CNC Cutting Services: 7 Checks Before You Order
This guide is for engineers and buyers who need parts cut, not a catalog page. It covers the cutting processes we run, the tolerance and edge quality each one holds, and the questions that separate a capable shop from a quoting desk. Read it before you send an RFQ.
In this article
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What matters most
Cutting process comparison by part requirement
Use this table to narrow the process before you compare quotes. Tolerances are what we hold in production, not the best number a machine can reach on a good day.
| Process | Typical tolerance | Best for | Watch out for |
|---|---|---|---|
| 3-axis milling | ±0.005 mm | Prismatic parts, pockets, flat faces | Undercuts need a second setup |
| 5-axis milling | ±0.005 mm | Contoured surfaces, angled holes | Programming time drives cost |
| CNC turning | ±0.005 mm | Shafts, bushings, threaded parts | Long slender parts deflect |
| Abrasive waterjet | ±0.1 mm | Thick plate, heat-sensitive alloys | Taper on the cut edge |
| Laser cutting | ±0.05 mm | Sheet below 6 mm, high volume | Heat-affected zone on edges |
| Wire EDM | ±0.005 mm | Hardened steel, sharp internal corners | Slow, one part at a time |
What CNC cutting services actually cover
The phrase covers more than one machine. In our shop it means milling, turning, abrasive waterjet, laser and wire EDM, and the choice between them is driven by geometry, not by preference. A bracket with flat faces and drilled holes belongs on a 3-axis mill. A turbine vane with a twisted profile needs simultaneous 5-axis work. A 30 mm hardened steel plate with a sharp internal corner is a wire EDM job, even though the cutting time looks bad on paper.
Material moves the decision too. Aluminium 6061 and 7075 cut cleanly on most platforms. Titanium TC4 and Inconel work-harden, so the cutting edge has to stay sharp and the feed has to stay under control. Plastics like POM and PEEK melt if the tool dwells, which rules out some laser work. When a buyer sends a drawing and asks for the cheapest process, the honest answer is often that the cheapest process will not hold the feature they drew.
A practical way to sort it: list every feature on the part, mark the ones with a tolerance tighter than ±0.05 mm, and mark the ones with a surface callout. Those features decide the process. Everything else is along for the ride.
Dimensions matter at the extremes. Our largest travel is 4,000 × 400 × 150 mm, and we run a Ø400 mm rotary table for parts that need rotation. Parts beyond those envelopes get split, welded and re-machined, which adds a setup and a risk of distortion. Tell us the envelope early. It is cheaper to redesign a part than to re-fixture it.
- 1Flat and prismatic3-axis milling, 27 machines available
- 2Contoured and angled5-axis simultaneous, 16 machining centers
- 3Round and threaded16 mill-turn centers, one setup for both
- 4Thick or heat-sensitiveAbrasive waterjet, no heat-affected zone
Tolerance, edge quality and what the drawing really asks for
Tolerance is where quotes diverge fastest. A ±0.1 mm part and a ±0.005 mm part can look identical on a drawing review and cost three times differently in production. We hold ±0.005 mm (±0.0002 in) on milling and turning when the setup supports it. That number is not free. It requires temperature-stable inspection, a rigid fixture and a metrology step that most low-cost shops skip.
Surface finish needs the same attention. As-machined surfaces land at Ra 1.6–3.2 μm. A callout of Ra 0.8–1.6 μm is a normal machined finish and needs a controlled finishing pass. Below that, Ra 0.2–0.8 μm, you are paying for a separate operation and a slower cycle. If the drawing says Ra 0.4 μm across a face that only touches a gasket, ask whether that number is functional or inherited from an older revision.
Edge condition is the most common gap between what buyers expect and what arrives. Milled and turned edges come off the machine clean. Waterjet and laser edges carry taper or a heat-affected zone unless someone removes it. If your assembly needs a deburred, chamfered edge, say so in the RFQ. Post-processing is a separate step with its own lead time.
One more point on measurement. A tolerance you cannot verify is a tolerance you cannot claim. Ask which instrument checks the critical feature, and whether the report travels with the parts. Raw material check, in-process monitoring and final inspection are the three points where a dimension can still be corrected. After shipment, it cannot.
- 1As-machinedRa 1.6–3.2 μm, standard cycle
- 2Fine machinedRa 0.8–1.6 μm, controlled finishing pass
- 3Polished or lappedRa 0.2–0.8 μm, separate operation
- 4Waterjet edgeExpect taper, add a finishing pass if cosmetic
Lead time, order quantity and how quotes are built
Lead time claims are easy to print and hard to prove. Ours start with a quotation and a free DFM analysis inside 12 hours. Production can begin within 24 hours of approval, and parts ship in 3–5 days. Our historical late-delivery probability sits below 2%. Those numbers assume the drawing is complete and the material is in stock. If you specify a 7075 plate in an unusual thickness, add sourcing time to every quote you receive.
Order quantity works the other way. Some cutting processes only make sense at volume, and some only make sense at one. Laser cutting a single 1 mm bracket wastes more time in setup than in cutting. A prototype run of one part is normal for us, and so is a 10,000-part production run. There is no minimum order quantity, which matters most to teams validating a design before tooling.
Read the quote structure, not just the total. A line that says "machining" tells you nothing. A useful quote separates programming, setup, cycle time, material, finishing and inspection. When a supplier cannot break the price down, they either do not know their own cost or do not want you to see it. Ask for the breakdown on the first order. It makes the second order easier to discuss.
