Why are cutting speed and feed rate so important when purchasing Inconel 718 bar stock?
For purchasing professionals, machinability is just as critical as mechanical properties. When machining Inconel 718 bar stock, incorrect cutting speeds and feed rates can lead to a 30% to 50% increase in tool wear, longer machining cycles, and significantly higher overall part costs.
Understanding recommended cutting parameters helps purchasing personnel to:
1. Select the appropriate bar stock condition (solution annealed or age-hardened)
2. Estimate true machining costs
3. Avoid suppliers who provide non-optimized materials
4. Improve delivery reliability and better control scrap rates
Machining Characteristics of Inconel 718 Rods
Inconel 718 (UNS N07718) is a precipitation-hardened nickel-based superalloy characterized by: high yield strength (≥1,000 MPa after aging treatment), significant work hardening, low thermal conductivity (approximately 11 W/m·K), and high concentration of heat at the cutting edge of the tool.
Buyer's Note:
Compared to stainless steel or low-alloy steel, these characteristics require lower cutting speeds, greater feed stability, and more robust tool clamping devices.
Recommended Cutting Speeds & Feeds
3.1 Turning – Inconel 718 Bar
| Tool Material | Cutting Speed (m/min) | Feed (mm/rev) | Depth of Cut (mm) |
|---|---|---|---|
| Carbide (Coated) | 20–35 | 0.10–0.25 | 1.0–3.0 |
| Ceramic | 60–120 | 0.15–0.30 | 0.5–2.0 |
| CBN | 80–150 | 0.10–0.20 | 0.3–1.5 |
3.2 Milling – Inconel 718 Bar
| Tool Type | Speed (m/min) | Feed per Tooth (mm) | Notes |
|---|---|---|---|
| Solid Carbide End Mill | 20–30 | 0.03–0.08 | Flood coolant recommended |
| Indexable Carbide | 25–40 | 0.06–0.12 | Use sharp positive inserts |
| Ceramic End Mill | 80–150 | 0.05–0.10 | Dry or minimal coolant |
3.3 Drilling – Inconel 718 Bar
| Drill Type | Speed (m/min) | Feed (mm/rev) |
|---|---|---|
| Solid Carbide | 8–15 | 0.05–0.15 |
| Indexable Drill | 10–20 | 0.10–0.25 |
4. Effect of Material Condition on Speeds and Feeds
| Bar Condition | Hardness | Machining Impact |
|---|---|---|
| Solution Annealed | ~220–260 HB | Best machinability |
| Aged (AMS 5663) | ~330–380 HB | Reduce speed by 20–30% |
| Cold Worked | Variable | High tool wear risk |
Is Inconel 718 difficult to machine?
Yes, Inconel 718 is notoriously difficult to machine due to its high strength, rapid work-hardening properties, and low thermal conductivity, which cause high cutting forces, rapid tool wear, and heat buildup, requiring robust machinery, specific tool grades, slow speeds, and heavy cuts.
What cutting speed is recommended for turning Inconel 718 bar?
For turning Inconel 718, recommended cutting speeds vary significantly with tool type, generally ranging from 40-55 m/min (130-180 SFM) with coated carbides for standard operations, but can reach 400-600 m/min with advanced tools like cBN for high-speed finishing, while roughing might start lower (30-80 m/min) to manage work hardening.
Should I buy solution-annealed or aged Inconel 718 bar?
You should buy aged Inconel 718 (precipitation hardened) if you need maximum strength and hardness for your finished part, avoiding post-machining heat treatment; choose solution-annealed 718 if you need easier machining and plan to perform the age-hardening treatment yourself later, but expect higher final strength after aging.
Inconel 718 suppliers
At GNEE, Inconel 718 is available in various forms to meet diverse industrial needs:
Plates and Sheets (cold rolled and hot rolled)
Bars and Rods (round, square, hexagonal)
Tubes (seamless and welded)
Wires and Strips (for springs, fasteners, electrical applications)
Forgings and Custom Parts (according to drawings or specifications)
Specifications: UNS NO7718, WNR 2.4668, AFNOR NC19FeNb, JIS NCF 718, GOST ХН75МБТЮ, EURONORM NiCr22Mo9Nb, OR ЭИ602, BS NA 21.
Temperature Range: -423°F to 1300°F.
Testing and Documentation: Mill Test Certificates, EN 10204 3.1, Chemical Reports, Mechanical Reports, Destructive Testing Reports, Non-Destructive Testing Reports, PMI Test Reports, Visual Inspection Reports, Third-Party Inspection Reports, NABL Certified Laboratory Reports.
Packaging: Wooden crates, bubble wrap, steel strapping, or packaged according to customer requirements.
