Application guide

CNC Phone Case Cutting

This page covers how a solid block of aluminum or titanium becomes a phone case on a CNC machine, what geometry the process can and cannot hold, and which checks separate a workable quote from an expensive mistake. It is written for product engineers and sourcing staff who need to judge a supplier before tooling is cut.

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Precision CNC cutting solution for cnc phone case cutting

On this page

1
Key takeaways
2
What CNC phone case cutting actually removes
3
Alloy choice for CNC phone case cutting
4
Walls, radii and features the cutter can hold
5
Finishing options and how they change the part
6
How to judge a supplier before you commit
7
From model to finished case
8
Which alloy for which case

Quick answer

Key takeaways

Subtractive, not moldedA case is cut from one billet, so corner radii and wall thickness are set by the tool, not by draft angle.

Aluminum 6061 and 7075 dominate6061 anodizes evenly; 7075 holds a thinner wall but costs more and cuts slower.

Wall thickness drives costBelow 0.8 mm the part needs more passes, more fixtures and more scrap risk.

Five-axis pays off on curved backsOne setup cuts the cavity, camera boss and side buttons without re-fixturing.

Finish decides the feelBead blasting plus anodizing gives the matte grip most buyers ask for.

Process

What CNC phone case cutting actually removes

CNC phone case cutting starts with a solid billet. A rotating cutter travels along programmed paths and removes material in layers until the outer shell and the inner device cavity are left. There is no mold, no draft angle and no ejector pin mark. The shape you draw is the shape you get, within the tolerance of the machine.

That freedom has a cost. Every cubic centimeter of removed material took spindle time. A typical 6.1-inch case blank starts around 180–260 g of aluminum and ships at 25–40 g. Most of the cutting is roughing, and roughing is where cycle time is won or lost.

For prototypes this is the right process. For 200,000 units of a flat-back case, injection molding or die casting will beat it on unit price. The crossover usually sits somewhere in the low thousands, depending on how much undercut and how many separate parts the design needs.

One practical note on fixturing. A case is thin and long. If the blank is held only in a vise, the floor of the cavity will chatter and the wall will spring. We normally rough the outside, flip, cut the cavity on soft jaws, then finish the outside on a custom fixture so the thin wall is supported from the inside.

1
Material removalUp to 85% of the billet becomes chips.
2
Setup countThree-axis work often needs 3–4 setups; five-axis can do it in 1–2.
3
Typical floor thickness0.8–1.2 mm for a rigid feel, 0.6 mm when weight is critical.

Material

Alloy choice for CNC phone case cutting

Aluminum 6061-T6 is the default. It machines fast, holds a wall, and takes clear, color or hardcoat anodizing with a consistent tone. If your case will be anodized black or blue, 6061 gives the fewest surprises.

Aluminum 7075 machines to a better surface and is noticeably stiffer, so you can push a wall down to about 0.6 mm without the case flexing in a pocket. It costs more per kilogram, cuts slower, and anodizes to a slightly darker, less uniform shade. Use it when thin and light is the selling point.

Titanium TC4 (Ti-6Al-4V) is the premium option. It is roughly one third the density of steel with high strength, so a titanium case can be very thin. It also wears tools quickly. Expect longer cycle times, more cutter changes and a higher price. Most buyers choose titanium for a brushed or bead-blasted natural finish rather than a colored one.

Stainless 316L and 17-4PH appear on cases that must survive salt spray or repeated drops. Both are heavy, and 316L is gummy to cut. They suit industrial housings, rugged field devices and instrument enclosures more than consumer phone shells.

1
6061-T6Best all-round balance of cost, finish and rigidity.
2
7075Thinner walls, higher cost, less uniform anodize.
3
TC4 titaniumLight and strong, slower to cut, premium price.
4
PC and PEEKFor non-metallic covers; PEEK resists heat and chemicals.

