Spray Painting
Spray painting atomises liquid paint into a fine mist and applies it to the part surface. It is used for colour/RAL finishes, corrosion protection, or situations where powder coating cannot achieve full coverage — for example, complex geometries with recesses or internal cavities.
See Threading and Finishing for the full surface treatment workflow.
When to Use Spray Painting
Use spray painting when:
- A specific colour or RAL finish is required
- Complex geometries need full coverage where powder coating cannot reach
- A thin coat is sufficient for the application
- Low to medium production volumes
- Quick colour changes between batches are needed
Step-by-step
- Select the node before or after which the paint should be applied, in the Tree View or Graph View.
- Right-click the node and choose Append node(s) (or Prepend node(s)) from the context menu.
- In the process selector dialog, choose Spray Painting.
- If prompted, choose the paint type and colour, and review the film thickness — for most coating types this dialog opens automatically right after the node is created. Three types — Cathodic dip painting, Electro galvanizing, and Hot dip galvanizing — auto-populate with no dialog at all.
Result
After running Spray Painting:
- A Transform node appears in the Graph View at the position where it was inserted
- The Tree View shows the paint parameters and any warnings
- Export data includes specifications for the spray painting process
Other Surface Treatment Methods
WSi supports multiple surface treatment methods:
- Powder Coating — thermally cured powder for durable, scratch-resistant finishes
- Countersinking — conical recesses for flush-fit fasteners
- Tapping — internal threads in sheet metal or tube
See Threading and Finishing for the full overview.
WARNING
Coating processes are optional modules. If the coating module is not licensed, Spray Painting is blocked. Contact your sales representative at WSoptics to obtain the relevant licence.
Parameters
The parameters for this process are configured in the database — see the Coating page.
Technical Background
Spray painting atomises liquid paint into a fine mist of droplets and applies it to the part surface as a uniform film. The atomisation method determines how the paint is broken into particles and delivered to the workpiece.
Conventional air spray uses compressed air to break the paint stream into droplets at the nozzle. Airless spraying forces paint through a small orifice at high hydraulic pressure; the exiting stream disintegrates into droplets, and the fan width is controlled by the pattern width setting. High volume low pressure (HVLP) spraying reduces overspray by delivering a large volume of air at lower pressure, making it more efficient and environmentally friendly.
Electrostatic spraying adds a negative electrical charge to the paint particles as they leave the gun. The grounded (positively charged) part attracts the particles, wrapping paint around edges and into recesses that conventional spray cannot reach. This improves transfer efficiency and reduces waste.
Between coats, a flash time is allowed for solvents to evaporate partially. Skipping this step can cause sags, runs, or solvent pop (bubbling) in the next coat. Film thickness is measured either wet (WFT, immediately after application) or dry (DFT, after curing); the conversion depends on the paint's volume solids percentage. Because spray painting produces overspray — paint that misses the target — masking of non-coated areas is required.