Arguably one of the most important engineering plastics is a material called PTFE. Although PTFE was invented back in the 1940's, it still remains a critical component that continues to outperform almost all other engineering plastic in specific and critical areas.
Manufacturers produce engineering plastics that are slightly oversize in either diameter and/or thickness. This oversize tolerance, which is listed in the tables below, is provided to assist customers to produce very accurate items within the size shown and remove any minor surface imperfections
PTFE Sheet Tolerances:
|Nominal Thickness||Tolerance in mm|
|0.25 - 0.5||-0 to +10%|
|1||-0 to +0.15|
|2||-0 to +0.3|
|3||-0 to +0.45|
|4||-0 to +0.6|
|5||-0 to +0.75|
|6 - 8 - 10 - 12||-0 to +15%|
|15 - 20 - 25 - 30||-0 to +15%|
|40 - 50||-0 to +15%|
PTFE Sheet Benefits
PTFE Sheet is a specially important engineering plastic because of its outstanding lack of friction and slippiness, this is so incredibly low that is has been described as being the most slippy solid material known to man and PTFE Sheet can be cut into strips and can offer a massive improvement in the sliding components.
PTFE is also highly specified due to its very high temperature resistance allowing components to withstand almost double that of other types of engineering plastic.
PTFE Sheet has the capability to also withstand very strong acids and chemicals helping to provide solutions to acid storage and chemical problems. High electrical resistance is yet another feature of PTFE Sheet and PTFE is often used in high end electrical resistance appliances.
PTFE Sheet Applications
PTFE Sheet is often used in the food preparation industry due to its food contact suitability and its very high operating temperatures meaning that the PTFE will be happy to continue along with the product and any product or contamination will not be allowed to stick.
PTFE Sheet is also highly successful when it comes to cryogenics, just as PTFE is comfortable at very high temperatures, PTFE is also very happy at extremely low temperatures. PTFE Sheet is also becoming popular in the building industry and is being specified by modern architects due to its substantial ability to withstand weathering and its environmental resistance.
PTFE Sheet is often used in wear strips and slideways within all types of engineering to take advantage of a stunning co-efficient of friction to guide high performance components a highly wear resistant and super sliding advantage to help reduce costs and improve component life.
PTFE Sheet is an engineering plastic that is also used in valve parts because it has the ability to conform to the shape of a mating or sealing, opposing component allowing PTFE to give a low friction long lasting valve seal that is heat and acid resistant. Because PTFE Sheet has excellent electrical insulation properties, it is often specified for the areas where other insulation is not sufficient and with the added benefit of the heat resistance which can often be associated with these applications.
PTFE Sheet Specifications
Maximum long term working temperature is plus 260°C. Maximum short term working temperature is plus 260°C. Co-efficient of friction is 0.08. Co-efficient of expansion is 12. Melting point is plus 327°C.
PTFE Sheet availability
PTFE Sheet is generally available in a standard sheet size of a nominal dimension of 1200 x 1200, although there is a limited option of 1500 x 1500 PTFE Sheet's are available in some selected sizes. PTFE Sheet is also often reduced in overall size availability of 600 x 600 due to weight and costs. Thickness of PTFE Sheet typically range from 0.25mm up to 100mm thick although specialist manufactures are capable of much greater thickness. PTFE Sheet offers a great and comprehensive range of thickness, although the thinnest sheet is very difficult to keep flat, smooth and wrinkle free.
PTFE Sheet Issues
PTFE has a few important areas to be aware of and they are it's thermal expansion, this means that components will expand at a high rate due to thermal changes, PTFE Sheet is also difficult to bond, there are modern adhesives that will bond PTFE, they are often a two part process although pre-etched PTFE Sheet is available. PTFE Sheet is also relatively heavy or dense compared with other engineering plastics and also it can be more expensive due to its manufacturing process.
PTFE Sheet History
PTFE is short for Polytetrafluoroethylene and is a synthetic fluoropolymer and was first invented in the early 1940's by a Mr Roy Plunkett by accident and is also known as Teflon®. There are many areas where Teflon® has been found favour including space exploration and Teflon® is a registered trade mark for Du Pont Company.
PTFE Sheet for low friction bearings
Very low friction is another attribute that PTFE Sheet excels at. It has one of the lowest co-efficient of friction of any material known to man and provides similar results as ice. This is particularly important in many applications for low friction slide ways where only PTFE Sheet will do.
PTFE Sheet for high temperature applications
One of the most famous and obvious applications for PTFE Sheet is for high temperature areas, this is because PTFE Sheet can withstand temperatures of in excess of plus 250°C and can also withstand excessively low temperatures and PTFE Sheet can still perform.
PTFE Sheet for acid resistance
Another important feature of PTFE Sheet is its acid resistance, this can be used to line acid tanks and PTFE Sheet can resist higher concentrations than many other materials.
PTFE Sheet for electrical insulation
PTFE is one of the best electrical insulation materials of all the engineering plastics it is often used for high end components and is often used in place of PVC when the insulation properties need to be much higher.
PTFE Sheet at Low Temperatures
One of the often overlooked and key features of PTFE Sheet as an engineering plastic is the low end temperature resistance and performance. Because PTFE Sheet can withstand temperatures as low as -260°C and still retain its properties, it is often chosen to line the inside of cryogenic vessels as there are very few materials that can withstand these extreme temperatures.
Chemical resistance of PTFE Sheet
An important advantage of PTFE Sheet is its chemical resistance which is probably better than most other plastics and much better than most other materials. There are few chemicals that will attach or cause any damage to the sheet under typical use and applications. This would allow PTFE Sheet to be used in applications as the lining of chemical tanks and any instances where chemical resistance is important.