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What is GRP?: If you aren’t familiar with the term ‘glass reinforced polymer,’ you’re probably scratching your head and wondering, “What is GRP?” There’s a good chance you’ve heard its more common name, fibreglass, although it’s also known as composite polymer or fibre reinforced polymer (FRP). GRP behaves in different ways compared to conventional thermoplastics, making it a popular choice for a wide range of applications in many industries.
GRP explained

The basic answer to the question, “What is GRP” is that it’s a combination of glass fibre and polymer or polymer. Among its desirable properties are its high strength to weight ratio and superb durability, as well as being electrically non-conductive, lightweight, non-corroding, and radar and radio wave transparent.

What is GRP made of?

GRP products such as GRP profiles are made from glass fibre reinforced polymers, most commonly with a polyester or vinyl ester thermoset resin matrix, and glass fibres.

How are GRP products manufactured?

Let’s explore the various ways to manufacture GRP products such as GRP nose covers.

GRP moulding: The GRP moulding process involves the use of a steel open mould with a cellular structure and a comb-like tool. Using the tool, glass fibre strands are woven back and forth over the mould to create a ‘skeleton’. Catalysed resin of the preferred colour and grade is poured into the heated mould, which is left until the product has cured and hardened.

GRP pultrusion: The GRP pultrusion process used to make structural profile sections takes place in an automated machine and uses a base mix of fire-retardant polyester resins interspersed with layers of incredibly strong interwoven glass fibres. Colour pigmentation is floated through the material’s entire thickness, so that the colour cannot wear off.

GRP hand lay-up moulding: The hand lay-up GRP process sees a glass fibre reinforcement (a woven or chopped strand mat) and occasionally inner core mats form a sandwich between layers of glass for extra strength. This ‘sandwich’ is cut to shape before being laid on the surface of a waxed open mould. After this, resin is applied to fully saturate the glass/core laminate. This is left to cure before being removed, trimmed, painted, and polished.

GRP spray lay-up moulding: The spray lay-up process is semi-automated. A pressurised spray gun with a glass fibre ‘chopper’ head unit is used to apply the laminate to the mould in a continuous process. The fibre is chopped directly into the resin stream being directed into the mould.

GRP resin transfer moulding: GRP resin transfer moulding sees a mixed resin injected at pressure into a mould. This process usually is used to produce high volumes of smaller parts of consistent quality.

GRP compression moulding: In the GRP compression moulding process, a preheated polymer is placed in an open mould cavity before it is closed in with a top plug to ensure the material is in contact with all the mould’s areas.

GRP long fibre injection moulding: The highly automated GRP long fibre injection moulding process is used to manufacture precision-made parts. The process requires a GRP moulding system which uses a polyurethane matrix and long glass fibres which are applied robotically to a mould, where the matrix and fibre mix is compressed, cured, and hardened to the desired shape.

Properties and uses of GRP products

GRP products such as GRP sheets have many desirable properties and uses. Properties include:

High strength to weight ratio
Lightweight
Superb durability
Non-corroding
Electrically non-conductive
Radar/radio wave transparent
Warm to the touch
Good resistance to many chemicals

Uses of GRP include:

Anti-slip protection for retrofitting wet and dry flooring
Electronic enclosures
Handrails
Helicopter rotor blades
Wind turbine blades
Safety grating in public and industrial areas
Sporting equipment such as crossbows and kayaks
Drain coverings
Water pipes
Many other uses in automotive, electronic, transportation, leisure, and other industries

Benefits Of GRP

In addition to the beneficial properties mentioned above, GRP offers the following benefits:

Long lifespan

Requires little to no maintenance

Flame-retardant GRP available

Sustainable, low-energy manufacturing process

Easy fabrication and machining

Insect infestation resistant

Wide operating temperature range

Can be reprocessed

Now that you know more about GRP, it’s uses and benefits, you can see why glass reinforced polymer remains a popular choice across diverse industries around the world. Choose the best GRP products for your needs with BM Steel.