Material Index
Hard data on the physical properties and machinability of common industrial alloys and polymers.
The baseline for machinability ratings is AISI 1212 cold-drawn steel, arbitrarily assigned a rating of 100%. Materials with ratings below 100% are harder to machine, while those above 100% are easier.
| Material Grade | Type | Machinability | Yield Strength (ksi) | Hardness (Brinell) |
|---|---|---|---|---|
| Carbon & Alloy Steels | ||||
| 1018 Cold Drawn | Low Carbon | 78% | 54 | 126 |
| 4140 Annealed | Chromium-Moly | 65% | 60 | 197 |
| Stainless Steels | ||||
| 304 | Austenitic | 45% | 30 | 129 |
| 17-4 PH (Cond. A) | Martensitic | 40% | 110 | 277 |
| Aluminum Alloys | ||||
| 6061-T6 | Wrought | 270% | 40 | 95 |
| 7075-T6 | Aerospace | 150% | 73 | 150 |
Applying Machinability Ratings
A machinability rating is not just a relative difficulty score; it is a direct multiplier used to calculate starting surface speeds. If the baseline 1212 steel has a recommended cutting speed of 100 SFM with a specific tool, and 304 Stainless has a rating of 45%, your starting SFM for 304 Stainless with that same tool should be 45.