Individual Materials
Due to its manufacturing process and subsequent processing, PTFE is ideally suited for the production of small quantities in different dimensions and with individual designs. The raw material is supplied in the form of powder which is compacted in rods, rings or slabs (Fig.1). These “blanks” are then sintered in large ovens. The temperature / time sintering process is adapted to the material and the dimensions of the components and can last for several days.
After the cooling down and stress relieving of the sintered blank it can be milled for which specific machines are required (Fig. 2). The geometry of the seal depends on what the requirements are. Shapes ranging form a simple PTFE O ring to a spring-energised U/V ring are possible.
PFTE has a thermal expansion coefficient of 10 to 16 x 10-5 K-1. This must be taken into consideration for the processing of PTFE components as well as for application purposes. If the application involves large ranges in temperature the design of the seal has to take into consideration the material itself as well as the application.
The PTFE component can, for instance, be provided with a step which forms a positive connection with the corresponding machine part. The production of filigree type geometry is carried out with a high degree of precision.
From double-motion agitators to bellows
 |
The finished blank is being turned on a lathe.
|
For an application in a double-motion agitator a vacuum seal was required. A spring-energised U/V ring manufactured from a PTFE compound was chosen. Its geometry, which is provided with a flange that is clamped in, prevents the seal from turning. The machine has a diameter of 1150 mm and rotates at a speed of up to 2.5 m per second and can have a life of up to 2000 hours. In order to ensure steady stress conditions at fluctuating temperatures during transport and storage, the seal is supplied to the user mounted on a sleeve .
PTFE parts in the XXL format are not only required as seals. There are requirements which make it necessary to have constructional parts produced from PTFE. The excellent anti-seizing properties are often the reason or such a choice. In addition PTFE offers a high degree of thermal stability and very good chemical resistance.
Bellows for the chemical engineering industry are a typical example of products which require all these properties. PTFE bellows are often used to connect up two parts of a plant. High temperatures up to 200° C occur. The component must be resistant to chemicals and the media must not adhere to its surface. The production of such bellows is particularly difficult since the part deforms during manufacture by its own weight.
PTFE structural elements of irregular or rectangular form can also be obtained from ElringKlinger GmbH. Dimensions up to 3 000 mm are no problem. We manufacture pump housings which incorporate all design details specified by the client. An in-depth consultation sometimes offers further advantages.
Due to the anti-seizing properties of PTFE spacers for heat exchangers offer longer maintenance intervals. PTFE slide rails make sliding action with little friction possible.
