CNC machining & finishing

Surface Finishing Services for CNC Parts

Choose the surface your part needs for fit, protection and appearance. PTSMAKE performs the CNC machining, coordinates applied surface treatments with specialist finishing partners, and reviews the finished parts against your drawing and agreed acceptance criteria.

Request a finishing quote

Compare surface finishing options

Start with the base material and the surface’s job. The same finish can look different after a change in alloy, preparation or part geometry. Mark close fits, sealing faces and electrical contacts before choosing a coating.

Scroll across to compare materials, appearance and drawing notes

Finish	Typical materials	Main purpose	Appearance	What to specify
Machined and mechanical finishes
As machined	Machinable metals and plastics	No secondary cosmetic treatment.	Tool marks may remain.	Call out any functional roughness or visible-face requirement separately.
Smooth machining	Machinable metals and plastics	Additional finishing cuts reduce tool marks.	More even than an ordinary machined face.	Give a roughness value and measurement location where function depends on it.
Fine machining	Selected metals	Finer cutting for a controlled functional surface.	Light marks can remain.	Specify the feature, roughness and final dimensional condition.
Micro-finishing	Selected metals	Lower roughness on defined surfaces.	Can be functional or cosmetic.	State the target Ra, surface area and method of verification; feasibility is reviewed per part.
Polishing	Selected metals	Reduce visible marks and create a brighter surface.	Appearance-led.	Identify primary faces and protect edges, threads and critical fits from unwanted rounding.
Bead blasting	Selected metals	Create a diffuse matte texture before or instead of coating.	Cosmetic when requested.	Agree media, sample texture, masking and any features that must stay untouched.
Brushing	Selected metals	Produce a directional grain.	Cosmetic when requested.	Show grain direction on the drawing and approve a representative sample.
Vibratory finishing / tumbling	Selected small metal or plastic parts	Batch deburring and edge blending.	Usually functional; texture varies.	Identify edges to break and sharp or precision features to preserve.
Aluminum conversion and oxide finishes
Type II anodizing	Compatible aluminum alloys	Corrosion protection with optional color.	Matte or brighter preparation; cosmetic grade by request.	Specify color, preparation, masking, rack points and dimensions after finishing.
Type III hardcoat anodizing	Compatible aluminum alloys	Wear-resistant oxide layer.	Functional appearance; color can vary.	Define coating specification, thickness, masking and finished fit limits.
Chromate conversion	Aluminum	Corrosion protection while retaining conductive contact where specified.	Usually functional.	Give the required conversion specification and any paint or electrical interface.
Trivalent conversion	Aluminum	Conversion treatment to a named specification.	Usually functional.	State the exact chemistry (such as SurTec 650 if required) or an approved equivalent, plus conductivity and corrosion requirements.
Metal coatings and chemical treatments
Black oxide	Selected steels and compatible alloys	Dark conversion finish.	Tool marks can remain visible.	Identify material, required post-treatment and corrosion expectations.
Electroless nickel plating	Compatible metals	Specified nickel deposit for corrosion or wear needs.	Functional or cosmetic by specification.	Define deposit type, thickness, masking and final sizes of mating features.
Electroplating: nickel, zinc, gold or chrome	Compatible metals, process dependent	Decorative or functional metal deposits.	Depends on metal and preparation.	Name the metal, deposit specification, layer thickness, contact areas and base material.
Powder coating	Selected metals	Colored protective coating.	Appearance can be specified by sample.	Define color, texture, gloss, masking and allowance for coating build.
Passivation	Stainless steel	Clean and treat the surface to support corrosion resistance.	Little visible change is expected.	State the governing process specification and any cleanliness requirement.
Electropolishing	Selected stainless steels	Electrochemical smoothing and brightening.	Can be appearance-led.	Identify critical edges, finished dimensions, roughness and required visual sample.
PVD coating	Compatible metal substrates	Thin decorative or wear-related coating.	Color and sheen depend on coating system.	Define substrate, coating stack, color reference, temperature limits and fit requirements.
DLC coating	Compatible metal substrates	Low-friction, wear-related coating.	Usually functional.	Specify contact surfaces, coating requirement, adhesion and final dimensions.

Need another treatment or a combined finish? Send the drawing and required standard. We can review preparation, treatment sequence and inspection together.

Discuss your finish

Choose the appearance level your part needs

A finish name alone does not define which marks are acceptable. State the visual goal separately from corrosion, wear, roughness or dimensional requirements.

