5-AXIS MACHINING5-axis machining

5-axis machining adds two rotary axes to the three linear axes (X, Y, Z) so you can cut while also changing the tool orientation. We start with the difference between “3+2 (indexed)” and “simultaneous 5-axis,” then cover machine types, NC functions, calibration, and where things tend to go wrong, all checked against public manufacturer and standards documents.

Most parts are fine
with 3+2!
First, the difference.

◇3+2 machining vs. simultaneous 5-axis machining

5-axis machining

Machining in which two rotary axes (two of A, B, C) are added to the three linear axes (X, Y, Z) so that the relative orientation of tool and workpiece (tool attitude) also changes during cutting. In theory the tool can reach any point in space from any direction.^[1][2][3]

3+2 machining (indexed machining, tilted-plane machining, multi-face machining)

The rotary axes first turn the tool to face the surface and lock (static orientation); after that, only the three linear axes cut. The rotary axes do not move while cutting.^{[1][4][2][5][6][7][8]}

Simultaneous 5-axis machining

The linear and rotary axes are interpolated together, and the tool attitude changes continuously during cutting (dynamic orientation). The program is usually generated by CAM.^{[1][4][2][5][6][7][9]}

5-face machine (not the same as a 5-axis machine)

A gantry machining center that automatically changes attachment heads (extension heads, 90° angular heads) to machine the top and four sides of a workpiece. The tool orientation only switches between fixed angles; it is not tilted continuously by rotary axes.One source / reference^[10]

≡Quick comparison

	3+2 machining	Simultaneous 5-axis machining
Tool orientation	Static (indexed and locked)	Dynamic (changes while cutting)^{[1][4][2][6][7]}
How the program is made	You can write an ordinary 3-axis program (fixed cycles can be used) on the tilted plane. It can also be written by hand.	CAD/CAM required^{[4][6][7][11]}
Main NC functions	Tilted working plane commands (FANUC Tilted Working Plane / Mitsubishi Electric tilted plane machining command), Siemens CYCLE800, Heidenhain PLANE, Haas G254 (DWO) and G268	Tool center point control (FANUC/Mitsubishi Electric G43.4 etc.), Siemens TRAORI, Heidenhain M128 / FUNCTION TCPM, Haas G234 (TCPC)^{[1][5][6][12][13][9][8][11][14]}
Suited parts (3+2)	Most general parts can be done with 3+2 (up to simultaneous 4-axis). Holes and pockets on tilted faces, multi-face machining, roughing and semi-finishing of 3D shapes, making tools and fixtures	—^[2][7]
Suited parts (simultaneous 5-axis)	—	Overhanging shapes such as impellers and blisks, turbine and aero-engine parts, aircraft structural parts, free-form surfaces of dies and molds, finishing of deep recesses and shapes with many curvature changes^[1][2][7]
Difficulties of simultaneous 5-axis	—	The motion is complex, so creating and verifying NC programs takes time; it is hard to read the motion at the machine; and with many moving axes, rigidity is hard to maintain^[15]

✓What do you gain from 5 axes?

You can reduce setup changes (re-fixturing the workpiece). Waiting between operations and machining time go down, and accuracy improves because the fixturing error introduced by each re-fixturing disappears.^{[6][7][16][17]}A FANUC development report (s6) splits the benefit into two: ‘less waiting between operations and shorter machining time’ and ‘eliminating fixturing error from setup changes.’ Manufacturer product pages (Mazak, Okuma) describe it as ‘process consolidation.’
Because the tool can be tilted, you need to stick it out less to avoid holder–workpiece collisions. A shorter stick-out raises tool rigidity, allows a higher feed, and reduces chatter.^[6][16][15]
Tilting a ball end mill lets you avoid cutting with the near-zero surface speed center, which gives a better finish (cutting with the center crushes the material instead of cutting it).^[18][15]In an experiment by the Kanagawa Institute of Industrial Science and Technology (KISTEC), the tilted surface had more gloss, but the surface roughness Rz was smaller without tilt (lead and tilt angles of 0°). The conclusion: the way you tilt must be chosen according to whether you prioritize appearance (surface quality) or surface roughness (s42).
Because the angle between the tool and the surface can be kept constant, the surface roughness stays uniform.One source / reference^[6]
With tool center point control and tilted working plane commands, there are more cases where you don't need to regenerate in CAM when the tool length or the workpiece position changes.^{[1][5][6][9][8]}

5-axis machining pages

⟲

5-axis machine configurations

The three types (head-head, table-table, head-table) with their advantages and drawbacks, the names and directions of rotary axes A, B, C, vertical vs. horizontal machines, and multitasking machines.

