5-Axis CNC Machining Inconel 718 — No Compromises.
Custom Inconel 718 CNC machining is among the most demanding work in precision manufacturing. This nickel superalloy work-hardens instantly, destroys tooling, and traps heat in ways that collapse dimensions. Baosheng runs dedicated Inconel 718 machining programs — purpose-built tooling, high-pressure coolant, 5-axis one-setup strategies — from 1 prototype piece to production batches. AMS 5664 certified stock. Full traceability. Quote in 2 hours.
- AMS 5664 / AMS 5662 certified stock
- 5-axis simultaneous in-house
- EN 10204 3.1 mill certs
- ISO 9001 + AS9100 aligned
// Inconel 718 chemistry (nominal)
Nickel + Cobalt：50–55 %
Chromium：17–21 %
Niobium + Tantalum：4.75–5.50 %
Molybdenum：2.8–3.3 %
Titanium：0.65–1.15 %
Aluminium：0.20–0.80 %
// Mechanical properties (solution + aged)
Tensile strength：1,375 MPa
Yield strength：1,100 MPa
Hardness：38–46 HRC
Service temperature：Up to 704 °C
Thermal conductivity：11.4 W/m·K (low — heat issue)
// Machining parameters (rough guidance)
Machinability index：~18 (vs Al 6061 = 80)
Cutting speed Vc：25–45 m/min
Tooling：PVD / CVD coated carbide
Coolant：High-pressure ≥70 bar — mandatory
~18/80
Machinability vs Al 6061
1,375MPa
Tensile strength
704°C
Max service temperature
5-axis
In-house simultaneous
Standards
ISO 9001:2015 AMS 5664 / AMS 5662 stock EN 10204 3.1 mill cert CMM inspection report NDA & full IP protection Quote in 2 hours
The 4 Properties That Make Inconel 718 a Machining Challenge
Any supplier can say they machine Inconel 718. Very few have the tooling programs, coolant infrastructure, and 5-axis strategy to do it without destroying margin — or the part. Here’s exactly why, in engineering terms.
Extreme work-hardening — the surface hardens as you cut it
Inconel 718 work-hardens more aggressively than any common stainless steel. The instant a tool touches the surface, the material beneath the cut becomes harder than the substrate. If the tool dwells or rubs instead of cutting cleanly, the next pass encounters a significantly harder surface — leading to accelerated tool wear, vibration, and dimensional scatter.
Practical consequence:Sharp tools at all times. No dwell codes in the CNC program. No feed-hold in a cutting zone. Interrupted cuts minimised with 5-axis approach strategies that maintain continuous chip formation.
Low thermal conductivity — 97% of the heat goes into the tool
At 11.4 W/m·K thermal conductivity, Inconel 718 is roughly 14× worse than aluminium at dissipating heat. During cutting, the vast majority of generated heat flows into the tool and chip — not into the workpiece. Tool tip temperatures exceed 700–900°C within seconds. Carbide softens. Chemical diffusion wear begins. Tool life collapses.
Practical consequence:High-pressure through-spindle coolant at ≥70 bar is non-negotiable. Flood coolant is insufficient — the pressure jet must physically break through the thermal barrier at the cutting edge. Dry cutting Inconel is not a choice; it is tool destruction.
High strength retained at temperature — won’t soften when hot
Most metals weaken at elevated temperatures — machining exploits this to reduce cutting force. Inconel 718 does not. It retains over 80% of its room-temperature strength at 600°C. This means the cutting force at machining temperatures is nearly identical to the force at room temperature, producing consistently high spindle loads that fatigue tooling and machine spindle bearings rapidly.
Practical consequence:Conservative radial and axial depths of cut. High-feed, low-speed tool paths that maximise material removal rate within spindle load limits. Toolpath verified in simulation before running — especially on thin walls and complex 5-axis geometries.
