Brown CNC Processing Company: Leading CNC Processing Solutions

A brown CNC processing company earns its keep by putting a part on the right machine. GreatLight runs 127 high-precision CNC machines across three wholly-owned plants covering 7,600 m², with 150 technicians. That mix matters because a simple bracket quoted on a 5-axis center carries a higher rate than the same bracket on a 3-axis mill, and the customer pays for that difference.

Three-axis work suits parts with features reachable from a small number of setups: plates, housings, manifolds with one dominant face. We keep 27 three-axis machines for exactly that. When a part needs features on four sides, a fourth axis or a tombstone fixture removes setups and the position error that comes with each one. We hold 12 four-axis mills.

Simultaneous 5-axis is where complex geometry becomes practical. We have 16 simultaneous 5-axis machining centers, and the payoff is not just surface finish on impellers or medical housings. It is the ability to reach undercuts and blend radii in one setup, so datum stack-up does not accumulate. For rotational parts with cross-features, 16 mill-turn centers cut both turning and milling without re-chucking.

Size sets the ceiling. Maximum processing size is 4,000 mm, with travel options of 4,000 × 400 × 150 mm for long parts, 750 × 1,150 × 550 mm and 600 × 600 × 600 mm for mid-size work, and 500 × 500 × 450 mm or 500 × 310 × 200 mm on compact machines. A Ø400 mm rotary table handles round work that needs indexing.

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  One setup beats tight fixture designEvery extra setup adds a datum. If 5-axis removes two of them, it usually wins on total cost.
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  Long parts need the right travelAnything past the compact envelope should be quoted against the 4,000 mm machine.
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  Turn-mill for cross holesDrilled and tapped features on a turned surface avoid a second operation.

The working tolerance is ±0.005 mm (±0.0002 in). That figure applies to critical features where the drawing calls for it, not to every dimension on the print. An engineer should expect to mark the three or four dimensions that actually control function and let the rest run to general tolerance. Tightening every dimension raises inspection time and scrap without improving the assembly.

Surface finish is chosen from three bands. As-machined runs Ra 1.6–3.2 μm and covers most structural parts. A high finish of Ra 0.8–1.6 μm is what we hold on sealing faces, bearing bores and sliding surfaces. Fine finish at Ra 0.2–0.8 μm is reserved for optical, fluid-contact and low-friction surfaces, and it needs a separate finishing pass, so budget for it.

Geometry limits tolerance more than the machine does. A deep pocket with a 6 mm tool deflects, and no control system fixes that. Thin walls under 1 mm move when the material is released. A feature far from the primary datum gains error with every setup. When we run DFM analysis, these are the items we flag, and we send the quotation with the analysis within 12 hours.

Qualification rate across production is 99.99%. That number comes from inspection, not from luck. We check incoming raw material, monitor in-process, and inspect 100% before shipment, with reports available on request.

Aluminum is the default for prototypes and light production. We stock 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075 and ADC12. The 7075 grades machine cleanly but move more after stress relief, so a part with a 0.05 mm flatness call needs roughing, a pause, and a finishing cut. 2024 behaves similarly and is often chosen for aerospace brackets.

Stainless covers 303, 304, 316, 316L, 420, 430, 431, 440C and 17-4PH (SUS630). Grade 303 is the easiest to machine and the usual choice for bushings and fittings. Grade 316L goes to medical and food-contact parts because of corrosion resistance, and it work-hardens, so feeds and speeds need attention. 17-4PH gives high strength after heat treatment and is common in valve and pump components.

Steel grades include 1018, 1045, 4130, 4140, 4340, A36 and tool steel. The 4140 and 4340 families are used for shafts and load-bearing parts, usually pre-hardened to reduce distortion. Copper and brass cover C101, C103, C110, beryllium copper, C27400, C28000 and C36000. Beryllium copper is specified for spring contacts and needs controlled handling during machining.

Titanium and specialty alloys include TA1, TA2, TC4 (Ti-6Al-4V), Inconel and magnesium AZ31B or AZ91D. Titanium cuts slowly and generates heat at the edge, so cycle times are longer than aluminum for the same geometry. Inconel is worse. Magnesium demands chip control because fine chips ignite. Plastics run from ABS, PC, PMMA, POM and PA through PEEK, PP, HDPE and carbon fibre, and they need sharp tooling and lighter depths of cut to avoid melting.

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  Stress relief before finishing7075, 2024 and 4340 move after roughing. Leave stock and take a finish pass.
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  Work-hardening grades316L and 17-4PH need a constant feed, not a dwell, or the surface hardens under the tool.
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  Thin plastic wallsCarbon fibre and PEEK are abrasive. Tool wear shows up as a rising surface finish.

Machining usually is not the last step. Anodizing in clear, color, hardcoat and conductive versions covers most aluminum parts. Electroless nickel, zinc, silver and gold plating handle wear and conductivity requirements. Powder coating and black oxide serve steel and larger frames. Bead blasting, tumbling, brushing and polishing address edges and cosmetic surfaces. Laser marking and engraving need a minimum character height of 1.5 mm to stay legible after coating.

Keeping finishing in the same building removes a common failure mode: parts damaged or contaminated in transit between suppliers. It also means one inspection record covers the finished part rather than a pre-plate measurement that no longer describes what ships.

There are jobs we turn down or re-scope. A single deep cavity with a 2 mm cutter and a 0.01 mm wall thickness is not a CNC part; it is a different process. A 50,000-piece simple bracket is usually cheaper as a die casting with a machining pass on the critical faces. We also say so when a tolerance on the print has no functional purpose, because removing it saves the customer money.

Volume is not a barrier here. There is no minimum order quantity, and runs go from one prototype to 10,000+ parts. Production can start within 24 hours of an approved quotation, and parts ship in 3–5 days. Historical late-delivery probability sits below 2%, though we do not promise dates before the drawing is reviewed.

Confidentiality is handled the same way. Uploads are secure and confidential, and an NDA is available on request for programs that need one.