| HS Code | 391073 |
| Product Model | RH-G603/50 |
| Material Type | Two-component addition-cure liquid silicone rubber |
| Appearance | Translucent or white |
| Density G Cm3 | 1.10–1.15 |
| Hardness Shore A | 50 ± 2 |
| Tensile Strength Mpa | ≥5.0 |
| Elongation At Break Percent | ≥300 |
| Tear Strength Kn M | ≥20 |
| Viscosity Mpa S | 50,000–100,000 |
| Mixing Ratio | 1:1 |
| Curing Condition | 120–150 °C for 10–15 min |
| Volume Resistivity Ohm Cm | ≥1×10^14 |
| Dielectric Strength Kv Mm | ≥20 |
| Dielectric Constant 50hz | ≤3.0 |
| Dissipation Factor 50hz | ≤0.01 |
| Tracking Resistance Kv | ≥4.5 |
| Flammability | UL94 V-0 |
| Operating Temperature C | -50 to 200 |
As an accredited Insulator Liquid Silicone Rubber RH-G603/50 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaging: Insulator Liquid Silicone Rubber RH-G603/50 is supplied in sealed, clearly labeled 20 kg plastic pails for safe storage and transport. |
| Container Loading (20′ FCL) | Insulator Liquid Silicone Rubber RH-G603/50 is securely packed in sealed drums, palletized and strapped in a 20′ FCL container. |
| Shipping | Insulator Liquid Silicone Rubber RH-G603/50 is typically supplied in sealed drums or pails. Ship in cool, dry conditions, away from direct sunlight, moisture, and contamination. Protect from freezing and extreme heat. Handle as a non-hazardous industrial chemical unless the SDS or local transport regulations state otherwise. |
| Storage | Store Insulator Liquid Silicone Rubber RH-G603/50 in original, tightly closed containers in a cool, dry, well-ventilated area away from heat, ignition sources, and direct sunlight. Protect from moisture, dust, and contamination; avoid freezing or excessive heat. Keep separate from incompatible materials. Maintain within the manufacturer’s recommended temperature range, observe shelf-life, and follow SDS/first-in, first-out. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored unopened in its original container under cool, dry conditions. |
For transmission-class composite suspension and tension insulator housings, RH-G603/50 is processed as a two-component platinum-catalysed addition-cure silicone elastomer with a nominal post-cure hardness of 50 Shore A measured to ASTM D2240-15(2021). The A and B components are metered at a 1:1 volume ratio through a static mixing nozzle containing 24 to 32 elements. Pigment masterbatch addition of 1.5–3.0 wt% and a silane-based self-adhesive additive at 0.3–0.8 wt% modify surface appearance and adhesion to the epoxy-impregnated glass-fibre core without shifting the hydrosilylation cure stoichiometry. On vertical liquid injection moulding lines with clamp force sized between 150 t and 300 t for multi-cavity sheds, gate pressure is held at 5–18 MPa while mould temperature is maintained between 130 °C and 170 °C. Cure time for shed wall sections from 3 mm to 12 mm usually falls between 90 s and 240 s. The principal process risk is air entrapment at the root of deep creepage sheds; vacuum-assisted filling at 0.1–1.0 kPa or staged injection with a short packing hold reduces void formation. If drums are opened at relative humidity above 60%, fillers and pigments should be pre-dried before addition because free moisture in thick sections and at the FRP interface can produce dielectric discontinuities.
