Five Axis Machine Swing: Spindle Swing and Table Swing Compared
Two five-axis layouts dominate real shop floors: the spindle that swings over a fixed table, and the table that swings under a fixed spindle. The kinematic result is the same. The error behavior is not. This page compares them on rigidity, tool length sensitivity, part size, and setup time so you can pick the right one for a specific part.
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Five axis machine swing: spindle swing vs table swing at a glance
Values reflect typical production machines; check the actual machine spec sheet before quoting.
| Criterion | Spindle swing (head swing) | Table swing (cradle / trunnion) |
|---|---|---|
| Moving mass | Spindle head and ram swing | Workpiece and table rotate |
| Rigidity at the cut | Lower, longer cantilever | Higher, short load path |
| Tool length effect | Amplifies angular error | Minimal, tool stays fixed |
| Error type | Position plus form error | Mainly position error |
| Part size limit | Limited by swing radius | Limited by table and travel |
| Setup and fixturing | Simple, part stays put | Part must be clamped to table |
| Best for | Large, awkward, heavy parts | Small to medium batch, tight form |
| Typical accuracy | ±0.01 mm on contoured walls | ±0.005 mm on round features |
What actually moves, and why it matters
On a spindle swing machine, the A or B axis sits in the head. The table stays flat and still. The tool tip travels along an arc, so the machine compensates the tool center point in real time. On a table swing machine, the rotary axes are in the table. The part turns; the spindle stays square to its own column.
The control sees the same thing in both cases: five coordinates, one tool tip. The mechanical difference shows up under load. A swinging head hangs the cutting force at the end of a long cantilever. A trunnion table carries that force through a short, closed structure.
This is why a table swing machine usually holds tighter form on a contoured wall. It is also why a spindle swing machine reaches into a part that a trunnion could never hold, because the table does not have to carry the whole workpiece through a rotation.
Neither layout is newer or more advanced. They solve different fixturing problems. The rest of this page is about matching the layout to the part in front of you.
Rigidity and dynamic behavior under load
Rigidity decides surface finish and tool life more than any spec sheet number. A spindle swing head has a longer load path from the cutting edge to the machine bed. Every millimeter of that path adds deflection, and deflection grows with the cube of length.
A table swing machine keeps the spindle short and stiff. The workpiece rotates instead, and the rotary axes are large bearings built to take that load. The result is a stiffer loop at the cut, which matters when you take deep passes in 4140 or 17-4PH.
The trade-off moves to the part. Everything on a trunnion table has to be clamped well enough to survive rotation. A thin wall part can distort under its own clamping load before the first cut starts.
For light finishing passes in aluminium 6061 or 7075, the rigidity gap rarely shows. For heavy roughing in steel or titanium, it shows in chatter marks and tool wear.
Tool length error: the hidden variable
On a spindle swing machine, the tool sits inside the swinging arm. Its length becomes part of the rotary radius. A longer tool means a larger swing radius, and any angular error at the pivot is multiplied by that radius at the tip.
Run the numbers on a typical job. A 100 mm tool on a head with 0.005° of residual angular error moves the tip roughly 0.009 mm off nominal. Shorten the tool to 50 mm and the same error drops to about 0.004 mm. The machine did not change. The setup did.
On a table swing machine, tool length does not enter the rotary geometry. The spindle stays in a fixed orientation, so a long reach tool only adds ordinary bending deflection, not amplified angular error.
This is why deep pockets and long-reach features behave better on a table swing machine. It is also why head swing operators keep tools as short as the geometry allows.
Position error vs form error
Every five-axis machine has position error. The control interpolates, the servos lag, and thermal growth moves the zero point. That error is roughly uniform and can often be compensated.
A spindle swing machine adds a second category: form error. Because the tip follows an arc, small angular deviations show up as shape distortion. Round bosses come out slightly oval. Sharp internal corners get cut away. The error is not constant across the feature, so a simple offset will not fix it.
A table swing machine mostly produces position error. The part rotates about a real axis, so a bore stays round and a corner stays sharp even when the whole feature sits a few microns off nominal.
If your print controls roundness or profile tolerance, this distinction decides the machine. If you only control a dimension, either layout can be dialed in.
