Did Tesla Got CNC Machines?
Yes. Every Tesla plant still runs CNC mills and lathes, even after the Giga Press arrived. This page explains which parts get cut, what tolerance they need, and where casting stops and machining starts.
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Did Tesla Got CNC Machines in Every Plant?
Yes, and the question keeps coming back because the Giga Press looks like it replaced them. It did not. A 6,000-ton die casting machine produces a rear underbody in one shot, but that shot comes out with draft angles, flash lines, and a skin that no suspension arm can bolt to directly.
Tesla still buys the same categories of machine tools every other automaker buys: vertical machining centers, horizontal mills, mill-turn centers, and grinders. The mix leans toward larger spindles and aluminum tooling, because the parts arriving from casting are big and gummy rather than small and hard.
So did Tesla got CNC machines is really a question about sequence, not about presence. Casting forms the shape. CNC holds the interface. If a face has to seal, rotate, or locate, it gets cut on a machine tool, not on a press.
- 1Casting sets geometryNear-net shape, wall thickness, and rib layout.
- 2CNC sets interfacesBolt patterns, bearing bores, sealing faces, datums.
Why a Giga Press Cannot Replace a Machine Tool
Die casting works by filling a steel die with liquid aluminum at roughly 650–700 °C and holding it under pressure until it freezes. The die has to open, so every surface parallel to the draw direction needs a draft angle of about 1–3°. A die cannot form a square shoulder, an undercut, or a press-fit bore.
Thermal shrinkage then moves everything. Aluminum AlSi10MnMg-type alloys shrink around 0.6–1.1 % as they cool from liquid to room temperature, and the shrinkage is not uniform across a 1.5 m casting. A bore designed at Ø 40.000 mm in the die does not come out at Ø 40.000 mm.
Casting also leaves a skin. The surface is a mix of oxide, released agent, and a thin chill layer with different hardness than the core. That layer has to be removed before any fatigue-loaded interface is trusted.
The press wins on cycle time and part count. It loses on dimensional control, surface finish, and repeatability at the micron level. That gap is exactly the size of a CNC department.
Which Tesla Parts Still Need CNC Machining
Start with the castings themselves. After the rear underbody comes out of the press, a 5-axis machining center fixtures it and cuts the motor mount pads, the subframe bolt bosses, and the shock tower faces. Those are the load paths. They need flatness in the 0.05 mm range and hole position within ±0.1 mm over a long span.
The drive unit is the second cluster. Motor housings, gearbox cases, inverter cold plates, and rotor shafts are all machined. Rotor shafts in particular run on tight geometry: journal diameter often held to ±0.005 mm with roundness under 0.005 mm, because bearing life depends on it.
Battery work is the third cluster. Module end plates, busbar interfaces, and the cooling manifold ports are cut, deburred, and often laser marked. A coolant port that leaks at 2 bar is a warranty claim, so the sealing face gets machined rather than cast.
Then there is the long tail: brake caliper brackets, steering knuckle interfaces, sensor housings, and the tooling that builds the line itself. Jigs, fixtures, and gripper fingers are machined parts too, and they get revised constantly.
- 1Giga castingsMotor pads, subframe bosses, strut faces
- 2Drive unitHousings, cold plates, rotor shafts
- 3Battery packEnd plates, busbars, coolant ports
How 5-Axis Work Fits the EV Part Mix
EV parts are wide and shallow. A rear casting can span more than 1,500 mm while staying under 200 mm thick, which is the opposite of the small, deep aerospace bracket that a 3-axis machine handles well. That shape drives machine choice.
A 5-axis center with a trunnion lets the spindle reach the underside of a casting without flipping it. Every flip costs a datum. Two flips on a 1.5 m aluminum part can add 0.1 mm of stacked error before the cutter even touches metal.
On our floor, 16 simultaneous 5-axis machining centers handle this class of work, alongside 12 four-axis mills and 27 three-axis machines. Large travels go up to 4,000 × 400 × 150 mm, with medium envelopes at 750 × 1,150 × 550 mm. That range covers castings, housings, and long extrusions.
Tooling matters as much as the machine. Aluminum at 3,000–8,000 rpm with high-helix carbide and generous coolant keeps chips clear and heat out of the part. Dry cutting aluminum in a deep pocket is how you get built-up edge and a torn finish.
What Tolerance Castings Actually Need After Machining
Not every surface on a machined casting needs the same number. Over-tolerancing is the fastest way to raise cost without raising quality. The useful split is interface versus non-interface.