Abrasive carbides in the matrix — tools wear by two mechanisms simultaneously
Inconel 718’s precipitation-hardening microstructure contains Nb-rich δ-phase (Laves) and γ” precipitate carbides that are harder than the carbide binder in cutting tools. This means tools experience both thermal/chemical wear (from heat) and abrasive wear (from hard particles) simultaneously — a combination that multiplies wear rate by a factor of 3–5× compared to stainless steel machining at the same cutting speed.
Practical consequence:CVD-coated submicron carbide grades only. TiAlN or AlTiN PVD coatings where heat is the dominant wear mechanism (finishing). Dedicated Inconel tooling never shared with titanium or stainless — cross-contamination of cutting geometry degrades performance immediately.
Our Inconel 718 machining — systematic, not improvised
Dedicated tooling programs per grade. High-pressure spindle coolant on every cut. 5-axis one-setup strategy to minimise interruptions. Every CNC program reviewed by engineer before it runs on a £100/kg billet. No trial-and-error on your material.
5-Axis CNC Machining for Inconel 718 — Not Optional, Necessary
5-axis machining is not just about geometric complexity on Inconel 718. Every extra setup is a re-clamping, a re-datum, and additional interrupted cuts through work-hardened surfaces. 5-axis simultaneous eliminates all three problems in one decision.
01 — SETUP REDUCTION
One clamping eliminates datum error accumulation
A complex Inconel 718 aerospace bracket machined in 4 setups on a 3-axis VMC accumulates positional error at each re-clamp. On titanium or aluminium this is manageable. On Inconel — where tolerances are tight and the part is expensive — any accumulated error can scrap a £400 billet. 5-axis simultaneous machines all faces in one clamping: one datum, zero accumulation.
Measured benefit:Positional accuracy on multi-face features improves from ±0.020–0.050mm (multi-setup) to ±0.005–0.010mm (one-setup 5-axis), purely from eliminating re-clamping error.
02 — INTERRUPTED CUT REDUCTION
Continuous cutting motion prevents work-hardening accumulation
Every time a 3-axis tool exits and re-enters the Inconel workpiece at a different approach angle, the surface has had time to work-harden at the exit point. The re-entry cut then starts on a harder surface — increasing cutting force, vibration, and edge wear. 5-axis simultaneous maintains continuous contact with consistent chip thickness, dramatically reducing the number of interrupted re-entries per operation.
Measured benefit:Tool life on complex Inconel parts increases 2–3× using 5-axis continuous cutting vs multi-setup 3-axis interrupted cutting strategies, on equivalent geometry.
03 — TOOL LENGTH MINIMISATION
Short tools, not long tools — the Inconel tooling principle
On a 3-axis machine, deep pockets and compound-angle features require long-reach tooling — end mills with L/D ratios of 6:1 or more. At these lengths, tool deflection under Inconel’s high cutting forces produces chatter, dimensional scatter, and surface integrity damage. 5-axis tilts the part to the tool, allowing the shortest possible tool to be used at every feature — dramatically reducing deflection and chatter.
Rule of thumb:Minimise tool overhang on every Inconel feature. Every 1× increase in effective L/D ratio approximately doubles the deflection force contribution to dimensional error. 5-axis eliminates most long-reach scenarios entirely.
04 — SURFACE INTEGRITY PROTECTION
Optimised tool approach angle preserves fatigue life
On aerospace and energy components, Inconel 718 surface integrity (residual stress state, white layer depth, microstructural damage) directly affects fatigue life — often the primary failure mode in service. 5-axis allows the tool approach angle and radial engagement to be optimised for compressive residual stress — particularly important on turbine blade leading edges, fillet radii, and bolt hole bores that are fatigue-critical locations.
Specification note:Surface integrity requirements (Ra, Rz, no white layer, residual stress state) should be specified on engineering drawings. Our DFM review will confirm 5-axis toolpath strategy compatibility before machining starts.
