Coating design means planning the part, substrate, surface condition, geometry, masking, tolerances, coating objective and inspection requirements as one system before production. Start with the service condition and failure mode, then review line-of-sight access, edges, recesses, critical dimensions and preparation before selecting PVD, DLC or another route.
This approach prevents a common mistake: choosing a coating name first and discovering later that the part cannot be cleaned, fixtured, coated evenly or returned to its required dimensions. The following framework helps you mark up a drawing, prepare a supplier brief and move from prototype approval to production release.
What Coating Design Means Before a Part Reaches Production
In industrial PVD work, coating design is the coordinated design of the substrate, baseline finish, surface preparation, deposition process, coating architecture, post-processing and quality control.
A complete coating system specification should describe what the surface must do in service, which areas require treatment, how the part will be prepared, which features must remain uncoated and how the finished result will be accepted.
“Coating” simply means a layer applied to a surface for a functional, protective or visual purpose. Industrial categories include PVD and other vapor-deposited films, thermal spray, electroplated or electroless layers, conversion treatments, paints and polymers. The useful classification depends on the part and the outcome required.
A stamping die may need control of galling and material pickup, a cutting tool may need wear resistance at a cutting edge, and a visible component may need repeatable colour and finish. These are different design problems, even if each request is described as “coating the part.”
Choose the Design Objective Before You Choose the Coating
The right starting direction depends on the failure mode, substrate, geometry, service environment and production requirements. PVD, DLC and Thermospray are not interchangeable labels, and performance must be validated on the actual part.
| Objective | Questions to answer | Starting direction |
|---|---|---|
| Wear resistance | What is wearing, at what load and speed, against which counterface? | Investigate PVD or Thermospray according to thickness, geometry, heat treatment and wear mechanism. |
| Friction or galling control | Is the problem adhesive transfer, sliding friction, lubricant breakdown or roughness? | Investigate PVD or DLC for compatible substrates and contact conditions. |
| Corrosion exposure | Which chemicals, moisture, temperature cycles and defects will the surface encounter? | Compare coating technologies and finishing requirements against the actual environment. |
| Localized rebuilding | Does the part need a thin film or a thicker layer finished back to size? | Investigate Thermospray or Pulsed HVOF where geometry, substrate and dimensional planning support it. |
| Appearance or colour | Which surfaces are visible, what finish is required and how will uniformity be judged? | Investigate decorative PVD after validating substrate, preparation, geometry, masking and appearance criteria. |
| Dimensional control | Which fits, sealing lands, threads, edges or mating faces have the smallest allowable change? | Assess process, masking and post-coating finishing together. |
DLC is a family of hard, low-friction amorphous carbon films applied by PVD or PECVD for compatible tools and components. It deserves investigation when friction, galling or adhesive buildup is central to the problem, but substrate, preparation, operating environment and the mating pair determine suitability. See the practical discussion of DLC coating for the relevant performance questions.
For forming tools, start with the failure pattern rather than the hardest available coating. A useful stamping die coating decision considers galling, wear, friction, lubrication, substrate condition, die geometry and surface preparation together.
Start With the Substrate, Finish and Service Conditions
Record the alloy or material grade, hardness, heat treatment, prior treatment, baseline roughness and areas that cannot tolerate dimensional or visual change.
- Normal and peak load, contact pressure or clamping force.
- Sliding, impact, forming, cutting or fretting motion.
- Speed, cycle frequency and expected production volume.
- Operating temperature and short-term thermal excursions.
- Lubricant, coolant, process fluid, chemicals and cleaning agents.
- Mating material, contamination risk and abrasive particles.
- Failure symptoms such as wear, pickup, scratching, corrosion, chipping or dimensional drift.
Surface finish is part of the design. Roughness, waviness, burrs, embedded particles and residues can affect adhesion, friction, appearance and how a thin film reproduces the underlying surface.
Before requesting a coating, identify whether the part needs degreasing, cleaning, stripping, polishing, blasting, microblasting or another preparation step. The route depends on the substrate and problem. More aggressive preparation is not automatically better.
Use the surface treatment planning framework to organize the substrate, service environment and treatment objective before narrowing the coating choice.
Design Geometry for Coverage, Masking and Tolerance Control
A PVD process must reach the surfaces that need treatment while avoiding surfaces that must remain clean or dimensionally unchanged. Geometry, fixture orientation and line of sight belong in the design review before tooling is finalized.
A practical drawing-markup sequence
- Mark coated surfaces. Separate wear, friction, corrosion-exposed and cosmetic areas because they may need different acceptance criteria.