| Property | Test method | Typical required range |
|---|---|---|
| Hardness | ASTM D2240-15(2021) | 48–52 Shore A |
| Tensile strength | ISO 37:2017 | >5.0 MPa |
| Elongation at break | ISO 37:2017 | >350% |
| Tear strength | ASTM D624-B | >15 N/mm |
| Dielectric strength | IEC 60243-1:2013 | >20 kV/mm on 2 mm slabs |
| Volume resistivity | IEC 62631-3-1:2016 | >1×10¹⁴ Ω·cm |
| Tracking and erosion resistance | IEC 60587 method 1A | 4.5 kV, no failure within 6 h |
The finished housing is cured onto the FRP core after core surface preparation, and the complete insulator is evaluated against IEC 62217 design, interface, and tracking requirements. For outdoor composite suspension and tension insulator applications, additional acceptance testing follows IEC 61109. The terminal product is a silicone-housed composite tension or suspension insulator for AC overhead lines from 110 kV to 420 kV, where the elastomer must survive coastal salt-fog, cement dust, and high UV exposure without loss of hydrophobicity. Tracking and erosion resistance is verified on inclined-plane test specimens according to IEC 60587 at 4.5 kV; failure is defined by the test criterion of tracking length or erosion depth specified by the purchaser. Thermal ageing, water immersion, and mechanical load-time performance are assigned to the complete insulator assembly rather than to the elastomer alone.
When the same 50 Shore A compound is used as a bonded internal coating on an epoxy/glass-fibre tube, the processing envelope shifts from injection-moulding-dominated shear flow to low-shear casting and pressure-gelation flow. The A:B ratio remains 1:1 by weight, but the mixture is vacuum-degassed at 50–100 Pa absolute pressure before being introduced into an annular gap of 8–15 mm between the FRP tube and a heated cylindrical mould. A solventless self-bonding additive or primer is introduced at 0.5–1.5 wt%; addition above this range can form low-modulus boundary layers that reduce burst strength and interfacial partial-discharge stability. Mould temperature is restricted to 110–150 °C because the filament-wound FRP core carries residual stress and may delaminate if heated too long above its glass transition temperature. Cure time is therefore extended to 300–600 s to compensate for the lower thermal conductivity of the composite wall and mandrel.
The bonded interface is assessed by water diffusion and partial-discharge tests defined in IEC 61462 for composite hollow insulators, with additional oil-exposure evaluation when the component is fitted to oil-filled instrument transformers covered by IEC 60137. Defects at the silicone–FRP interface, including entrapped volatiles and incomplete primer wet-out, are detected by ultrasonic scanning or X-ray imaging after demoulding. Terminal product: a hollow composite insulator body for 245 kV current transformers, bushings, or SF₆-filled circuit breakers, where the internal silicone layer must tolerate hot insulating oil without swelling, hardening, or releasing low-molecular-weight siloxane into the oil. Post-cure is set at 200 °C for 4 h in an air-circulating oven; incomplete devolatilisation can raise oil dissipation factor after the first energisation period.
Where a pre-moulded cable joint body must accept continuous mechanical stress from XLPE insulation growth and conductor thermal cycling, RH-G603/50 is mixed at 1:1 by volume and injected into polished steel moulds without added adhesion promoter. The cleanroom line maintains particulate contamination below 50 particles/m³ at 0.5 µm and larger to prevent interfacial defects at the silicone–semicon boundary. Mould temperature is deliberately reduced to 100–120 °C for overmoulded joint bodies that enclose preinstalled EPDM stress-control components, because prolonged exposure of the EPDM element to higher temperature can alter trap-charge behaviour. Cure time for wall sections from 2 mm to 8 mm is extended to 8–15 min; cable accessory lines accept longer cycle times to minimise differential shrinkage between the silicone insulation body and the cable semicon layer.
The assembled joint is tested according to IEC 60502-4 for extruded cable accessories in distribution networks, or under HD 629.1 S2 where European utility specifications govern. Electrical acceptance includes partial discharge extinction below 10 pC at 1.73 U₀ for accessory classes from 12 kV to 36 kV. The terminal product is a three-layer cable joint insulation body for 12–36 kV single-core polymeric distribution cable, installed within a heat-shrink or cold-shrink system with outer semicon and copper mesh. No post-cure is normally applied for cleanroom-moulded cable bodies when cure temperature is below 150 °C; instead, room-temperature stabilisation for 24–48 h is used to allow network completion and removal of trace volatiles before dispatch.