3-Axis vs 5-Axis for Inconel 718 Complex Parts — Side-by-Side
| FACTOR | 3-AXIS MULTI-SETUP | 5-AXIS SIMULTANEOUS |
|---|---|---|
| Setup count | 4–6 setups typical | 1 setup |
| Positional accuracy | ±0.020–0.050mm | ±0.005–0.010mm |
| Tool life (complex part) | Baseline | 2–3× better |
| Interrupted cut count | High — each setup change | Minimised — continuous |
| Lead timeLonger — setup changes | Longer — setup changes | 30–50% faster total |
| Billet scrap risk | Higher — cumulative error | Lower — single datum |
| Surface integrity control | Limited approach options | Full approach optimisation |
Inconel 718 vs Other Superalloys — When 718 is the Right Choice
| Property | Inconel 718 | Inconel 625 | Hastelloy C-276 | Waspaloy | Ti-6Al-4V |
|---|---|---|---|---|---|
| Tensile strength | 1,375 MPa | 830 MPa | 760 MPa | 1,275 MPa | 950 MPa |
| Max service temp. | 704 °C | 982 °C (corrosion) | 1,040 °C (corrosion) | 980 °C | 315 °C |
| Machinability index | ~18 | ~15 | ~12 | ~12 | 30–40 |
| Weldability | Good (age-hardened) | Excellent | Excellent | Limited | Good |
| Corrosion resistance | Very good | Excellent (seawater) | Outstanding (acids) | Good | Excellent |
| Density (g/cm³) | 8.22 | 8.44 | 8.89 | 8.19 | 4.43 |
| Relative cost (vs 718) | 1× baseline | 0.9× | 1.2× | 1.5× | 0.55× |
| Primary use case | Structural high-strength ≤704°C | Corrosion / high-temp ducting | Extreme acid/chloride | Gas turbine blades ≤980°C | High strength, light weight |
When to choose Inconel 718 vs alternatives
Inconel 718 is the right choice when you need high structural strength ≤704°C, good weldability, and proven aerospace qualification. If your application requires primarily corrosion resistance (chloride or acid environments) at lower mechanical loads, Inconel 625 or Hastelloy may serve better at lower machining cost. If service temperature exceeds 704°C, Waspaloy or CMSX single-crystal alloys are necessary. Our DFM review includes a grade-selection note for every Inconel order — we flag over-specification.
How We Machine Inconel 718 — 6 Non-Negotiable Protocols
Every Inconel 718 order at Baosheng runs against these six mandatory protocols. Each one is driven by the material’s physical behaviour — not by convention or preference.
01 — TOOLING SELECTION
CVD/PVD-coated submicron carbide — grade-specific
Roughing: CVD TiCN/Al₂O₃/TiN coated grades for maximum thermal barrier. Finishing: PVD TiAlN or AlTiN coated for sharp-edge retention and reduced edge buildup. Ceramic inserts used for semi-finishing on stable features where cutting speed can be pushed to 100–200 m/min. Dedicated Inconel tooling — never shared with titanium or steel between jobs.
Tool change protocol:Inconel jobs start with new or freshly measured tools. Tool wear monitored by cycle count and inspection of chip morphology. Any sign of built-up edge or chatter triggers immediate tool change — not “run to failure.”
02 — COOLANT STRATEGY
≥70 bar through-spindle — delivered at the cutting edge
Flood coolant is insufficient for Inconel 718. High-pressure through-spindle coolant at ≥70 bar (and up to 140 bar on critical finishing operations) physically penetrates the thermal barrier at the tool-chip interface. This is not a preference — removing it immediately degrades tool life by 60–80% and risks thermal damage to the workpiece surface that changes hardness and fatigue behaviour.
Zero-tolerance policy:If coolant delivery fails during an Inconel cut, the operation stops. Parts machined with interrupted or failed coolant are scrapped regardless of visual appearance — thermal damage is subsurface and not visible without metallographic cross-section.
03 — CUTTING PARAMETERS
Low Vc, high feed per tooth — counterintuitive but correct
Inconel 718 roughing: Vc 25–35 m/min with conventional carbide, 100–200 m/min with ceramics. Feed per tooth 0.08–0.15 mm/tooth (thick chips carry heat away — do not reduce below chip thinning threshold). Axial depth: 1.0–2.5× insert IC depending on stability. The instinct to reduce feed when facing difficulty is exactly wrong — reducing feed causes chip thinning, work-hardening, and rubbing.
