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CNC Machining Processes: The Complete List
91 processes and operations, from 3-axis milling to wire EDM and gear grinding. What each one does, the tolerance and surface finish it usually holds and the parts it is used for.
On this page
- Milling: machine configurations
- Milling: operations on the quote
- Turning
- Hole making and threading
- Grinding and abrasive finishing
- EDM (electrical discharge machining)
- Other CNC cutting and forming processes
- Heat treatment
- Surface finishing
- Process route
- Feature to process
Tolerance and surface roughness (Ra) are typical values a shop holds without special effort. They are a starting point for the conversation, not a quote and not the limit of the process.
Milling: machine configurations
Milling removes material with a rotating cutter while the part or the spindle moves along programmed axes. The machine configuration decides how many faces a shop can reach in one setup, which drives both price and feature-to-feature accuracy.
| Process | What it does | Typical tolerance | Typical Ra | Used for |
|---|---|---|---|---|
| 3-axis milling (VMC) | Tool moves in X, Y and Z over a fixed part. One face per setup. | ±0.025 mm, ±0.01 mm on request | 1.6 to 3.2 µm | Plates, brackets, pockets and holes on one or two faces. |
| 4-axis indexing | A rotary table turns the part about one axis between cuts. | ±0.025 mm | 1.6 to 3.2 µm | Features around a shaft or block, cams and bolt patterns on several sides. |
| 3+2 positional 5-axis | Two rotary axes tilt the part to a fixed angle, then the machine cuts in 3 axes. | ±0.01 to ±0.025 mm | 0.8 to 3.2 µm | Housings, manifolds and brackets with angled holes and faces on four or five sides. |
| Simultaneous 5-axis | All five axes move together so the tool stays normal or tilted to a curved surface. | ±0.01 to ±0.025 mm, profile 0.02 to 0.05 mm | 0.4 to 1.6 µm | Impellers, blisks, turbine blades, implants, ports and mold cores. |
| Horizontal machining center (HMC) | Horizontal spindle with a rotary pallet, often 4 or 5 axes, chips fall away from the cut. | ±0.01 to ±0.025 mm | 0.8 to 3.2 µm | Valve bodies, gearbox housings and medium to high volume prismatic parts. |
| Mill-turn (multitasking) | A lathe with a milling spindle on a B axis. Turns and mills the part in one clamping. | ±0.005 to ±0.02 mm | 0.4 to 1.6 µm | Shafts with flats and cross holes, valve stems, medical screws, hydraulic fittings. |
| Gantry and bridge milling | Spindle on a moving bridge over a long fixed table, travel from 2 m to over 10 m. | ±0.03 to ±0.05 mm over the length | 1.6 to 6.3 µm | Machine bases, frames, large mold plates, aerospace skins and spars. |
| CNC routing | Light, fast gantry machine with high spindle speed and low rigidity. | ±0.1 to ±0.25 mm | 3.2 to 6.3 µm | Plastic sheet, composite panels, aluminum plate and wood. |
| Micro milling | Tools from about 0.1 mm diameter on spindles running 30,000 to 60,000 rpm or more. | ±0.002 to ±0.005 mm | 0.2 to 0.8 µm | Medical and dental parts, micro fluidics, connector and watch parts. |
- Every extra setup adds a re-clamp and a chance to lose position between faces. 3+2 and simultaneous 5-axis exist mainly to cut the number of setups.
- Simultaneous 5-axis is only needed when the tool must tilt while it cuts: blades, impellers, ports and freeform surfaces. A part with angled flat faces is usually a 3+2 job and quotes for less.
- Large parts are limited by travel and table load before anything else. Give the overall envelope and weight on the RFQ.
