Norton 66623399140 Flap Disc 4.5in 36 Grit Type 27

Product Description

The NORTON 66623399140 is a Type 27 zirconia alumina flap disc designed for aggressive material removal on metal, weld seams, and surface preparation work. The disc measures 4-1/2 inches in diameter with a 7/8 inch center arbor hole and runs at a maximum rated speed of 13,300 RPM. At 36 grit, it falls in the very coarse grade range, making it well-suited for rapid stock removal, deburring, and weld blending. The cloth backing provides durability under heavy grinding pressure, and the trimmable design allows the operator to expose fresh abrasive as flaps wear down, extending usable disc life. This disc is intended for use with a 4-1/2 inch angle grinder.

This flap disc is used in metalworking and fabrication environments where fast, controlled grinding is required. Typical applications include weld smoothing, rust and scale removal, edge chamfering, and surface conditioning on structural steel, mild steel, and similar ferrous materials. It is commonly used by ironworkers, pipefitters, welders, and maintenance mechanics in both shop and field settings. The Type 27 flat profile positions the abrasive face parallel to the workpiece, giving the user better control on flat surfaces compared to a conical Type 29 profile.

Key Features

• 4-1/2 inch diameter with 7/8 inch arbor hole for standard angle grinder compatibility
• 36 grit very coarse zirconia alumina abrasive for rapid stock removal
• Type 27 flat profile for controlled grinding on flat and contoured surfaces
• Cloth backing provides strength and flexibility under load
• Trimmable flap design extends disc life by exposing fresh abrasive
• Maximum rated speed of 13,300 RPM

Compatibility

Designed for use with 4-1/2 inch angle grinders accepting a 7/8 inch arbor attachment. Verify that the grinder's rated RPM meets or exceeds the 13,300 RPM disc rating before use.

Installation Notes

Installation and disc changes must be performed with the grinder unplugged or the power source locked out. Ensure the mounting arbor and flange are clean and free of debris before seating the disc. Always verify the grinder's no-load RPM does not exceed the disc's maximum rated speed. Operators should wear appropriate personal protective equipment including face shield and gloves per ANSI B7.1 and OSHA grinding safety standards.