Case-hardening response
Carbon can be introduced at the surface and followed by quenching and tempering to create high surface hardness while retaining lower-carbon core behavior.
Custom 8620 alloy steel machining in China
China factory OEM CNC machined 8620 steel parts
We manufacture custom CNC machined 8620 steel parts from customer drawings, 3D models, physical samples and functional requirements. Our 8620 CNC machining service supports precision shafts, gears, pinions, splined components, sleeves, hubs, bushings and other wear-resistant alloy steel parts. Production can be arranged from one prototype or replacement component through low-volume batches and repeat mass production.
AISI 8620 is especially valuable when a component needs two different behaviors: a hard, wear-resistant case and a comparatively tough core. CNC turning, CNC milling, drilling, boring, reaming, threading, spline machining, gear-related features, heat-treatment allowance, finish grinding and dimensional inspection can be coordinated around the final drawing requirements.
Manufactured from drawings, CAD data or physical samples
Prototype, low-volume and mass-production support
Machining planned around carburizing and final grinding
Dimensional inspection selected for each critical feature
Material overview
Why manufacturers specify SAE 8620 steel
SAE 8620 is a low-carbon nickel-chromium-molybdenum alloy steel widely selected for carburized mechanical parts. The alloy combines useful machinability before heat treatment with the hardenability required to produce a durable case and a load-bearing core.
Wear and contact duty
The hardened case can resist sliding wear, rolling contact stress and repeated tooth or spline engagement in power-transmission components.
Tough supporting core
Nickel, chromium and molybdenum improve hardenability and help the core carry shock and bending loads after an appropriate heat-treatment cycle.
Machining before hardening
Most material removal is completed in the annealed, normalized or supplied condition, with planned stock left only where post-heat-treatment finishing is needed.
Related products
Custom machined 8620 steel parts
Representative OEM steel components include splined shafts, gear-and-shaft assemblies, cutting components and precision transmission parts. Every production part is made to the geometry, tolerance, heat-treatment and surface requirements stated on the customer drawing.
Custom spline shaft
Machined cutting component
Gear and splined shaft
8620 precision splined shaft
Composition and performance
AISI 8620 steel properties for CNC machining
Alloy composition, starting condition, section size, carburized case depth, quench severity and tempering cycle all influence the final result. Drawing requirements should therefore separate raw-material chemistry, core properties, case hardness, effective case depth and finished dimensions.
| Element | Typical SAE 8620 range by weight | Practical influence |
|---|---|---|
| Carbon | 0.18–0.23% | Supports machinability in the core and allows a high-carbon case to be created by carburizing. |
| Manganese | 0.70–0.90% | Contributes to strength and hardenability. |
| Silicon | 0.15–0.35% | Functions as a deoxidizer and contributes modestly to strength. |
| Nickel | 0.40–0.70% | Supports toughness, especially in the load-bearing core. |
| Chromium | 0.40–0.60% | Improves hardenability, wear behavior and carbide formation in the case. |
| Molybdenum | 0.15–0.25% | Improves hardenability and helps maintain useful core strength. |
| Phosphorus | 0.040% maximum | Controlled as a residual element because excess content can reduce toughness. |
| Sulfur | 0.035% maximum | Controlled to balance machinability and mechanical performance. |
Chemical ranges are typical reference values for SAE 8620. The purchase specification, applicable product standard, bar or forging condition and actual heat analysis must govern production. A grade name alone does not define final mechanical properties.
Density and stiffness
Typical density is approximately 7.8–7.9 g/cm³ and elastic modulus is approximately 200–210 GPa, similar to many engineering alloy steels.
Surface hardness
A carburized, quenched and tempered case is commonly specified around 58–62 HRC, but the drawing and heat-treatment specification must define the acceptable range.
Core properties
Core hardness, tensile strength and impact behavior depend strongly on section size, material hardenability and the exact thermal cycle.
Case depth
Effective case depth is selected from contact stress, wear allowance and component size. Values around 0.5–1.5 mm are common, but thinner or deeper cases may be specified.
Machinability
8620 machines well in a softer supplied condition. Stable workholding, controlled tool load and appropriate cutting data help maintain concentricity and tooth-location accuracy.
Dimensional response
Carburizing and quenching can move bores, faces, splines and long shafts. Process planning must anticipate distortion rather than treating heat treatment as a final cosmetic step.
