What Makes a Good Spearpoint Drill - And Why It Matters in Aerospace

In aerospace engineering, precision isn't a luxury - it's a requirement. When you're drilling into sandwich materials, there's one tool that can make or break the job: the spearpoint drill.

In this post, we're taking a closer look at what makes a good spearpoint drill, why it matters in aerospace machining, and where standard tooling often falls short.

Drilling into a sandwich material

1. The Challenge of Drilling in Aerospace Materials

Aerospace components often involve complex assemblies and difficult materials: titanium, Inconel, carbon fibre, honeycomb structures, and sometimes all of the above in a single part.

When you're drilling through sandwich layers of vastly different hardness, density, and thermal properties, your tool needs to do more than just 'cut'. It needs to;

• Enter precisely, without wandering off-centre

• Hold position through multiple materials

• Exit cleanly, with minimal delamination or burrs

This is where a well-designed spearpoint drill becomes critical. Inconsistent results from standard drills can lead to scrap, rework, or worse, non-conformance.

2. Key Design Features of a Good Spearpoint Drill

So what actually makes a good spearpoint drill?

At first glance, they look simple. But their performance is built on fine-tuned geometry and material science:

• Spearpoint Geometry

The sharp centre tip reduces wandering on entry, especially useful on curved or uneven surfaces. It also helps the drill self-centre without a pilot hole.

• Optimised Web Thickness

Too thick, and the drill generates too much heat. Too thin, and strength suffers. Aerospace-specific drills need this balance nailed down to cut consistently through tough materials.

• High-Quality Substrate

Aerospace demands premium-grade carbide or cobolt steel to cope with high temperatures, abrasiveness, and low margin for tool wear.

• Coatings That Withstand Heat and Friction

Think AlTiN, TiCN or diamond coatings. These help reduce wear, extend tool life, and keep cut quality high, especially when working dry or nearly dry.

• Step Geometry

Helps reduce friction on the tool body and clears chips more effectively, crucial in deep hole applications common in aerospace components.

3. Why It Matters for Aerospace Machining

   
   

Every hole in aerospace manufacturing is a potential fail point if it's not perfect. Whether it's a hole for a rivet, bolt, or bushing, the margins are tight, and the risks are high.

Here's why choosing the right spearpoint drill matters:

• Improves Hole Quality

Clean entry and exit points mean fewer burrs, less secondary deburring and more reliable part integrity.

• Reduces Scrap and Rework

A tool that performs well the first time around means fewer delays, less downtime, and lower risk of non-conformance.

• Protects High-Value Materials

When you're drilling into £20,000 components, there's no room for cheap tooling experiments.

• Supports Automation and Repeatability

  In a sector where more operations are becoming automated, you need tooling that performs reliably across batches and materials.

4. When to Go Custom (And Why It Pays Off)

Sometimes, even the best off-the-shelf spearpoint drills won't quite cut it.

If you're facing one or more of the following, it might be time to look at a custom or modified drill:

• Drilling through multiple materials in a single pass

• Needing tighter tolerances than stock tools can offer

• Unusual hole sizes or geometries

• Problems with burrs, delamination, or poor chip control.

At that point, a custom drill isn't just a nice-to-have; it becomes a process improvement tool. We've worked with aerospace clients who've switched to custom spearpoints and seen:

• 20-30% reductions in cycle time

• Dramatic improvements in hole quality

• Less downtime caused by tool changes or manual deburring.

5. Final Thoughts: Don't Let the Tool Hold You Back

In aerospace engineering, you already deal with enough complexity: tight specs, long lead times, rigorous QA. Your tooling shouldn't be one more thing to worry about.

A well-designed spearpoint drill might be a small part of the overall job, but it can have a big impact on performance, consistency, and cost. Whether you're working with titanium stack or carbon fibre skins, it's worth asking: Is my drill really fit for this job?

If you're unsure or you're tired of seeing inconsistent results, we're always happy to take a look and see what's possible.