Milling: operations on the quote
These are the cuts a CAM programmer builds the program from. They are not ordered separately, but knowing them helps you read a quote, a process sheet or a question from the shop.
| Process | What it does | Typical tolerance | Typical Ra | Used for |
|---|---|---|---|---|
| Face milling | Flattens the top of the stock or a datum face with a large cutter. | Flatness 0.01 to 0.03 mm per 100 mm | 0.8 to 3.2 µm | Datum faces, sealing faces, squaring stock. |
| Shoulder and peripheral milling | Side of the cutter makes a vertical wall and a floor at 90°. | ±0.01 to ±0.025 mm | 1.6 to 3.2 µm | Steps, outside profiles, square shoulders. |
| Slot and keyway milling | Cuts a groove at full or partial tool width. | Width ±0.02 mm, H9 keyways | 1.6 to 3.2 µm | Keyways, T-slots, O-ring grooves on flat faces. |
| Pocketing | Clears a closed area to a floor depth. | ±0.025 mm | 1.6 to 3.2 µm | Lightening pockets, cavities, electronics housings. |
| Adaptive (trochoidal) roughing | Constant engagement toolpath that cuts deep at low radial width and high feed. | Roughing only | Not a finish pass | Hard-to-cut alloys and deep pockets, longer tool life. |
| Plunge roughing | Tool feeds straight down in overlapping plunges like a drill. | Roughing only | Not a finish pass | Deep cavities and long-reach work where side load causes chatter. |
| Contour and profile milling | Follows a 2D outline at one or several depths. | ±0.01 to ±0.025 mm | 0.8 to 3.2 µm | Outer shapes, cams, flanges. |
| 3D surface milling | Ball, bull-nose or barrel cutters step over a freeform surface. | Profile 0.02 to 0.05 mm | 0.4 to 1.6 µm, depends on stepover | Mold cavities, blades, organic housings, implants. |
| Swarf (flank) milling | Full side of the tool lies along a tilted ruled surface. Needs simultaneous 5-axis. | Profile 0.01 to 0.03 mm | 0.4 to 1.6 µm | Impeller blades, tapered walls, aerospace pockets with drafted walls. |
| Chamfer and edge milling | Breaks or chamfers edges with a chamfer mill or deburr tool on the machine. | ±0.1 mm on chamfer size | As machined | Edge breaks called out on the drawing, lead-ins for fasteners. |
| Thread milling | A threaded cutter follows a helical path to cut an internal or external thread. | Thread class 6H / 6g, 2B / 2A | 1.6 to 3.2 µm | Large threads, threads in hard materials, threads close to a blind bottom. |
| Engraving | Small tool cuts text, part numbers or scales into the surface. | Depth ±0.05 mm | As machined | Part marking where laser marking is not allowed. |
- Roughing removes most of the volume and leaves 0.2 to 0.5 mm for finishing. Finishing passes decide the tolerance and the surface you get.
- Adaptive (trochoidal) roughing keeps a constant, light tool engagement at high feed. It is the standard way to rough titanium, stainless and nickel alloys today.
- Swarf milling cuts with the side of the tool along a ruled surface. It is faster and smoother than point milling with a ball end mill where the geometry allows it.
Turning
Turning spins the part and moves a stationary tool along it. Anything round with a central axis is cheaper and more accurate on a lathe than on a mill.
