u/SlideOne4757

Alright, I need some brains on this one.

I've got a Genesis G90 wheel center cap sitting on my desk right now. Part number 52960-T4000. Material is MPPO. It's a bicolor piece — charcoal metallic body, silver metallic spokes. Two completely different paint finishes on the same part.

The groove between the two colors? 0.5mm. That's it.

And the paint lines are perfect. Not good. Perfect. No bleed. No overlap. No witness marks. Nothing. Every piece comes off the line looking identical. This isn't a show piece — it's mass production.

So here's my question. How are they doing this?

been turning this thing over in my hands for days and here's what I've ruled in and out:

1. Metallic masking jig — Spray the charcoal first over the whole part. Drop a precision metal mask over the charcoal zones. Spray the silver second coat over the exposed spoke areas. Pull the mask. Done. Makes sense in theory. But that groove is 0.5mm. You're running thousands of cycles. Paint builds up on that mask fast. Every layer of accumulation changes how the mask seats. How do you hold that tolerance at volume without the mask fit drifting? You'd need constant cleaning or rotation of masks. And even then — 0.5mm is brutal.
2. Two-shot injection molding — Skip the paint entirely. Shoot two different colored resins in sequence. Clever idea. But I've looked at this part under good light. No second gate mark anywhere. And the mold for this spoke geometry in a two-shot setup would be an absolute nightmare. I don't think that's it.
3. Something else? — Pad printing? Selective PVD? Some robotic micro-spray system I've never seen? Honestly, I don't know. That's why I'm here.

Here's what I do know. That 0.5mm groove is molded into the part on purpose. It's not decorative. It's functional. It acts as a physical dam between the two paint zones. Smart design. But even with a built-in groove acting as your boundary, holding that kind of precision across a multi-spoke 3D surface at production speed is no joke.

Specs for context:

- Part: Genesis G90 center cap
- OEM number: 52960-T4000
- Diameter: 163.5mm
- Material: MPPO (Modified Polyphenylene Oxide)
- Finish: Charcoal metallic + silver metallic

If you've worked on bicolor automotive trim — wheel caps, grille inserts, pillar garnish, anything with two paint zones on one plastic part — I want to hear from you. What's the actual production method here? What am I missing?

I've attached an image of the part. Heads up — the colors might look slightly different on your screen depending on lighting. In hand, the charcoal and silver are clearly distinct.
https://postimg.cc/gallery/js76H4M

Alright, I need some brains on this one.

I've got a Genesis G90 wheel center cap sitting on my desk right now. Part number 52960-T4000. Material is MPPO. It's a bicolor piece — charcoal metallic body, silver metallic spokes. Two completely different paint finishes on the same part.

The groove between the two colors? 0.5mm. That's it.

And the paint lines are perfect. Not good. Perfect. No bleed. No overlap. No witness marks. Nothing. Every piece comes off the line looking identical. This isn't a show piece — it's mass production.

So here's my question. How are they doing this?

been turning this thing over in my hands for days and here's what I've ruled in and out:

1. Metallic masking jig — Spray the charcoal first over the whole part. Drop a precision metal mask over the charcoal zones. Spray the silver second coat over the exposed spoke areas. Pull the mask. Done. Makes sense in theory. But that groove is 0.5mm. You're running thousands of cycles. Paint builds up on that mask fast. Every layer of accumulation changes how the mask seats. How do you hold that tolerance at volume without the mask fit drifting? You'd need constant cleaning or rotation of masks. And even then — 0.5mm is brutal.
2. Two-shot injection molding — Skip the paint entirely. Shoot two different colored resins in sequence. Clever idea. But I've looked at this part under good light. No second gate mark anywhere. And the mold for this spoke geometry in a two-shot setup would be an absolute nightmare. I don't think that's it.
3. Something else? — Pad printing? Selective PVD? Some robotic micro-spray system I've never seen? Honestly, I don't know. That's why I'm here.

Here's what I do know. That 0.5mm groove is molded into the part on purpose. It's not decorative. It's functional. It acts as a physical dam between the two paint zones. Smart design. But even with a built-in groove acting as your boundary, holding that kind of precision across a multi-spoke 3D surface at production speed is no joke.

Specs for context:

- Part: Genesis G90 center cap
- OEM number: 52960-T4000
- Diameter: 163.5mm
- Material: MPPO (Modified Polyphenylene Oxide)
- Finish: Charcoal metallic + silver metallic

If you've worked on bicolor automotive trim — wheel caps, grille inserts, pillar garnish, anything with two paint zones on one plastic part — I want to hear from you. What's the actual production method here? What am I missing?

I've attached an image of the part. Heads up — the colors might look slightly different on your screen depending on lighting. In hand, the charcoal and silver are clearly distinct.