Integral Skin (I-Skin) Injection Molding
AdvancTEK produces integral skin molding parts for armrests, center consoles, and other components that need a soft-touch surface and a durable finish. I-Skin – short for integral skin reaction injection molding – forms a self-skinning polyurethane foam surface and a foam core in a single molding step, from one material system, with no separate topcoat required.. AdvancTEK molds these parts at our Concord, North Carolina facility, with in-house design support to move a part toward production.
One material system. One molding step. Skin and core, together.
💡 Key takeaway: I-Skin creates a soft-touch surface and a durable, self-skinning finish in a single step – one polyol-and-ISO material system, no separate top coat.
The Integral I-Skin Molding Process
Integral I-skin injection molding begins with a mold – aluminum or epoxy, with aluminum preferred for its heat transfer. A mold release is applied to the cavity and core of the tool. When a part calls for a painted surface, paint goes inside the cavity and core before the mold closes, typically a urethane-based 2K (two-part) paint, or a 1K (one-part) paint. The mold then closes and the foam system is injected.
I-Skin runs on one material system: a polyol and an ISO (isocyanate). Integral skin molding forms a durable surface and a foam core from that single system, and the result is an integral skin foam that develops its own skin as it cures.
The self-skinning action is what sets I-Skin apart from other reaction injection molding systems:
It’s a self-skinning foam… it allows you to have one foam system that gives you multiple densities in the tool, and that’s the big thing that makes all the difference.
Mold temperature controls the skin thickness, forming a thicker skin at lower mold temperatures, while the rest of the cavity fills with foam at a predetermined density AdvancTEK can tune firmer or softer feel depending on the application.
Parts and Components Best Suited for I-Skin
I-Skin fits parts that need a soft-touch surface for an operator and still have to stand up to heavy use.
Anywhere you want a softer component, but you still need a product that’s going to take a lot of wear and tear, I-Skin is a great fit. It works well in high-use environments.
Common applications include:
✓Armrests for seating systems
✓Center consoles for commercial and construction vehicles
✓I-Skin pads on doors, where an operator rests an elbow or forearm
✓Bump pads for areas where a person might strike their head, wrapping sharp corners
AdvancTEK also overmolds components into I-Skin parts. We regularly overmold stamped steel components for attachment points and rigidity in armrests and consoles, and have overmolded sheet metal panels, angle irons, and plywood panels for larger parts.
Industries That Use I-Skin Parts
I-Skin components appear across industries where operators are in direct contact with equipment surfaces:
- Commercial vehicles – Including Class 4 through 8 trucks and refuse trucks
- Construction equipment – Such as telehandlers and excavators
- Industrial and material handling equipment
- Construction and office seating – armrests typically use integral skin
- Low-speed vehicles and golf carts – Where AdvancTEK builds hip-restraint armrests
Advantages of the I-Skin Process
Because the skin and core form from one foam system, an I-Skin part carries its color all the way through.
The good thing about it is its integral skin. So if there is a cut on it, you’re not going to see the bottom – the foam inside is going to be the same color as your exterior foam.
AdvancTEK molds integral skin polyurethane foam in a range of colors – gray, brown, blue, and black – and color-matches the paint to the foam, running the foam at roughly 80% of the value of the top coat. Parts can be produced with or without paint; painted surfaces are recommended for highly cosmetic parts, where paint hides surface imperfections from the molding process and surface geometry. Because a urethane paint chemically bonds to the urethane foam, adhesion is strong, and there is no concern about the paint peeling.
| I-Skin (Integral Skin RIM) | Soft-Touch Injection Molding | |
|---|---|---|
| Process steps | Single step | Two steps (hard substrate + TPO overmold) |
| Material system | One system (polyol + ISO) | Hard substrate + separate TPO layer |
| Color | Runs through the entire part | Applied as an overmolded surface layer |
| Tooling | Cast or billet aluminum – lower investment | Injection molding tooling – higher investment |
Other advantages of the process:
✓Single process step – Soft-touch injection molding pairs a hard substrate with a TPO overmold in a secondary step; I-Skin does it in one.
✓High design flexibility – This provides part thicknesses and densities that standard injection molding cannot match.
✓Overmolding for rigidity – Companies can commonize part numbers by integrating several components into one.
✓Cost-competitive tooling – I-Skin tools are cast or billet aluminum, a lower investment than injection molding tooling.
AdvancTEK supports part design from the start and can take a part from napkin sketch to reality with design-for-manufacturing input before tooling begins. For a broader comparison, AdvancTEK’s guide to selecting the right plastic manufacturing process weighs RIM against injection molding and thermoforming.
Inside AdvancTEK’s I-Skin Production
AdvancTEK controls I-Skin quality through temperature and material metering. Here’s how a part moves through production:
| 1 | Heat the mold – Production begins by bringing the mold up to temperature, since mold temperature sets the skin thickness |
| 2 | Manage material temperature and ratio – Engineered equipment manages material temperature and the polyol-to-ISO ratio, calibrated for a repeatable part every time |
| 3 | Paint and load inserts – Paint is applied as needed to the A or B surface, and any inserts for overmolding are loaded |
| 4 | Close and inject – The mold closes for injection, with gating depending on part size and visual criteria; AdvancTEK typically gates on the backside, using edge gating when a part requires it |
| 5 | Cure – A standard cure cycle runs two to four minutes on average |
| 6 | Demold and trim – Parts are demolded and trimmed to remove gates and the flash that forms along the edges (left intentionally to let air escape during the fill) |
| 7 | Move to assembly or finished goods – From there, a part moves into assembly or straight to finished goods |
Density, skin thickness, and color are all adjustable:
| Property | How it’s set | Result |
|---|---|---|
| Density | AdvancTEK’s metering units | Firmer or lighter, within the range the application allows |
| Skin thickness | Mold temperature | Hotter mold = thinner skin; colder mold = thicker skin |
| Color | Introduced at the tool | Quick changeovers between runs |
“That skin thickness is driven off your molding temperature. The hotter your mold, the thinner the skin; the colder the mold, the thicker the skin.”
Integral I-Skin Molding FAQs
What does I-Skin stand for?
I-Skin is short for integral skin reaction injection molding. The “I” is the integral part – the foam forms its own skin as it cures, so the surface and the core are one continuous material.
How is I-Skin different from standard injection molding for soft-touch parts?
Standard injection molding builds a soft-touch part in two steps, with a hard plastic substrate with a TPO soft-touch layer molded over it. I-Skin produces the skin and the foam core in a single step, from one polyol-and-ISO material system.
Can I-Skin parts be made in different colors, and do they need paint?
Yes. AdvancTEK molds the foam in several colors and color-matches paint to the foam. Parts can be made with or without paint. Paint is recommended for highly cosmetic parts. Because the color runs through the foam, a cut or scuff does not expose a different color underneath.
How quickly can an I-Skin part reach production?
I-Skin has a shorter tooling lead time than injection molding, so the launch cycle is quicker. Once a design is complete, a part can reach production in a matter of months rather than years.
💡Quality:
AdvancTEK meets IATF requirements and can run in-house density checks and measurements to hold each I-Skin part to spec – with through-coloration as a key differentiator.