Bangalore CNC Service Explained

A CNC service starts with your 3D model and 2D print, not with a machine. The first real work is deciding how the part will be held. Fixture choice sets the datums, the datums set the toolpaths, and the toolpaths decide whether your tight callouts are reachable at all. A shop that skips this step and quotes straight from the file will usually come back later with a tolerance waiver.

The CAM programmer picks tooling based on feature size. A 2 mm deep pocket with a 6 mm corner radius cuts fast on a 5 mm end mill. The same pocket with a 1 mm radius forces a small tool, slower feed, and more passes. That single detail can double cycle time, and it is the reason two shops can quote the same model very differently.

Setup count matters more than spindle speed on small batches. Every extra orientation adds a re-fixture, a new zero point, and a fresh chance of alignment error. On a three-axis machine a part with features on five faces may need four setups. On a five-axis center the same part often runs in one or two. For quantities under a few hundred, the setup savings usually outweigh the higher machine rate.

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  Send a STEP file plus a PDF printThe print carries tolerances, finishes and inspection notes the model cannot.
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  Mark critical dimensionsEngineers can then plan the setup around what actually matters.
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  State the material temper6061-T6 and 6061-O machine very differently.

Three-axis machining covers most prismatic parts: plates, brackets, housings with features on one side. It is the cheapest and fastest option when the geometry allows it. Reach for three-axis first. Move up only when the part forces you to.

Four-axis adds a rotary table, usually Ø400 mm on our machines. A part that needs holes indexed around a cylindrical body, or features on four sides of a shaft, becomes a single-setup job. Deep cavities that would otherwise need multiple orientations also benefit. The trade-off is that the rotary axis adds a positioning error you have to budget for.

Five-axis simultaneous machining rotates the tool or the table on two extra axes while cutting. Contoured surfaces, impellers, and deep pockets with drafted walls can be cut in one continuous pass. The tool stays normal to the surface, so you get a better finish with a shorter tool. Short tools deflect less, which is how ±0.005 mm stays reachable on a curved face.

Not every part needs five axes. A flat plate with drilled holes will not run faster on a five-axis center, and the hourly rate is higher. The honest rule: if the part has undercut geometry, compound angles, or more than three faces of features, five-axis usually wins. If it does not, it usually does not.

General machining tolerance of ±0.005 mm is achievable, but it should not be your default on every dimension. Tight callouts cost money on every part, forever. Put ±0.005 mm on the two or three dimensions that drive function, and let the rest sit at a general tolerance note.

Surface finish follows the same logic. As-machined surfaces land around Ra 1.6–3.2 μm. A high-quality finish of Ra 0.8–1.6 μm is normal for sealing faces and bearing bores. Fine finishes of Ra 0.2–0.8 μm need slower feeds, lighter depths of cut, and often a separate finishing pass or a secondary operation. Specify them only where a seal, a sliding fit or an optical surface demands it.

Two factors quietly destroy tolerance in production. The first is heat. Aluminium grows about 23 μm per metre per degree Celsius. A part machined warm and measured cold can read out of tolerance even though the machine was accurate. The second is residual stress. Hogging out a billet releases internal stress and the part moves after clamping is removed. Rough, stress-relieve, then finish is the standard answer.

Inspection closes the loop. We run a raw material check, in-process monitoring, and a final inspection on 100% of parts before shipment, with reports on request. If a dimension matters to your assembly, say so on the print and ask for the CMM report. It is cheaper to inspect once than to sort a shipment twice.

Material choice drives machinability more than any other decision. Aluminium 6061-T6 is the default for prototypes and light structural parts: good strength, easy to cut, takes anodizing well. 7075 cuts harder but gives you near-steel strength at a third of the weight. For high-volume die-cast housings, ADC12 is the usual pick, though it will not hold the same tolerance as a billet part.

Stainless behaves differently. Grades 303 and 304 machine cleanly; 316L resists corrosion and is common in medical and food-contact work. 17-4PH gives high strength after heat treatment and holds up in aerospace brackets. Titanium TC4 (Ti-6Al-4V) and Inconel cut slowly, wear tooling fast, and should be reserved for parts that genuinely need heat resistance or a high strength-to-weight ratio.

Finishing is usually where a part becomes a product. Anodizing in clear, colour, hardcoat or conductive form is standard on aluminium. Electroless nickel, zinc, silver and gold plating cover EMI and wear requirements. Powder coating and black oxide handle larger frames and steel parts. Bead blasting, tumbling, brushing and polishing control appearance and surface texture. Laser marking and engraving work down to a minimum character height of 1.5 mm, which matters for traceability and part numbers.

Plan the finish before the last cut. A hardcoat anodized surface adds roughly half the coating thickness per side, so a bore that is on size before coating will be undersize after. Tell the shop which surfaces must stay bare and which need masking. It is a two-line note that prevents a scrapped batch.

A free DFM review on your model and print takes about 12 hours and answers most of the risk upfront. The review looks for features that will drive cost or scrap: thin walls, deep narrow slots, sharp internal corners, and holes that intersect at an angle.

Corner radii are the most common cost driver. An internal corner radius equal to the cutter radius lets the tool run at full load. A radius smaller than the standard cutter forces a smaller tool, more passes and a higher chance of chatter. If a corner radius is not functional, open it up.

Wall thickness matters too. Aluminium walls under about 1 mm deflect during cutting and are hard to hold flat. Deep pockets where depth exceeds four times the cutter diameter need a long tool, and long tools chatter. Sometimes the fix is a design change, not a machining trick.

Thread depth, hole depth-to-diameter ratio, and surface callouts on non-functional faces all add cost. Getting these on the table before the first chip is cut is the whole point of DFM. Production can start within 24 hours once the design is locked, and parts ship in 3–5 days.

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  Open internal radiiMatch the corner radius to a standard cutter diameter.
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  Limit deep pocketsKeep depth under four times the cutter diameter where possible.
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  Tolerance only what mattersTight callouts on every dimension raise unit cost.
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  Note finish and maskingCoating adds thickness; bare surfaces need masking.

A useful quote tells you more than a number. Ask which machine configuration was assumed, how many setups, and whether any dimension was flagged as hard. A shop that explains its assumptions is easier to work with when a tolerance question comes up mid-run.

Order quantity is flexible. There is no minimum order quantity, so a single prototype and a 10,000-part run go through the same process. Prototype work and production work share the same inspection standard, which is how you catch a problem before tooling is committed.

Confidentiality is standard. Uploads are secure and confidential, and an NDA is available on request. If your part sits inside an unreleased product, say so early and the file handling changes from the first email.

GreatLight runs three wholly-owned plants, 127 high-precision CNC machines and 150 technicians, with 15 years in the trade since 2011. The Singapore factory at No.3 Joo Koon Circle sits close to Southeast Asian supply chains, which shortens the loop for teams that need parts moved quickly. For a Bangalore CNC service explained in practical terms, that combination of machine range and inspection discipline is what determines whether your drawings come back as parts.