls high stacking, shelf life 2 years. Inspect if stored >1 year before installation.

Daily: visual pressure check. Weekly: inspect each nozzle for clogging — one clogged nozzle = stripe of accelerated wear. Monthly: full system inspection (filters, pressure, oscillation). Quarterly: chemical descaling of pipes/nozzles. After every fabric change: verify alignment with new fabric.

CaCO₃/fillers: dilute acid wash (pH 3-4). Organics/stickies: alkaline wash (pH 10-11) + surfactant. Combined: alternate acid/alkaline (never mix). Frequency: every 2-4 weeks (high filler/recycled), every 4-8 weeks (virgin). Precautions: rinse thoroughly between types, never exceed pH 2-11, verify PET compatibility with alkali at temperature.

Generally NO for modern triple-layer/SSB — dedicated top (sheet) and bottom (wear) sides. Fix root cause of uneven wear instead. Exception: some dryer fabrics can reverse direction at mid-life to equalize seam wear. Consult PAPTEX engineers.

Forming: 4-8 kN/m. Press: 2-5 kN/m. Dryer: 2-5 kN/m. Correct value depends on width, speed, roll diameters, grade. Insufficient = flapping, poor formation, tracking issues. Excessive = reduced life, higher power, bearing overload. Follow PAPTEX fabric data sheet — calculated for your specific machine. Verify with calibrated meter at install + monthly.

Use fabric caddies/spreader bars — never drag on floor. Keep in packaging until installation. Clear path of sharp edges. Use sufficient personnel (wet forming fabric = 200-500 kg+). Avoid oil/grease contact. Prevent twisting (180° twist destroys fabric). Protect seam area during handling. Remove all tools before starting.