Certification is part of the same question. ISO 9001:2015 covers general quality systems. IATF 16949:2016 applies to automotive work, ISO 13485:2016 to medical devices and ISO 27001:2022 to information security. If your part sits in a regulated program, match the certificate to the program before you compare prices. A cheap quote from a shop without the right system is expensive once the audit arrives.
- 1Quote turnaround12 hours with free DFM analysis
- 2Production startWithin 24 hours of approval
- 3Shipping3–5 days for standard parts
- 4Quantity rangeOne prototype to 10,000+ parts
Cost drivers and the questions that save money
Five things push the price of a cut part: tolerance, feature count, material, finishing and quantity. Tolerance is usually the largest. Tightening a non-critical dimension from ±0.1 mm to ±0.01 mm adds inspection time and often a second operation. Feature count matters because every new tool, every new angle and every undercut adds a setup or a tool change. Ten simple holes cost less than one deep slot with a 2 mm corner radius.
Material choice is a quiet driver. A 6061 aluminium bracket and a 7075 version can differ by a factor in material cost and in tool wear. Titanium and Inconel cut slowly, so cycle time rises even when the part is small. If the design allows aluminium, the quote will show it.
Finishing is the line item buyers forget. Anodizing, electroless nickel, powder coating and bead blasting all sit after machining. Laser marking adds another step, with a minimum character height of 1.5 mm on most surfaces. List every finish on the RFQ, including the ones you think are obvious. A part that arrives machined but not anodized is a part that ships twice.
Confidentiality belongs in the same checklist. Uploads are secure and confidential, and an NDA is available on request. If your drawings carry export-controlled or unreleased geometry, sort that out before sending files, not after. It costs nothing to sign first and avoids a difficult conversation later.
- 1Biggest driverTolerance, then feature complexity
- 2Second driverMaterial and cycle time
- 3Often missedPost-processing and marking
- 4Always freeNDA before files are exchanged
How to qualify a cutting supplier in 6 steps
Run these in order. Each step can eliminate a supplier before you spend time on a full RFQ.
- 1Send the 3D model and a marked drawingSTEP or IGES plus a PDF with critical dimensions flagged. Mark which tolerances are functional and which are reference. Suppliers quote what they read, not what you meant.
- 2Ask for a DFM response, not just a priceA useful reply lists thin walls, deep pockets, tool reach limits and any feature that needs a second setup. If the response is a number with no comments, the quote is a guess.
- 3Confirm the process and the machine envelopeAsk which machine will run the part and whether the part fits its travel. Large parts near the limit of a 4,000 mm bed need extra setup planning.
- 4Check the inspection planAsk which features are measured, with what instrument, and whether a report ships with the parts. 100% inspection before shipment should come with evidence on request.
- 5Match certificates to your programISO 9001:2015 for general work, IATF 16949:2016 for automotive, ISO 13485:2016 for medical, ISO 27001:2022 for data handling. Wrong certificate means a re-audit later.
- 6Start with a small orderPlace one or two parts before the full run. Check the critical dimensions and the edge condition yourself. A first article tells you more than a capability sheet.
Questions buyers ask before the first order
What file formats do you need for a cutting quote?
A STEP or IGES model covers most geometry. Add a PDF drawing with critical dimensions, tolerances and surface callouts marked. If you have a 2D DXF for a flat cut part, that is enough for waterjet or laser work.
A complete package shortens the quote. Missing tolerance callouts are the most common reason a quote comes back with questions instead of a price.
Can you cut hardened steel or heat-treated parts?
Yes, within limits. Milling and turning handle hardened material with the right tooling and reduced depth of cut. For hardness above roughly 45 HRC with sharp internal corners, wire EDM is usually the better route.
Abrasive waterjet cuts hardened plate without adding heat, which suits parts that cannot tolerate a heat-affected zone. Tell us the hardness and the corner radii up front.
How tight a tolerance can you hold on a long part?
Our standard machining tolerance is ±0.005 mm on setups that support it. On long parts, the limiting factor is usually thermal drift and fixture rigidity rather than the machine. A 4,000 mm part and a 50 mm part do not hold the same number.
Send the drawing and we will tell you which dimensions need a special setup and which can run at standard tolerance.
Do you work from a single prototype?
Yes. There is no minimum order quantity, and one-part runs are normal for us. The setup cost is spread across the quantity, so a single part carries a higher unit price than a 1,000-part run.
If the design is still moving, a prototype first usually costs less than tooling a design that changes twice.
What surface finishes can you apply after cutting?
Anodizing in clear, colour, hardcoat and conductive versions; electroless nickel, zinc, silver and gold plating; powder coating and black oxide; bead blasting, tumbling, brushing and polishing.
Laser marking and engraving are available with a minimum character height of 1.5 mm. List every finish in the RFQ so it lands in the routing.
How do you handle confidentiality?
Uploads are secure and confidential, and we sign an NDA on request before files change hands. If your drawings are export-controlled or unreleased, raise it at first contact.
Nothing about the geometry is shared outside the team that quotes and machines the part.
Send the drawing and get a real answer
Upload your model and drawing. We return a quotation and a free DFM analysis within 12 hours, with the process, tolerance and finishing route spelled out.
12-hour quote100% inspectionNo minimum order quantityNDA on request
More from the shop floor
We publish setup notes, tooling trials and inspection data from the factory floor.
