Thermoplastic Welding - Our Core Technology

Thermoplastics Welding  is the process by which an energy source is used to permanently bond multiple plastic materials together.  This is different than other processes, such as bonding (gluing), in that the desired result is a hermetic, cohesive bond between the polymers, not an adhesive bond.  This type of welding can only occur between materials that can be melted (as opposed to burnt), hence only thermoplastics.  A list of the common processes and their advantages / disadvantages can be found here.

Dielectrics is an established leader in plastic welding, and especially in RF (Radio Frequency) Welding.  RF is also known as "dielectric" sealing (from which our company name is derived). The principle behind the process is the use of high frequency radio energy to produce molecular agitation in thermoplastic materials (ie:, polyurethane or pvc) to the point where they literally melt and weld together, typically forming a bond that is as strong as the original material.

To achieve the weld, plastic components (typically flexible films) are placed between a machined brass die (with raised areas representing the desired weld pattern) and a platten on the RF machine. The head of the machine comes down and generates pressure. The RF comes on and is channeled through the material in the pattern areas only, fusing the materials together at those points.

Advantages

There are a number of advantages of RF welding over alternative welding technologies:

  • RF sealing occurs from the inside out by using the material itself as a heat source.  The heat is focused at the weld target so that the surrounding material does not have to be super-heated to arrive at a target temperature at the joint.
  • With RF heat is generated only when the field is energized. Once the generator cycles, the heat is turned off. This allows for greater control over the amount of energy that the material sees over the entire cycle. In addition, RF-generated heat does not radiate off the die like on a heated die. This prevents heat-degredation of the material abutting the weld.
  • RF tooling is usually run "cold". This means that once the RF is turned off, the material stops being heated, but remains under pressure. In this fashion it is possible to both instantly heat, weld, and cool the material under compression. More control over the weld means more control over the melt, the extrusion, and the resulting strength of the seal.
  • RF welds are "clean" because the only material needed to produce an RF weld is the material itself. There are no messy adhesives or by-products involved in RF welding.