Weldability
The low carbon level can permit welding with a controlled procedure, but welding near carburized or finish-hardened surfaces is generally avoided unless engineering approval is provided.
Corrosion behavior
8620 is not stainless steel. Oil, conversion coating, plating, paint or another corrosion-control system may be required for storage and service exposure.
Cross-standard comparison
8620 equivalent and related material grades
International designations are frequently compared during global sourcing, but they are not automatically interchangeable. Chemistry limits, hardenability bands, cleanliness requirements, product form, grain size and heat-treatment response must be checked before substitution.
| Country or system | Common designation | Relationship to SAE 8620 | Engineering note |
|---|---|---|---|
| United States | SAE/AISI 8620; UNS G86200 | Primary American designation used for the material on this page. | 8620H is a hardenability-controlled variant and should not be assumed identical to ordinary 8620 without review. |
| European EN | 20NiCrMo2-2; material number 1.6523 | Frequently cross-referenced European case-hardening grade with closely overlapping alloy content. | Confirm the applicable EN product standard and compare every chemistry limit on the drawing or purchase specification. |
| United Kingdom | 805M20 | Commonly cited British comparison for a low-carbon Ni-Cr-Mo case-hardening steel. | Legacy and current specifications may differ; verify revision, condition and hardenability requirements. |
| Japan | JIS SNCM220 | Common Japanese comparison with similar carbon, nickel, chromium and molybdenum ranges. | Use the current JIS specification and approve substitution from a direct composition and property comparison. |
| China | GB/T 3077 20CrNiMo | Common Chinese alternative used for gears, shafts and other carburized parts. | Some manganese, chromium, nickel and molybdenum limits differ from SAE 8620, so it is a related grade rather than a universal drop-in replacement. |
For custom 8620 steel parts, the safest drawing practice is to state the required standard and revision, permitted alternatives, raw-material condition, hardenability requirement if applicable, core hardness, case hardness and effective case depth. Substitution should be approved before material is cut.
Manufacturing capability
CNC machining processes for 8620 steel parts
The manufacturing route is chosen from geometry, annual quantity, datum structure, heat-treatment condition and the relationship between critical features. Combining operations in stable setups can reduce accumulated error and improve repeatability.
CNC turning
Outside diameters, shoulders, tapers, grooves, seal lands, threads, bores and end faces for shafts, hubs, sleeves, rollers and bushings.
Three-axis CNC milling
Flats, pockets, keyways, slots, mounting faces, hole patterns and prismatic features on blocks, hubs and transmission components.
Four-axis machining
Indexed radial holes, circumferential features, multiple keyways and milled profiles around shafts with fewer datum transfers.
Five-axis machining
Compound-angle holes, complex faces and multi-sided geometry where controlled access and fewer setups improve feature relationships.
Gear and spline features
External or internal tooth and spline features can be planned by milling, hobbing, shaping, broaching or wire EDM according to geometry and volume.
Drilling and precision bores
Drilling, boring, reaming, spot-facing and counterboring produce assembly holes, bearing seats, dowel locations and oil passages.
EDM operations
Wire EDM or sinker EDM may be used for sharp internal details, narrow slots, hardened profiles or features that are inefficient to cut conventionally.
Post-treatment finishing
Cylindrical grinding, surface grinding, honing, hard turning or selective polishing can restore critical dimensions after heat treatment.
Carburizing-aware production
Planning 8620 machining around case hardening
A good process plan begins with the final hardened geometry. Case depth, masked areas, grinding stock, stock-removal limits and distortion risk are decided before rough machining, not after the parts leave heat treatment.
Define the functional case
Identify surfaces that require hardness, the effective case-depth criterion, permitted soft areas and any hardness transition requirements.
Machine the stable datum system
Establish centers, faces, bores and reference surfaces that can be reused through roughing, finishing and final inspection.
Leave controlled finish stock
Reserve material on bearing journals, seal diameters, precision faces or bores that will be ground or hard-finished after carburizing.
Protect selected surfaces
Threads, weld areas, centers, deep holes or features that must remain machinable may require masking or copper plating under the heat-treatment plan.
Carburize, quench and temper
A process-specific thermal cycle develops the specified case and core. Fixture method, load arrangement and quench control influence distortion.