5-axis NC functions

Tool center point control, tilted working plane commands, and 3D tool radius compensation. A comparison of commands by NC maker, G93 inverse time feed, tool length and the center of rotation.

◎

Calibration, collision, workholding and tools

Kinematics calibration with a reference sphere, accuracy test standards, collision checking and simulation, 5-axis vises, tool stick-out and how to tilt a ball end mill.

Common 5-axis mistakes

Singularities, the two solutions of a rotary axis and the long way around, feed units, forgotten tool length, and forgetting to cancel a tilted plane. A checklist to verify on the shop floor.

5-axis calculations

F value for G93 inverse time feed, ball end mill tilt angle, angles from a direction vector, and the shortest way for a rotary axis to turn.

⌗

CAD/CAM

CAM workflow, toolpath types, a list of software, data formats (STEP, IGES, Parasolid), coordinate systems and post-processors.

A5-axis machining terms

Term	English	Meaning
5-axis machinegojiku kakoki	5-axis machining center	A machining center that adds two rotary axes to the three linear axes and can cut while also changing the tool orientation.^[1][3]
3+2 machiningsan purasu nijiku kako	3+2-axis machining / tilted plane machining	Machining in which the rotary axes set the tool orientation and lock, and the three linear axes cut. Also called indexed machining or tilted-plane machining.^[4][5][7]
Simultaneous 5-axis machiningdoji gojiku kako	simultaneous 5-axis machining / 5-axis simultaneous	Machining that interpolates the three linear axes and two rotary axes simultaneously, changing the tool orientation while cutting.^[2][6][7]
Indexed machiningwaridashi kako	multi-face machining	Machining in which a rotary axis is indexed to a fixed angle and locked, and cutting is done in that orientation. Mitsubishi Electric uses the term to include multi-face and tilted-plane machining.^[7][4]
5-face machininggomen kako	5-face machining / 5-sided machining	Machining the top and four sides in a single setup. It is done both on gantry machines that swap attachment heads (5-face machines) and with 3+2.^[10][25]
Process consolidationkotei shuyaku		Combining operations that were spread across several machines and setups into one machine and fewer setups.^[6][17][16]
Tool center point controlkogu sentan-ten seigyo	tool center point control (TCP) / TCPM (Heidenhain) / TCPC (Haas) / TTPC (Mazak)	A function in which the NC automatically calculates the linear-axis compensation so that the tool tip follows the programmed position even when rotary axes turn.^{[1][6][13][9][14]}
5-axis transformationgojiku henkan	5-axis transformation / TRAORI (Siemens)	An NC function that converts the tool tip position and orientation written in workpiece coordinates into the motion of each machine axis. Corresponds to Siemens' tool center point control.^[1][2]
Tilted working plane commandkeishamen kako shirei	tilted working plane (TWP) / inclined surface machining command / PLANE (Heidenhain) / CYCLE800 (Siemens) / feature coordinate system G268 (Haas)	A function that defines a coordinate system along a tilted face so you can machine it as if it were the XY plane.^{[5][7][13][1][11]}
Tilted coordinate systemkeisha zahyokei	tilted coordinate system / feature coordinate system	The coordinate system along the machining surface that is defined in tilted-plane machining.^[7][11]
Tool axis direction controlkogu jiku hoko seigyo	tool axis direction control / tilted working plane indexing	A function that automatically indexes the rotary axes so the tool is perpendicular to the tilted plane, and links the tilted coordinate system to the rotary axes.^[26][7]
Work coordinate systemwaku zahyokei	workpiece coordinate system (WCS)	A coordinate system referenced to the workpiece origin. Programs are usually written in it, and the NC converts it to the machine coordinate system (MCS).^[1][11]
Machine coordinate systemkikai zahyokei	machine coordinate system (MCS)	A coordinate system referenced to the machine origin.^[1][19]
Kinematicskinemateikusu	kinematics / machine kinematics	The geometry of how the machine axes are arranged and the positions and orientations of the rotary axes. The NC calculates the tool tip position using the registered kinematics.^[1][27]
Head-head typeheddo heddo gata	head-head kinematics / head rotation type	A configuration with both rotary axes on the spindle head side.^[2][6][3]
Table-table typeteburu teburu gata	table-table kinematics / table rotation type	A configuration with both rotary axes on the table side. The trunnion type is the typical example.^[2][6][3]
Head-table type (mixed type)heddo teburu gata	head-table kinematics / mixed kinematics / mixed type	A configuration with one rotary axis on the spindle head side and one on the table side.^[2][6][3]
Trunnion tabletorunion teburu	trunnion table	A table with a tilt axis plus a rotary axis, in which the rotary table is supported at both sides and tilted.^[28][17][16]