| Process | What it does | Typical tolerance | Typical Ra | Used for |
|---|---|---|---|---|
| CNC lathe (2-axis) | X and Z axes, one spindle, tool turret. | ±0.01 to ±0.025 mm | 0.8 to 3.2 µm | Shafts, bushings, spacers, flanges. |
| Turning center with live tooling | C axis (and often Y axis) plus driven tools for milling and drilling. | ±0.01 to ±0.02 mm | 0.8 to 1.6 µm | Fittings and shafts with cross holes, flats and hex features. |
| Twin-spindle turning | A sub-spindle picks up the part and machines the back side. | ±0.01 mm | 0.8 to 1.6 µm | Parts finished on both ends with no manual second operation. |
| Swiss-type (sliding headstock) | Bar slides through a guide bushing while the tool cuts next to it. | ±0.005 mm on diameter | 0.4 to 0.8 µm | Bone screws, pins, connector contacts, small shafts up to about 32 mm diameter. |
| Vertical turning lathe (VTL) | Large horizontal chuck table, tool comes down from above. | ±0.02 to ±0.05 mm | 1.6 to 3.2 µm | Rings, large flanges, valve bodies, turbine casings. |
| Hard turning | Turning parts hardened above 45 HRC with CBN or ceramic inserts. | ±0.005 mm | 0.2 to 0.8 µm | Bearing seats, gear bores and hardened shafts. |
| Facing | Tool feeds across the end of the part to make a flat face. | ±0.01 mm on length | 0.8 to 1.6 µm | Every turned part, end faces and shoulders. |
| OD turning and contouring | Tool follows the outside profile, including tapers and radii. | ±0.01 mm | 0.8 to 1.6 µm | Diameters, tapers, spherical ends. |
| Boring (on the lathe) | Single-point bar opens and sizes an internal diameter. | ±0.005 to ±0.01 mm | 0.4 to 1.6 µm | Bearing bores, cylinders, internal tapers. |
| Grooving and parting | Narrow insert plunges to make grooves or cut the part off the bar. | Width ±0.02 mm | 1.6 to 3.2 µm | O-ring grooves, retaining ring grooves, undercuts. |
| Single-point threading | Insert cuts the thread in several passes synchronized with the spindle. | 6g / 6H, 2A / 2B, 3A on request | 1.6 µm | External and internal threads of any pitch, API and ACME threads. |
| Knurling | Hardened wheels press or cut a diamond or straight pattern. | Pattern pitch per drawing | Not applicable | Grip surfaces, press-fit knurls. |
| Polygon turning | Synchronized rotating tool cuts flats while the part spins. | ±0.02 mm across flats | 1.6 to 3.2 µm | Hex and square heads on turned parts, fast in volume. |
- Live tooling (driven tools on the turret) lets a turning center drill cross holes and mill flats without a second machine.
- Swiss-type lathes support the bar right next to the cut, so long slender parts stay straight. They are the default for small precision turned parts in volume.
- Hard turning with CBN inserts can replace grinding on hardened shafts when the tolerance allows it, which saves a setup.
Hole making and threading
Most machined parts are mostly holes. The process behind each hole decides its size tolerance, straightness, position and finish, so it is worth knowing which one your callout needs.
| Process | What it does | Typical tolerance | Typical Ra | Used for |
|---|---|---|---|---|
| Spot and center drilling | Short stiff tool marks the hole position so the drill does not wander. | Position ±0.02 mm | Not applicable | Before every drilled hole on precision parts. |
| Twist drilling | Carbide or HSS drill cuts the hole in one pass. | ±0.03 to ±0.1 mm on diameter | 1.6 to 6.3 µm | Clearance holes, tap drill holes. |
| Peck drilling | Drill retracts in steps to clear chips. | ±0.05 mm | 3.2 to 6.3 µm | Deeper holes in stringy materials. |
| Gun drilling | Single-flute drill with coolant through the tool, chips leave along a V-groove. | ±0.01 to ±0.03 mm, straight within about 0.05 mm per 100 mm | 0.4 to 1.6 µm | Holes deeper than 10 × D up to 100 × D or more: hydraulic galleries, mold cooling, barrels. |
| BTA deep-hole drilling | Coolant pushed around the head, chips leave through the tube. | ±0.02 to ±0.05 mm | 0.8 to 3.2 µm | Deep holes from about 20 mm diameter: cylinders, shafts, oil and gas tools. |
| Reaming | Multi-flute tool takes a light cut to size a drilled hole. | H7, about ±0.008 mm at 10 mm | 0.4 to 1.6 µm | Dowel and pin holes, slip fits. |
| Precision boring | Adjustable single-point head sizes and straightens a hole. | ±0.005 mm, position corrected | 0.4 to 1.6 µm | Bearing bores, large precise holes, holes that must be on true position. |
| Back boring and back facing | Tool reaches through a hole and cuts the far side. | ±0.01 to ±0.02 mm | 0.8 to 1.6 µm | Spot faces and counterbores on the hidden side without a second setup. |
| Counterboring and countersinking | Stepped or conical seat cut at the top of a hole. | Depth ±0.05 mm, angle ±1° | 1.6 to 3.2 µm | Socket head and flat head screw seats. |
| Cut tapping | Tap cuts the thread and makes chips. | 6H / 2B | Not applicable | Most internal threads M1.6 to M24. |
| Form (roll) tapping | Tap displaces material to form the thread, no chips. | 6H / 2B | Not applicable | Aluminum, copper, mild and stainless steel. Stronger thread. |
| Helical interpolation | End mill circles down to cut a hole larger than the tool. | ±0.01 to ±0.02 mm | 0.8 to 1.6 µm | Large or odd sized holes without a special tool. |
- A drilled hole is not a precision hole. Anything tighter than about ±0.05 mm on diameter is reamed, bored or ground after drilling.
