Technical Info

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Kilwell Fibretube, Composite Tubing Solutions

Over 40 years experience in Composite Tubing Design and Manufacture

  • Applications include Fishing rods, Dinghy and Yacht masts, booms, spinnaker poles, stanchions, stern tubes and sundry marine tubing, Kayak paddle shafts, Sailboard masts, Model and Unmanned Aircraft, Hang glider, Spars, Rowing Oars, Aerials, plus numerous other applications
  • Custom Design projects are welcomed. One-Off to High Volume Production Run capabilities
  • Existing Worldwide customer base
  • Wide range of Carbon Fibre, Fibreglass, Aramid raw materials, plus Nano Technology
  • Extensive range of tooling in both parallel and tapered profiles
  • In-house precision grinding, sanding, painting and machining facilities
  • Specialists in optimised cost/benefit laminate designs

If your tubing requirement is not covered in the information on our site, please detail your needs on our Custom Design form or contact us for more information, design assistance, or a prompt quotation.

1. Process

Kilwell Fibretube uses the efficient and high quality 'Roll-Wrapping' process where layers of carbon, glass or other fibres that are pre-impregnated with thermosetting epoxy resin are rolled onto steel or aluminium mandrels. The layers are then compressed to remove entrapped air and heated to cure the resin, after which the mandrel is withdrawn.

Roll Wrapping has several critical advantages over other production methods:

  • A very high and acurately controlled fibre to resin content is obtained with prepreg raw materials.
  • Fibres can be precisely aligned along the tube axis, ensuring maximum strength and stiffness under pure bending loads.
  • Increased torque, shear, crushing or splitting strength can be built into the laminate design at any point along the tube.
  • The ability to make tapered tubes and vary wall thicknesses along their length allows precise engineering of bend profiles and eliminates excess material usage.
  • Mixed fibre types can be used in laminates to provide the best possible combination of strength, stiffness, weight and cost for any application.
  • Roll Wrapping is extremely cost effective for small production runs due to the inexpensive tooling costs and is also well suited to high volume outputs.

2. Materials

2.1 Carbon Fibre

The majority of our carbon fibre tubes are designed and manufactured with Toray T700 unidirectional prepreg, providing a high level of tensile strength with a standard modulus fibre. An additional wide range of higher modulus fibres plus woven and double bias styles allows us to design and manufacture tubes with precise mechanical properties that ensure the most efficient use of materials, maximising the advantages of carbon fibre's strength and stiffness at minimum cost.

E-Glass, S-Glass or Aramid fibres are often included in our carbon laminate designs for the best combination of physical properties and price of the finished article. Our expertise in this area regularly results in significant cost savings for our customers.

2.2 Fibreglass

The majority of fibreglass fabrics used by Kilwell Fibretube are specifically designed for making tubes or similar products, which require maximum stiffness and strength in one direction. These typically have approximately 90% of the fibre running lengthwise (the warp directions) and 10 percent at 90 degrees (the weft direction), and our use of low fibre crimp satin weave fabrics ensures a very high transfer of fibre strength and stiffness in the finished laminate. Several other weave styles are used to design the complex combinations of bending, crushing and torque resistance dictated by the various end uses that our tubes fulfill.

We stock ten pre-impregnated colours of fibreglass prepreg, and can also sand and paint tubes in any colour requested by our customers.

2.3 Material Properties

Material Ultimate Tensile Strength (MPa) Young's Modulus (Gpa) Density (gms/cc)
Carbon T700 Laminate 2600 133 1.55
E-Glass Laminate 1300 39 1.8
S-Glass Laminate 2000 48 1.8
Aramid Laminate 2200 50 1.35
Aluminium 300 72 2.7
Steel 750 200 7.9

Note: The above laminate figures are for typical resin contents and 100% unidirectional fibre orientation. Variations in fibre orientation, resin content and production processes significantly alter laminate strength and stiffness properties.

3. Sizes

3.1 Parallel Sizes

Our extensive range of parallel mandrel diameters and the maximum length of each size is detailed in the Parallel Mandrel List. New sizes can be made or existing sizes can be extended to 5200mm maximum length with very low tooling costs if required.

(View Parallel Mandrel List here.)