Tilt-rotary table (swivel rotary table)chiruto rotari teburu	tilt-rotary table / swivel rotary table / tilting rotary table	A table that combines a tilting axis and a rotating axis into one. The name used by Mazak, DMG MORI, GROB, Hermle and others.^{[16][29][25][30]}
Swivel headsuiberu heddo	swivel head	A spindle head that tilts (swivels) on a rotary axis.^[31][1]
Tilt axiskeishajiku	swivel axis	A rotary axis that tilts the tool or the workpiece. The A axis or the B axis, depending on the machine.^[32][22]
Center of rotation (pivot)kaiten chushin	center of rotation / pivot point / MRZP (Haas: machine rotary zero point)	The center about which a rotary axis turns. If the center of rotation held by the NC differs from the real machine, machining that moves the rotary axes will show errors.^{[9][33][26][34]}
Pivot lengthpibotto cho	pivot length	(On machines whose spindle head tilts) the distance from the center of rotation of the tilt axis to the spindle end (the tool reference).^[35]
Kinematics calibration (measuring the rotary axis center)kinemateikusu kosei	kinematics calibration / rotary axis position calibration / KinematicsOpt (Heidenhain) / CYCLE996 (Siemens)	Measuring the center and orientation of the rotary axes with a reference sphere and touch probe, and correcting the NC's machine configuration parameters.^[1][26][27]
Reference sphere (calibration sphere)kijun kyu	datum sphere / calibration sphere	A sphere with an accurately known radius. It is fixed on the table and measured during kinematics calibration.^{[27][26][28][35]}
Ballbarboru ba	ballbar	A telescoping measuring instrument with a ball at each end. It measures the change in distance between the tool tip and the workpiece during circular moves or simultaneous 5-axis motion.^[14]
Singularitytokuiten	singular point / singularity	A tool orientation near which the rotary axes become unstable and swing around widely.^[6]
Inverse time feedgyaku jikan okuri	inverse time feed (G93)	A way of commanding feed in which F means ‘the block is completed in 1/F minutes.’ Used in 4- and 5-axis CAM output.^[36][21][37]
Direction vectorhoko bekutoru	direction vector / tool orientation vector / A3/B3/C3 (Siemens) / I/J/K (FANUC type II)	The tool orientation expressed as X, Y, Z components. It does not depend on the machine configuration, unlike writing rotary axis angles.^[1][6]
Lead anglerido kaku	lead angle / LEAD (Siemens)	The angle the tool is tilted in the feed (travel) direction.^[18][1]
Tilt anglechiruto kaku	tilt angle / TILT (Siemens)	The angle the tool is tilted in the direction perpendicular to the feed direction (Siemens defines TILT as a rotation about the surface normal).^[18][1]
Surface normal vectormen no hosen bekutoru	surface normal vector	A vector perpendicular to the machining surface. Used as the reference for 3D tool radius compensation and LEAD/TILT. Output by CAM.^[1][13]
3D tool radius compensationsanjigen kogu-kei hosei	3D cutter compensation / 3D tool radius compensation	A function that compensates the tool radius in three dimensions using the surface normal and the tool orientation.^[1][5][13]
Tool orientation controlkogu shisei seigyo	tool posture control / vector interpolation of orientation	A function that interpolates between the tool orientations at the start and end points so that side milling produces a flat surface.^[5][6][34]
Workpiece setup error compensationwaku setchi gosa hosei	workpiece setup error compensation / G54.4 (FANUC)	A function that measures the position and rotation offset of the placed workpiece and corrects the path so you can machine without changing the program.^{[5][6][34][38]}
Post-processorposuto purosessa	post processor	Converts CAM toolpaths into NC code for that machine and NC. For 5-axis, one is needed for each machine configuration.^[1]
Barrel toolbareru kogu	barrel cutter / barrel end mill / circle segment cutter	A tool whose profile is barrel-shaped when rotated, with a large radius cutting edge on the periphery. Allows large depths of cut in 5-axis and indexed machining.^[39]
Gripping depthtsukamishiro	clamping depth / gripping depth	The height at which a vise grips the workpiece. 5-axis vises have a small one, a few mm.^[40][41]
Nutating axisnyuteito jiku	nutated axis	A rotary axis that is not orthogonal to the linear axes (tilted at an angle). For example, a 45° head.^[1]
Multitasking machine (mill-turn)fukugo kakoki	multitasking machine / mill-turn	A machine that does turning and milling (including simultaneous 5-axis) on one machine.^[6][42]

📚Sources

The 5-axis machining pages are based on public manuals and technical documents from NC and machine tool makers, public pages of standards bodies, and reports from universities and public research institutes. Whether an NC command is available depends on the model and options, so always check your machine's instruction manual.