Finish and verify
Critical features are ground or hard-finished, then checked for size, form, location, surface texture and specified hardness or case-depth results.
Accuracy and finish
Machining tolerances and surface quality
Achievable values depend on feature size, length-to-diameter ratio, wall thickness, datum access, material condition, heat treatment, quantity and inspection method. The ranges below are realistic planning references, not universal limits for every 8620 part.
| Feature or process | Typical planning capability | Important conditions |
|---|---|---|
| General CNC turned or milled dimensions | Often ±0.05 mm | Suitable for many non-critical dimensions before heat treatment. |
| Precision machined dimensions | Often ±0.01–0.02 mm | Requires stable geometry, controlled setup, appropriate tool access and matched inspection. |
| Ground journals and selected diameters | Approximately ±0.003–0.008 mm where geometry permits | Normally completed after heat treatment; roundness and cylindricity must be specified separately when functional. |
| Precision bores | H7 or drawing-specific limits may be achievable | Method may include boring, reaming, honing or internal grinding according to size and condition. |
| Position, runout and concentricity | Drawing-specific geometric tolerances | Results depend on datum design, setup sequence, section rigidity and whether features are measured before or after hardening. |
| Standard CNC turned or milled finish | Commonly Ra 1.6–3.2 µm | Tool path, feed, insert geometry, stock condition and feature accessibility affect texture. |
| Fine machined finish | Commonly Ra 0.8–1.6 µm | Applicable to selected accessible surfaces with a dedicated finish operation. |
| Ground or honed finish | Commonly Ra 0.2–0.8 µm | The process is selected from functional directionality, size, form tolerance and stock allowance. |
Dimensions that deserve explicit controls
- Bearing seats, seal lands and press-fit diameters
- Spline major diameter, minor diameter, tooth thickness and runout
- Gear pitch relationship to bore and mounting faces
- Coaxial journals machined across multiple diameters
- Hole position from functional datums
- Flatness, parallelism and perpendicularity after heat treatment
Details needed for reliable inspection
- Clear datum references and a consistent dimension origin
- Separate size, form, orientation and location tolerances
- Surface roughness only on functionally important areas
- Measurement condition for heat-treated or coated dimensions
- Gear, spline, thread and keyway standard with class or fit
- Defined sampling or reporting requirements for production batches
Heat treatment and surface protection
Finishing options for machined 8620 components
Case hardening changes mechanical performance; coatings and conversion finishes mainly change corrosion behavior, appearance, friction or break-in performance. The sequence must account for masking, hydrogen-embrittlement risk, dimensional buildup and post-treatment grinding.
Carburizing
The principal treatment for 8620 gears, pinions, shafts and wear surfaces requiring a hard case over a tough core.
Carbonitriding
A shallower case-hardening option for selected small parts when the drawing and service conditions call for it.
Black oxide
A thin dark conversion finish used for appearance and light corrosion protection when paired with oil or wax.
Phosphate coating
Zinc or manganese phosphate can support oil retention, running-in behavior, paint adhesion or temporary corrosion protection.
Zinc plating
Provides sacrificial corrosion protection; coating thickness, masking and post-plating treatment must suit the hardened part.
Electroless nickel
Offers relatively uniform coverage and improved corrosion or wear behavior, with dimensional buildup included in final limits.
Shot peening
Can introduce compressive surface stress on specified regions to support fatigue performance when the process is properly controlled.
Paint or powder coating
Suitable for non-fitting external areas that need color and environmental protection; threads, datums and fits are normally masked.
Typical applications
Common parts made from 8620 alloy steel
8620 is most useful where surface contact or wear is severe but the entire section should not become extremely hard and brittle. Part suitability still depends on load spectrum, geometry, lubrication, impact, case depth and core-property requirements.
Transmission gears
Pinion gears
Ring gears
Worm gears
External splined shafts
Internal spline hubs
Drive shafts and axles
Clutch hubs
Camshafts and cams
Sprockets
Bushings and sleeves
Guide pins and piston pins
Rollers and bearing components
Collets and tool holders
Couplings and drive hubs
Custom wear-resistant machine parts
End-use sectors
Industries using CNC machined 8620 parts
Custom 8620 components serve power transmission, motion systems and heavy-duty mechanisms where repeat contact, torque, shock and wear must be balanced against manufacturability and cost.