Finishing strategy:Final passes with fresh tools: Vc 15–25 m/min, fz 0.05–0.08 mm/tooth, ap ≤0.3mm. No dwelling. Coolant on from entry to clear of workpiece. Ra verified with profilometer after each finishing pass.
04 — CHIP MANAGEMENT
Continuous chip evacuation — long stringy chips are a fire risk
Inconel 718 produces long, tough, stringy chips that wrap around tooling and workpiece features, causing recutting, heat concentration, and surface damage. Chip breaker geometry critical — not all insert geometries break Inconel chips at production feed rates. High-pressure coolant also serves as a chip flush. All Inconel machining includes chip conveyors and regular manual clearance checks on long-running programs.
Chip wrapping consequence:A wrapped Inconel chip re-cutting a finished surface creates surface integrity damage (white layer, tensile residual stress) that cannot be detected visually and can reduce fatigue life by up to 50% in service. Chip clearance is not optional.
05 — WORKHOLDING & FIXTURING
Maximum rigidity — vibration destroys Inconel tools in seconds
Chatter on Inconel 718 is catastrophic — not just annoying. Vibration during cutting causes work-hardening of the surface in a pattern that matches the vibration frequency, creating alternating hard and soft bands that rapidly wear the next tool pass. Fixtures designed for Inconel machining must eliminate every source of compliance: no thin clamping arms, no overhang beyond what the 5-axis strategy requires, damped clamping for thin-wall features.
Thin-wall Inconel:Wall thickness below 2.5mm requires DFM review before quoting. Deflection under cutting force at Inconel’s high material strength can be significant. Our engineer will assess and recommend fixturing or geometry changes where needed.
06 — FIRST-ARTICLE & IN-PROCESS INSPECTION
Measure early, scrap nothing — Inconel billets are expensive
An Inconel 718 AMS 5664 billet costs 10–15× an equivalent aluminium billet by weight. Scrapping one because of a measurement error caught at final inspection is unacceptable. Our Inconel protocol: first-article CMM inspection after roughing (verify stock distribution for finishing), in-process inspection at each fixture change, full CMM before surface finishing — before you spend finishing time on a part that cannot be saved.
Inspection accuracy:CMM accuracy ±0.0008mm MPE. Temperature-stabilised measurement room 20°C ±0.5°C. Parts temperature-soaked minimum 4 hours before CMM on precision Inconel work (higher CTE impact than titanium at this temperature).
Where Custom 5-Axis Machined Inconel 718 Parts Are Used
Inconel 718’s combination of extreme strength, temperature resistance, and weldability makes it the default choice in three industries. Each has specific certification and documentation requirements.
Inspection & Documentation for Inconel 718 Parts
Inconel 718 parts go into safety-critical applications. Traceability is not optional — it is the product. Here is every inspection step and every document we produce.
Incoming material verification
AMS 5664 / AMS 5662 certificate verified against melt heat number before machining starts. XRF spot-check on every Inconel billet to confirm Ni/Cr/Nb/Mo spec. Rejected if chemistry outside AMS 5664 limits — regardless of supplier cert.
- EN 10204 3.1 mill certificate
Inspection plan creation
Every feature on your drawing mapped to a CMM measurement method before the first chip is cut. Critical characteristics flagged. Inspection plan reviewed and signed off by quality engineer — not by the machinist.
- Inspection plan PDF
Post-roughing CMM (before finishing)
After roughing, before finishing operations begin: CMM verifies stock distribution on all surfaces. This catches any distortion from machining stress relief early — before expensive finishing time is spent on a part that cannot be corrected.
Final CMM — 100% critical dimensions
Zeiss Contura G2 / Renishaw CMM. Actual vs. nominal with deviation for every critical dimension. CMM accuracy ±0.0008mm MPE. Parts temperature-soaked ≥4 hours at 20°C ±0.5°C before measurement. No batch sampling — every Inconel part fully inspected.
