While polytetrafluorethylene (PTFE) is a thermoplastic
polymer, it can not be directly processed into items using worm
extrusion or compression molding due to its high melt viscosity.
Therefore, polytetrafluorethylene processing methods are two-stage:
1) pressing PTFE into a preform and 2) subsequent thermal treatment
of the preform in a furnace. The resultants products are basic
stock shapes such as plates, bushings, rods, tubing billets which
are then machined into finished products.
Standard sizes of fluoroplastic stock shapes are dependent on
the available molding tools.
1. Square fluoroplastic plates (available in
the following standard sizes: 250ő250, 300ő300, 500ő500) with
thicknesses as specified in the table. PTFE sheets which can be
used as lining material are also available.
2. Fluoroplastic rods are divided into the
following categories based on the molding process:
a) horizontally pressed fluoroplastic rods. Stock shapes
have the following characteristics:
- length of rods is equal to the length of the molding tool.
Standard lengths are as follows: 200, 300, 400, 500 mm;
- rods have a side gate runner along the full length;
- rods can be supplied in blocks.
b) vertically pressed fluoroplastic rods. Stock shapes have
the following characteristics:
- length of rods is 50-110 mm. Custom height rods can be
- fluoroplastic rods do not have side gate runners;
- more even distribution of material throughout the stock shape
which ensures uniform density of the material and improved physical
and mechanical properties;
- rods with new standard sizes can be fabricated at Clients'
3. Rings and bushings made from PTFE and
PTFE-based compounds are fabricated in accordance with the
regulatory specifications and have the following standard sizes
(see the table). Fluoroplastic ring and bushing stock shapes can be
machined into gaskets, packing rings, sleeves and liners,
insulation bushings, etc.