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SKU 7000045884
Legacy SKU 61500036092
UPC 00048011059693
Part Number 7212

The 3M™ Roto Peen Mandrel grips small flaps containing captive shot for peening of fine tolerance metals components. For use with flap assembly, it is available in three sizes for internal diameters and flat surfaces.

  • Use with Roto Peen Flap Assemblies for die grinders and disc sanders
  • Flap/mandrel assembly is portable for added convenience
  • Available in three sizes for both small and large surface areas
  • For aerospace and other applications in industries with rigorous metal performance standards and specifications
Estimated date of shipment April 28  


Minimum Order 1 Item
Order Increment 1 Item
Product Dimensions
Imperial Metric
Shipping Dimensions
Weight 1 lb
Length 6.4 in
Width 4.7 in
Height 4.7 in
Brochures, Catalogs & Data Sheets
  • Pdf   Catalogs_3m indl prds accessor
For industrial/occupational use only. Not for consumer sale or use.
3M industrial and occupational products are intended, labeled, and packaged for sale to trained industrial and occupational customers for workplace use.  Unless specifically stated otherwise on the applicable product packaging or literature, these products are not intended, labeled, or packaged for sale to or use by consumers (e.g., for home, personal, primary or secondary school, recreational/sporting, or other uses not described in the applicable product packaging or literature), and must be selected and used in compliance with applicable health and safety regulations and standards (e.g., U.S. OSHA, ANSI), as well as all product literature, user instructions, warnings, and other limitations, and the user must take any action required under any recall, field action, or other product use notice.  Misuse of 3M industrial and occupational products may result in injury, sickness, death, or property damage.  For help with product selection and use, consult your on-site safety professional, industrial hygienist, or other subject matter expert.
Science in the Service of U.S. Soldiers
The 3M™ Roto Peen Mandrel is engineered to deliver quick, efficient repair and maintenance to U.S. Army helicopters to components like rotors and rotor hubs in the field, this tool and its associated flap assembly allowed peening action using a die grinder or disc sander. In the early 1970s, the 3M™ Roto Peen Flap Assembly (or TC 330) was qualified and written into military specifications. It soon spread to other aerospace applications.

Used today primarily for aerospace applications, the mandrel comported with a flap assembly allows use of a die grinder or disc sander to perform captive shot peening to repair metal surfaces. The assembly consists of tungsten carbide shot bonded to a flexible polymeric flap gripped by the mandrels attached to the power tool. The spinning flap is held near the surface so that the captive shot hammers the metal surface with each revolution.

Portable, Able to Reach Small Areas and Large Components
3M flap/mandrel assemblies provide convenient portability and are especially effective for precision in-service rework, manufacturing, repair of small areas, and peening holes with diameters down to 1/2 inch (12.7mm). Flaps can also be cut with scissors to peen confined areas or peen into areas with a radius down to 1/16 inch (1.6mm) .

Captive shot peening is used for repair or limited access work or when free shot cannot be tolerated. Having the shot used to peen metal surfaces in a captive flap allows for more control and greater access to areas that require this strengthening procedure.

Evolved from the days of blacksmiths hammering swords, peening is a process that utilizes compressive surface stress to strengthen metals, improving resistance to fatigue fracture and stress corrosion cracking. The aerospace industry has stringent peening specifications, in which adherence must frequently be documented. Off-spec peening can result in the failure of parts.

3M also provides Almen gauges to provide precise readings of strip deflections to measure peening intensities. Adopted by the SAE (Society of Automotive Engineers), the Almen Scale of Peen Intensity measures the curvature of a standardized steel strip when peened on one side.

Recommended Applications

MRO in aerospace, military and small shop environments
For parts that are too large to fit in a peening cabinet
Parts that are subjected to mechanical rework and require rework
Landing gear assemblies
Wing structures
Helicopter rotor hub
Jet engine support members
Peening after grinding
Peening before plating
Peening of surfaces subject to stress corrosion
Peen straightening
Peen forming
Weld heat affect zone
Bond testing   Add to cart