RTV Gasket Forming
Precision RTV silicone and FIPG (formed-in-place gasket) dispensing for automotive electronics housing seals — ECU covers, control unit lids, gearbox electronics and power distribution boxes.
Precision RTV and FIPG Gasket Dispensing for Automotive Electronics Housings
Automotive electronics housings — ECU covers, power distribution box lids, gearbox control unit enclosures and junction box covers — are sealed against the environment with formed-in-place gaskets (FIPG) dispensed from RTV silicone or anaerobic sealant compounds. FIPG has replaced traditional cut gaskets in most automotive electronics applications because it eliminates gasket inventory, provides a perfect contact fit to the specific housing surface finish and waviness, and can be dispensed at the speed of automated production. For IP69K-rated housings that must withstand 80–100 bar water spray, the FIPG bead must be continuous, void-free and uniform in cross-section around the entire housing perimeter — including corners where traditional cut gaskets are most vulnerable.
The dispensing challenge with RTV gasket forming is applying a high-viscosity silicone (50,000–500,000 mPa·s) in a controlled bead geometry at production speed, along complex housing flange paths with inside radii as tight as 2 mm, elevation changes up to ±5 mm, and oblique surfaces. The bead must return to the start point with a seamless overlap joint — a visible gap or undercut at the overlap position is the most common cause of IP test failures on FIPG-sealed automotive housings.
SANCO DS series inline dispensing machines and offline high-speed dispensing machines are equipped with high-torque auger valves and 3D path interpolation to dispense RTV and FIPG gaskets at production rates compatible with Tier 1 automotive assembly lines.
Why Automotive RTV Gasket Forming Demands Process Control
FIPG gasket forming on automotive electronics housings must achieve IP69K sealing performance with void-free, uniform beads on complex 3D housing geometries at production speed.
High-Viscosity Silicone at Consistent Volume
Automotive FIPG compounds have viscosities of 50,000–500,000 mPa·s — 10–100× higher than standard adhesives. Dispensing at consistent bead cross-section requires positive-displacement auger valves with high-torque drive and pre-heated barrels.
3D Housing Flange Path Following
Automotive housing sealing flanges follow complex perimeters with elevation changes, inside radii and angled surfaces. The Z-axis must track the flange surface profile within ±0.2 mm to maintain consistent standoff height and bead cross-section throughout.
Seamless Overlap Joint at Start/End Point
The bead start and end points must overlap and blend into a seamless joint with no gap or build-up. A gap as small as 0.2 mm at the overlap joint is sufficient to fail IP69K testing.
Open Time Management for Assembly
RTV silicone begins skinning within 5–20 minutes of dispensing. On high-volume lines, dispensing takt time, transfer time and assembly time must all be controlled to ensure every unit is assembled within the open time window.
Aluminium Substrate Adhesion
Automotive ECU housings are predominantly die-cast aluminium. Surface contamination from casting release agents can prevent RTV adhesion, causing the cured gasket to peel under vibration. Pre-cleaning and adhesion promotion are required.
100% Bead Continuity Verification
IP69K-rated housings require 100% bead continuity verification before assembly — a single pinhole or discontinuity causes immediate IP failure. Inline laser profilometer or vision inspection is required with automatic rejection of incomplete beads.
Key Capabilities for Automotive RTV Gasket Forming
High-Torque Auger Valve up to 500,000 mPa·s
Positive-displacement auger valve meters high-viscosity RTV silicone and FIPG at precise volumes with no lag, drool or tail — essential for consistent bead geometry on automotive housings.
3D Path Interpolation for Complex Flanges
Simultaneous X/Y/Z path interpolation tracks automotive housing sealing flanges with elevation changes and inside radii as tight as 2 mm — maintaining ±0.2 mm standoff height throughout.
Heated Barrel for Viscosity Stabilisation
Barrel heater maintains RTV and FIPG at 40–60°C, reducing viscosity by 40–60% and ensuring consistent flow rate from first housing to last in a production shift.
Overlap Joint Programme Control
Programmable volume ramp-down and blend profile at the bead start/end point creates a seamless overlap joint — eliminating the gap that is the most common cause of FIPG gasket IP test failures.
Inline Bead Continuity Inspection
Optional laser profilometer integration measures bead height and continuity in real time. Incomplete or under-height beads trigger automatic rejection before housing cover assembly.
Multi-Housing Programme Library
Production programmes for all housing variants recalled by barcode scan. Supports mixed-model automotive lines with zero changeover time between ECU cover, PDB lid and junction box variants.
Housing CAD Import for Path Generation
Import housing 3D CAD data to auto-generate dispensing toolpaths along sealing flange surfaces including Z-height profile extraction — reducing NPI programming time from days to hours.
