A working reference for engineers and machinists: cutting data, tool choice, GD&T callouts and the checks we run before a part ships. Written from the floor, not from a catalog.
The part passes on the first run, then fails on the second. Usually the datum is implied rather than stated, or a tight tolerance sits on a surface nobody can hold after heat treat. Fix the drawing before you fix the machine. A drawing that only one machinist can read is a single point of failure, so we mark up the datum scheme during DFM review and send it back with the quote.
Surface speed depends on hardness, tool coating, coolant and rigidity. A number that works on a rigid 40-taper mill chatters on a long-reach end mill. The scrapped part at hour five is the real cost, and it never shows up on the quote. We log the productive cutting parameters per material and update them when a tool change moves the number.
Ra 0.4 μm on a 200 mm bore means a specific stone, a specific feed and a specific inspection method. If the callout says Ra 0.8–1.6 μm but the drawing also demands a mirror look on a sealing face, the two requirements were never reconciled. Ask what the surface actually does before you tighten it.
The first article runs on a five-axis center with a skilled setup. Volume runs on a different machine with a different fixture, and dimensions drift. Hand over the setup sheet, the tool list and the inspection report at the same time you hand over the CAD file. Otherwise the second run restarts from zero.
One route, from the file you send to the box on the dock.
Every job starts with a manufacturability review, not with a program. We read the drawing for datum structure, tolerance stack, tool reach and feature accessibility. If a bore needs a 0.8 mm radius cutter at 6× diameter reach, we say so before the quote lands, because that single feature can double cycle time. The review comes back inside 12 hours with the quotation.
After approval we fix the setup: which faces get machined in which order, where the soft jaws or fixture plate locate, and which dimensions must be probed in-process rather than checked at the end. For parts up to 4,000 mm we can hold a single setup across a long bed and avoid the stack-up error that comes from re-clamping.
Speeds and feeds are starting points. On the floor we adjust feed per tooth, depth of cut and coolant pressure until the chip breaks cleanly and the tool load sits inside a stable band. Aluminum 6061 and 7075 run at very different surface speeds, and 17-4PH in the H900 condition will work-harden under a rubbing cut, so the pass has to bite.
Inspection is built into the route rather than bolted on at the end. Raw material certificates are checked on receipt, critical dimensions are monitored during the run, and every part gets a final inspection before it is packed. Reports are available on request, including first article inspection for the dimensions you nominate. Where a customer needs it, we hold ±0.005 mm on the features that matter and leave the rest at general tolerance.
Use this to decide where a feature should be cut, and where it should not.
| Feature or part type | Recommended route | Why |
|---|---|---|
| Deep pocket, single setup | 5-axis simultaneous | Short tool, less re-clamping, tighter position |
| Prismatic plate, 2 faces | 3-axis with soft jaws | Fastest cycle, lowest setup cost |
| Round part with cross holes | Mill-turn center | One chucking, no second-op runout |
| Thin washer under 1 mm | Fine blanking or grinding | Turning distorts thin stock |
| Long shaft over 2,000 mm | Long-bed milling or turning | Avoids stacking two setups |
| Hardened tool steel | Pre-machining plus grinding | Cuts cost before heat treat |
| Prototype in 3 days | 3-axis plus hand finishing | No fixture lead time |
16 simultaneous 5-axis centers for contoured surfaces, deep cavities and parts that need five faces in one setup. Impellers, housings and brackets with compound angles.
27 three-axis machines and 12 four-axis mills for prismatic parts, plates, manifolds and fixtures. The workhorse route for volume.
16 mill-turn centers with a Ø400 mm rotary table for shafts, bushings and fittings that need cross-drilling or milling in the same chucking.
Machined prototypes and printed parts for fit checks before you commit to tooling. Useful when the geometry is still moving.
Anodizing, electroless nickel, zinc, powder coat, bead blasting and laser marking with a 1.5 mm minimum character height.
Dimensional reports, material certificates and first article inspection documents supplied with the shipment on request.
Numbers we can commit to on a drawing.
| Item | Range | Note |
|---|---|---|
| Maximum processing size | 4,000 mm | Long-bed milling and turning |
| Large travel | 4,000 × 400 × 150 mm | Single setup on long parts |
| Medium travel | 750 × 1,150 × 550 mm | General prismatic work |
| Compact travel | 500 × 500 × 450 mm | High-speed small parts |
| Achievable tolerance | ±0.005 mm | On nominated features |
| Fine surface finish | Ra 0.2–0.8 μm | Grinding or fine boring |
| Standard finish | Ra 0.8–1.6 μm | Milling and turning |
| As-machined finish | Ra 1.6–3.2 μm | Non-critical surfaces |
Fifteen years of production work across aerospace, automotive, medical and industrial machinery. The process library comes from parts that shipped, not from a textbook.
