Capability — Deep-Hole Drilling
Deep. Straight. Precise.
Produce difficult deep bores accurately in demanding materials or geometries without adding another specialist supplier to the job.
MIR performs deep-hole drilling and boring where conventional drilling no longer delivers the depth, straightness or reliability the component requires. Begin with the full part or a drilling-only need; the method, size and capacity detail below is there when technical evaluation calls for it.
Applications & suitable jobs
- Deep bores in solid material — through, blind or stepped
- Boring and finishing existing holes in tube
- Offset holes and bore circles in difficult materials
- Drilling-only support for other manufacturers
Technical detail
The BTA/STS and gun-drilling methods, hole configurations, materials, common drill-head sizes and capacity limits.
- Hole diameter
- up to 80 mm (3.150 in) hole diameter in solid material
- Depth
- up to 2 m (80 in) deep
- Boring
- boring of existing holes up to 150 mm (6 in)
- Hole types
- through, blind and stepped holes
Why deep holes are different
With a standard twist drill it is difficult to maintain precision when the depth-to-diameter ratio is high. Holes deeper than about 20:1 generally require a dedicated deep-hole machine to achieve productivity and process reliability. Deep-hole methods produce accurate, repeatable, burr-free holes with excellent surface finish, and hold location to precise tolerances.
BTA/STS vs gun drilling
Both methods pump cutting fluid to the workpiece while the head advances. Gun drills feed coolant through a small hole within the tool and evacuate chips along a groove outside it; BTA/STS drilling feeds fluid around the tool and evacuates chips through the drill itself. MIR selects the method against the hole size, depth and material.
Materials
The process works well in difficult materials, including stainless steels, duplex alloys and heat-resistant super alloys — common in energy, oil and gas, engine, diesel-fuel and mould applications.
Capacity
Continuous holes up to 80 mm (3.150 in) diameter in solid material, up to 2 m (80 in) deep. Existing holes can be bored to sizes up to 150 mm (6 in). Where the final bore needs tighter size or finish, honing completes the work in-house.
Common drill head sizes
| mm | inch | mm | inch |
|---|---|---|---|
| 31.75 | 1.250 | 50.80 | 2.000 |
| 34.93 | 1.375 | 53.00 | 2.087 |
| 36.00 | 1.417 | 54.00 | 2.126 |
| 38.10 | 1.500 | 57.90 | 2.280 |
| 39.00 | 1.535 | 60.30 | 2.374 |
| 41.30 | 1.625 | 62.00 | 2.441 |
| 43.00 | 1.693 | 63.50 | 2.500 |
| 44.45 | 1.750 | 67.30 | 2.650 |
| 45.20 | 1.780 | 69.80 | 2.748 |
| 47.00 | 1.850 | 76.10 | 2.996 |
| 47.60 | 1.875 | 79.90 | 3.146 |
| 49.28 | 1.940 | 80.00 | 3.150 |
| 50.70 | 1.996 |
Quality & inspection
Bore size, straightness and finish requirements are confirmed against the drawing at review; finishing to tolerance can continue into honing without a supplier handoff.
Frequently asked questions
Can you drill just the hole if I machine the rest?
Yes. Drilling-only work for other manufacturers is a standard part of the service — supply the part or the prepared blank.
What if my hole size isn't in the common-size table?
The table lists common drill head sizes only. Contact MIR for other sizes — many can be accommodated.
Do you finish bores to final tolerance?
Where drilling alone can't reach the final size or surface finish, the bore moves to in-house honing.
Accepted upload formats for this service: PDF, STEP, IGES, DXF, DWG