Automotive and mobility
Differential parts, transmission components, hubs, shafts, pinions and other case-hardened drive elements.
Industrial gearboxes
Custom gears, splines, couplings, output shafts and compact power-transmission components.
Agricultural equipment
Sprockets, shafts, pins and drivetrain parts exposed to impact, dirt and intermittent loading.
Mining and construction
Wear-resistant mechanical components for drives, handling systems and rugged machinery assemblies.
Oil and gas equipment
Selected drive, coupling and tool components where the material and heat-treatment specification fits the service environment.
Material handling
Rollers, hubs, sprockets and drive-system parts for conveyors, lifting systems and warehouse machinery.
Pumps and compressors
Selected shafts, sleeves, gears and motion-transfer components outside unsuitable corrosive service.
Automation and robotics
Compact splined shafts, pinions, rotary elements and precision wear parts for repeated motion.
Machining and inspection
Production control for precision 8620 steel components
Inspection equipment is matched to the feature being controlled. Shop-floor checks support process stability, while optical and coordinate measurement are used for dimensions and geometric relationships that need more complete verification.
CNC milling
Controlled fixtures, datum planning and tool-path strategy support repeatable faces, pockets, slots and hole patterns.
CNC turning
Turning operations establish functional diameters, shoulders, bores, threads and coaxial reference features.
Optical measurement
A 2D profile projector is useful for profiles, radii, edge features, angles and selected small-part dimensions.
CMM inspection
Coordinate measurement supports complex datum systems, hole locations, profiles and geometric relationships.
Incoming material checks
Grade, product form, starting condition and blank dimensions are reviewed against the manufacturing plan before machining begins.
In-process dimensional checks
Critical diameters, lengths, runout, tool wear and datum locations are monitored before value is added by later operations.
Gear and spline verification
Feature-specific gauges or measurement methods can check fit, tooth thickness, runout, lead, profile or span dimensions as required.
Surface texture checks
Specified sealing, bearing and sliding surfaces can be evaluated with a roughness tester using the drawing’s parameter and cutoff requirement.
Hardness verification
Surface and core hardness checks are coordinated with the heat-treatment requirement and the permitted test location.
Final dimensional review
Finished parts are evaluated in their required post-treatment condition, including coating or grinding where dimensions depend on those operations.
Drawing-to-production workflow
From one custom part to repeat production
Prototype and volume production use the same engineering logic, but the fixture, inspection frequency, tool strategy and process controls are scaled to the quantity and repeat-order requirement.
Requirement review
Drawing, model, material, heat treatment, quantity and end-use priorities are checked together.
Manufacturing plan
Datums, machines, setups, tooling, treatment sequence, finishing stock and inspection methods are defined.
Blank preparation
Bar, tube, plate or forging is selected and cut with allowance for clamping, scale removal and machining.
Rough machining
Major stock is removed while leaving support and finish allowance where distortion or heat treatment matters.
Precision machining
Critical features are produced in a controlled sequence to manage location, runout and accumulated tolerance.
Thermal processing
Carburizing or another specified cycle is completed with masking, test method and distortion considerations.
Finish operations
Grinding, honing, hard turning, deburring and protective finish are applied only where the drawing requires them.
Final verification
Dimensions, geometry, surface texture and specified heat-treatment results are reviewed before packing.
Flexible order quantities
8620 CNC machining from prototype to mass production
Order size changes the most economical route, but not the need for clear datums, controlled processes and measurable requirements. Production planning can evolve from a single validation part into fixtures and repeatable batch controls.
One-off parts
Replacement components, development hardware and special machine parts produced without a high minimum quantity.
Prototype batches
Small quantities used to verify assembly, function, material choice, case-depth strategy and dimensional response.
Low and medium volume
Reusable workholding, planned tool life and defined in-process checks improve consistency and unit economics.
Repeat mass production
Dedicated fixtures, stable programs, controlled tool replacement and batch inspection support long-running requirements.
Engineering input
Information to define on an 8620 part drawing
A complete technical package reduces assumptions, shortens process planning and helps the manufacturer choose the correct machining, heat-treatment and inspection route.
