What is TUFNOL?

TUFNOL is a proprietary brand of laminated plastic material. It has been made in Birmingham, England since the mid-1920s and is one of the pioneering types of resin bonded plastic materials used for engineering components.

Many people know of laminates as hard, thin sheet materials used for kitchen worktops, flooring and the like. These are 'decorative laminates'. TUFNOL is an 'industrial laminate'. It does not have a specially coloured or patterned surface layer but it is made in big chunks as well as thin sheets, and these are used to make components for machinery and industrial purposes. It is usually brown to white in colour, depending on the grade, and can be made in solid sheets up to 225mm (9 inches) in thickness, and also in round rods and tubes.

How High Pressure Laminates are made
impregnating cotton fabric
After dipping in resin, the
cotton fabric is passed
through 'nip rollers' to
control the percentage
of resin to fabric.

TUFNOL laminates are made from layers of paper, cotton cloth or glass fibre cloth which are dipped into a resin or varnish and then strongly bonded together under high pressure in a hot press.

In manufacture, the cloth or paper is first impregnated by passing it through a bath of liquid resin and the resin is then dried off.

A roll of impregnated fabric
After impregnating with resin,
the dried 'pre-preg' is re-
rolled, prior to being cut
into sheets for pressing.

To make the final sheet of material, many layers of this 'varnished' paper or cloth are placed between polished metal plates and put into an industrial press. Each gap in the press is called a 'daylight'. For thick sheets, each daylight would typically contain one sheet but, when making thin sheets, up to 20 can be put into each daylight, seperated by polished steel plates. The contents of the press is then heated up and a very high pressure is applied to squash the layers together. As this happens, the resin melts and becomes gluey, sticking the layers firmly together into one solid mass.

Tufnol sheets in a high pressure press
Tufnol sheets moulded from
many layers of 'pre-preg', in a
heated high pressure press.

Whilst still under the heat and pressure, the resin then 'cures', that is, it undergoes a chemical change, becoming a hard, solid material which can no longer be melted with heat.

Round rods and tubes can also be moulded from the impregnated material by rolling it into a cylindrical shape and moulding it in a press.

Tufnol rod and tube in a press
A rod and a tube in a press.

Using similar principles, many different sections can be moulded, including angles, channels, square and rectangular tubes and solid bar, and hexagonal bar.

Tufnol moulded sections
A selection of Tufnol
laminated moulded sections.

Once cured in the press, this resin bonded material cannot melted to re-shape it, so finished components are made by machining the TUFNOL, using ordinary machine tools such as saws, drills, lathes, milling machines, etc. or, very commonly these days, high-speed computer-controlled CNC machines.

Why use Tufnol?

TUFNOL is a non-metallic material with very useful properties. It hard, rigid and strong, light in weight (about a fifth of the weight of steel and half the weight of aluminium). It is a good electrical insulator, some grades extremely good, and is also resistant to long-term immersion in water. It is exceptionally resistant to weathering, much more so than most other plastics, and it has been used for components in outdoor and marine environments for many decades without corroding or degrading. Some grades are very resistant to wear in applications involving friction, and can be lubricated with water as well as oil or other conventional lubricants. This makes them extremely useful in marine applications.

Many grades for different uses.

By using different varieties of resin with various types of cloth or paper, many different grades of TUFNOL can be produced. These can be divided into three main types:-,
 - grades made from layers of paper - known as SRBP, or 'synthetic resin bonded paper'.
 - grades made from layers of cotton cloth - known as SRBF, or 'synthetic resin bonded fabric'
 - grades made from layers of glass fibre cloth - the most common of which is epoxy glass laminate.

To see the full range of TUFNOL grades currently manufactured for different engineering uses, use the link here to visit the company website of Tufnol Composites Ltd.