Direct overmoulding of metal-oxide varistor stacks with RH-G603/50 requires a separate injection strategy because the MOV blocks are brittle and cannot tolerate high packing pressure. The A:B ratio is held at 1:1 by volume; a heat-stabiliser masterbatch at 0.2–0.5 wt% is metered into the base component where continuous operating voltages produce surface temperatures above 60 °C. Injection speed is profiled, beginning at a cavity pressure of 2–8 MPa until the stack is fully covered, followed by a short packing stage below 10 MPa. Mould temperature is set to 120–150 °C and cure time ranges from 180 s to 300 s depending on varistor diameter and housing wall thickness between 4 mm and 10 mm. The mould must be vacuum-vented to 0.1–0.5 kPa to prevent voids on the underside of sealing lips and around inserted FRP end fittings.
The moulded arrester housing is evaluated according to IEC 60099-4 for metal-oxide surge arresters without gaps for AC systems, and under IEEE C62.11 for utility procurement in North America where duty-cycle, switching-surge energy, and pressure-relief behaviour are specified. Production-line failure modes include poor adhesion to the fibreglass cage, air entrapment near flange inserts, and tearing at sharp transitions in shed geometry. Terminal product: a polymer-housed distribution-class surge arrester for system voltages from 3 kV to 36 kV, installed on pole-top transformers, switchgear, and underground-to-overhead riser poles. The operational boundary of this grade is the continuous service temperature of the silicone network; sustained surface temperatures above 180 °C can initiate oxidative reversion of the methyl silicone backbone and reduce long-term tracking resistance. Sulfur-containing release sprays and amine-bearing adhesion promoters should be excluded from the moulding cell to avoid platinum-catalyst inhibition and surface tack after demoulding.
In rail-traction environments where arc resistance and fire-performance acceptance are evaluated simultaneously, RH-G603/50 is processed at a 1:1 A/B ratio with a flame-retardant masterbatch addition of 2–8 wt% depending on the hazard level specified by the rail operator. The masterbatch raises compound viscosity; processors typically switch from a 24-element static mixer to a 32-element mixer and raise injection pressure by 10–30% while maintaining mould temperature at 140–160 °C. The mould is configured for a one-piece roof bushing geometry with alternating sheds and a central conductor bore. Cure time for wall sections of 5–15 mm is set at 240–480 s; post-cure follows at 200 °C for 4 h in forced air to develop final mechanical properties and reduce volatile condensables that could support surface arcing.
Compliance for the rail insulator is demonstrated under EN 45545-2 for fire safety of rolling stock, with the relevant requirement set evaluated at the specified hazard level, commonly HL2 for roof-mounted electrical equipment. Additional tracking and erosion acceptance is performed using IEC 60587 method 1A at 4.5 kV. The terminal product is a 25 kV AC railway roof insulator for current collectors, busbar supports, or roof feedthroughs on electric rolling stock, where the elastomer must retain arc resistance after exposure to moisture, UV, and airborne abrasive particulates. Batch-to-batch fire-performance variation is controlled by measuring limiting oxygen index to ASTM D2863 above 28% O₂ and by cone calorimeter smoke-density checks referenced to ISO 5660-1; the exact acceptance threshold remains set by the rail operator’s specification and hazard-level designation.
For indoor switchgear bushing insulation, RH-G603/50 is injected under vacuum-assisted pressure gelation at a 1:1 by weight mix ratio; mould cavity pressure is maintained at 4–12 MPa while the bushing insert and conductor are held in position. Mould temperature is set at 140–160 °C, and the insulation body can be demoulded after 120–240 s. If post-cure is shortened below 120 min at 200 °C, residual low-molecular-weight siloxane oligomers and catalyst remnants remain in the polymer network; this condition can produce frequency-dependent dielectric losses that appear as elevated dissipation factor at 50 Hz. The bushing insulation should therefore be tested to IEC 60250 or ASTM D150 to confirm tan δ below the utility specification limit, commonly 5×10⁻³ at 20 °C and 50 Hz, before any shortened post-cure is accepted. Published data for this specific configuration is limited; verification on production samples is required when cycle-time reductions are implemented.