- Deep holes are counted in diameters. Up to about 10 × D a standard carbide drill works. Beyond that the shop needs gun drilling or BTA.
- Form taps make stronger threads with no chips in ductile materials. Thread milling is safer in hard materials and expensive parts because a broken tap can scrap the part.
Grinding and abrasive finishing
Abrasive processes take over where cutting tools stop: hardened material, tolerances in microns, flatness and surface finish below Ra 0.4 µm. They are usually the last operation before inspection.
| Process | What it does | Typical tolerance | Typical Ra | Used for |
|---|---|---|---|---|
| Surface grinding | Wheel passes over a part held on a magnetic or vacuum chuck. | ±0.002 to ±0.005 mm, flatness 0.002 mm | 0.2 to 0.8 µm | Tool steel plates, gauge blocks, die components, parallel faces. |
| Cylindrical OD grinding | Part turns between centers or in a chuck against a rotating wheel. | ±0.0025 mm, roundness 0.001 mm | 0.1 to 0.4 µm | Shafts, bearing journals, pins. |
| Internal (ID) grinding | Small wheel on a high speed spindle inside the bore. | ±0.0025 mm | 0.2 to 0.4 µm | Hardened bores, bearing races, die bushings. |
| Centerless grinding | Part rides between a grinding wheel and a regulating wheel, no centers. | ±0.002 mm, roundness 0.001 mm | 0.1 to 0.4 µm | Pins, rods, needles and tubes in volume. |
| Jig grinding | Planetary grinding spindle on a jig-bore style machine. | Position ±0.002 mm | 0.2 to 0.4 µm | Hole patterns in hardened dies and fixture plates. |
| Profile and creep-feed grinding | Dressed wheel grinds a full profile in deep, slow passes. | ±0.005 mm on profile | 0.4 to 0.8 µm | Turbine blade roots, punch profiles, form tools. |
| 5-axis tool grinding | CNC grinder makes cutting tools and complex small parts from carbide or HSS. | ±0.002 to ±0.005 mm | 0.1 to 0.4 µm | Custom end mills, drills, medical burrs and reamers. |
| Honing | Abrasive stones expand and stroke inside a bore. | Size ±0.002 mm, cylindricity 0.002 mm | 0.1 to 0.4 µm, crosshatch | Hydraulic cylinders, engine bores, valve bodies. |
| Lapping | Loose abrasive between the part and a flat plate. | Flatness under 0.001 mm | 0.05 to 0.2 µm | Sealing faces, valve seats, gauge surfaces. |
| Superfinishing and polishing | Fine abrasive film, stone or compound removes the peaks of the profile. | Removes 0.001 to 0.005 mm | 0.025 to 0.1 µm | Bearing surfaces, implant surfaces, optical and mold polish. |
- Leave stock for grinding on purpose. A typical allowance is 0.1 to 0.3 mm per side after heat treatment, which the drawing or the shop sets.
- Honing and lapping control shape (roundness, cylindricity, flatness) as much as size. Call out the form tolerance, not only the diameter.
- Grinding can burn the surface and change its hardness. Aerospace and bearing parts often specify a temper etch or nital etch inspection for this.