Geometry

Walls, radii and features the cutter can hold

The single biggest constraint is the ratio of wall thickness to depth. A cutter has to reach the bottom of the cavity and still have enough shank behind it to resist deflection. Deep, narrow pockets force small-diameter tools, and small tools must run slower and take lighter passes.

Internal corners cannot be sharper than the cutter radius. If your model shows a 0.2 mm internal corner, the tool must be 0.4 mm or smaller, which is slow and fragile. Design internal radii at 1 mm or above and cycle time drops sharply. External corners are far more forgiving.

Camera openings, speaker slots and button holes are all cut in the same program. Laser engraving handles logos afterward, with a minimum character height of 1.5 mm to stay readable. Anything smaller tends to fill during anodizing.

Threaded inserts, lanyard holes and magnetic ring pockets are common additions. Each one adds a tool change but rarely adds a new setup. Group them on the same face so the machine does not have to re-orient the part.

1
Minimum internal radius1.0 mm is comfortable; below 0.5 mm gets slow and risky.
2
Wall thickness0.8–1.2 mm typical; 0.6 mm only with 7075 or titanium.
3
EngravingLaser marking, minimum character height 1.5 mm.

Finishing

Finishing options and how they change the part

Anodizing is the standard finish for aluminum cases. Clear, color, hardcoat and conductive variants are all available. Anodizing adds a thin oxide layer, so account for roughly 5–15 μm of growth on critical mating faces. If a camera bezel must sit flush, mask or machine it after coating.

Bead blasting before anodizing produces the soft matte texture that most phone case buyers want. Brushing gives a directional grain, which looks sharp on titanium but shows fingerprints. Polishing to a mirror takes time and hides tool marks only if the surface underneath is already clean.

For steel and stainless parts, electroless nickel, zinc, silver and gold plating are options, along with powder coating and black oxide. Powder coating builds 60–100 μm, which is too thick for tight-fit joints but fine for an outer shell that never touches the device.

Laser marking is the last step. It survives anodizing, plating and blasting. Send vector artwork with the case model so the marking position is defined on the same coordinate system as the cavity, not measured by hand.

1
Anodize growthAbout 5–15 μm per surface; mask tight fits.
2
TextureBead blasting for matte, brushing for grain, polishing for gloss.
3
MarkingLaser engraving is durable and needs 1.5 mm minimum character height.

Quality

How to judge a supplier before you commit

Ask what machine will run the job, not just what tolerance the shop claims. A curved back with undercuts needs simultaneous five-axis work. If the shop only has three-axis mills, they will split the part or add setups, and that shows up as seam lines and longer lead time.

Ask for the inspection plan. On a phone case, the critical dimensions are the cavity length and width, the camera opening position and the wall thickness at the thinnest point. A supplier who inspects only the outside profile will ship parts that do not fit the phone.

Confirm the material grade in writing. "Aluminum" is not a specification. 6061-T6 and a generic 6061 casting behave differently under anodizing and under load. The same applies to titanium: TC4 is not the same as commercially pure TA2.

Finally, check how they handle the first article. A DFM note that flags a 0.3 mm internal radius before cutting is worth more than a fast quote. At GreatLight, quotation and free DFM analysis come back within 12 hours, and production can start within 24 hours after approval. Parts ship in 3–5 days. Raw material check, in-process monitoring and final inspection are standard, with reports on request and 100% inspection before shipment. Uploads stay confidential, and an NDA is available on request.

1
Machine matchCurved backs and undercuts need simultaneous five-axis.
2
Inspection planCavity size, camera position and minimum wall must be measured.
3
Material calloutSpecify 6061-T6, 7075 or TC4, not just "aluminum".

