Process walkthrough

Machining Process 2: 7 Steps From CAD to Finished Part

This page walks through the machining process the way it actually runs on the floor: file prep, toolpath, fixturing, cutting, deburring, inspection. Engineers and buyers can use it to spot where a design will cost time or miss tolerance before the quote is signed.

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Machining process 2 cutting custom auto spare parts on a 5-axis machine

On this page

1
Key takeaways
2
Where machining process 2 actually starts: the model and the stock
3
CAM setup and toolpath strategy in machining process 2
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Workholding choices that hold tolerance during machining process 2
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Cutting parameters, deburring, and finish in machining process 2
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Inspection and documentation before the part ships
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Step by step: running machining process 2 on a real part
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Which setup and tolerance band fits your part

Quick answer

Key takeaways

Design decides most of the costWall thickness, corner radii, and hole depth set the tool and the cycle time before a machine is chosen.

Sequence matters more than spindle speedRough, semi-finish, finish, then drill and tap. Skipping semi-finish shows up as chatter on thin walls.

Fixturing is the usual failure pointMost out-of-tolerance parts move in the vise or lift off the fixture, not in the toolpath.

Tolerance drives inspection cost±0.005 mm features need a CMM report. General features at ±0.1 mm only need calipers.

Start with the material grade6061-T6 and 304 stainless cut very differently. Grade changes the feeds, speeds, and tool life.

Step 1-2

Where machining process 2 actually starts: the model and the stock

Machining process 2 begins long before a spindle turns. The first real decision is which surfaces the part will be located from. Pick two or three datums that stay accessible through every operation. If a datum only exists on the first setup and gets cut away later, every downstream operation inherits that error.

Next, look at the stock. A part machined from 6061-T6 plate behaves differently than the same part cut from extruded bar. Plate is usually stress-relieved and stays flatter after material removal. Extruded bar can move once one side is opened up, especially on long thin parts.

Then check wall thickness. Anything below 1.0 mm on aluminum or 1.5 mm on stainless starts to deflect under normal cutting forces. You can still machine it, but expect to slow down, use lighter radial engagement, and possibly add support material or a sacrificial web.

Finally, ask whether the part needs to be a single piece at all. Two bolted or doweled pieces are sometimes cheaper and straighter than one deep pocket hogged out of solid stock.

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Datum checkKeep the same datums valid across all setups.
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Stock formPlate for flatness, bar for length, near-net for volume.
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Thin wallsBelow 1.0 mm aluminum, plan for light passes and support.

Step 3

CAM setup and toolpath strategy in machining process 2

In CAM, the toolpath is chosen to match the geometry, not the other way around. Deep pockets want a high-feed or dynamic roughing path that keeps radial engagement constant. Shallow open faces can be faced with a large-diameter cutter and fewer passes.

Feeds and speeds come from the material, not from habit. A 12 mm carbide end mill in 6061 typically runs a surface speed around 300 to 500 m/min, while the same tool in 304 stainless drops to roughly 60 to 120 m/min. Ignoring that gap is the fastest way to burn an edge.

Leave stock for semi-finishing. On a ±0.05 mm feature, a typical sequence is 0.3 mm radial roughing stock, then 0.1 mm semi-finish, then a finish pass at 0.05 mm or less. Skipping the semi-finish leaves witness marks and uneven wall thickness.

Climb milling is the default on modern machines with low backlash. Conventional milling still has a place on hard or work-hardened material, and on older machines where the lead screw has noticeable play.

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Constant engagementDynamic roughing keeps tool load steady and heat down.
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Separate finish passFinish with a sharp tool, not the one that roughed.
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Cutter diameterUse the largest tool that reaches the corner radius.

Step 4

Workholding choices that hold tolerance during machining process 2

A three-jaw vise is fast and fine for blocky parts. It is a poor choice for thin rings or long brackets, where clamping pressure distorts the part during the cut and it springs back after unclamping.

Soft jaws machined to the part profile distribute clamping load over more area. For a 100 mm aluminum bracket, boring the jaws to match the profile can hold flatness within 0.02 mm where a standard vise gives 0.1 mm or worse.

For the second operation, a fixture plate with dowel pins and low-profile clamps keeps the part located while the top face is finished. Where the part cannot be clamped from the outside, vacuum chucks work well on flat non-porous material.

On 5-axis work, a dovetail or self-centering vise on the trunnion is common. It gives access to five sides in one setup, which removes stacked tolerance from re-clamping. Our 16 simultaneous 5-axis machining centers handle parts up to a Ø400 mm rotary table envelope.

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Match the jawsMachined soft jaws for thin or irregular parts.
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Second-op fixturePin location plus low-profile clamps, not edge clamps.
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One setup if possible5-axis work removes stacked re-clamping error.

Step 5-6

Cutting parameters, deburring, and finish in machining process 2

During the cut, watch chip color and sound. Silver or straw chips in steel mean the speed is reasonable; blue or purple means heat is building and tool life is dropping fast. In aluminum, long stringy chips can wrap the tool, so a pecking or high-pressure coolant strategy helps.

Coolant choice is not cosmetic. Flood coolant handles deep pockets and high material removal. Minimum quantity lubrication works well on aluminum and on near-dry operations, but it struggles in deep holes where chip evacuation matters more than lubrication.

