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HELICOIL
®
Plus HELICOIL
®
Plus HELICOIL
®
Plus
13
shear stress
tensile stress
The table of values to determine the nominal length applies to aluminium as well as to materials with a ratio from 0.6 to 0.7
Some iron cast alloys have a ratio ranging from = 0.8 to 1.4 (source: VDI 2230)
For these guide values, the screw is the weaker joint member.
Lengths can be shorter than the recommended nominal lengths if tests confirm this.
Intermediate lengths are also available.
Temperature limits for validity: aluminium alloys T
max
= 300°C, magnesium alloys T
max
= 100°C.
For the design of screw joints under thermal stress, the changes of temperature-dependent material parameters
must be taken into account.
* 1 N/mm² equals 1 MPa
HELICOIL
®
Plus design guidelines
Determination of nominal length
Minimum wall thickness
(related to outside diameter of the HELICOIL
®
receiving thread)
The minimum wall thickness mainly depends on
individual operating data.
These define material strength and length of thread
engagement. The indicated guide value formulas apply
to aluminium, cast and wrought alloys and a length of
thread engagement of the HELICOIL
®
Plus of 1.5 d.
d = nominal Ø
D
HC
= outside Ø of the receiving thread
a = residual wall thickness
Diagrammatic representation with the example of M 10 x 15:
HELICOIL
®
Plus thread insert installed
HELICOIL
®
Plus thread insert installed,
with screw
=
shear stress
tensile stress
Strength of
parent material Screw property class
Tensile strength
R
m
(N/mm
2
)*
3.6
4.6
4.8
5.6
5.8
6.6
6.8
6.9
8.8 9.8 10.9 12.9 14.9
to  100 1.5 d 1.5 d 2.5 d 2.5 d 3.5 d 3.5 d – – –
> 100 – 150 1.5 d 1.5 d 2.5 d 2.5 d 2.5 d 2.5 d 2.5 d 2.5 d 3.5 d
> 150 – 200 1.5 d 1.5 d 1.5 d 1.5 d 2.5 d 2.5 d 2.5 d 2.5 d 2.5 d
> 200 – 250 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 2.5 d 2.5 d 2.5 d
> 250 – 300 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 2.5 d 2.5 d
> 300 – 350 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 2.5 d
> 350 – 400 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d
> 400 – 000 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d 1.5 d
Guide values to determine the minimum length of the HELICOIL
®
Plus thread insert depending on parent material
and screw property class, valid for 20°C.
Free CAD download
We offer a free CAD download service. Download 3-D models of Böllhoff products and directly integrate them
into your designs.
www.boellhoff.de/en/cad
**
**
** For grey cast iron on request.