Demtech Pro-Wedge VM-20 - Page 14

Rev. F, December 2020
Page 10 Pro-Wedge VM-20 Operator’s Manual
Refer to Figure 7.4 for an example of an upper contour roller assembly recommended
for HDPE welding.
Location:
The upper contour roller assembly is located above the heating wedge and is fixed to the
bottom of the nip arm assembly. Adding or removing the flat leaf springs will increase or
decrease the upper contour roller tension. For materials not shown on chart, contact
DEMTECH for recommendation.
Note: There are two types of springs, one that the roller axle mounts to and one that is used
as a stiffener or “back up spring”. There are also two mounting locations on the mount
plate (#3, Figure 7.4), one for the rear roller set (closest to the nip rollers) and one for the
front roller set (furthest from the nip rollers).
Upper Contour Roller Assembly Spring Configuration Chart:
Material
Thickness
Rear Set Installed
Front Set Installed
HDPE/LLDPE
40-120 mil
Yes w/two backup springs
Yes w/one backup spring
HDPE/LLDPE
20-30 mil
Yes w/one backup spring
No
PP Non-Reinforced
20-40 mil
Yes w/no backup spring
No
PP Reinforced
30-45 mil
Yes w/no backup spring
Yes w/no backup spring
PVC
50-100 mil
Yes w/no backup spring
No
PVC
20-40 mil
Yes (light spring# 100-012A)
No
Geotextiles
4-50 oz. / sq. yd.
Contact Manufacturer
Contact Manufacturer