Example of a functional surface finish with visible machining marks

Functional finish

The treatment is chosen for function. Ordinary machining marks or process variation may remain where they do not violate the drawing.

Example of a part finished for cosmetic appearance on request

Cosmetic on request

Identify visible faces, an appearance sample and the permissible marks. Blasting, brushing or anodizing may be prepared to this goal when specified.

Appearance-led finish

For prominent polished or coated surfaces, approve the visual reference and define how parts will be compared across the batch.

More restrictive limits may require added preparation, protected handling, sorting, rework or inspection. We quote the finish and its acceptance level together; a less restrictive level may reduce those costs when the part’s use permits it.

Mark A and B surfaces on your drawing

A surfaces are the primary faces seen in normal use. B surfaces are secondary or concealed faces. Show the boundary, orientation and any edge that remains visible after assembly. Sealing, mating and electrical contact surfaces need their own functional requirements regardless of appearance grade.

In the enclosure example below, the visible outside is marked A. Remove the cover and the concealed inner cavity is marked B. A rack or hanging point should be placed away from the primary view and from functional interfaces.

Closed enclosure highlighting the visible blue exterior A surfaces — Illustrative enclosure shown closed and open. Your drawing, assembly state and approved sample define the actual A/B boundaries.

Opened enclosure showing the concealed gray inner cavity B surfaces — Illustrative enclosure shown closed and open. Your drawing, assembly state and approved sample define the actual A/B boundaries.

PTSMAKE default visual inspection conditions

These are our starting conditions for a cosmetic review. The buyer and PTSMAKE can agree different conditions for the part, finish and intended use before production.

Check each marked surface from all directions with the light measured at the part.

50 cm ± 10 cmViewing distance

About 45°View the surface from all directions

500–1000 luxIllumination at the part

3300–5300 KLight color temperature

10/10 visionNatural or corrected visual acuity

Inspect a clean part with protective film removed where the agreed procedure requires it. Where blasting or brushing is specified, keep the agreed media or grit and grain direction consistent. Where color or gloss is an acceptance criterion, compare it with the approved physical reference. Specify the comparison light and method separately; a screen image is not the acceptance reference.

Visible condition under the agreed inspection method	A · primary surface	B · secondary surface
Scratches, stains and blemishes	Not accepted	Not accepted
Rack or hanging marks	Not accepted	Minor localized marks may be accepted away from functional areas
Other minor nonfunctional appearance variations	Not accepted	Up to two per part, subject to the agreed type, size and location limits

These A/B limits do not replace the drawing, approved appearance sample or functional acceptance criteria. The quote or quality plan resolves any tighter or finish-specific requirements before production. Our default cosmetic lot sampling starts at general inspection level II; the order-specific plan also states the lot definition, defect classes, AQL value, sample size and accept/reject rule.

For a worked example of zoning, defects, viewing conditions and sample approval, see our cosmetic acceptance criteria for CNC aluminum enclosures. That guide addresses aluminum enclosures; other parts need their own agreed limits.

What to include in a finishing RFQ

Secondary surface treatments are carried out by specialist finishing partners. Before confirming the quote and schedule, PTSMAKE reviews machining allowance, masking, the treatment route and inspection requirements against your drawing.

Send your drawing

Base material and part geometryAlloy or polymer grade, drawing, model and quantity.
Required treatmentFinish specification, color, texture, thickness or roughness target.
Surface mapA/B zones, functional faces, masking and acceptable rack locations.
Acceptance referenceApproved sample, viewing conditions, defect limits and sampling requirements.
Final conditionDimensions, fits, electrical contacts or sealing surfaces after treatment.

Surface finishing questions

Who performs the CNC machining and surface treatments?

PTSMAKE performs the CNC machining. Specialist finishing partners carry out secondary surface treatments. We review the machining, finishing and inspection requirements for each order.

Can a coating change the final fit?

Yes. Deposits, conversion processes, preparation and material removal can affect a feature differently. Identify the surfaces that must meet dimensions after finishing and any areas that need masking.

Can we use a different cosmetic acceptance standard?

Yes. Share your drawing, samples or customer specification during the RFQ. We can agree different A/B zones, viewing conditions, defect limits and inspection coverage. Stricter controls can increase processing and quality-management cost.

Can I request a treatment not listed above?

Yes. Send the exact treatment specification and base material. We will check partner suitability, sequence, inspection and the quoted production schedule before confirming it.

Plan machining and finishing together

Send your part drawing, finish requirement and visible-surface map. PTSMAKE will review the treatment route and the acceptance level with you before quoting.

Request your quote