- CMM dimensional report
Surface integrity check (aerospace/energy)
Ra / Rz profilometer measurement on all specified surfaces. Visual inspection for white layer indicators (surface discolouration, heat tint). For critical aerospace applications: Barkhausen noise or X-ray diffraction residual stress measurement available on request.
- Surface finish report
Documentation — What Ships with Every Inconel 718 Order
| Document | Prototype | Production ≥10 pcs | PPAP / FAIR |
|---|---|---|---|
| EN 10204 3.1 mill certificate | ✓ Included | ✓ Included | ✓ Included |
| XRF material verification | ✓ Per billet | ✓ Per lot | ✓ Per lot |
| CMM dimensional report | ✓ 100% parts | ✓ 100% parts | ✓ 100% parts |
| Inspection plan | ✓ Included | ✓ Included | ✓ Included |
| Surface finish report (Ra) | On request | ✓ Included | ✓ Included |
| Process capability (Cpk) | N/A | On request | ✓ Included |
| First Article Inspection (FAIR) | N/A | On request | ✓ AS9102 format |
| PPAP Level 1–3 | N/A | On request | ✓ All levels |
FAIR and PPAP for Inconel 718 aerospace orders
First Article Inspection Reports (FAIR) per AS9102 and PPAP Level 1–3 packages are available for Inconel 718 production orders. Specify your requirement when submitting the RFQ — the DFM response will confirm document scope, any additional lead time required, and the cost of the quality package included in the itemised quote.
Custom Inconel 718 Machining — What Drives the Cost
Inconel 718 CNC machining is expensive — for specific, defensible reasons. Every cost driver is quoted as a separate line item so you can see exactly where the premium sits. And when we think a cheaper alternative achieves the same result, we say so in the DFM report.
Cost Drivers — Inconel 718 CNC Machining
Material cost — 10–15× aluminium per kg
AMS 5664 certified Inconel 718 billet costs 10–15× more than equivalent aluminium 6061, and 2–3× more than Ti-6Al-4V. Solution-annealed and age-hardened condition adds a further heat treatment premium. These are unavoidable material-grade costs, not machining margin.
- Highest absolute cost driver
Cycle time — 5–7× longer than aluminium
Machinability index ~18 vs 80 for aluminium means 4–5× longer base cycle time. Combined with slow finishing passes (Vc 15–25 m/min), mandatory tool change intervals, and temperature soak between operations, total Inconel cycle time runs 5–7× equivalent aluminium geometry. This is a machine-hour cost quoted transparently per operation.
- Major multiplier at any volume
Tooling consumption — most expensive per cut in common alloys
Tool life on Inconel 718 is typically 3–5× shorter than on titanium, and 15–20× shorter than on aluminium. CVD-coated carbide inserts for Inconel cost more than standard inserts and wear faster. At low volumes (1–5 pieces), tooling cost per part can exceed material cost for complex geometries with many features.
- Significant at 1–10 pc volume
5-axis programming & setup time
A complex Inconel 718 5-axis part requires 3–6 hours of CAM programming, simulation, and toolpath verification before the machine runs. This setup cost is absorbed 100% by a 1-piece order and amortised over larger batches. At 10+ pieces, the per-part setup contribution becomes minor. The 5-axis strategy is always worth it — it saves more in tool life and scrap than it costs in setup time.
- Amortised with volume
When Inconel 718 is the wrong choice — we’ll tell you
If your part operates below 400°C at moderate stress levels, 316L stainless or 17-4 PH may serve identically at 1/3 of the machining cost. If corrosion resistance is the primary driver and strength is secondary, Inconel 625 may be more appropriate at lower machining cost. Our DFM review always includes a grade-suitability note — we do not machine Inconel 718 when a cheaper alternative genuinely meets the spec.
