PTFE Cover Strip is used as a covering over Heatseal Bands to prevent the hot plastic material from sticking to the heat seal band as well as over the silicone elastomers on the opposing jaw. It is occasionally used as an electrical insulator between the Heatseal Band and the jaw when a minimum thermal insulation is desired. The proper selection of thickness and style is imperative if good consistent seals are to be obtained. Contact a TOSS Application Engineer to learn more and to design the perfect configuration for you.

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SNAPLON makes replacing heat sealing cover strips a snap. SNAPLON is availble in rolls. PTFE is sold with mating zipper style plastic strips. By placing your permanent mounting strips in the desired position, you insure repeatable placement and tensioning of the coverstrip for every replacement in the future.

SNAPLON Tech Sheet PDF

The upper temperature limit for safe operation with most all PTFE coatings is 250°C as with all PTFE products. Polyimide is the cover material of choice if sealing temperatures exceed 250ºC. Polyimide has a non-stick surface which should be mounted facing the sealed goods.

A TOSS Application Engineer will gladly help you choose the type of materials to use under your heat seal band. The face of the opposing jaw must be soft enough to deform and compensate for any deviation or deformation in the alignment or flatness of the face of the Heatseal Jaw. In addition, the jaw facing must be covered with PTFE-SA Tape to assure a clean release of the film after sealing. The jaw facing must also be hard enough to present a firm face so that the jaw force is directed principally on the band and not on the adjacent surfaces of the soft face. For general applications a strip of self-adhesive, 30° durometer silicone rubber, 2mm thick and 15mm wide is satisfactory.

Durometers of up to 60° Shore Hardness or Durit are often used for cutting and work well, even on thin films.

Siglaha
This material, pronounced sig-la-ha, is named as a contraction for “silicone-glass-hard”. It is 1mm thick and available with a self-adhesive backing in standard widths of 12 and 15mm. Other widths are available on special order. This material is a very good electrical insulator and a reasonably good thermal conductor. It is durable and works well for temperatures up to 280°C. It is often preferred for backing beneath Beaded Bands, T-Profile Bands, and Cutting Wires because it provides maximum hardness and support to enhance cutting action. It is hard enough to be surface ground after being adhered to the face of the jaw should such precision be necessary.

Durit
Featuring a convenient self-adhesive backing, this versatile material comes in a standard thickness of 1mm, with widths available in both 12 and 15mm. Not limited to these dimensions, Durit is also offered in various other widths. Distinguished by its flexibility and lower hardness compared to Siglaha, Durit proves itself as an excellent option for a myriad of applications.

With an impressive operating temperature range of up to 400°C, it stands out as a reliable insulator with a lower thermal conductivity than both Siglaha and Cover Strip. The durability of Durit makes it a preferred choice for machinery engaged in prolonged heating cycles, constant heat, or scenarios where the cool-down rate is not of critical concern.

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