Leader in machined plastics and resin bonded fabrics Engineering plastics and composites

TUFNOL Filament Wound Composite Tubes

Epoxy glass fibre composite tubes and

Filament wound pneumatic cylinders


  -  Outstanding strength to weight ratio.

  -  Excellent chemical & corrosion resistance.

-  Good resistance to weathering and U.V. light.

  -  Replacement for stainless steel, brass, glass and aluminium.

  -  High precision, smooth, low friction bore.

  -  Good  electrical  properties.

  -  Available in a large range of standard sizes.

 

FILAMENT WINDING

 

Filament winding is a versatile process for producing composite sections in a hollow or tubular form, by winding resin impregnated fibres onto a rotating mandrel.  The physical properties of the tube can be controlled by altering the types of resin and reinforcement and by varying the angle at which the fibres are wound onto the mandrel.  This process can be carried out under computer control and, if required, the final component can be made with a combination of different wind angles.

 

Fibre Reinforcement

 

Glass, when drawn into fine fibres of 10-15 micron diameter, has a very high tensile strength - up to 4000 MPa, or about ten times that of steel.  However, to make a usable material, the glass fibres have to be bonded together with synthetic resins.  Other fibres such as carbon, aramid (e.g. Kevlar), polyester, cotton and asbestos can be used, where their special properties are sought.

 

Resins

 

Thermosetting resins are used in the manufacture of Filament Wound tubes.  Epoxy resin is used for the majority of TUFNOL Filament Wound Tubes but polyester,  vinyl-ester and acrylic (Modar)  resins are also used, with glass or other fibres.  Special resins can be formulated for particular high temperature, electrical performance or chemical resistance requirements.

 

Composite tubes

 

The properties of Filament Wound composites depend not only on the characteristics of the materials used but also on the position and direction of the fibres in the component.  Fibre reinforced composites have much greater strength in the direction of the fibres, than at right angles to them.  For example, tubes in the TUFNOL cylinder range are wound at a shallow helix angle of about 15o, to give good hoop strength and therefore a higher bursting strength.   Physical properties, such as strength and elastic modulus, are quoted both in the hoop direction and axially.

 

The use of a reinforcement made from polyester yarn, instead of glass,  results in a material with good bearing characteristics.  Similarly, other combinations of reinforcement and resin produce materials for electrical  insulation,  materials for pump bodies, structurally strong types for aerial masts, and so on.

 

Size Range

 

TUFNOL Filament Wound composite tubes can be produced in a wide range of sizes, with internal diameters from 25mm up to 500mm (1" to 20").  They are available in lengths up to 3 metres approx. (10 ft.), subject to availability of tooling.

 

Click here for the full list of Standard Sizes

 

STANDARD CYLINDER RANGE

 

The TUFNOL Filament Wound cylinder range of tubes are manufactured by a process specially developed to give a smooth, high precision, low friction bore requiring no further finishing.  The tubes have a composite structure of glass fibre filaments, bonded by epoxy resin and are designated TUFNOL Grade FWG/1.

 

TUFNOL smooth bore composite tubes are ideal for use as pneumatic cylinders and actuators, and for similar applications with low pressure hydraulics, filling, metering and dispensing equipment, and pumps.  In these applications, they have proved a superior replacement for stainless steel, brass and aluminium.  In addition to the low friction bore, the tubes have an outstanding strength to weight ratio, and they are frequently used where their economical price and excellent chemical corrosion resistance make them a most cost effective choice.  For example, light weight pneumatic cylinders offer particular benefits in robotics applications.   Also the low friction, smooth bore makes them ideal for use in compressor and pumps, with non-lubricated air.

 

Technical Data for Standard Range

 

TUFNOL Grade FWG/1 Filament Wound composite tubes are normally supplied in lengths up to 3 metres, with a ‘wound-finish’ outside diameter.  If required, they can be supplied cut-to-length and with a machined outside diameter, or as finished components, if further machining is needed.

 

Cylinder Design  -  Tie-Rod Tension

 

TUFNOL Grade FWG/1 tubes are ideal for use in tie-rod construction pneumatic cylinders.

 

It is recommended that the tubes be compressed axially by pre-tensioning the tie-rods. This will counteract the extension of the tie-rods when the cylinder reaches operating pressure and is particularly important when using a seal on the end face of the tube wall.  Should a state be reached when the tube is no longer in compression, the end face seal may fail.  To prevent this, an end load compressive stress of 20 MPa is applied to the tube.  This stress, multiplied by the cross sectional area of the tube wall, gives the recommended cylinder compression load.

 

Recommended tube end compression loads are given in the size range tables.  These loads are applied by pre-tensioning the cylinder tie-rods as described above.  The recommended compression loads should result in a reduction of the unpressurised tube of about 0.3%.

 

The tightening torque to be applied to the tie-rods, to produce the required load, depends on the size and material of the tie-rods and lubrication.

 

Operating Conditions

 

  Working Pressure      0 to 20 bar        0 to 300 lbf/in2

  Peak Pressure*         40 bar                 600 lbf/in2

  Temperature Range  -40o to 120oC    - 40oF to 250oF

 

*Theoretical tube failure is between 4 and 10 times peak pressure rating, depending on diameter.  Failure is normally by gradual release of pressure rather than a sudden burst.

 

Tolerances

 

 Internal Diameter      H9

 External Diameter     -0.5 + 1.0mm   - 0.02 + 0.04in.

 Wall Thickness          -0.3 + 0.5mm   - 0.01 + 0.02in.

 Straightness              1 in 2000

 

TYPICAL PROPERTIES

TUFNOL Grade FWG/1 (15º wind angle) 

 

PROPERTY

TYPICAL RESULT

UNITS

Hoop tensile Strength

300

MPa

Hoop tensile Modulus

16000

MPa

Axial Compressive Strength

100

MPa

Axial Compressive Modulus

7000

MPa

Density

1.9

g/cm3

Coefficient of Thermal Expansion

7

X 10-6 /ºC

Temperature Range

-40 to +120

ºC

 MACHINING SERVICE

 TUFNOL Ltd. operates a comprehensive machining service for all types of engineering plastics.  The facilities are probably the largest of their kind in the U.K.   Customers not wishing to finish-machine their Filament Wound components in their own workshops can take advantage of the total TUFNOL service and obtain both material and machining from the same source.

 

NEW APPLICATIONS

 

In this leaflet, we have indicated the versatility of the filament winding process.  At all times we are actively seeking new applications and we welcome enquiries from designers and engineers who feel that this process may lead to the solution of problems for them.