Calculator input
Large screens use three columns. Smaller screens use two, then one.
Plotly graph
The chart shows aspect ratio growth with depth for the current drill diameter.
Example data table
| Example | Diameter (mm) | Depth (mm) | Aspect Ratio | Tool | Risk |
|---|---|---|---|---|---|
| Micro cooling hole | 1.20 | 4.80 | 4.00 : 1 | Carbide | Controlled |
| Fixture plate hole | 3.00 | 12.00 | 4.00 : 1 | HSS | Controlled |
| Manifold passage | 6.00 | 36.00 | 6.00 : 1 | Coated Carbide | High |
| Deep steel bore | 8.00 | 72.00 | 9.00 : 1 | Coated Carbide | Critical |
| Composite stack drill | 5.00 | 20.00 | 4.00 : 1 | Carbide | Controlled |
Formula used
Aspect Ratio = Hole Depth ÷ Drill Diameter
Maximum Depth = Target Aspect Ratio × Drill Diameter
Required Diameter = Hole Depth ÷ Target Aspect Ratio
Drill aspect ratio expresses how deep a hole is relative to tool diameter. Higher ratios usually increase chip evacuation difficulty, heat, deflection, and alignment sensitivity. This page also estimates a planning guideline ratio from material, tool type, and coolant choice.
How to use this calculator
- Select the mode matching your design question.
- Enter the known dimensions in millimeters.
- Choose work material, tool type, and coolant method.
- Press calculate to show results above the form.
- Review aspect ratio, utilization, and guideline depth.
- Check the graph to see how depth changes ratio.
- Export the result as CSV or PDF if needed.
Frequently asked questions
1. What does drill aspect ratio mean?
It compares hole depth to drill diameter. A 60 mm deep hole drilled with a 10 mm tool has a 6:1 aspect ratio.
2. Why does a higher ratio matter?
Higher ratios usually raise the chance of tool deflection, poor chip evacuation, extra heat, and surface quality problems during drilling.
3. Is the guideline ratio an exact machining limit?
No. It is a planning estimate. Actual capability depends on spindle rigidity, holder quality, feed, speed, coolant pressure, and drill geometry.
4. Can I use inches instead of millimeters?
Yes, if every input uses the same unit. The ratio is unitless, so matching units keep the result correct.
5. What is depth in diameters?
Depth in diameters is another way to state aspect ratio. A 5:1 ratio means the hole depth equals five drill diameters.
6. Why is peck interval shown?
It gives a planning suggestion for chip breaking and evacuation. Use machine manuals and tooling guidance before setting real cycle values.
7. Does coolant choice change deep drilling performance?
Yes. Better coolant delivery often improves heat removal and chip transport, especially in deeper holes and tougher materials.
8. Which mode should I choose first?
Use aspect ratio mode when both dimensions are known. Use max depth or required diameter modes during design and process planning.