Workflow

From model to finished case

1
Send the 3D model and target quantitySTEP or native CAD plus the phone model reference. Note the quantity band so the process choice can be checked.
2
Review the DFM noteWe flag internal radii under 1 mm, walls under 0.8 mm, deep pockets and any feature that forces a tiny cutter.
3
Fix the material and finish6061-T6 for anodized color, 7075 for thin and stiff, TC4 for premium. Choose bead blasting, brushing or polishing.
4
Rough and stress-relieveRough the outside first, leave 0.3–0.5 mm of stock, then relieve stress before finishing so the thin floor does not bow.
5
Cut the cavity on soft jawsHold the roughed blank in machined soft jaws so the thin wall is backed up and the floor does not chatter.
6
Finish the outside on a custom fixtureA support fixture inside the cavity lets the outer faces be cut cleanly without squeeze marks.
7
Anodize, blast and markMask tight fits, apply the chosen finish, then laser mark at 1.5 mm minimum character height.
8
Inspect and packMeasure cavity dimensions, camera opening and wall thickness. 100% inspection before shipment.

Selection

Which alloy for which case

Alloy	Wall range	Best for	Watch out for
6061-T6	0.8–1.2 mm	Anodized color cases, general use	Softest of the three; dents on hard drops
7075	0.6–1.0 mm	Thin, stiff, lightweight shells	Darker anodize; higher material cost
TC4 titanium	0.6–1.0 mm	Premium brushed or blasted cases	Slow cutting; tool wear; high price
316L / 17-4PH	1.0–1.5 mm	Rugged industrial housings	Heavy; 316L is gummy to machine
POM / PC	1.0–2.0 mm	Non-metallic covers and jigs	Lower stiffness; limited finish options

When CNC is the right call

Choose CNC phone case cutting when the design has undercuts, a curved back, a thin wall or a metal body that must be anodized; choose molding or die casting only when the shape is simple, the volume is high and a draft angle is acceptable.

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FAQs

Questions buyers ask

How thin can a CNC machined phone case wall be?

With 6061-T6, 0.8 mm is a safe working floor and 1.0–1.2 mm feels more solid in the hand. With 7075 or TC4 titanium you can go to about 0.6 mm on the side walls, provided the floor of the cavity stays thicker so it does not flex against the phone.

Below 0.6 mm the risk is not just breakage. Thin walls deflect during cutting, so the finished thickness varies across the part and anodizing color shifts where the wall changes section.

Do I need five-axis machining for a phone case?

Only if the back is curved, if there are undercuts around the camera boss, or if side buttons sit on a sloped face. A simple flat-back, flat-side case can be cut on a three-axis machine in three or four setups.

Five-axis work removes the seam lines that come from re-fixturing and usually shortens the schedule, because the cavity and outer profile can be reached without moving the part.

What is the smallest internal corner you can cut?

The cutter diameter sets the limit. A 1 mm internal radius needs a 2 mm cutter, which is rigid enough to run at a reasonable feed. A 0.3 mm radius needs a 0.6 mm cutter, which must run slower and can snap in a deep pocket.

If the corner is cosmetic rather than functional, open it to 1 mm or more. Cycle time often drops by a third with no visible change to the finished case.

Which finish holds up best on a daily-use case?

Hardcoat anodizing over bead-blasted aluminum is the most durable combination we run. It resists scuffs better than clear anodizing and keeps the matte grip. Brushed titanium also wears well and hides small scratches because the grain breaks up the reflection.

Powder coating builds 60–100 μm and can chip at sharp edges. It suits an outer shell that never contacts the device, not a precision fit.

Can you cut a case for a phone model you have not seen?

Yes, if you supply the device outline or a reference case to measure. We work from your 3D model and confirm cavity dimensions against the drawing before cutting. For a new model, a first article is the normal route.

Uploads stay confidential and an NDA is available on request. There is no minimum order quantity, so a single prototype and a 10,000-part run go through the same first-article check.

What lead time and quantity should I plan for?

Quotation and free DFM analysis come back within 12 hours. Production can start within 24 hours after you approve the DFM and material, and parts ship in 3–5 days. That applies from one prototype upward.

The historical late-delivery probability is below 2%, but we do not promise fixed delivery dates before the DFM is signed off, because an unresolved thin wall or a special finish can change the schedule.