After machining, deburr before the part leaves the machine where possible. Hand deburring costs time and adds variability. A chamfer tool run at the same coordinates as the edge is repeatable and cheap.

Surface finish is specified, not guessed. As-machined at Ra 1.6–3.2 μm suits most brackets and housings. Ra 0.8–1.6 μm needs a dedicated finish pass with a sharp tool. Ra 0.2–0.8 μm usually means lapping or fine grinding after milling, and it should only be called out on the surfaces that actually need it.

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Read the chipsColor and shape tell you if the tool is happy.
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Deburr in cycleChamfer tools beat hand files for repeatability.
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Finish on demandCall out Ra only where the function requires it.

Step 7

Inspection and documentation before the part ships

Inspection starts with the raw material certificate, not the finished part. Grade and heat treatment are checked against the drawing before a single cut is made. A 7075 part cut from 6061 stock will pass a visual check and fail in service.

In process, the operator checks critical features after roughing and again after finishing. Dimensions that sit close to the tolerance band get measured more often, because tool wear moves them steadily in one direction.

Final inspection is 100% before shipment at GreatLight. Depending on the drawing, that means calipers and micrometers for general features, bore gauges for holes, and CMM reports for tight or geometric callouts. Reports are available on request.

The point is not paperwork for its own sake. It is knowing which dimension is most likely to drift, and measuring that one first.

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Material firstVerify grade and temper before machining.
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In-process checksMeasure near-limit dimensions more often.
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Reports on requestCMM data for tight and GD&T features.

On the floor

Step by step: running machining process 2 on a real part

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1. Review the drawing and DFM notesConfirm datums, tolerances, and finish callouts. Flag any wall below 1.0 mm (aluminum) or 1.5 mm (stainless) and any pocket deeper than 4× the cutter diameter.
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2. Choose stock and verify gradeSelect plate, bar, or near-net stock. Check the mill certificate against the drawing grade and temper before loading.
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3. Build the CAM setupSet WCS to the datums. Rough with constant radial engagement, leave 0.3 mm stock, then semi-finish at 0.1 mm and finish at 0.05 mm or less.
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4. Set feeds and speeds by material6061 at roughly 300–500 m/min surface speed, 304 stainless at 60–120 m/min. Reduce feed on long overhangs rather than raising speed.
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5. Mount and indicate the workholdingMachine soft jaws to profile for thin parts. Indicate the fixture within 0.01 mm before the first cut. Re-check clamping pressure on thin sections.
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6. Cut, then check in processMeasure critical features after roughing and after finishing. Adjust cutter compensation if a dimension drifts toward the tolerance limit.
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7. Deburr, finish, and inspectChamfer edges in cycle where possible. Apply the specified finish (anodize, plating, bead blast). Run 100% final inspection and issue reports on request.

Decision aid

Which setup and tolerance band fits your part

Pick the row that matches your geometry and tolerance.

Part situation	Typical setup	Tolerance band	Watch out for
Blocky housing, open faces	3-axis vise	±0.05 mm	Vise jaw marks on finished faces
Thin bracket or plate	Soft jaws, matched profile	±0.02 mm flatness	Spring-back after unclamping
Five-sided part, one-off	5-axis with dovetail	±0.005 mm	Dovetail removal adds a setup
Long shaft, turned features	Mill-turn center	±0.01 mm	Bar whip on long overhangs
Deep pocket, small corner	3-axis, long reach tool	±0.05 mm	Tool deflection in deep cuts
Prototype, 1 to 5 parts	3-axis or 5-axis, no fixture	±0.1 mm	Hand deburr adds variability

FAQs

Questions engineers ask about machining process 2

How tight a tolerance can machining process 2 hold in production?

On aluminum and stainless parts with stable geometry, ±0.005 mm is achievable on critical features. That requires a dedicated finish pass, a rigid setup, and temperature-stable measurement.

General features at ±0.05 to ±0.1 mm are more economical and cover most brackets, housings, and fixtures.

What file format do you need to quote?

STEP and IGES work for solid models. Native CAD files are fine if you can share them under NDA. 2D PDF drawings are still needed for tolerances, finish, and GD&T callouts that the model does not carry.

Quotation and free DFM analysis come back within 12 hours.

Does part quantity change the process?

Yes, mostly in setup and fixturing. One prototype might run in a vise with hand deburring. A 10,000-part run justifies a dedicated fixture, in-cycle deburring, and tighter tool-wear monitoring.

There is no minimum order quantity here, so the same drawings can move from one piece to full production.

Which materials are the hardest to machine?

Titanium Ti-6Al-4V, Inconel, and 17-4PH stainless are the usual suspects. They generate heat at the cutting edge, work-harden quickly, and shorten tool life.

Magnesium AZ31B and AZ91D cut fast but need chip-handling care because fine chips are flammable.

How do you handle confidential designs?

Uploads are treated as secure and confidential. An NDA is available on request before files are exchanged, and ISO 27001:2022 covers our information handling.

If you prefer, send a simplified model for the first quote and the full drawing after the NDA is signed.

What causes most rework in this process?

Fixturing and tool wear, in that order. Parts move under clamping or lift slightly in the second operation. Tool wear pushes dimensions steadily in one direction until they cross the limit.

Both are caught by measuring critical features after roughing, not only at final inspection.