EDM (electrical discharge machining)
EDM erodes metal with controlled sparks between an electrode and the part, in a dielectric fluid. There is no cutting force, so it cuts hardened steel, carbide and thin walls without distortion. The part must conduct electricity.
| Process | What it does | Typical tolerance | Typical Ra | Used for |
|---|---|---|---|---|
| Wire EDM | A brass or coated wire of 0.1 to 0.3 mm diameter cuts a 2D or tapered profile through the part. | ±0.005 mm, ±0.002 mm with skim passes | 0.2 to 1.6 µm | Punches and dies, gears, splines, extrusion dies, thin precise slots. |
| Sinker (ram) EDM | A shaped graphite or copper electrode sinks its form into the part. | ±0.01 mm | 0.4 to 3.2 µm (VDI 12 to 30) | Mold cavities, sharp internal corners, deep narrow ribs, blind splines. |
| Small-hole (fast hole) EDM | Rotating tube electrode drills small deep holes. | ±0.02 to ±0.05 mm | 1.6 to 3.2 µm | Turbine cooling holes, wire start holes, holes in hardened parts. |
- Wire EDM only cuts through the part. Sinker EDM makes blind shapes, sharp internal corners and deep ribs a milling cutter cannot reach.
- EDM leaves a thin recast layer. Fatigue-critical aerospace parts often need it removed or limited, so say if your specification controls it.
- EDM is slow compared with milling. Use it for the features that need it, not for the whole part.
Other CNC cutting and forming processes
These are also CNC-controlled and often show up on the same part. Some cut a profile from sheet or plate, others make features milling cannot make economically.
| Process | What it does | Typical tolerance | Typical Ra | Used for |
|---|---|---|---|---|
| Broaching (linear) | Long toothed tool pulled or pushed through or across the part, each tooth cuts a bit deeper. | ±0.01 to ±0.025 mm | 0.8 to 1.6 µm | Internal keyways, splines, hex and square holes. |
| Rotary broaching | Wobbling broach on a lathe or mill punches a shape into a blind hole. | ±0.02 mm | 1.6 µm | Hex and Torx sockets in screws and fittings. |
| Gear hobbing | Rotating hob and blank turn in sync to generate the teeth. | ISO 1328 grade 7 to 9 typical | 1.6 to 3.2 µm | Spur and helical external gears, splines, worm wheels. |
| Gear shaping and power skiving | Cutter reciprocates (shaping) or rotates at an angle (skiving) to cut teeth. | ISO 1328 grade 7 to 9 | 1.6 to 3.2 µm | Internal gears, gears next to a shoulder. |
| Gear grinding | Profile or generating wheel finishes hardened teeth. | ISO 1328 grade 4 to 6 | 0.4 to 0.8 µm | Quiet, high load gears for robotics, aerospace and EV drives. |
| Laser cutting | Fiber or CO2 laser melts a narrow kerf through sheet or plate. | ±0.1 mm | Cut edge, small heat-affected zone | Sheet metal blanks up to about 25 mm steel. |
| Waterjet cutting | Water at 4,000 bar or more, usually with garnet abrasive. | ±0.1 to ±0.2 mm | 3.2 to 6.3 µm | Thick plate, titanium, composites, glass and stone. No heat-affected zone. |
| Plasma cutting | Electric arc through ionized gas cuts conductive plate. | ±0.5 mm | Rough edge | Thick steel plate for weldments and frames. |
| Electrochemical machining (ECM) | Shaped cathode dissolves metal by electrolysis. No tool wear and no burrs. | ±0.02 to ±0.1 mm | 0.2 to 0.8 µm | Turbine blades, blisks, deburring of intersecting holes. |
| Ultrasonic machining | Tool vibrates at about 20 kHz with an abrasive slurry or diamond tool. | ±0.01 to ±0.025 mm | 0.4 to 1.6 µm | Fired ceramics, glass, sapphire and silicon. |
- Laser, plasma and waterjet cut 2D blanks. Close features are usually finished by milling afterwards.