Interface surfaces carry load, seal fluid, or locate another component. Those get the tight numbers: ±0.005 mm on bearing bores and rotor journals, flatness around 0.05 mm on motor pads, and surface finish between Ra 0.8–1.6 μm on sealing faces. Anything finer is usually unnecessary outside of bearing seats and hydraulic spools.
Non-interface surfaces just need clearance. Bolt boss faces, rib ends, and weight-reduction cutouts can run at ±0.1 mm with an as-machined finish of Ra 1.6–3.2 μm. Machining them to a finer spec adds cycle time and tool wear for no functional gain.
One more constraint: thin cast walls move. A 3 mm wall on a 1.2 m casting will deflect under clamping force. Light fixtures, sequenced cuts, and a rough-then-finish pass with a stress interval keep the part where it was modeled.
Why EV Programs Buy Machined Parts From Job Shops
Tesla does machine in-house, and it also buys machined components. So does every other EV program. The reason is simple: a new model year changes bracket geometry faster than a captive machining line can retool.
A tier-2 job shop absorbs that change. Design revisions arrive, fixtures get modified, and the first articles ship before the stamping dies are even cut. That is why prototype and low-volume machining sits next to production work in the same building.
Automotive quality expectations come with it. IATF 16949:2016 governs the process side, covering traceability, change control, and PPAP-style documentation. ISO 9001:2015 covers the base system. For battery and sensor work, ISO 27001:2022 matters too, because drawings and BOMs are confidential.
Volume is not the blocker. Runs from one prototype to 10,000+ parts happen on the same equipment, and a quotation with DFM feedback can come back within 12 hours.
Casting vs CNC Machining vs Hybrid Flow
Where each route fits in an EV part
| Route | Best for | Tolerance reach | Watch out for |
|---|---|---|---|
| Die casting only | Large body and underbody shapes | ±0.5 mm typical | No square shoulders or bores |
| CNC only | Brackets, shafts, prototypes | ±0.005 mm | Cost per part at high volume |
| Hybrid: cast + CNC | Giga castings, housings, cases | ±0.005 mm on interfaces | Extra fixture and datum control |
| CNC + welding | Frame nodes, battery trays | ±0.1 mm at weld joints | Distortion after welding |
The Verdict
If a surface seals, rotates, or locates another part, machine it. If it only shapes airflow or fills space, let the casting keep it.
Common Questions
Does Tesla own its own CNC machines?
Yes. Tesla operates machining capacity inside its own plants for castings, drive units, and tooling. It also purchases machined components from outside suppliers, which is normal across the auto industry.
The split changes by program and by part. High-volume interfaces that never change tend to stay in-house, while low-volume brackets, prototype hardware, and line tooling often go out.
Why are Giga castings machined instead of used as-cast?
A die casting cannot form undercuts, square shoulders, or press-fit bores, because the die has to open. Shrinkage of roughly 0.6–1.1 % also moves bore positions across a long casting.
Machining removes the oxide skin and chill layer, then cuts the bolt patterns, motor pads, and bearing bores to the numbers the assembly actually needs.
What tolerance can machined aluminum EV parts hold?
For bearing seats and rotor journals, ±0.005 mm is achievable with temperature control and in-process gauging. Motor mount pads typically run flatness around 0.05 mm.
Non-critical faces do not need that. Running them at ±0.1 mm with an Ra 1.6–3.2 μm finish keeps cost down without affecting function.
Which aluminum alloys are common for EV structural parts?
Die-cast structural work often uses AlSi10MnMg-type alloys, which we list as ADC12 family material. Forged or billet-machined parts more often use 6061-T6, 6082, or 7075 when strength matters.
The choice affects machining. High-silicon casting alloys are abrasive on tooling, so cutter life is shorter than on 6061 and speeds need to come down.
How long does it take to get machined prototypes for an EV program?
A quotation with free DFM analysis comes back within 12 hours, and production can start within 24 hours of approval. Parts typically ship in 3–5 days.
For first-fit prototypes that means a bracket can be cut, finished, and inspected faster than a typical design review cycle.
Is machining a cast part harder than machining from billet?
Different, not simply harder. Castings have a hard skin and possible internal porosity, so the first pass cuts interrupted material and tool load varies.
Fixturing is the bigger challenge. A thin-walled casting deflects under clamping force, so light clamping, sequenced cuts, and a rough-then-finish strategy keep the finished part in tolerance.
Send Us the Interface, Not the Whole Car
Upload a drawing or STEP file and get a quote with DFM notes within 12 hours.
12-hour quote±0.005 mmIATF 16949NDA on request
More Machining Notes
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