The terminal product is a 24 kV switchgear bushing or indoor transformer bushing conforming to IEC 60137 for bushings for alternating voltages above 1 kV, and to IEEE C57.19.100 where North American dielectric, thermal, and partial-discharge requirements apply. Partial-discharge acceptance is normally set at 5 pC or 10 pC depending on equipment class and purchaser specification. The main process boundary is post-cure throughput: when line speed is prioritised, the extended 200 °C bake may be reduced only if dielectric-loss verification on moulded bushings shows no statistical difference from fully post-cured controls. The silicone insulation must also maintain stable dielectric strength at the conductor interface, which is inspected by X-ray or computed tomography on first-article production runs to detect microvoids and filler settlement.
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Insulator Liquid Silicone Rubber RH-G603/50 is a two-part, platinum-catalyzed addition-cure liquid silicone rubber grade intended for high-voltage outdoor insulation components. The designation suffix /50 is consistent with a nominal 50 Shore A hardness target; actual as-molded hardness is determined by ISO 48-4 or ASTM D2240 on production-representative plaques. The uncured system consists of a vinyl-functional polydimethylsiloxane base and a silicon-hydride crosslinker/catalyst component, usually metered at a 1:1 ratio by volume or weight depending on the supplier’s metering configuration. The material is processed by liquid injection molding into suspension insulator sheds, bushings, surge arrester housings, and high-voltage cable accessories. Because the hydrosilylation cure reaction generates no condensation byproducts, thick sections can be cured more uniformly than condensation-cure room-temperature-vulcanizing systems, and mold fouling from acetic acid or alcohol evolution is avoided. The cured network is based on polydimethylsiloxane with reinforcing fillers and tracking-resistant fillers; final dielectric performance depends on filler dispersion, knit-line closure, and post-cure completion.
Published numerical values for the specific RH-G603/50 formulation are limited; numerical ranges given in this technical introduction refer to the general addition-cure LSR class for insulator applications and must not be read as a certified lot-specific certificate of analysis. The manufacturer’s current technical data sheet should be consulted for release values.
Material specifications relevant to electrical insulation include volume resistivity under IEC 60093, short-term dielectric strength under IEC 60243-1, tracking and erosion resistance under IEC 60587, and mechanical behavior under ISO 37 and ISO 34-1. For complete polymeric insulators, the system-level design and test standard is IEC 62217, which covers interface connections, core joints, shed geometry, and tracking performance rather than raw material plaques. Compliance with these standards is component-specific: a laboratory plaque result does not transfer directly to a molded shed with deep undercuts, cold-runner gates, and weld lines. Hydrophobicity and hydrophobicity transfer are evaluated on complete insulator geometries or on plaques after defined corona, UV, or salt-fog exposure; clean polydimethylsiloxane surfaces commonly show static water contact angles above 90°, but the relevant service property is retention of hydrophobicity after pollution accumulation and dry-band arcing.
Addition-cure LSR cure uniformity is controlled by the molar balance of silicon-hydride crosslinker to vinyl-functional polymer. A deviation in A/B ratio changes the effective crosslink density and leaves unreacted functional groups that can act as moisture uptake sites or dielectric loss sites. Production-scale metering commonly uses piston or gear pumps with ratio monitoring and an in-line static mixer of 24 to 36 elements; component viscosities are often measured by rotational viscometry under ISO 2555. For filled liquid silicone rubber of this class, component viscosities can range from 5 Pa·s to 50 Pa·s at 25 °C. Thick insulator sheds create a separate thermal limitation: the exothermic hydrosilylation reaction is accelerated by mold temperature, but the low thermal conductivity of silicone rubber means the core of a thick section can remain below cure temperature after the surface has solidified. Mold temperatures in the 120 °C to 180 °C range are common for LSR injection molding; below 110 °C the platinum catalyst is slow, and above 200 °C local overheating can create voids, discoloration, or residual stress. Lower mold temperature and extended cure time may be required for thick sections, unless the mold design includes conformal cooling or staged heating cycles.
