PEMPEM Fastener Catalogue
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AC–0428–2

ALA Floating Self-Clinching Fasteners · Unified · PDF page 13 · PEM Fastener Catalogue

ALA Floating Self-Clinching Fasteners · Unified · thread .250-28 (1/4-28)

Non-locking, 300 series stainless, Passivated and/or tested per ASTM A380.

Also written as AC-0428-2.

Part number breakdown

SegmentCodeMeaning
TypeANon-locking
Retainer Material CodeC300 series stainless
Thread0428Thread size .250-28 (1/4-28)
Shank2—

Dimensions

Defines A, T1, C, D. This technical drawing is a cross-sectional view of a self-clinching fastener, likely a blind nut. Key Dimensional Parameters: A: Width of the clinching/base section. T1: Overall depth/thickness of the cap portion. C: Diameter of the base/clinching interface. D: Overall external diameter of the body. Key Features: Internal Threading: Centrally located within the body. Blind Design: Features a closed cap to prevent fluid or debris ingress. Clinching Profile: Noted as variable, designed for permanent installation in sheet metal.Defines E. Technical drawing of a circular component cross-section: Dimension E: Represents the outermost diameter. Features: Multiple concentric and eccentric circular elements. Reference: Includes vertical and horizontal centerlines for alignment.Defines float. Technical diagram showing a top-down view of a mechanical component: Central feature: A circular opening housed within a square element. Housing: Outer concentric circles with a serrated or threaded ring detail. Float specification: An orange arrow points to the internal square, corresponding to text indicating a float of .015”/0.38 mm minimum in all directions from the center (.030”/0.76 mm total. Alignment: Horizontal and vertical centerlines intersect at the midpoint of the component.
DimensionValue
Thread Size.250-28 (1/4-28)
Type – Non-Locking (Fastener Material) › 300 Series StainlessAC
Thread Code0428
Shank Code2
A (Shank) Max..054
Min. Sheet Thickness.054
Hole Size in Sheet +.003 −.000.515
C Max..514
D Max..510
E ±.015.600
T1 Max..210
T2 Max..310
Min. Dist. Hole ℄ To Edge.42

Material and finish

PropertyValue
TypeAC
Fastener MaterialsThreads › Non-locking › Internal, ASME B1.1, 2B / ASME B1.13M, 6H; Retainer › 300 Series Stainless Steel; Nut › 300 Series Stainless Steel
Standard FinishesNon-locking › Retainer & Nut › Passivated and/or tested per ASTM A380
For Use In Sheet HardnessHRB 70 / HB 125 or Less

Source: Material and Finish Specifications · PDF page 13

Performance data

PropertyValue
Thread Code0420 / 0428
Shank Code2
Test Sheet Material › 5052-H34 Aluminum › Installation (lbs.)3000
Test Sheet Material › 5052-H34 Aluminum › Retainer Pushout (lbs.)400
Test Sheet Material › 5052-H34 Aluminum › Retainer Torque-out (in. lbs.)325
Test Sheet Material › Cold-Rolled Steel › Installation (lbs.)5000
Test Sheet Material › Cold-Rolled Steel › Retainer Pushout (lbs.)500
Test Sheet Material › Cold-Rolled Steel › Retainer Torque-out (in. lbs.)325

Source: AC/AS/LAC/LAS Nuts · PDF page 14

Single groove identifies A4/LA4 for stainless sheets. PEM® Double Squares: Registered trademark feature located on the top inner rim of the fastener. PEM® Single groove: Registered trademark feature on the outer side wall; identifies products for installation into stainless steel sheets (A4 and LA4 types. Fastener Type: Circular threaded insert with a knurled base and specialized identifying marks.The image displays four types of circular aerospace fasteners: AC/AS: Standard non-locking fastener. LAC/LAS: Locking fastener with a dark-colored insert. LA4: Locking thread version with a dark insert. A4: Non-locking thread version.

Source

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Part number breakdownDimensionsMaterial and finishPerformance dataRelated drawingsSource