- Broaching and gear cutting need dedicated tools. They pay off in volume and for standard profiles such as keyways and involute splines.
Heat treatment around the machining
Heat treatment changes hardness, strength and size. Where it sits in the route decides which surfaces are cut soft and which are ground or cut by EDM after hardening. Name the condition and the specification on the drawing.
| Treatment | What it does | When in the route | What to know |
|---|---|---|---|
| Stress relieving | Heats the part below the transformation range to release stress from rolling, welding or roughing. | Between roughing and finishing | Keeps thin and asymmetric parts from moving after finish machining. |
| Annealing | Softens material for machining or forming. | Before machining | Tool steels are bought annealed and hardened later. |
| Through hardening and tempering | Austenitize, quench in oil, gas or salt, then temper to the target hardness. | After rough or semi-finish machining | Leave grinding stock. Expect size change and some distortion. |
| Vacuum hardening | Hardening in a vacuum furnace with gas quench. | After semi-finish machining | Clean, bright surface and less distortion. Common for A2, D2, H13 and stainless. |
| Solution treatment and aging | Dissolves alloying elements, then ages them out to raise strength. | Before or after machining, by alloy | 6061-T6, 7075-T6, 17-4 PH (H900 to H1150), Inconel 718 and titanium STA. |
| Carburizing | Adds carbon to the surface of low carbon steel, then hardens it. | After machining, before grinding | Hard case and tough core for gears and shafts in 8620 or 9310. Mask areas to stay soft. |
| Nitriding (gas, plasma, ferritic nitrocarburizing) | Diffuses nitrogen into the surface at a low temperature. | After finish machining | Little distortion, case 0.1 to 0.5 mm. Used on 4140, H13 and nitriding steels. |
| Induction hardening | Heats only the surface zone with a coil, then quenches. | After machining, before grinding | Local hardness on journals, cams and gear teeth. |
| Hot isostatic pressing (HIP) | Heat and gas pressure close internal porosity. | Before machining | Castings and metal 3D printed parts for aerospace and medical. |
Surface finishing and coating
Most coatings add thickness. Tell the shop whether your tolerances apply before or after the finish, and which features must be masked. Many shops send finishing to a specialist, so ask who controls it.
| Finish | What it does | When | What to know |
|---|---|---|---|
| Bead blasting | Glass bead or ceramic media gives an even matte surface. | Before anodizing or as final | Hides tool marks. Mask threads, bores and sealing faces. |
| Anodizing Type II (MIL-A-8625) | Electrolytic oxide on aluminum, dyed in most colors. | Final | Coating 5 to 25 µm, about half of it grows outward. Specify which features to mask. |
| Hard anodizing Type III | Thick, hard oxide for wear. | Final | Coating 25 to 75 µm, about half outward. Machine the size allowance into tight bores. |
| Chem film (MIL-DTL-5541, Alodine) | Thin conversion coating on aluminum that stays electrically conductive. | Final | No dimensional change you can measure. Used for grounding surfaces and paint base. |
| Passivation (ASTM A967, AMS 2700) | Acid treatment removes free iron from stainless steel. | Final | Standard for medical, food and semiconductor stainless parts. |
| Electropolishing (ASTM B912) | Reverse plating removes a thin surface layer and the peaks of the profile. | Final | Bright, clean, smoother surface on stainless. Removes about 5 to 25 µm. |
| Electroless nickel (AMS 2404) | Even nickel-phosphorus layer without electric current, also inside bores. | Final | Typical 5 to 25 µm. Hardness can be raised by baking. |
| Zinc and zinc-nickel plating (ASTM B633) | Sacrificial corrosion protection on steel. | Final | High strength steel needs a hydrogen embrittlement bake. |
| Black oxide (MIL-DTL-13924) | Conversion coating on steel, kept with oil. | Final | Under 2 µm. Mild corrosion resistance, often on tooling. |
| Hard chrome (AMS 2460) | Thick, hard chromium layer, often ground after plating. | Final, then grind | Hydraulic rods and wear surfaces. |
| PVD and DLC coatings | Thin hard films such as TiN, CrN and diamond-like carbon. | Final | 1 to 5 µm. Low friction and wear resistance on precision parts. |
| Powder coating and painting | Polymer coating for color and corrosion. | Final | Builds 50 to 150 µm. Mask every precision feature. |
| Laser marking | Marks part numbers, serials and UDI codes on the surface. | After finishing, by coating | Medical UDI and aerospace traceability. Give the content and location. |
More on roughness values and callouts in 5-axis surface finish explained.
