Page 700 - Mastik®

Direct assembly in thermoplastics Construction recommendations
®
using PT / eco-syn screws

®
®
Advantages of PT screws / eco-syn The PT / eco-syn screws have been
r -PX ESJWJOH UPSRVF IJHI TUSJQQJOH used successfully for years. PT screws
®
torque have the necessary features to enable a
r )JHI BTTFNCMZ TBGFUZ secure joint in thermoplastics.
r &YDFMMFOU WJCSBUJPO SFTJTUBODF
r -PX CVSTUJOH UFOEFODZ
P 30°
r /P FYDFTTJWF KPJOU SFMBYBUJPO UIFSFGPSF
plastic components do not shift
r Cost-effective fastener for direct fas-
tening in thermoplastics

Design guidelines r %P OPU VTF DPVOUFSTVOL TDSFXT 5IF torque to be bigger than the under-
r 'PS GBTUFOJOH QMBTUJD QBSUT TQFDJGZ B 90° head angle not only results in axial head friction torque. Such a joint
large head diameter (BN 20040). This forces but also radial forces, hence would be unsafe.
increases friction under the head, causing greater joint relaxation in r 4IFBS GPSDFT TIPVME CF BCTPSCFE CZ
making a safer joint. Also a larger head parts with narrow edge margins. The form-fitting components.
reduces the surface pressure which preload would be unsafe. r 'VSOJTI UIF QJMPU IPMF FOUSBODF XJUI B
in turn minimizes joint relaxation and r "WPJE FMPOHBUFE IPMFT JO QMBTUJD QBSUT counterbore (avoids stress cracking)
ultimately increases the residual clamp as they would create a small bear-
load. ing area, possibly causing the driving

®
Boss design for PT / eco-syn screws Material hole Ø d external Ø D length of thread
An optimum boss design that will hold engagement te
up in the application, requires the boss ABS / PC blend 0,80 x d1 2,00 x d1 2,00 x d1
geometry to be adjusted to the different ASA 0,78 x d1 2,00 x d1 2,00 x d1
plastics. PA 4.6 0,73 x d1 1,85 x d1 1,80 x d1
PA 4.6 - GF 30 0,78 x d1 1,85 x d1 1,80 x d1
The details shown here are based on PA 6 0,75 x d1 1,85 x d1 1,70 x d1
laboratory testing. Some changes may PA 6 - GF 30 0,80 x d1 2,00 x d1 1,90 x d1
be needed to fit your application. PA 6.6 0,75 x d1 1,85 x d1 1,70 x d1
PA 6.6 - GF 30 0,82 x d1 2,00 x d1 1,80 x d1
We recommend that users PBT 0,75 x d1 1,85 x d1 1,70 x d1
conduct application testing PBT - GF 30 0,80 x d1 1,80 x d1 1,70 x d1
PC 1)
and joint analyses. 0,85 x d1 2,50 x d1 2,20 x d1
PC - GF 30 0,85 x d1 2,20 x d1 2,00 x d1 1)
PE (soft) 0,70 x d1 2,00 x d1 2,00 x d1
PE (hard) 0,75 x d1 1,80 x d1 1,80 x d1
D
PET
Pressure 0,75 x d1 1,85 x d1 1,70 x d1
0,3–0,5 x d 1 PMMA 0,85 x d1 2,00 x d1 2,00 x d1
relief hole PET - GF 30 0,80 x d1 1,80 x d1 1,70 x d1
de = 1,05 x d 1 POM 0,75 x d1 1,95 x d1 2,00 x d1
PP 0,70 x d1 2,00 x d1 2,00 x d1
PP - TV 20 0,72 x d1 2,00 x d1 2,00 x d1 1)
L = 1,1–1,2 x te = d t e PS 0,85 x d1 2,50 x d1 2,20 x d1
PPO
=
0,80 x d1
2,00 x d1
2,00 x d1
PVC (hard)
0,80 x d1
2,00 x d1
2,00 x d1
SAN
s 0,77 x d1 2,00 x d1 1,90 x d1
Taper 0,5–1,0°
d1 = nominal thread diameter Ø
D outside Ø 1) Since these materials are more susceptible to stress cracking, it is highly recommended to carry
d pilot holed Ø out application testing. Also, a counterbore (relief bore) is strongly recommended to minimize stress
t e length of thread engagement risers.
d e edge relief
d 1 nominal Ø of the screw