- Mark excluded surfaces. Identify threads, bores, sealing lands, datum faces, press fits, electrical contacts and mating faces.
- Check line of sight. Deep blind holes, narrow slots and enclosed recesses can create shadowing or uneven coverage.
- Review edges and radii. Sharp edges can be vulnerable to chipping, poor coverage or local stress.
- Review cleaning and inspection access. A feature that is difficult to clean may also be difficult to verify.
- Plan fixture contact points. Support repeatable orientation without blocking critical or visible surfaces.
- Protect the tolerance stack. State whether dimensions are measured before coating, after coating or after lapping or polishing.
Do not insert a universal coating thickness into a drawing without process review. The correct value depends on coating architecture, substrate, geometry, target performance and dimensional allowance. Identify the functional limit, measurement location and allowable finished condition instead.
Masking should be defined feature by feature. “Mask all holes” is rarely precise enough because through-holes, blind holes, threaded holes and sealing bores have different risks.
Treat Preparation, Deposition and Finishing as One Workflow
Reliable coating design connects the drawing to the complete routing. Cleaning, degreasing, blasting or microblasting, polishing, deposition, lapping and quality control each affect what the next step can achieve.
- How will oil, coolant, oxide, residues and handling contamination be removed?
- What surface condition must exist before deposition?
- How will the part be oriented and supported?
- Will post-coating lapping, polishing or dimensional correction be required?
- Which records show that the finished part meets the brief?
The preparation, deposition, finishing and inspection route should be assigned, documented and reviewed as one process. Confirm which steps the selected supplier performs, which are outsourced and how the handoffs will be controlled.
The selected PVD coating systems must support the required geometry, batch size, fixture strategy and production volume. Equipment becomes part of coating design when loading, source access, rotation, capacity or repeatability limits consistent processing.
When Standard Processing Needs a Design Review
Request an early technical review when a part has unusual weight or shape, deep features, many masked areas, strict cosmetic requirements, narrow tolerances, complex fixturing or a large change between prototype and production quantity. This does not mean custom equipment is automatically required. It means the part and process should be reviewed together.
Sputtek identifies the SPUN 2,000 as a high-capacity PVD system with a stated capacity of up to 1,200 kg per cycle. This figure is production-planning context, not a guarantee that every part mix can use the full nominal capacity.
A custom PVD coating system may be worth discussing when part shapes, loading arrangements or source configurations do not fit a standard approach. Whether that flexibility is useful depends on the production mix and required process.
Common Coating-Design Failures and How to Prevent Them
Many coating failures begin before deposition. The visible symptom may be a flake, scratch, bare area or interference, while the underlying cause is a drawing, substrate, preparation, masking, fixture or service-condition problem.
| Problem | Likely causes | First review |
|---|---|---|
| Poor adhesion | Contamination, unsuitable substrate condition or unstable preparation. | Confirm material and heat treatment, define cleaning and validate adhesion on representative parts. |
| Uneven coverage | Line-of-sight obstruction, poor orientation or fixture shadowing. | Review target surfaces, orientation, motion, spacing and access. |
| Edge chipping | Sharp geometry, damaged edges or concentrated service load. | Review edge preparation, radii, handling and actual contact load. |
| Cosmetic variation | Variable finish, cleaning, orientation, masking or inspection lighting. | Define visible zones, finish, viewing method and acceptable variation. |
| Dimensional interference | Omitted coating allowance, unmasked mating surfaces or unplanned finishing. | Identify critical fits and measurement points before and after processing. |
| Premature wear | Mismatch between route, counterface, lubricant, load, temperature or substrate. | Diagnose service conditions and compare functional results with an uncoated baseline. |
Hypothetical example: suppose an automotive forming tool develops material pickup after a design change. Do not automatically apply the hardest coating. Review die radius, surface finish, alignment, lubricant coverage, workpiece material, substrate condition and contact pattern first. A PVD or DLC investigation may be appropriate after those contributors are understood.
Define Inspection and Acceptance Before the First Trial
Acceptance criteria should define the property, measurement location, test method and allowable result. Visual inspection alone cannot prove wear life, adhesion, friction or corrosion performance.
- Thickness and uniformity at defined locations.
- Adhesion using a method suitable for the coating, substrate and geometry.
- Hardness or modulus where relevant.
- Surface roughness before and after coating.
- Tribology or wear testing representing actual contact conditions.
- Corrosion or chemical compatibility testing.
- Functional trials such as forming, cutting, sealing, cycling or assembly checks.
- Visual colour, gloss, defect and masking-boundary inspection.
