PEMPEM Fastener Catalogue
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LAC–0420–2MD

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

ALA Floating Self-Clinching Fasteners · Unified · thread .250-20 (1/4-20)

Self-locking, 300 series stainless, Passivated retainer · black dry-film lubricant nut.

Also written as LAC-0420-2MD.

Part number breakdown

SegmentCodeMeaning
TypeLASelf-locking
Retainer Material CodeC300 series stainless
Thread0420Thread size .250-20 (1/4-20)
Shank2—
Finish CodeMDPassivated retainer · black dry-film lubricant nut

Dimensions

Defines A, C, D, T2. Technical cross-section diagram of a clinching fastener with the following dimensional labels: A: Thickness of the clinching base/flange. C: Outer diameter of the base. D: Outer diameter of the body/housing. T₂: Length/depth of the threaded internal component. Key Features: Internal threads, multi-piece assembly, and cross-hatched sections indicating a metal component.Defines E. Subject: Technical engineering diagram of a circular component, likely a tube or pipe end. Key Features: Dimension E: Represents the total outer diameter of the assembly. Concentric/Eccentric Rings: Shows multiple circular layers, with an arrow pointing to an internal feature or "Formed" area. Centerlines: Horizontal and vertical dashed lines indicate symmetry and axial center. Line Styles: Uses solid lines for visible edges and dashed lines for hidden features or internal diameters.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.250-20 (1/4-20)
Type – Self-Locking (Fastener Material) › 300 Series StainlessLAC
Thread Code0420
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
TypeLAC
Fastener MaterialsThreads › Self-locking › Internal, UNJ Class 3B per ASME B1.15 / MJ Class 4H6H per ASME B1.21M (M6 thread 4H5H); Retainer › 300 Series Stainless Steel; Nut › 300 Series Stainless Steel
Standard FinishesSelf-locking › Retainer › Passivated and/or tested per ASTM A380; Self-locking › Nut › Black Dry-film Lubricant
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

Installation tooling

PropertyValue
Thread Code0420/M6
Counterbore A › ±.001 (in.).092
Counterbore A › ±0.03 (mm)2.34
Hole Depth Below Counterbore B › ±.005 (in.).220
Hole Depth Below Counterbore B › ±0.13 (mm)5.59
Anvil Part Number8021392
Punch Part Number8012030

Source: PEMSERTER® Installation Tooling – AC/AS/LAC/LAS/A4/LA4 Nuts · PDF page 14

Axial strength and tightening torque

PropertyValue
Thread Code0420
Locknut Min. Axial Strength (lbs.)5728
Mating Screw Strength Level (ksi)180
Mating Screw Tightening Torque (in. lbs.)186

Source: Axial Strength and Tightening Torque – Types LAC/LAS/LA4 · PDF page 12

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 dataInstallation toolingAxial strength and tightening torqueRelated drawingsSource