EFZ Expansion Fin Inserts


EFZ Insert Features

  • Simple press–in installation for most thermoplastics.
  • Mating screw resistant to loosening after installation.
  • High pull–out and torque–out resistance.
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Loading Parts

Insert ThreadInsert Thread CodeBossD Insert Diameter
B Hole Dia. +0.10 -0.00W Wall Thickness Min.
M2 x 0.4M23.201.603.70
M2.5 x 0.45M2.
M3 x 0.5M34.002.004.50
M3.5 x 0.6M3.54.802.405.30
M4 x 0.7M45.602.806.20
M5 x 0.8M56.403.206.90
M6 x 1.0M68.004.008.50
M8 x 1.25M89.604.8010.10
(1) All dimensions are in millimeters and reference unless toleranced.
Stud Length
Insert ThreadL Insert LengthInsert Length Code
M2 x 0.44.0024.00
M2.5 x 0.454.004.00
M2.5 x 0.455.8025.80
M3 x
M3 x 0.55.8025.80
M3.5 x
M3.5 x 0.67.2027.20
M4 x 0.75.805.80
M4 x 0.78.2028.20
M5 x 0.85.805.80
M5 x
M5 x 0.89.5029.50
M6 x
M6 x 1.09.509.50
M6 x 1.012.70212.70
M8 x 1.2512.70212.70
(1) All dimensions are in millimeters and reference unless toleranced. (2) Preferred length. Custom insert lengths available by request. (3) Custom insert lengths available by request.
Press the insert into the boss using a squeezing action – never a hammer blow. Ensure that the insert maintains axial alignment during installation to prevent tilting which will induce side loads on the boss. Oversize boss holes weaken the insert’s self-aligning characteristics causing side loads which may lead to possible boss cracking. Install fixing screw from the knurled end with sufficient length to fully penetrate the insert and achieve maximum fin expansion prior to applying full clamping load.
Boss Design Recommendation
The EFZ Expansion Fin Zert is designed to be installed into a straight hole with a 1° inclusive taper. The top of the hole should not be countersunk or counterbored as this will decrease the insert’s performance. The recommended hole size applies at the point reached by the bottom of the insert. Molded holes should be used wherever possible as drilled holes may result in diminished performance. Minimum boss wall thicknesses shown are for reference and may vary depending on the type of plastic.