Part size, weight, and reach
A spindle swing machine is limited by the swing radius of the head, not by the table. That is an advantage for long, flat, or awkward parts. A 1,200 mm bracket can sit on the table and the head reaches the features that need to be tilted.
A table swing machine is limited by what the trunnion can carry and rotate. Small trunnions with a Ø400 mm rotary table suit compact housings and medical implants. Larger cradles handle parts up to a few hundred millimeters in each direction.
Our own five-axis fleet spans several travel envelopes, from 500 × 310 × 200 mm compact centers up to 4,000 × 400 × 150 mm for long parts, plus a Ø400 mm rotary table for trunnion work. The envelope you need usually makes the choice for you.
Weight matters too. A heavy steel part on a trunnion adds inertia to every rotary move. On a head swing machine the same part is static, and only the head accelerates.
Setup, fixturing, and batch size
Setup effort is where the table swing layout wins on batch work. Once the part is indicated on the trunnion, the control knows exactly where the rotary center is. Repeat parts drop in with a fixture and run.
A spindle swing machine needs the tool center point set for each tool length. Get it wrong and the error is amplified by the swing radius, so a 0.05 mm tool setting mistake can look like a 0.1 mm form error.
For one-off prototypes and repair work, the head swing layout is often faster. The part does not have to be clamped for rotation, so an odd-shaped casting can be set on the table and probed in place.
For a 5,000-part run, that advantage disappears. The trunnion fixture pays for itself in repeatability within the first few hundred parts.
Material and feature combinations that decide it
Hard materials push you toward the stiffer layout. Titanium Ti-6Al-4V and Inconel resist cutting, so any extra deflection turns into chatter. A trunnion keeps the load path short, which is why most titanium airframe brackets run on table swing machines.
Aluminium lets you be flexible. 6061, 6082, and 7075 cut easily enough that head swing deflection stays small at moderate feed rates, and the larger working envelope often matters more than a micron of stiffness.
Feature type matters more than material. Deep bores, long-reach pockets, and any feature that needs a short tool belong on a table swing machine. Wide, shallow faces on a long part belong on a head swing machine.
We run both layouts and choose per job. For a batch of aluminium housings with round bores, the trunnion is the safer pick. For a 900 mm steel weldment with features on five sides, the head swing machine is the only realistic option.
Which layout to choose
Choose spindle swing when the part is long, heavy, or awkward to clamp and you can hold a short tool; choose table swing when roundness, profile tolerance, and repeat batch accuracy matter more than reach.
Questions engineers ask before choosing
Can a spindle swing machine hold ±0.005 mm?
Yes, but only with the right setup. Keep tool length short, warm the spindle before the finishing pass, and probe the tool center point on the machine rather than trusting the preset.
The tolerance is a process result, not a property of the layout. A table swing machine reaches it more easily on contoured features because the angular error is not multiplied by tool length.
Does a trunnion table limit the part weight?
It does. The rotary axes carry the part plus the fixture through every move, so inertia and bearing load set the practical limit. Check the trunnion load rating before quoting a heavy steel part.
A head swing machine has no such limit on the part itself, because the part never rotates. The limit moves to the head swing radius and the table size instead.
Which layout gives better surface finish?
On hard materials and deep cuts, the table swing layout usually finishes better because the cutting loop is stiffer. On aluminium with short tools, the difference is often inside Ra 0.8–1.6 μm for both.
Finish also depends on the CAM strategy. Smooth continuous toolpaths matter more than the layout once you are past roughing.
How do I know which layout my quote was priced on?
Ask. The machine choice changes setup time, fixture cost, and cycle time, so it should be stated on the quote or the DFM notes.
If a feature needs a specific layout, say so when you upload the model. We review the geometry before quoting and will flag it if the part does not suit the machine it was priced on.
Can the same part run on either layout?
Often yes. Simple prismatic parts with features on five sides can run on both, and the choice comes down to fixture cost and batch size.
Parts with tight roundness, deep long-reach pockets, or heavy rotation loads usually commit you to one layout. Review those features before the first cut, not after.
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More five-axis process notes
We publish setup notes, tooling trials and inspection data from the factory floor.
