Sudans CNC edge in five-axis machining

• 1
  What the Sudans CNC edge in setups changes
• 2
  Where the tolerance budget goes
• 3
  Surface finish and what drives it
• 4
  How parts get checked before shipping
• 5
  Lead time and how it is spent
• 6
  Which process fits which part

A three-axis machine moves the tool in X, Y and Z. Every face you cannot reach from the top needs a second setup, and every setup adds a new datum. The part comes off the vise, goes back on, and the position error from the first operation no longer lines up with the second. On a part with four angled faces, that error stack is what pushes a feature out of tolerance.

Five-axis machining adds two rotary axes, so the tool can tilt and the table can turn while cutting. The practical result is fewer setups. A housing with ports on three sides can often be finished in one clamping. Fewer datums means a shorter tolerance chain, and a shorter chain is easier to hold at ±0.005 mm.

The gain is not automatic. Rotary axes carry their own positional error, and a tilted tool changes how the cutter contacts the wall. A shop that bolts a five-axis machine down and runs three-axis toolpaths on it gets the setup savings and none of the accuracy. The Sudans CNC edge comes from programming the rotary moves, not from owning the iron.

When does a second setup still make sense? Short runs of simple prismatic parts. If a plate has two flat faces and a few holes, a three-axis machine with a good fixture is faster and cheaper. Five-axis pays off when the part has compound angles, deep pockets, or walls you cannot reach straight on.

Tolerance is a budget, not a single number. On a typical bracket, the ±0.005 mm we quote applies to the features called out on the drawing. The rest of the part has looser limits, and mixing them up is the most common reason a first article gets rejected. Read the title block before anything else.

Thermal drift is the quiet one. Aluminium 6061 expands about 23 µm per meter per degree Celsius. A 300 mm part that warms 5 °C between roughing and finishing moves roughly 35 µm. That is seven times the tolerance band. Shops that hold tight limits rough, cool, then finish, and they measure at 20 °C.

Tool deflection is the other half. A long, slender end mill pushed too hard bends away from the wall, so the finished slot comes out undersized at the top and oversized at the bottom. The fix is a shorter tool, a lighter radial cut, or a finishing pass at 0.2 mm radial engagement.

Workholding matters as much as the spindle. A part clamped on a thin web will spring when you release it. For thin walls, we rough with the part supported, stress-relieve if the material allows, then take light finishing cuts on both sides.

Surface finish follows tool radius, feed per tooth and spindle speed. A 12 mm carbide end mill at 0.05 mm per tooth leaves a visible scallop pattern. The same cutter at 0.02 mm per tooth with a higher spindle speed gets you into Ra 0.8–1.6 μm without a second operation.

Ra 0.2–0.8 μm is a different job. It usually means a separate finishing pass with a small stepover, or a polishing step after machining. On aluminium that is routine. On stainless 316L or 17-4PH it costs more time, and on Inconel it may not be worth specifying unless a seal or a bearing sits there.

Ask what the surface does. A cosmetic cover needs Ra 1.6–3.2 μm as machined and an anodize. A hydraulic bore needs Ra 0.2–0.8 μm and a controlled bore size. A mounting face needs flatness, not finish. Specifying Ra 0.4 μm everywhere on a part triples the cycle time for no functional reason.

Deburring belongs in the plan too. A sharp edge on a machined pocket becomes a crack starter under vibration. We break edges to 0.2–0.3 mm unless the drawing calls for sharp.

Inspection is where a process proves itself. We check incoming raw material against the mill certificate, monitor critical dimensions in process, and run a final inspection on 100% of parts before shipment. Reports are available on request.

In-process checks catch drift early. If a bore is walking 10 µm over twenty parts because the tool is wearing, the operator sees it on the third part, not the twentieth. That is cheaper than sorting a full batch at the end.

Final inspection uses CMM and hand gauges depending on the feature. A tight bore gets a bore gauge or an air gauge. A profile gets a CMM scan against the CAD model. A thread gets a go/no-go gauge, not a caliper.

What about first articles? A first article inspection compares every dimension on the drawing to the actual part. It is the cheapest way to find a misread callout before a run of 5,000 parts exists. Ask for it on any part with more than a few tight features.

Quotation and a free DFM analysis come back within 12 hours. Production can start within 24 hours of approval. Parts ship in 3–5 days for most work. That schedule assumes the drawing is complete and the material is in stock.

Most delay comes from the drawing, not the machine. An ambiguous datum, a missing thread depth, or a tolerance that cannot be measured will stop a job faster than any spindle problem. DFM feedback catches these before the first cut.

Material availability is the second lever. 6061 and 303 stainless are usually on the shelf. Inconel, beryllium copper and 17-4PH often need to be ordered, which adds days. If your schedule is tight, tell us the material early and we will confirm stock.

We hold no minimum order quantity. A single prototype and a 10,000-part run go through the same first-article process. The difference is fixture design and how much of the cycle we automate.