HOW TO CHOOSE THE RIGHT DRILL BIT FOR COMPOSITES

Composite materials are now used across a wide range of industries—from automotive manufacturing and boat building to caravans, sporting equipment and mechanical engineering. Thanks to their high strength and low weight, they are gradually replacing traditional materials. However, machining them requires the right cutting tool.

An unsuitable drill bit will quickly become dull when drilling composites and may damage the material or produce a poor-quality hole.

What Is a Composite?

A composite is a material made up of two or more different components. In drilling applications, the most common composites consist of a polymer matrix reinforced with fibres.

The most common types include:

• fibreglass (GFRP)
• carbon fibre composites (CFRP/CFK)
• other fibre-reinforced plastics
• thermosetting plastics

What these materials have in common is their high abrasiveness, which causes conventional HSS drill bits to wear rapidly.

Why Are Composites Difficult to Drill?

Unlike ordinary metals or plastics, composites contain hard reinforcing fibres. During drilling, these fibres act like an abrasive against the cutting edge of the drill bit.

Using an unsuitable drill bit may result in:

• rapid drill bit wear,
• fraying of fibres around the hole,
• delamination of individual layers,
• reduced hole quality.

For this reason, choosing a drill bit with high wear resistance is essential.

Which Drill Bit Should You Choose?

For drilling fibre-reinforced composites, fibreglass (GFRP), thermosetting plastics and other abrasive materials, we recommend using solid carbide drill bits.

Compared with conventional HSS drill bits, they retain their cutting edge much longer and provide significantly better resistance to abrasive reinforcing fibres.

For general drilling of composite materials, we recommend:

Solid Carbide Twist Drill Bits DIN 338

These drill bits are suitable not only for fibre-reinforced composites and thermosetting plastics, but also for cast iron, bronze, aluminium-silicon alloys (AlSi) and other abrasive materials.

How to Drill Composites Correctly

To achieve a clean, high-quality hole, we recommend following these basic guidelines:

• use a sharp drill bit,
• clamp the workpiece securely,
• keep the drill perpendicular to the surface,
• use a smooth feed without excessive pressure,
• select appropriate cutting conditions according to the material and drill diameter.

Using the right drill bit together with the correct drilling technique significantly extends tool life and helps produce clean, accurate holes.

Need a Different Diameter?

Our online shop offers the most commonly used sizes.

On request, we can also supply intermediate diameters from 1.0 mm to 10.0 mm in 0.1 mm increments, which are frequently used in mould making, tooling and precision engineering.

We Also Supply Other Versions

In addition to standard DIN 338 drill bits, we can also supply:

• solid carbide drill bits with Morse taper (MT) for machine drilling,
• short solid carbide drill bits according to DIN 6539, particularly suitable for CNC machining and applications requiring maximum rigidity and precision.

If you are looking for a specific size or version that is not listed in our online shop, please contact us. We will be happy to check availability.

Summary

When drilling composite materials, the most important factor is the drill bit's resistance to abrasive wear. Solid carbide drill bits are an excellent choice for fibreglass (GFRP), other fibre-reinforced composites, thermosetting plastics and many abrasive metallic materials.

Choosing the correct drill bit will extend tool life while reducing the risk of damaging the workpiece.

Related Topics

Not all composite materials behave the same during drilling. If you are working with a specific material, you may also find these detailed guides helpful:

• 7 Mistakes When Drilling Fibreglass
• How to Drill Carbon Fibre
• How to Drill Cast Iron