- DFM catches over-specification
Indicative Inconel 718 Machining Pricing
Prototype / 1–3 pieces — simple geometry
From $280 / pc
AMS 5664 · 3-axis · ±0.025mm · CMM report · mill cert · 7–10 day lead
Complex 5-axis prototype (1–3 pcs)
From $750 / pc
AMS 5664 · 5-axis simultaneous · ±0.010mm · CMM 100% · mill cert + XRF · 10–14 day lead
Production run (10–100 pcs)
Volume pricing + Cpk documentation
Dedicated tooling program · SPC monitoring · PPAP / FAIR available · batch CMM
PPAP / FAIR aerospace package
On request · per part type
AS9102 FAIR · full traceability package · Cpk ≥1.67 on critical characteristics
Free Inconel DFM — Every Quote
Engineer reviews your drawing for grade suitability (is Inconel 718 actually required?), thin-wall vibration risk, 3-axis vs 5-axis strategy, tooling feasibility on complex features, and documentation package scope. Written report with cost breakdown. Average DFM-driven saving on Inconel orders: 10–25% through grade or geometry optimisation.
Upload STEP or 2D PDF · Quote in 2 hours · No obligation · NDA on request
Inconel 718 CNC Machining Supplier Comparison
| Capability | Baosheng Industry ✓ | General CNC platform | Standard job shop |
|---|---|---|---|
| AMS 5664 / AMS 5662 certified stock | In stock — from 1 piece | Supplier-dependent | Order lead 1–2 weeks |
| Dedicated Inconel tooling program | Yes — CVD/PVD per operation | Supplier-dependent | Rarely systematic |
| ≥70 bar through-spindle coolant | Mandatory on all Inconel cuts | Not verified | Often not available |
| 5-axis simultaneous in-house | Yes — no subcontracting | Network supplier | Often not available |
| EN 10204 3.1 mill cert + XRF | Included every order | Extra cost | On request only |
| Post-roughing CMM checkpoint | Standard on all Inconel | Not standard | Not standard |
| FAIR (AS9102) capability | Available — quoted per order | Limited | Rarely available |
| Free DFM with grade review | Written, every quote | Algorithm only | Verbal only |
| Quote turnaround | 2 hours — real engineer | Instant — algorithm | 2–5 days |
From Inconel Drawing to Finished Part — 5 Steps
1.Upload Drawing
STEP or 2D PDF. Specify grade (AMS 5664 or AMS 5662), condition, tolerance, quantity, and any cert requirements.
2.Inconel DFM
Engineer reviews grade suitability, thin-wall risk, 3-axis vs 5-axis strategy, tooling feasibility, and documentation scope. 2 hours.
3.Certified Quote
Material, tooling, cycle time, inspection, and certs itemised separately. Mill cert availability confirmed before you commit.
4.Machine & Inspect
Dedicated Inconel tooling. HP coolant. Post-roughing + final CMM. Every part inspected before it leaves the floor.
5.Certified Shipment
CMM report + AMS 5664 mill cert + XRF verification enclosed. Export packaging protects precision surfaces. Tracking at dispatch.
Custom 5-Axis CNC Machining Inconel 718 — Questions Answered
What makes Inconel 718 harder to machine than stainless steel?
Four compounding problems: (1) work-hardening — the surface hardens faster than stainless under the tool; (2) low thermal conductivity (11.4 W/m·K vs 16 for 316L) — nearly all heat goes into the tool; (3) hot strength retention — Inconel 718 doesn’t soften at machining temperatures, so cutting forces remain high throughout; (4) abrasive carbide precipitates in the microstructure accelerate tool wear mechanically while heat does the same chemically. These four factors combine to give Inconel 718 a machinability index of ~18 vs ~45 for 316L stainless.
Why is 5-axis machining specifically recommended for Inconel 718 parts?
Three structural reasons beyond geometry access: (1) Setup reduction — every re-clamp on an expensive Inconel billet introduces positional error and a new interrupted cut entry through work-hardened surface; (2) Tool length minimisation — 5-axis tilts the part to the tool, allowing short tools that resist deflection; (3) Continuous cutting — 5-axis simultaneous maintains contact and chip thickness through complex surfaces, reducing the interrupted cuts that accelerate work-hardening. For any Inconel 718 part with compound angles or multi-face features, 5-axis is the economically correct decision even if it costs more per setup-hour than 3-axis.
