The manufacturing of PVC windows typically involves welding in the corner to create a unitized frame or sash. In many cases, these welded areas will resemble a common picture frame with 45° mitered corners. These welds are achieved by bringing the PVC profile corners into contact with a heated plate or platen at a specific temperature for a specified time, resulting in a controlled melt of the PVC plastic. Once the plastic is melted, the heated platen is withdrawn and the corners are brought together to create the weld.
How Do PTFE Coated Fabrics and Tapes Work?
If the PVC profile was brought into contact with the bare metal of the heating platen, it would not only melt, but also would adhere to the plate and build up until the heat transfer was interrupted, leading to a mess with poor welding results. The PTFE (polytetrafluoroethylene, most common brand name is Teflon®) coated fabric or tape solves this by putting a non-stick surface between the bare metal and the PVC profile.
The PTFE-coated fabric is produced by applying multiple layers of PTFE coating to a fiberglass fabric. These multilayer coatings provide abrasion-resistance, non-stick properties, while allowing effective heat transfer from the metal platen to the plastic profile. A silicone adhesive can be applied to one side to create a “peel and stick” product for platens that have no clamps or clips to hold the fabric in place. Other welder platens do have clips or clamps that preclude the need (and extra expense) for the silicone adhesive.
So What Is PTFE?
PTFE (polytetrafluoroethylene) is a synthetic fluoropolymer made from the polymerization of tetrafluoroethylene. In simpler terms, it’s a high-performance material that is resistant to heat, chemicals, and moisture. PTFE has outstanding non-stick, low-friction properties that make it ideal for use across industrial manufacturing, and PTFE’s resistance to heat, chemicals, and moisture makes it a long-lasting and durable solution.
Green Belting Industries Ltd.
Green Belting Industries manufactures a wide range of fabrics, tapes, and belts to support various manufacturing processes. For PVC window manufacturers, their 100 Series Tapes are very effective for most window welders and can be provided with and without silicone adhesive.
They also offer a DXL Series with a higher performance coating that results in improved abrasion resistance and longer life for fewer part changeovers.
To view the welding process, please see the Green Belting YouTube video below:
The Advantages of Die Cut Parts
Window manufacturers often resort to cutting the PTFE to size to match the metal platen dimensions using scissors or paper cutters. This process is not only time-consuming, but also results in excessive material waste.
TBI can cut any of the PTFE fabrics or tapes to shape quickly and accurately using our flat-bed die-cutting presses. Ranging simple rectangles and squares to any intricate shape, they are custom packaged in any quantity specified per box. This saves shelf space, and makes inventory counts go much faster.
Want to know more about how Tom Brown, Inc. can help you streamline your PVC welding operation? Contact us at www.tbi.com