We quote the tolerance the drawing needs. If a feature cannot hold ±0.005 mm on the chosen process, we say so at DFM stage rather than at first article.
Send a STEP file and a 2D drawing. A quotation with manufacturability notes comes back within 12 hours, and production can start within 24 hours of approval.
Sixteen 5-axis centers, sixteen mill-turn centers and a full 3-axis and 4-axis floor. Work does not get subcontracted out and re-quoted.
Raw material check, in-process monitoring and final inspection on every part. Reports on request, including first article inspection.
Parts ship in 3–5 days on standard work. Scheduling is done against machine capacity, so the date we give is a date we can hold.
Thin-wall ribs and compound-angle faces cut in one 5-axis setup to avoid re-clamp error.
Aluminum housings with sealing faces and dowel-pin bores, machined on mill-turn centers to keep bore-to-face position.
Stainless 316L and 17-4PH components with fine bores, deburred and passivated before packing.
Long plates and frames up to 4,000 mm machined on a long bed so one datum carries across the whole part.
Treat it as a starting point, not a rule. On 6061-T6 with a coated carbide end mill and flood coolant, most shops run high surface speed and a feed per tooth that keeps the chip thick enough to carry heat away. If the chip turns to powder, the feed is too light and the tool will rub.
The limiting factor is usually the machine, not the material. A small spindle at high rpm may not have the torque to keep the feed up, so you back off speed and hold the chip load instead. Check the tool load meter before you trust the chart.
It saves money when the alternative is three or four setups with a fixture between each one. Every re-clamp adds position error and setup hours. If a part has features on four or five faces, or a contoured surface that would need a ball-nose sweep with a long tool, 5-axis usually wins on total cost even at a higher hourly rate.
It does not save money on a simple prismatic plate. A 3-axis machine with soft jaws will beat it on cycle time and programming effort every time.
The tap rubs instead of cutting. On 304 and 316 the material hardens at the surface when the tool slides, and the next revolution cuts into harder metal. Small taps break quickly.
Use a cut tap with the correct drill diameter, keep the feed rigid, and use a tapping fluid rather than a general coolant. On 17-4PH in the H900 condition, pre-drill slightly oversize within thread tolerance and keep the tap moving forward without dwell.
Name the surface function first, then the Ra value. A sealing face, a bearing bore and a painted cover need very different finishes. If the drawing says Ra 0.4 μm but the part is a non-contact cover, you are paying for grinding you do not need.
Also state the inspection method. Ra measured on a curved surface with a skidless pickup reads differently from a flat comparator. When in doubt, specify Ra 1.6–3.2 μm as-machined and tighten only the faces that seal, slide or mate.
Put the general tolerance block at a level the process holds without effort, then tighten individual features. On a milled aluminum part, general tolerance at ±0.1 mm is routine. Holding ±0.005 mm on every dimension multiplies cost and inspection time for no functional gain.
Pick the two or three features that control fit and position, and mark those. Everything else can stay loose. That one habit removes most of the arguments at first article.
Yes, for anything with a tight tolerance or a finish callout. A STEP file carries geometry but no tolerance, no datum and no surface requirement. The machinist has to guess, and guesses get quoted as assumptions.
Send the 3D model for shape and the 2D drawing for the tolerances, datums and notes. If you have no drawing yet, send a marked-up model screenshot with the critical dimensions and we will work from that and confirm in the DFM notes.
Record how the prototype was made. Which machine, which fixture, which tool, which inspection points. When the design moves to a different process, those notes are the baseline for comparison.
Then set the critical dimensions before the second run starts. If the first article drifts outside the band, you know it at hour one instead of at the end of the batch.
A 3D file in STEP or IGES, a 2D drawing with tolerances and finish callouts, the material and the quantity. Tell us which features are critical, and whether the part is a prototype or a production run.
If a drawing does not exist yet, send the model plus a note on function. We can still quote and add manufacturability notes. Uploads stay confidential, and an NDA is available on request.
Upload a STEP file and a 2D drawing. A quotation with manufacturability feedback comes back within 12 hours.
12-hour quote100% inspectionNo minimum order quantityNDA on request
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Upload your 3D model or 2D drawing and get a quotation with a free DFM analysis. Maximum processing size 4,000 mm.
CNC Metals 13 grades
CNC Plastics 10 grades
Machines & processes 12 options
Surface & post-processing 10 options
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