Structural Steel
Highly recommended and widely used for drilling structural steel.
ANNULAR BROACH CUTTERS – TECHNICAL GUIDE
Annular broach cutters provide an efficient method of producing accurate holes in steel and other metals. This HMT technical guide covers material suitability, drilling machine selection, material thickness, lubrication, arbors and accessories, recommended cutting speeds and best practice for HSS and TCT annular cutters.
Which Materials Can Annular Broach Cutters Drill?
Hardened Steel
It is feasible to drill some grades of hardened steel in controlled situations. For best results in hardened steel, the HMT Ultra tooling range is recommended. Hardened or heat-affected materials may require reduced RPM, increased feed pressure and additional coolant.
Stainless Steel
TCT cutters are suitable for use on stainless steel.
Important: Magnetic drills will not adhere directly to stainless steel, so the workholding and drilling setup must take this into account.
Non-Ferrous Metals
Annular cutters are suitable for drilling aluminium and other non-ferrous metals.
Important: Magnetic drills will not adhere directly to non-ferrous materials.
Which Drilling Machine Should I Use?
| Machine | Suitable? | Guidance |
|---|---|---|
| Impact Wrench | No | Annular broach cutters are not suitable for this type of drilling machine. |
| Rotary Pistol Drill | No | Annular broach cutters are not suitable for this type of drilling machine. |
| Compact Magnet Drill | Yes | Normally used with cutters approximately 12 mm to 36 mm diameter. Typically used with a higher spindle speed. |
| Large Magnet / Pillar Drill | Yes | Larger machines generally have more powerful motors and lower rotation speeds, making them more suitable for larger annular cutters. Pillar drills with suitable Morse Taper spindles can also be fitted with an annular cutter arbor. |
Using Annular Cutters in Different Material Thicknesses
Sheet Metal
Up to 4 mm
Standard Plate
5–12 mm
Medium Plate
12–25 mm
Heavy Plate
Above 25 mm
- For sheet metal and thinner plate, consider whether the magnetic drill has sufficient material thickness to achieve secure magnetic adhesion.
- Medium plate is a typical application for annular broach cutters.
- When drilling heavy plate or deeper holes, periodically ventilate the hole during cutting to help clear swarf.
- For best results, select a cutter with sufficient cutting depth for the material being drilled.
Recommended Cutting Lubricants
SpeedLube
Recommended for general-purpose drilling applications.
BioCut Paste
Recommended for overhead drilling and other applications where liquid lubricant is not suitable.
BioCut Blue
Recommended for general-purpose drilling in harder steels and stainless steels where heat reduction is particularly important.
Annular Cutter Arbors and Accessories
Impact Adapters
Not suitable for annular broach cutters.
Pistol Drill / Chuck
Not suitable for annular broach cutters.
Weldon Adapters
Most magnetic drills use the universal Weldon shank arrangement used by annular broach cutters.
Morse Taper Adapters
For larger magnetic drills and pillar drills, an appropriate annular broach cutter arbor is required. Morse Taper arrangements are commonly used on larger machines.
Annular Broach Cutter Best Practice and FAQ
Do I need a pilot hole or a centre punch?
A conventional pilot hole is not required. Centre punch the surface accurately where the hole is to start. This allows the centre or pilot pin to engage positively and helps position the cutter correctly.
What is the correct feed pressure?
Apply firm, steady feed pressure throughout the cut. Apply the feed steadily and cautiously during the first millimetre of the cut. Excessive feed pressure can increase heat build-up and reduce cutter life.
How many holes can I expect an annular cutter to last?
There is no single fixed number. Tool life varies depending on material, cutter diameter, cutting speed, feed pressure, lubrication, machine condition and application.
How can I prevent chipping or breakage?
Avoid lateral movement or tilting while cutting. Do not use excessive feed pressure. Apply steady feed pressure and maintain a consistent flow of swarf.
Should the cutter be deeper than the material?
Yes. For best results, select a cutter with a cutting depth greater than the thickness of the material being drilled.
TCT Annular Broach Cutter Recommended RPM
Recommended spindle speed depends on cutter diameter and material.
| Diameter | Structural Steel – 30 m/min | Hardened Steel – 10 m/min | Stainless Steel – 15 m/min | Non-Ferrous – 80 m/min |
|---|---|---|---|---|
| 12–19 mm | 800–505 | 265–170 | 400–255 | 2130–1345 |
| 20–25 mm | 480–380 | 160–125 | 240–190 | 1280–960 |
| 26–32 mm | 370–300 | 125–95 | 185–150 | 990–810 |
| 33–39 mm | 300–245 | 100–80 | 150–120 | 810–690 |
| 40–46 mm | 240–210 | 80–65 | 120–105 | 650–575 |
| 47–53 mm | 205–180 | 70–55 | 105–90 | 555–475 |
| 54–60 mm | 180–160 | 60–50 | 90–80 | 475–425 |
| 61–70 mm | 160–135 | 55–45 | 80–65 | 425–370 |
| 71–80 mm | 135–120 | 45–40 | 65–55 | 370–335 |
| 81–90 mm | 120–105 | 40–35 | 55–50 | 335–280 |
| 91–110 mm | 105–95 | 35–30 | 50–45 | 280–255 |
| 111–112 mm | 95–85 | 30–25 | 45–40 | 255–230 |
| 113–124 mm | 85–75 | 25–20 | 40–35 | 230–205 |
| 125–136 mm | 75–70 | 25–20 | 35–30 | 205–185 |
| 137–150 mm | 70–60 | 20–15 | 30–25 | 185–170 |
| 151–174 mm | 60–50 | 20–15 | 25–20 | 170–145 |
| 175–200 mm | 50–45 | 15–10 | 20–15 | 145–125 |
HSS Annular Broach Cutter Recommended RPM
HSS annular cutters require different cutting speeds from TCT cutters.
| Diameter | Structural Steel – 20 m/min | Hardened Steel – 8 m/min | Stainless Steel – 12 m/min | Non-Ferrous – 50 m/min |
|---|---|---|---|---|
| 12–19 mm | 530–335 | 210–135 | 315–200 | 1325–830 |
| 20–25 mm | 320–255 | 125–100 | 190–150 | 800–635 |
| 26–32 mm | 245–200 | 95–75 | 145–115 | 610–500 |
| 33–39 mm | 190–160 | 75–60 | 115–95 | 475–405 |
| 40–46 mm | 160–140 | 60–50 | 95–80 | 400–345 |
| 47–53 mm | 140–120 | 55–45 | 80–70 | 345–300 |
| 54–60 mm | 120–105 | 45–40 | 70–60 | 300–265 |