ISO 25164:2026 specifies technical requirements for magnetron-sputtered TiAlSiN thin films and also applies to TiN, TiAlN and TiSiN films on cemented carbide substrates. It is not a universal pass-fail specification for every PVD coating, substrate or application. Review the relevant ISO coating specification when its scope matches the design.
Prepare a Coating Design Brief or RFQ
A supplier can give a more useful response when the RFQ describes the part and problem, not just a coating name. Drawings and CAD files show geometry, tolerances, critical surfaces, masking boundaries and fixture constraints. If CAD is unavailable, provide dimensioned drawings, photographs, sectional views and a marked-up surface map.
- Part: number, revision, drawing date, batch quantity and annual volume.
- Substrate: material, hardness, heat treatment, prior processing and existing treatment.
- Geometry: drawing or CAD, recesses, holes, threads, radii, edges and inaccessible features.
- Surface map: coated, masked, visible, mating and sealing surfaces.
- Service: load, motion, speed, temperature, lubricant, chemicals, counterface and failure history.
- Objective: wear, friction, galling, corrosion, appearance, release or dimensional protection.
- Surface condition: roughness, finish, burr condition, cleanliness and preparation limits.
- Dimensional controls: fits, threads, sealing surfaces, allowances, datums and post-coating finishing.
- Process needs: masking, orientation, batch size, packaging and contamination controls.
- Acceptance: thickness, uniformity, adhesion, roughness, appearance, functional tests and documentation.
- Qualification: representative samples, approval process, permitted deviations and release conditions.
Ask the supplier to identify assumptions, inaccessible surfaces, preparation risks, masking limits, measurement locations, proposed trials and missing information. Ask whether the route fits the substrate, heat treatment, geometry and service environment, rather than requesting only a price.
Move From Prototype Approval to Production Release
A representative prototype should prove more than colour or initial appearance. It should test the surfaces, geometry, preparation, masking, fixturing and operating conditions that production will use.
- Freeze the trial definition. Record revision, substrate, objective, critical surfaces, preparation and criteria.
- Use representative parts. Include difficult geometry, edges, recesses, masking boundaries and service surfaces.
- Record the process. Document cleaning, preparation, fixture orientation, coating, post-processing and inspection.
- Compare results. Check dimensions, appearance, adhesion, roughness and function.
- Resolve deviations. Separate coating problems from geometry, substrate, lubricant, alignment or fixture problems.
- Release the routing. Approve the drawing markup, masking, fixture, records, inspection plan and packaging.
Sputtek states that its PVD and Thermospray work supports production from prototype through high-volume manufacturing. The handoff between trial and production should therefore be part of the design discussion from the beginning.
Frequently Asked Questions About Coating Design
What is a decorative coating?
A decorative coating is selected mainly for appearance, such as colour, gloss, visual uniformity or finish, although it may also provide functional protection. It still requires control of substrate finish, cleaning, geometry, masking, adhesion and inspection.
What is color coating, and how does it differ from decorative PVD coating?
Color coating describes a coating selected to produce a specified visual colour or shade. Decorative PVD is a broader term for a PVD-based treatment used to achieve colour, gloss, finish or appearance, sometimes with functional properties. Define the colour standard, visible surfaces, lighting conditions and allowable variation.
Can PVD coatings be applied to plastic parts?
PVD can be considered for some plastic parts, but suitability depends on the plastic, finish, preparation, geometry, thermal budget, adhesion requirements and appearance target. Validate the substrate and representative part before approving production tooling.
What is the difference between coating and plating?
Coating is the broad term for applying a layer to a surface, while plating commonly refers to electrochemical or chemical deposition. PVD is vapor deposition, not electroplating. The comparison depends on thickness, substrate, geometry, chemistry, dimensional effect, adhesion and service requirements.
When should a coating supplier review a part drawing?
Involve a supplier before production tooling, masking hardware, critical finishes or tight tolerances are finalized. Early review is especially useful for deep recesses, narrow slots, sharp edges, threads, sealing lands, complex visible surfaces and prototype-to-production changes.
Do I need CAD files or drawings?
CAD or dimensioned drawings are the best starting point for reviewing geometry, loading, line of sight, masking, fixtures and critical dimensions. If unavailable, provide photographs, key dimensions, sectional views, surface markings, substrate details, service conditions, quantity and uncoated surfaces.
Does manufacturer size determine the right supplier?
No. Application fit, process capability, preparation and finishing control, quality documentation, capacity, engineering support and the ability to validate the actual part are more useful criteria than global company size.
If you are moving from a coating idea to a marked-up drawing, qualification plan or production route, Sputtek can review the requirement through its PVD coating services for work ranging from prototypes to high-volume manufacturing.