Inline Housing Assembly Integration
SMEMA-compatible conveyor integration links SANCO gasket forming machines between housing cleaning, dispensing, cover assembly press and IP test stations.
The RTV Gasket Forming Process Step by Step
Automotive FIPG gasket forming requires consistent high-viscosity silicone dispensing with seamless overlap joints and 100% continuity verification before assembly.
Housing Surface Clean & Inspection
Housing sealing flange cleaned of release agents and contamination. Surface finish verified. CCD vision captures flange fiducials for path alignment.
Continuous FIPG Bead Dispensing
SANCO machine traces full housing perimeter with continuous RTV/FIPG bead. Volume and cross-section maintained through all corners, radii and elevation changes.
Overlap Joint Completion
Bead volume ramped down on approach to start point. Blended overlap joint completed with no gap or build-up — verified by inline bead inspection.
Assembly Within Open Time
Housing cover assembled and torqued within material open time (5–20 min). Assembly force and gap height controlled per material specification.
Cure & IP69K Test
Room temperature moisture cure 24 h, or heat-accelerated at 80°C / 60 min. IP69K pressure spray test validates seal integrity before release.
RTV & FIPG Material Types & SANCO Compatibility
SANCO dispensing machines handle all RTV silicone and FIPG sealant compounds used in automotive electronics housing sealing.
| Material Type | Viscosity Range | Cure Method | Typical Application | SANCO Compatibility |
|---|---|---|---|---|
| RTV Silicone (1-Component) | 50,000 – 300,000 mPa·s | Moisture cure, room temp 24 h or 80°C 60 min | General automotive ECU housing, PDB lid and junction box cover sealing — IP67 to IP69K rated | Recommended |
| FIPG Silicone (High-Viscosity) | 200,000 – 500,000 mPa·s | Moisture cure | OEM-spec FIPG for aluminium ECU housings and transmission control unit covers; high compression-set resistance | Recommended |
| Anaerobic Flange Sealant | 5,000 – 30,000 mPa·s | Anaerobic cure (metal contact), 10–30 min | Metal-to-metal flanges on gearbox electronics and engine management unit covers — locks and seals simultaneously | Recommended |
| UV + Moisture Dual-Cure Silicone | 20,000 – 150,000 mPa·s | UV 365 nm pre-cure + moisture cure | High-speed FIPG lines requiring rapid handling strength before full moisture cure — automotive power electronics | Recommended |
| High-Temperature RTV (250°C Rated) | 80,000 – 400,000 mPa·s | Moisture cure | Exhaust-adjacent electronics housings, turbo control units and engine bay covers operating above 150°C continuously | Recommended |
Frequently Asked Questions
How does SANCO achieve a seamless FIPG overlap joint to pass IP69K testing?
SANCO dispensing machines use a programmable volume ramp-down profile on approach to the bead start point, reducing dispensed volume progressively over the last 5–10 mm to blend the return bead into the original profile. This approach consistently achieves overlap joints with less than 0.1 mm height variation — well within IP69K test pass criteria. Contact our application engineers for overlap joint programme development.
What viscosity range can SANCO auger valves handle for automotive FIPG applications?
SANCO high-torque auger valves dispense RTV silicone and FIPG compounds with viscosities from 20,000 to 500,000 mPa·s — covering all standard automotive FIPG materials. The heated barrel option reduces material viscosity by 40–60%, allowing consistent flow rates even for the highest-viscosity OEM-specified FIPG compounds.
How does SANCO handle Z-axis height variation on automotive housing sealing flanges?
SANCO DS series dispensing machines use 3D path interpolation with programmable Z-height profiles imported from housing CAD data. The Z-axis tracks the flange elevation profile within ±0.2 mm around all corners and elevation changes. For housings with significant warpage, inline laser height sensing provides real-time Z-correction during dispensing.
What inspection method does SANCO recommend for 100% FIPG bead verification?
SANCO recommends inline laser profilometer integration immediately after the dispensing station. The laser measures bead height and width continuously along the full perimeter path. Any bead gap or under-height section triggers automatic rejection before housing cover assembly — preventing IP test failures from reaching end-of-line.
Can SANCO machines dispense FIPG on both aluminium and plastic automotive housings?
Yes. SANCO dispensing machines are compatible with RTV and FIPG dispensing on aluminium die-cast, magnesium, engineering plastic and composite housing substrates. For aluminium housings requiring adhesion promotion, SANCO machines can be integrated with upstream primer dispensing stations.
Where can I learn about related automotive electronics sealing applications?
Visit our Applications section for guides covering ECU encapsulation, conformal coating, waterproof connector sealing and sensor dispensing. For equipment, see our dispensing machine product pages.
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