Rheological characterization for incoming inspection usually includes dynamic viscosity at low shear and a cure-rheology scan. A moving-die rheometer under ISO 6502 provides scorch time and torque development, but the method is more common for high consistency rubber than for LSR; rotational viscometry and a simple curometer test are used on the mixed liquid. The glass transition temperature of polydimethylsiloxane networks is near -120 °C; the filled LSR remains flexible below typical outdoor service temperatures. This low glass transition contributes to resistance to cracking during cold-weather operation, but it does not replace ice-load and wind-load mechanical testing of the final insulator. Dynamic mechanical analysis under ISO 6721 is used to measure the temperature dependence of storage modulus and loss factor, which can reveal filler-polymer interface issues that are not visible in a single hardness value.
Mixing-induced filler orientation is another processing variable. The flow path through the cold runner and gate can align plate-like fillers and create anisotropic shrinkage or dielectric properties. In production-scale LSR molding, batch-to-batch filler settling can alter effective viscosity if drums are not agitated or recirculated before use. White hard spots are observed when reinforcing or tracking-resistant filler agglomerates are not completely dispersed in the static mixer. The mixed material is injected into a water-cooled cold runner maintained below 60 °C; the material then enters the heated mold, usually at 140 °C to 170 °C, where the platinum catalyst initiates rapid crosslinking. For suspension insulator components, the projected area of the part determines the required clamp force; injection pressures in conventional LSR molding often remain below 30 MPa, but specific values depend on runner diameter, gate size, and mold temperature. Production equipment should be dedicated to addition-cure LSR or thoroughly purged, because residues of tin-catalyzed RTV can inhibit cure at the interface and create weak knit lines.
| Test method | Property | Relevance to insulator service |
|---|---|---|
| IEC 60587 | Inclined-plane tracking and erosion | Material classification under 4.5 kV AC voltage with contaminant flow |
| IEC 60243-1 | Dielectric strength | Short-term breakdown through the insulating section |
| IEC 60093 | Volume resistivity | Leakage-current limitation under direct-current stress |
| ISO 37 | Tensile strength and elongation | Mechanical load resistance in handling, wind vibration, and ice shedding |
| ISO 34-1 | Tear strength | Damage tolerance at flash lines and sharp undercuts |
| ISO 815-1 | Compression set | Retention of interfacial fit after thermal cycling |
| UL 94 | Flammability | Fire containment in electrical equipment enclosures |
| IEC 62217 | Complete polymeric insulator design tests | Qualification on full component geometry, interfaces, and core joints |
Track resistance is evaluated by the inclined-plane test specified in IEC 60587, in which a contaminant solution flows along the surface while voltage is applied. The test distinguishes materials that form conductive carbonaceous paths from those that erode without forming a continuous track. Because polydimethylsiloxane decomposes to insulating silica rather than conductive char, silicone compounds can interrupt the leakage-current path; the filler package in the RH-G603/50 class is formulated to increase resistance to dry-band arcing and UV-induced chalking. A common service-related failure is not bulk breakdown but progressive erosion at ground-end sheds under salt pollution or coastal fog. Hydrophobicity transfer arises from low-molecular-weight siloxane species migrating through the pollution layer; this mechanism is assessed by recovery-of-hydrophobicity tests in which the contact angle is measured after corona exposure or salt-fog aging. Published data for this specific configuration is limited, and final qualification should include IEC 62217 tests on the complete insulator assembly rather than raw material coupons.
In the inclined-plane test, the usual criterion is not the absence of erosion but the maximum erosion depth and the ability of the material to maintain the leakage-current path without forming a continuous conductive track. Several commercial silicone compounds are tested at 4.5 kV with a contaminant flow rate and electrode spacing specified by the standard. The test is comparative rather than absolute; results are strongly influenced by electrode geometry, sample orientation, and pre-cleaning. For this reason, raw material data sheets that list a single IEC 60587 class without quoting the test voltage and method should be considered insufficient for high-voltage component release.
