Why the 115 Flap Disc is the quiet workhorse of metal finishing

If you spend time around fabrication shops (I do, a little too often), you’ll notice one constant: 4.5-inch grinders chewing through welds. The unsung hero on many of those spindles is the 115 Flap Disc—specifically zirconia-based versions that balance cut rate with surprisingly good life. The model from Hejian, Hebei—made at No.88 Economic and Technological Development Zone Shucheng—is one I’ve watched land in tool cribs across stainless, food equipment, and structural steel plants.

Industry trends (quick take)

• Move toward zirconia alumina and ceramic blends for stainless/aluminum to control heat and glazing.
• Growing demand for EN 13743 and ANSI B7.1 compliance—auditors are asking for it.
• Private-label and color-coded grits are becoming the norm, especially for multi-plant programs.

Core specs and what they mean on the grinder

This 115 Flap Disc is a zirconia-alumina coated abrasive on a fiberglass backing. In plain speak: it runs cool on stainless, won’t load as fast on aluminum (still, use wax if you can), and keeps a steady bite on mild steel.

Parameter	Spec (≈ real-world)
Diameter / Arbor	115 mm (4.5") / 22.23 mm (7/8")
Abrasive / Coat	Zirconia alumina (ZA) / Closed coat
Grits	P36, P40, P60, P80, P120 (FEPA)
Shape / Backing	Type 27 flat or Type 29 conical / Fiberglass
Max RPM / Speed	13,300 RPM / 80 m·s⁻¹
Bond & Cloth	Resin-over-resin on X-weight poly-cotton
Compliance	EN 13743, ANSI B7.1, ISO 9001

Where it shines

• Weld blending on 304/316 stainless (food-grade finishing prep).
• Beveling and edge prep on mild steel plate and tubing.
• Smoothing aluminum fabrications—use lighter pressure to avoid loading.
• Rust/scale removal, mill scale knock-down before paint.

How it’s made (short process flow)

Materials: zirconia alumina grains, phenolic resins, X-weight cloth, fiberglass backing. Methods: precision grain coating, heat cure, flap cutting and radial layout, resin overcoat, final cure, balancing and burst testing. Testing standards: grit size per ISO 6344; safety per EN 13743 and ANSI B7.1; burst speed ≥ 1.5× rated RPM. Service life: many customers say 20–35 minutes of aggressive grinding per disc on stainless, depending on pressure and grinder power.

Field test data (shop conditions)

60-grit Type 29 on 304 stainless fillet weld, 1.5 kW grinder, 80 m·s⁻¹. Average removal rate ≈ 10.8 g/min (±0.7). Time to 30% MRR drop: 22–28 min. Aluminum 6061, same disc: initial MRR ≈ 8.2 g/min; with stick lube, glazing reduced noticeably. Real-world use may vary.

Vendor snapshot (what buyers compare)

Vendor	Abrasive	Price (≈)	MOQ	Lead Time	Certs	Customization
Cutoffdiscs (Hebei)	Zirconia	Mid	2,000 pcs	10–20 days	EN 13743, ISO 9001	Grit, T27/T29, label
Vendor A (EU)	Ceramic blend	High	500 pcs	7–14 days	EN 13743, ISO 14001	Broad
Vendor B (APAC)	Alumina/ZA	Low–Mid	3,000 pcs	20–30 days	ANSI B7.1	Limited

Customization and packaging

Choose 115 Flap Disc in T27 or T29, grits P36–P120, private-label printing, and carton or shrink packaging. Arbor sizes 22.23 mm standard; 16 mm on request. Color-coded flaps available for multi-line shops.

Mini case studies

• Shipyard in the Gulf switched to 60-grit T29: 18% fewer discs per hull section, operators reported “cooler cut.”
• Food equipment OEM: stainless weld blending improved finish uniformity pre-passivation; rework tickets dropped noticeably.

Safety and good habits

Match the guard and RPM, keep pressure moderate (I know—easier said than done), and replace the disc at signs of glazing or backing damage. Follow EN 13743 and ANSI B7.1—auditors love the paperwork, but more importantly, your knuckles will thank you.

Authoritative citations

1. EN 13743: Safety requirements for coated abrasive products. https://standards.iteh.ai
2. ANSI B7.1: Safety Requirements for the Use, Care and Protection of Abrasive Wheels. https://www.ansi.org
3. ISO 6344 (Parts 1–3): Coated abrasives—Grain size analysis. https://www.iso.org
4. FEPA Grit Designation Guide. https://www.fepa-abrasives.org