Geometry and dimensional data
- 2D drawing with revision and a matching STEP, IGES, Parasolid or other 3D model when available
- Functional datums, fits, threads, gear data, spline standard and geometric tolerances
- Dimensions that apply before heat treatment, after heat treatment or after coating
- Deburring, edge-break, undercut, center-hole and grinding-relief requirements
- Assembly interfaces and any dimensions that must be matched to a mating component
Material and performance data
- SAE 8620, 8620H or an approved cross-standard grade with the governing specification
- Starting condition, product form and any special hardenability or cleanliness requirement
- Carburized case hardness, core hardness and effective case depth with a defined test method
- Masking, copper plating, soft-machining zones and post-treatment stock-removal restrictions
- Surface finish, protective coating, quantity per order and expected repeat demand
Material selection guidance
8620 steel compared with common alternatives
The best alloy is determined by the required property profile. A cross-standard equivalent matches a similar chemistry system; an alternative grade may solve the same design problem by a different heat-treatment route.
8620 versus 4140
Choose 8620 when a carburized wear case and tough core are central. Consider 4140 when through-hardening, higher bulk carbon and general high-strength service are more appropriate.
8620 versus 9310
9310 contains substantially more nickel and is often considered for more demanding core toughness and fatigue duty, with higher material and processing cost.
8620 versus 16MnCr5
16MnCr5 is a widely used European case-hardening steel with a different alloy balance. It may suit gears and shafts, but it is not chemically identical to 8620.
8620 versus stainless steel
8620 offers a strong case-hardening route but limited corrosion resistance. Select a suitable stainless grade when environmental resistance is the primary requirement.
Related search topics
Custom 8620 machining services and search terms
The phrases below reflect common ways engineers and purchasing teams describe custom 8620 alloy steel machining, carburized parts, transmission components and international material comparisons.
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Technical FAQ
Frequently asked questions about 8620 CNC machining
These answers summarize the main design and purchasing questions for custom CNC machined 8620 steel parts. Final decisions must always follow the specific drawing and service conditions.
What is AISI 8620 steel?
AISI 8620 is a low-carbon nickel-chromium-molybdenum alloy steel commonly used for carburized parts that need a hard, wear-resistant surface and a tougher core.
Is 8620 steel suitable for gears?
Yes. It is widely selected for gears, pinions, splines and other contact-loaded transmission parts. Tooth geometry, case depth, core strength, finish and lubrication must suit the load.
Should 8620 be machined before or after carburizing?
Most machining is normally completed before carburizing. Critical hardened dimensions may receive grinding, honing, hard turning or EDM after heat treatment.
Can carburized 8620 reach about 60 HRC?
A case hardness around 58–62 HRC is common with an appropriate carburize, quench and temper cycle. The exact range, test method and test location should be specified.
Is 8620 the same as 20NiCrMo2-2 or SNCM220?
They are frequently cross-referenced because their alloy systems and chemistry ranges are similar. They should still be treated as comparable grades until the governing specifications are checked and substitution is approved.
What is the Chinese equivalent of 8620?
GB/T 3077 20CrNiMo is a commonly used Chinese comparison. Its composition limits are not identical in every element, so the substitution must be reviewed against the drawing and performance requirements.
What tolerances can be held on 8620 machined parts?
General CNC dimensions are often planned around ±0.05 mm, while selected stable features may reach ±0.01–0.02 mm. Ground features can be tighter. Geometry and heat-treatment distortion determine what is practical.
What surface finish is available?
Standard CNC machining commonly produces Ra 1.6–3.2 µm, fine machining may reach Ra 0.8–1.6 µm, and grinding or honing can produce approximately Ra 0.2–0.8 µm on suitable features.
Can one custom 8620 component be produced?
Yes. Manufacturing can begin with one prototype, repair or replacement part and then scale to low-volume or repeat production after fit and function are confirmed.
Which files are useful for an 8620 machining project?
A controlled 2D PDF or DWG drawing plus a matching STEP, IGES or Parasolid model is ideal. Physical samples can also be used when drawings are incomplete, with critical requirements defined separately.
OEM alloy steel machining
Custom 8620 steel parts manufactured to drawings and samples
Our China factory supports CNC machined 8620 steel parts for new product development, equipment replacement, low-volume industrial demand and repeat mass production. Material selection, machining sequence, carburizing allowance, final finishing and inspection are planned as one connected process so the finished component can meet its dimensional and functional requirements.