What AMS specifications do you stock for Inconel 718?
We stock AMS 5664 (solution annealed + precipitation hardened — the most commonly specified condition for aerospace structural applications) and AMS 5662 (solution annealed only — for applications requiring subsequent field welding before final aging). Both supplied with EN 10204 Type 3.1 mill certificates traceable to the melt heat. XRF verification on every billet as incoming inspection. Specify your required condition and UNS N07718 chemistry confirmation level when submitting your RFQ.
What tolerance can you hold on Inconel 718 parts?
Standard Inconel 718 tolerance on 5-axis one-setup machining: ±0.010–0.025mm on linear dimensions and ±0.010mm on positional features. With dedicated precision setup and thermal stabilisation: ±0.005mm on specific features is achievable. Note: Inconel’s higher coefficient of thermal expansion than aluminium combined with heat generated during machining means parts must be allowed to fully temperature-stabilise before CMM measurement — we enforce a minimum 4-hour soak at 20°C ±0.5°C on all precision Inconel work.
Do you provide FAIR (First Article Inspection Report) for Inconel 718 parts?
Yes — FAIR per AS9102 Rev D is available for Inconel 718 production orders. The FAIR package includes: balloon drawing, parts list, material certifications (AMS 5664 3.1 cert + XRF results), dimensional results for 100% of characteristics, functional test records where applicable, and process capability data (Cpk) on critical characteristics. Specify FAIR requirement and AS9102 level (partial vs full) when requesting the quote — it is priced as a separate line item in the quality package.
What coolant pressure do you use for Inconel 718 machining?
Minimum 70 bar through-spindle coolant on all Inconel 718 roughing and semi-finishing operations. Finishing operations on critical surfaces: up to 140 bar. The pressure is critical — not just the flow volume. The high-pressure jet must physically penetrate the thermal boundary layer at the tool-chip interface to extract heat before it transfers into the tool. Flood coolant (typically 3–8 bar) is insufficient for Inconel. If a machine cannot deliver ≥70 bar at the spindle, it should not be running Inconel 718 in our view.
How does Inconel 718 compare to Inconel 625 for machinability?
Inconel 625 has a machinability index of approximately 15 vs 18 for Inconel 718 — so 625 is actually slightly harder to machine due to its higher work-hardening rate and stronger matrix. However, 625 is typically specified at lower strength levels and simpler geometries (tubing, cladding, sheet metal parts), so the practical machining challenge is often less severe. If you’re choosing between 718 and 625 for a machined structural component, 718 is usually the better machining choice (marginally) while delivering significantly higher strength. Specify 625 only when corrosion resistance in seawater or oxidising acids is the primary requirement.
Is Inconel 718 actually needed, or can a cheaper alloy do the job?
This is the most important question — and the one our DFM review always answers explicitly. Inconel 718 is genuinely necessary when you need: tensile strength >800 MPa at temperatures above 400°C, or sour-service (H₂S) environments per NACE MR0175, or a weldable high-strength nickel alloy with proven aerospace qualification. For applications below 400°C, 17-4 PH stainless delivers similar strength at 1/4 the machining cost. For applications primarily requiring corrosion resistance rather than strength, 316L or 2205 duplex may suffice. We flag over-specification in writing — it saves you money and saves us explaining scrap risk on an unnecessarily hard-to-machine part.
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Custom 5-axis Inconel 718 machining. Done properly.
Upload your drawing. Free DFM reviews grade suitability, 3-axis vs 5-axis strategy, and documentation scope. Certified quote with AMS 5664 stock confirmation in 2 hours.
✓ AMS 5664 / 5662 in stock | ✓ EN 10204 3.1 cert included | ✓ 5-axis in-house | ✓ FAIR / PPAP available | ✓ Free DFM review | ✓ Quote in 2 hours