Parallel Mandrel List

Dia. (mm) Max. Lgth Dia (mm) Max. Lgth Dia (mm) Max. Lgth Dia (mm) Max. Lgth
4.0 1000 25.0 3000 42.0 3300 75 3100
5.0 2100 25.3 2000 43.00 1150 76.2 5000
6.0 1000 25.4 4300 43.2 3000 79.4 3430
6.4 1550 26.0 2900 43.5 2300 80.3 4000
7.0 1400 26.5 4000 44.0 5000 82.5 5050
7.9 4025 26.8 2000 44.5 5100 85.0 5300
8.0 2000 27.0 5200 45.0 4500 85.7 3900
8.7 3000 27.3 2000 45.3 4500 86.0 4000
9.0 1800 27.5 4100 46.0 5000 90.0 4000
9.5 2850 27.8 4440 46.7 1800 93.0 1200
10.0 4000 28.0 3100 47.0 4100 95.0 5100
10.5 3800 28.5 3100 47.5 3950 95.2 5000
11.0 2000 29.2 1100 48.2 1800 99.2 2200
11.1 3000 29.4 1000 48.3 2000 105.0 3100
12.0 5000 29.6 1000 48.6 2500 106.7 2200
12.5 5000 30.0 4000 50.0 3100 108.0 5200
12.7 3000 30.3 2900 50.3 2900 110.0 5200
13.0 4000 30.6 3470 50.8 5100 115.0 3100
13.5 1400 31.7 3000 54.3 2900 118.0 2600
14.3 5000 32.0 4000 55.0 4000 124.1 1000
15.0 3000 33.0 3200 56.0 5300 125.0 5000
15.9 5000 33.2 4100 57.1 3400 127.0 2200
16.0 3000 33.4 1900 57.7 4500 135.0 1000
17.4 3000 34.0 5200 58.2 4100 136.0 3000
17.8 3100 34.5 2200 59.0 1100 144.0 1100
18.0 2950 35.0 3000 60.0 4200 160.0 1650
19.0 5000 35.5 3000 60.3 5200 160.4 1000
19.5 2100 36.0 2800 62.0 1000 164.0 900
20.0 5000 37.0 4000 63.5 4200 182.0 1000
20.6 1000 37.2 3400 65.0 3100 202.0 1000
22.2 4000 38.1 5000 65.3 2300 211.0 1000
23.0 3600 38.6 2500 66.0 4000 273.0 900
23.4 1050 38.7 3000 66.7 5200
23.8 3500 40.0 5200 68.3 2900
24.0 2720 40.3 2900 70.0 5200
24.5 2900 41.3 4850 70.3 4200

3.2 Oval Sizes

Our Oval mandrel sizes are below, suitable for producing yacht booms, handrails or other items suited to an oval cross section.
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Model Dim. A Dim. B Length
OV32/18 32 18 2500
OV69/30 69 30 1200
OV75/35 75 35 1900
OV100/50 100 50 3900
OV125/95 125 95 5000
OV125/100 125 100 3000

3.3 Mast Tube Sizes

Our preferred mast base inside diameters are: 40.0mm, 46.0mm, 50.8mm, 56.0mm, 60.3mm, 66.7mm, 70.0mm, 76.2mm, 82.5mm, 85mm and 95mm. All of these mandrels are at least 5000mm long.

We have tapered mast tip mandrels to suit the above diameters plus offset joining spigots to join base and tip tubes with the finished mast having a straight edge to carry the sail track. Other sizes can be designed on request but there may be a tooling cost involved.

3.4 Spinnaker and Prod Mandrels

Spinnaker Poles and Prods are often made on parallel mandrels but we have a number of special mandrels with tapered ends as shown below. Prods made on these mandrels are one-piece with the tapered end saving weight and looking neater than parallel tubes. Spinnaker poles made on these mandrels are two-piece, joined in the centre to make 'double ended' poles.

Sizes of the special spinnaker pole mandrels are below, and smaller double-ended poles can also be made using other tapered mandrels in our range.

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Model Dim. A (mm) Dim B (mm) Dim. C (mm) Dim.D (mm) Dim. E (mm)
SPIN66 63.5 48.6 2000 2050 4050
SPIN68 68.5 52.4 2200 1550 3750
SPIN89 89.0 65.0 2600 2000 4600
SPIN92 92.0 44.0 500 4500 5100
SPIN100 100.0 54.8 3300 1700 5000
SPIN135 135.0 72.0 2790 2410 4940

4. Custom Tubing

Custom and partnership design solutions are our speciality and the ability to rapidly apply our diverse design, materials, tooling and manufacturing resources makes Kilwell Fibretube the natural choice to get your project moving without delay.

Although we have a huge number of specifications on file, the versatility of Roll Wrapped composite tubing can provide stiffness and strength precisely where it is required, eliminating excess weight and material costs. Our design software, coupled with long experience, allows us to generate specifications that will meet the physical and cosmetic properties you require with the most cost effective use of materials.

Providing we can use existing mandrel sizes there are no tooling costs, and production runs can be from one-off to thousands of items.

If your tubing requirement is not covered in the information on our site, please detail your needs on our Custom Design form or contact us for more information, design assistance, or a prompt quotation.

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