CNC Phone Case Handmade: Machining Metal Cases That Fit
This page explains how a CNC phone case handmade process works when the part has to wrap a real phone. It is written for product engineers and sourcing teams who need wall thickness, camera ring flatness, and finish to hold on every unit. You will see which geometries suit 5-axis machining, which do not, and what to check before you release a drawing.
Key takeaways
What makes a phone case a CNC job
A phone case looks simple until you measure it. The part is a thin-walled box with a floor, four side walls, and a set of openings for the camera, buttons, and port. On a 6.1 in handset, the outer length sits near 150 mm and the wall is often 0.8–1.2 mm in aluminium. Those two numbers set the whole process. Long and thin means deflection; the tool pushes the wall away instead of cutting it.
Injection moulding handles this shape cheaply at volume, but it cannot produce a 0.9 mm anodized aluminium wall with a machined chamfer on the camera ring. Die casting gets closer, yet the draft angle and porosity show up once you bead blast the surface. That is the gap CNC fills. The trade is cycle time. A single shell may take 40–90 minutes across two or three setups.
A CNC phone case handmade approach is used when the run is short, the geometry changes between colourways, or the customer wants a metal body that feels solid in the hand. Runs from one prototype to 10,000+ parts fit this model at GreatLight. Below about 50 units, machining usually beats tooling cost. Above a few thousand identical parts, it is worth comparing against die casting plus light finishing.
- 1Good candidateAluminium or titanium shell, wall 0.8 mm and up, distinct camera boss, short or mixed run
- 2Poor candidateWall under 0.5 mm, uniform thin shell with no stiffening rib, very high volume
- 3Watch the corner radiusInternal corners below 1 mm force a small tool and slow the whole cycle down
Five-axis workholding for thin walls
The floor and outer profile usually run on the first setup from a solid billet. We leave 1.5–2 mm of stock on the walls so the second setup has something rigid to hold. Clamping on a 1 mm finished wall is where most shops lose the part. Vise jaws crush it; a vacuum plate can lift it. The workable answer is a soft jaw or a dedicated fixture that contacts the part on the floor and on the pocket bosses only.
The second setup is where the openings get cut. A Ø 0.8–1.2 mm end mill finishes the speaker slots, and a Ø 2–3 mm tool cuts the port and the button openings. On 16 simultaneous 5-axis centers, the tool stays normal to the surface through the corner radii, so the camera ring is cut in one continuous pass. Re-fixturing that ring is the fastest way to get a visible seam.
Light finishing passes keep heat out of the wall. We run 0.1–0.2 mm radial steps at 8,000–12,000 rpm on aluminium, with air blast instead of flood coolant so chips clear from the pocket. Titanium TC4 runs slower, around 40–60 m/min surface speed, and needs more attention to tool wear. A dull tool on a 1 mm wall will pull the part, no matter how good the fixture is.
- 1Roughing stockLeave 1.5–2 mm on walls until the final setup
- 2Fixture contactFloor and internal bosses only, never the finished outer wall
Matching the case to the handset
Every phone generation shifts the button positions and the camera bump by a fraction of a millimetre. A drawing alone is not enough. We ask for the handset model or a physical unit, then machine a master gauge from the same program. Each finished shell is trial-fitted on that gauge. If the case rocks, the floor is bowed; if the buttons bind, the opening is 0.1 mm too tight. Both are correctable before anodizing.
Tolerance on the interface features is tighter than on the outer skin. The camera opening and the button clearances are held at ±0.005 mm where the drawing calls for it. The outer profile can run at ±0.05 mm and still look right in the hand, because nothing touches it. Sorting features by function saves cycle time and keeps the cost down.
Finish is the last variable. Clear or coloured anodizing adds 15–30 μm of oxide, which closes a loose button opening and can make a tight one worse. Hardcoat adds more. We mask the openings that must stay at size and note the build-up on the inspection report so the customer sees what changed. Bead blasting before anodizing gives a matte surface; brushing leaves directional lines that hide small machining marks.
- 1Interface featuresCamera ring, buttons, port: hold to drawing, mask before anodizing
- 2Outer skinCosmetic only, ±0.05 mm is enough
Which process suits which phone case
Runs from one prototype to 10,000+ parts. Compare before you commit to tooling.
| Process | Best for | Wall limit | Rough cost driver |
|---|---|---|---|
| 3-axis CNC | Flat back plate, simple openings | 1.5 mm and up | Setup count, usually three or more |
| 5-axis CNC | Full shell with camera boss and curved sides | 0.8 mm and up | Cycle time, 40–90 minutes per shell |
| Die casting + CNC | Runs above a few thousand units | 1.2 mm and up | Tooling cost plus porosity risk |
| Injection moulding | High volume plastic or composite cases | 0.6 mm and up | Tooling only, no per-part machining |
When to machine, when not to
If the case is metal, has a machined camera ring, and the run is under a few thousand units, machine it in 5-axis. If the design is a uniform plastic shell at 10,000 pieces, mould it and skip CNC entirely.
Questions engineers ask before ordering
What is the thinnest wall you can machine on a phone case?
On aluminium we hold 0.8 mm reliably and can push to 0.6 mm with a dedicated fixture and light finishing passes. Below that, the wall deflects under clamping and the part will not stay flat.
Titanium TC4 needs more stiffness for the same wall, so we treat 1.0 mm as the practical floor unless the geometry has ribs.
Can you match a Pantone colour on an anodized case?
We can get close on clear, black, and the common blues and reds. Anodizing colour depends on alloy, bath, and part geometry, so a small batch is run first and sent for approval before the full run.
Hardcoat anodizing is darker and less saturated than standard anodizing on the same dye, and that difference should be planned for in the design.
How do you keep the camera opening flat?
The ring is cut in one continuous 5-axis pass with the tool normal to the surface. We do not re-fixture the part between the rough and finish of that feature.
Flatness on the rim is checked on the master gauge. A visible seam or a light leak around the lens usually means the part moved between setups.
Do you need a physical phone, or is a 3D model enough?
A 3D model is enough to quote and to start programming. For the first article we prefer a physical handset or a master gauge, because button feel and camera clearance cannot be judged from a screen.
If you cannot ship a handset, we machine the gauge from your model and you check the fit on your side.
What file formats and tolerances should the drawing carry?
STEP or IGES for the solid, plus a 2D drawing for the interface features. Put ±0.005 mm on the camera ring, button openings, and port, and a looser ±0.05 mm on the outer skin.
If the whole drawing is set to ±0.005 mm, the cycle time goes up for features that do not need it.
Can you handle small runs and one-off prototypes?
Yes. There is no minimum order quantity, from one prototype to 10,000+ part runs. Quotation and free DFM analysis come back within 12 hours, and production can start within 24 hours.
Prototypes ship in 3–5 days. Uploads are secure and confidential, and an NDA is available on request.
Send the model, get a machinable answer
Upload your case model and drawing. We check wall thickness, opening clearances, and finish build-up, then quote with a DFM note inside 12 hours.
12-hour quoteNo MOQ100% inspection
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