Tarpaulin welding
Frequently asked questions about tarpaulin welding
A distant heir to the waxed canvas of the 18th century, renowned for its waterproof qualities and multiple uses, plastic tarpaulin is a must-have in many sectors of activity. In transport (for trucks, semi-trailers and boats), construction (for fittings, swimming pools and pergolas), events (for reception tents, barnums and marabouts) and communications (advertising banners), plastic sheeting is widely used, especially in large formats, often requiring adaptation of standard formats.
Tarpaulin welding is a way of meeting these needs for customized supplies before the printing phase, when eyelets or any other fastening or fixing system is installed.
What plastic materials are used to manufacture large tarpaulins?
Depending on the type of use (single or multiple), the degree of resistance required and the sector of activity for which it is intended, large-scale plastic sheeting can be made from various thermoplastics such as Polyvinyl Chloride (PVC) and Polyethylene (PE).
When a high level of resistance is required or for intensive use, the tarpaulin is produced on a polychloride base with a vinyl coating that makes it waterproof, tear- and abrasion-resistant. This coating also facilitates printing operations.
The strength of plastic sheeting also depends in part on its thickness. PVC tarpaulins are characterized by high grammage: between 400 and 900 grams per square meter of surface area.
Used in the manufacture of swimming pool covers, polyethylene is characterized by both strength and flexibility. Highly insulating and waterproof, it can be used as HDPE (High Density Polyethylene) or LDPE (Low Density Polyethylene).
Finally, the term “plastic tarpaulin” is often misused to designate acrylic canvas. These lightweight technical textiles are used to make shade sails, pergola covers, marquees and other event tents.
How are custom-made rigid tarpaulins assembled?
For the design of custom-made rigid tarpaulins, it is usually necessary to cut and assemble standard tarpaulin formats to create customized protective or covering equipment.
Plastic tarpaulin assembly operations can be carried out as follows:
- bonding,
- heating,
- welding.
Thermoplastic adhesives can be used to repair or join PVC or PE tarpaulin components, provided they are small in size. This is because it is very difficult to achieve a very regular assembly with equal strength along the entire length, for the manufacture of large, custom-made tarpaulins.
Thermoplastic assembly using hot-knife or mirror heating of the elements to be joined before they come into contact with each other can be used for modest-sized welds (tanks, filters, equipment, etc.). This technology is difficult to use for joining large plastic sheets.
Welded tarpaulin assembly is based on the use of waves to cause molecular excitation, which results in the heating of the material on the lips of the two pieces of polyvinyl chloride or polyethylene tarpaulin.
Ultrasonic welding uses a sonotrode that oscillates and emits waves to generate molecular excitation, enabling the assembly of parts of rather limited dimensions.
High-frequency welding is based on the generation of an electromagnetic field that causes molecular agitation using an electrode. This welding technique is best suited to the assembly of large plastic tarpaulins.
Why do some tarpaulin assemblies require a welding rail?
Fitted to the heating plate of certain models of HF welding presses, the welding rail enables tarpaulin joints to be made over long lengths. Installed on a high-frequency welder, the rail produces regular, strong welds for large advertising posters and protective tarpaulins for buildings.
This range of HF welding machines from Forsstrom, distributed by Matrelec, produces continuous welds characterized by their strength, straight lines and invisible appearance.
How are truck tarpaulins welded?
Truck tarpaulin welding can be carried out using two different technologies: hot-air welding and high-frequency welding.
For the assembly of large trailer tarpaulins, the high-frequency welding machine is the most suitable solution due to :
- its ability to assemble very large-format products,
- the mobility of its welding head,
- its programmability (welding cycles).
For van tarpaulin assembly and repair, flashlight welding with pressure roller and flat nozzle enables hot-air welding of thermoplastic parts of the same type (usually PVC).