How the processes fit together
The usual route of a precision machined part. Simple parts skip most of these steps. Hardened, coated or certified parts go through all of them.
Stock and cut
Bar, plate, forging or casting is sawn or cut to a blank with a material certificate.
Rough
Milling or turning removes most of the material and leaves 0.5 to 2 mm.
Stress relieve
Optional, for thin, long or asymmetric parts that would move later.
Semi-finish and finish
Finishing passes, holes, threads and the features that set the tolerance.
Heat treat
If needed. Hardening comes before grinding, hard milling or EDM of the final size.
Grind, EDM or hone
The micron-level features and hardened surfaces.
Deburr and clean
Manual, vibratory, thermal or electrochemical deburring, then washing.
Surface finish
Anodize, passivate, plate or coat, with masking where called out.
Inspect and pack
CMM, surface and thread checks, first article report when requested.
From the feature on your drawing to the process
One feature often decides the whole route. If a quote comes back higher than expected, check this list for the callout that pulls in an extra process.
Say it once, on the RFQ
You do not have to pick processes. Send the drawing with material, quantity, tolerance and finish. Mention only what is fixed for you, for example a ground bore, no EDM on a fatigue part or a rolled thread.
- Freeform surface, blade or portSimultaneous 5-axis milling
- Holes and faces on four or five sides3+2 milling, or HMC in volume
- Round part with cross holes and flatsMill-turn or turning center with live tooling
- Small diameter, long and slenderSwiss-type turning
- Hole tolerance tighter than ±0.02 mmReaming, precision boring or ID grinding
- Hole deeper than 10 × diameterGun drilling or BTA drilling
- Sharp internal corner, deep narrow slotSinker EDM or wire EDM
- Hardened above 50 HRC, tolerance in micronsGrinding, hard milling or wire EDM
- Internal keyway or splineBroaching, wire EDM or gear shaping
- Flatness under 0.005 mm or Ra under 0.2 µmSurface grinding, lapping or polishing
- Flat profile from thick plateWaterjet or laser blank, then milling
- Fired ceramic or glassDiamond grinding or ultrasonic machining
Send your drawing
We read it, then match you with up to 3 shops that run 5-axis machines and the other processes your part needs. Reply within 24 business hours.
Questions about machining processes
Something else? Email .
Do I need to tell the shop which process to use?
No. Send the drawing and the shop picks the process. Name one only when it is a requirement, for example a ground surface, a no-EDM rule or a thread that must be rolled.
What is the difference between 3+2 and simultaneous 5-axis?
In 3+2 the part is tilted to a fixed angle and then cut in three axes. In simultaneous 5-axis all axes move during the cut. Most prismatic parts only need 3+2. See 3+2 vs simultaneous 5-axis.
Can one shop do milling, turning, grinding and finishing?
Many 5-axis shops also run turning and EDM in house. Grinding, heat treatment and plating are often sent to specialist subcontractors. Ask the shop which steps it runs in house and which it sends out, and who holds the responsibility for the whole part.
Why is my part quoted with EDM or grinding when it looks like a milling job?
Usually because of one feature: a sharp internal corner, a hardened surface, a tolerance in microns or a very fine finish. Ask which feature drives it. Relaxing that one callout can remove the extra operation.
Which processes do you match for?
We match RFQs with shops that run 5-axis machines. Shops tell us what else they run: turning, Swiss-type, wire and sinker EDM, grinding, CMM and finishing. When your part needs one of these we shortlist shops that do it in house where we can.