Silicone elastomer formulations for outdoor insulation are also exposed to ultraviolet radiation, rain, and temperature cycling. Ultraviolet exposure can be evaluated under ISO 4892-2 or IEC 61109 annexes, with mechanical and electrical properties measured before and after aging. The main concern is not initial breakdown but long-term surface roughening and loss of hydrophobicity recovery. Because the material is intended for non-ceramic insulators, the relevant product specification should include a wet-service tracking test and a defined ageing sequence, not only a dry dielectric strength test. Low-volatile cyclic siloxane content is another practical control; excess free siloxane can temporarily lower the surface leakage resistance and produce a conductive water layer before hydrophobicity recovery occurs.
Replacing high consistency rubber (HCR) with LSR changes the production economics and the post-cure requirements. HCR is a gum-stock material that is usually fed by a screw ram and crosslinked with peroxides at temperatures above 160 °C; the peroxide-derived residues must be removed by post-curing for many hours. LSR of the RH-G603/50 class can be injected at lower pressures because the uncured viscosity is lower, and it cures by addition without volatile byproducts. The tradeoff is in tear strength and tensile modulus: heavily filled HCR formulations can develop higher tear resistance than many LSR grades, and LSR requires a more expensive precision metering unit and cold-runner mold system. For high-voltage insulators, the reduction in volatile condensation products is relevant because low siloxane oligomer loss during service preserves hydrophobicity recovery. The final selection between LSR and HCR is therefore not merely a material family choice but includes vulcanization kinetics, mold cycle time, automation, and long-term dielectric stability.
| Process or material factor | Addition-cure LSR RH-G603/50 class | Condensation-cure RTV | Peroxide-cured HCR |
|---|---|---|---|
| Cure mechanism | Platinum-catalyzed hydrosilylation, two-part | Moisture-initiated condensation | Peroxide-initiated free-radical crosslinking |
| Cure byproducts | None expected from cure; trace cyclic siloxanes may remain | Alcohol or acetic acid released | Peroxide decomposition residues |
| Uncured rheology | Pumpable liquid; component viscosity roughly 5–50 Pa·s at 25 °C | Low-viscosity to paste depending on grade | High-viscosity gum requiring heavy equipment |
| Processing | Two-component metering, static mixer, liquid injection molding at 120–180 °C | Mixing and dispense, ambient or RTV cure limited by moisture diffusion | Compression or injection molding at 160–200 °C |
| Typical use | Molded insulator sheds, bushings, arrester housings | Sealing, coating, field repair | Molded or extruded high-strength parts |
| Primary limitation | Catalyst inhibition by amines, tin, sulfur; dedicated metering equipment required | Slow moisture cure; thick sections retain volatiles | Peroxide residue and volatile load require post-cure |
In production-scale liquid silicone molding lines, the A and B components are typically supplied in 20 L or 200 L drum kits. The material is pumped through precision metering pumps, mixed in a static mixer, and injected into a water-cooled cold runner. A common failure mode is cure inhibition at the surface from mold release agents containing tin or amine; release agents should be selected from non-amine, non-tin chemistries and validated on a first-article basis. Storage recommendations for similar filled LSR systems are from 5 °C to 30 °C, with an unopened shelf life of 6 to 12 months. Freezing can cause filler separation, and condensed moisture from cold storage can form surface porosity when the material is introduced directly into a hot mold. The user must verify viscosity, cure rate, hardness, tensile strength, elongation, tear strength, dielectric strength, and tracking resistance on production-representative plaques before high-voltage release.
Contact with sulfur-containing rubbers, amine-based epoxy compounds, tin-catalyzed RTV residues, or certain organic salts can prevent crosslinking at the surface or produce tackiness in deep sections. The use of a dedicated closed feeding system and purged mold surfaces reduces the risk of batch-to-batch contamination. Because platinum catalysts are active at trace concentrations, even small residues transferred from an HCR line can alter the cure profile at gate and vent locations. For high-voltage insulators, such under-cured regions can create localized water uptake, ionic migration, and partial discharge sites. The operational boundary is therefore set by contamination control, not only by the material’s inherent thermal stability. Published data for this specific configuration is limited; each molded insulator design should be qualified under the complete IEC 62217 test program before field deployment.
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