Inner Fiber Outside Silicone Rubber Sleeving
A composite non-shrink sleeve with the layers in this order: braided fiberglass on the inside, silicone rubber on the outside. The woven glass bore slides over the harness and grips it; the silicone face (the side the world touches) seals out fluids, resists contamination loading and takes the surface wear. Rated -60℃~+200℃ for high-temperature harness and motor lead runs. The earlier catalogue line "soft inside, rigid outside" described this construction backwards: the structural element here is the glass braid, and the rubber face is the outer skin. Send the harness OD and environment and we return the size.
Construction: glass bore, silicone skin
The wall is built in two layers and the order decides everything. The inner fiberglass braid is the structure: it holds the bore open, carries bend after bend without taking a set, and contributes the temperature backbone: glass tolerates far more heat than any rubber bonded to it. Because the bore is woven, it also grips the harness with a light friction instead of sliding like a smooth rubber bore. The outer silicone rubber coating is the working face: it seals the braid so fluids cannot wick along the glass fibres, keeps oil mist and dust from packing into the weave, and takes the rubbing where the run passes brackets, covers and clamps.
What that means in practice: abrasion is handled by the outer rubber face until it is worn through: after that the exposed braid frays, so severe edge contact needs routing care or an added guard. Flexibility comes from the braid structure and survives the full temperature range. Contamination lands on the sealed silicone skin and wipes off, instead of loading into an open weave. For electrical use, the conductor's own insulation remains the primary dielectric; no primary-voltage duty is claimed for this sleeve without the grade's test documentation.
Note on the inverse construction: the range also includes a tubing grade with the layers reversed (silicone rubber inside, fiberglass braid outside) specified where the outer glass layer is wanted as the abrasion skin. That construction has its own page (inner rubber / outer glass fiber tubing) and its own selection logic; the two are not the same spec.
Where Inner Fiber Outside Silicone Rubber Sleeving is used
Primary applications: high-temperature harness protection, engine and motor bay runs, heating equipment looms, and leads routed through zones with oil mist, dust and radiant heat. It installs over assembled looms because nothing shrinks; there is no threading-before-termination constraint.
How to select the right size
Sizing is by the part it covers and the wear it will see:
- Harness or hose OD. Choose the sleeve ID with light clearance: too loose and the sleeve migrates under vibration, too tight and the braid binds on bends and the rubber face wrinkles.
- Temperature exposure. Continuous and peak temperature at the sleeve location against the -60℃~+200℃ rating; hotter zones need a different construction family.
- Abrasion source. What the sleeve rubs against : bracket edges, moving parts, clamps : decides whether the standard wall is enough or the route needs protection added.
- Which face you need exposed. If the drawing wants glass as the outer wear layer, that is the inverse tubing construction, not this sleeving.
Specification
| Material | Inner fiberglass braid + outer silicone rubber coating |
|---|---|
| Contact face (to harness) | Woven fiberglass bore |
| Outer face (to environment) | Silicone rubber : sealing and wear skin |
| Operating temperature | -60℃~+200℃ |
| Shrink behaviour | Non-shrink, slip-on |
Common Failure Modes & How to Prevent Them
These are the failures specific to a glass-bore / silicone-skin sleeving, with the root cause and the prevention for each.
The silicone skin wore through on a bracket edge
Root cause: The outer rubber face is the wear layer. Hard bearing against a sheet-metal edge thins it locally; once it is through, the exposed inner braid frays and the wall loses its sealed face.
Fix: Route clear of edges, add a grommet or guard at unavoidable contact points, and clip the run so vibration does not hold the sleeve against the edge.
The sleeve migrated along the harness
Root cause: The ID was chosen too loose. The woven bore grips by fit; with excess clearance, vibration walks the sleeve off the section it was meant to cover, exposing the harness end to end.
Fix: Size with light clearance only, and clip long runs at intervals. Where the run is vertical or mobile, anchor both ends by turning the sleeve mouth back over the bundle.
The sleeve was installed inside-out
Root cause: With both layers bonded, the difference between faces is easy to miss at the bench. Inside-out installation puts rubber against the harness (where its grip and sealing do nothing), and leaves the absorbent braid exposed to oil mist and wear.
Fix: Check the bore texture before pushing on: the woven glass side goes to the harness, the smooth rubber side faces out. Mark the orientation on the bench instruction for production fitters.
Fluids loaded into an exposed braid end
Root cause: A cut end leaves glass braid faces open; wicking along the fibres carried oil into the wall even though the outer skin was intact.
Fix: Seal cut ends, a dab of silicone compatible with the grade, a heat-formed pinch, or ordering factory-cut lengths. Do not leave open braid ends in oil-mist zones.
It was placed where the drawing wanted glass outside
Root cause: The spec called for an outer abrasion layer of fiberglass, but the sleeving ordered had silicone outside. The wear face was the wrong material and the skin scuffed through early.
Fix: Match the construction to the drawing's wear intent: silicone-outside for sealing duty (this page), glass-outside for the abrasion skin (the inverse tubing page). Confirm the layer order at RFQ stage, not at installation.
Frequently asked questions
What is the purpose of the outer silicone layer?
It is the sleeve's working face to the world. Sitting outside, the silicone seals the glass braid so fluids do not wick into the wall, keeps oil mist and dust from loading into the weave, and takes the rubbing where the sleeve passes brackets and covers. Everything the environment does to the sleeve, the silicone layer meets first.
How does the inner fiberglass support the sleeve?
The braid is the structural wall: it holds the bore round so the sleeve pushes on without collapsing, it keeps the wall flexible along bends, and it sets the temperature backbone of the construction: glass tolerates far more heat than the rubber on top of it. The inner position also means the bore face is the woven glass itself, which grips the harness lightly instead of sliding like a rubber bore.
Which surface is intended to contact the protected conductor or component?
The inner fiberglass bore. The braid is the contact face against the wire insulation, hose or bundle; the silicone side is the outside face against the environment. Installing the sleeve inside-out would put rubber against the harness and leave bare braid exposed: the sealing and wear face would then be on the wrong side.
Is this the same construction as the silicone-coated fiberglass sleeving page?
The layer order is the same: glass inside, silicone outside. This page covers the sleeving grade positioned for high-temperature harness runs where the woven bore grips the bundle; the silicone-coated fiberglass page is specified from motor-lead diameters and its own size table. Confirm the size code from the drawing rather than assuming the two ranges interchange.
Does the sleeve keep the wire's own insulation doing its job?
Yes, and that division of labour is the point: the conductor's insulation stays the primary dielectric, this sleeve adds heat, fluid and abrasion protection over it. No primary-voltage duty is claimed for the sleeve on this page; if a job calls for a dielectric classification, that must come from the grade's test documentation, not from the construction description.
How is the non-shrink installation done?
Push it on. The bore slides over the harness or hose with light clearance and holds position by fit: no heat, no recovery step, no threading before termination. On long runs, clip the sleeve at intervals so vibration does not migrate it; at ends, a short turn back over the bundle edge stops the mouth from working loose.
Request a quote for Inner Fiber Outside Silicone Rubber Sleeving
Send the harness or hose OD, the temperature and wear environment, and quantity. We return the size recommendation, the confirmed layer order and lead time.
Size range & specification notes
Slip-on ID range per the size table; glass braid and silicone grade details are held in the data note above until verified.