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PEM® brand miniature fasteners fit into a minimal space and provide strong, reusable threads.

Types FE, FEO and UL are self-locking. Types FE and FEO thread locking torque performance is equivalent to applicable NASM25027 specifications. Type UL self-locking nuts meet locking torque requirements specified herein. Some sizes of FE, FEO, and UL can be ordered to NASM45938/7 specifications. Types FEX, FEOX and U have free-running class 2B/6H threads.

PEM miniature fasteners provide immediate visual indication when proper installation has been accomplished.

A strong, knurled collar, which is completely embedded in the sheet, guarantees against rotation of the fastener in the sheet. The torque-out resistance of the knurl greatly exceeds the torque that can be exerted by the selflocking feature.

When this collar is embedded in the sheet, the undercut cavity beneath the collar is filled with displaced sheet material thereby developing pushout resistance.

A dry-film lubricant applied to these fasteners provides the smooth, non-galling prevailing torque performance necessary for reliable locking and for reusability.
Unit of Measure

Thread Size

N/A .250-20 (1/4-20)

Thread Type

N/A Self-Locking

Thread Code

N/A 0420

A (Shank) Max.

N/A .060 in a1387.jpg
Sheet Thickness1 N/A .059 to .070 in

Hole Size in Sheet + .003 - .000

N/A .344 in

C + .000 - .005

N/A .343 in

D Max.

N/A .318 in

E ± .005

N/A .384 in

T + .015 -.000

N/A .120 in

Min. Dist. Hole C/L to Edge

N/A .28 in

Max. Hole in Attached Parts

N/A .270 in
For Use in Sheet Hardness2 N/A HRB 70 / HB 125 or Less

Thread Specification

N/A Internal, MIL-S-8879, UNJ-3B

Fastener Material

N/A 300 Series Stainless Steel

Standard Finish

N/A Black, Dry-film Lubricant

CAD Supplier

N/A PennEngineering® (PEM®)
  • 1 In applications between the sheet thicknesses for your thread size, see last paragraph of installation data on page FE-6. Knurled collar may fracture if fastener is used in sheets thicker than the specified range and the screw is tightened beyond maximum
  • 2 HRB - Hardness Rockwell “B” Scale. HB - Hardness Brinell.

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