EMS-Grivory Grilamid LV-3H is a 30% glass-fibre-reinforced polyamide 12 compound supplied and reported in the dry-as-moulded state. The term dry in this product designation refers to the conditioning state of the specimen set rather than a visible surface finish or an absolute moisture-free guarantee. Dry-as-moulded data are generated after injection moulding and desiccated storage, without equilibrium conditioning at 23 °C and 50% relative humidity according to ISO 291. The base polymer is PA12, in which the comparatively long aliphatic segment between amide groups lowers the amide-group density relative to PA6 and PA66. That structural feature restricts equilibrium water uptake and reduces the mechanical property shift between dry and conditioned service. The glass-fibre content is 30% by weight, the density is 1.22 g/cm³ per ISO 1183-1, and the melting peak is 178 °C per ISO 11357-1/-3. Water absorption at saturation in 23 °C water is 1.2% per ISO 62; moisture absorption at 23 °C and 50% relative humidity is 0.7% per ISO 62.

Dry-as-moulded mechanical performance is measured on type 1A specimens according to ISO 527-1/-2. Tensile modulus is 6500 MPa, tensile stress at break is 105 MPa, and elongation at break is 4% at a test speed of 5 mm/min. Notched Charpy impact strength is 12 kJ/m² at 23 °C and 10 kJ/m² at −30 °C per ISO 179/1eA. Unnotched Charpy impact strength is 55 kJ/m² at 23 °C per ISO 179/1eU. Heat deflection temperature is 160 °C under 1.8 MPa and 170 °C under 0.45 MPa per ISO 75-1/-2. The comparative tracking index is 600 V per IEC 60112, and the UL 94 classification is HB. The low-temperature notched impact retention is significant for snap-fit clips, pneumatic line clamps, and exterior sensor brackets exposed to winter road conditions.

What Distinguishes Dry-As-Moulded Data from Conditioned Data?

The dry state produces the highest tensile modulus and strength but the lowest elongation and notched impact energy for this PA12/GF30 formulation. The absorbed water acts as a plasticiser at the amide linkages, not as a debonding agent at the glass surface. Manufacturer-published conditioned data at 23 °C and 50% relative humidity, where listed, show a tensile modulus of 5000 MPa, tensile stress at break of 75 MPa, elongation at break of 6%, and notched Charpy at 23 °C of 16 kJ/m². The −30 °C notched Charpy value remains close to the dry value because moisture content is low and the impact failure is dominated by the glass-fibre length distribution rather than matrix plasticisation. For finite-element calculations, the dry-as-moulded dataset should be used for low-humidity interior conditions and for short-term load cases, while conditioned data should govern exterior enclosures that experience condensation or prolonged humidity. A single design modulus should not be selected without defining the operating relative humidity profile, part wall thickness, and load duration.

Drying before injection moulding is performed in a closed-loop desiccant dryer at 80 °C for 4–8 h, with a supply-air dew point not warmer than −30 °C. The target residual moisture is below 0.10% when checked by Karl Fischer titration. In manufacturing areas above 60% relative humidity, granulate removed from sealed bags should be transferred directly to hopper receivers, and open-machine residence time should not exceed 30 min. Hopper temperatures above 100 °C can cause local surface melting or granule bridging, especially on low-draw pneumatic conveying lines. A 25 mm three-zone reciprocating screw with L/D 22:1 and a check-ring assembly is adequate, but the plastication profile should use a reverse-temperature or flat profile to limit shear heating. Melt temperature measured at the nozzle should be 220–250 °C, with 240 °C preferred; above 270 °C, PA12 undergoes measurable chain scission and may emit visible volatiles at the vent. Mould temperature should be 40–80 °C, with 60 °C preferred for adequate crystal growth and low part warpage. If the mould temperature falls below 40 °C, the surface freezes before glass fibres are fully wetted, producing visible fibre bundles and reducing notched impact at the gate region.

On production injection machines, the main batch-to-batch processing bottleneck is not melt pumping but fibre-length preservation and moisture control. The screw peripheral speed should be 0.2–0.5 m/s to limit glass-fibre attrition; back pressure should not exceed 50 bar. Holding pressure is typically 60–70% of peak injection pressure, and the holding-pressure transition should occur after 90–95% of the fill volume is reached to avoid jetting and glass orientation streaks. Mould shrinkage is 0.1% in the flow direction and 0.5% transverse per ISO 294-4; post-mould shrinkage after 24 h can shift machined dimensions if parts are measured before crystallisation is complete. Weld lines in 30% glass-fibre-reinforced PA12 retain only a fraction of the unidirectional strength because fibre orientation is transverse to flow at the meeting front. Gate placement should therefore keep weld lines away from snap-fit roots and clip deflection zones. Regrind above 20% from three-plate cold-runner systems may reduce fibre length distribution and notched Charpy impact; lot-to-lot variation is controlled by limiting regrind percentage and drying the regrind fraction separately before blending.

When a Chassis-Mounted Enclosure Replaces PA66-GF30 in Low-Voltage Architecture

The choice between Grilamid LV-3H and a PA66-GF30 grade depends on the relative weight assigned to moisture stability, low-temperature impact, and heat resistance. PA12/GF30 offers lower density and lower equilibrium moisture absorption than PA66/GF30, but the heat deflection temperature under 1.8 MPa is lower. Grilamid LV-3H is therefore not suitable for continuous load-bearing in high-temperature underhood positions above 140 °C, where PA66-GF30 retains greater stiffness retention. The comparison is reversed for exterior chassis-mounted enclosures, cable conduits, and pneumatic line clamps exposed to condensation, winter road de-icers, and cyclic humidity. In those conditions, the lower moisture uptake of PA12 reduces dimensional growth and property creep caused by water plasticisation.

The above table uses representative supplier-published values for dry-as-moulded 30% glass-fibre-reinforced polyamides; exact values differ by heat stabilisation and impact-modification package. Against PA6-GF30 and PA66-GF30, Grilamid LV-3H sacrifices dry stiffness and heat deflection temperature to obtain lower moisture absorption and better dimensional stability in humid service. Within the PA12-GF30 class, the LV-3H designation indicates an impact-modified and heat-stabilised grade; its dry notched Charpy at −30 °C is 10 kJ/m², which is higher than unmodified PA12-GF30 grades that can drop to 6–8 kJ/m² in the same test. Melt volume-flow rate at 275 °C/5 kg is 15 cm³/10 min per ISO 1133-1, a value that supports thin-wall fill in multi-cavity tools but is lower than high-flow PA6-GF30 grades used for large flat housings.

Operational boundaries are defined by chemical exposure and moisture state. The material is not suitable for continuous exposure to methanol, ethanol, or zinc-chloride-heavy road de-icing brines above 60 °C without pre-testing because PA12 can undergo environmental stress cracking; bent-strip testing per ISO 22088-3 is required for each fluid formulation. Hydrolysis risk increases when residual moisture exceeds 0.15% at the melt stage. Avoid barrel residence times beyond 10 min at 240 °C melt temperature; longer residence accelerates molecular-weight reduction and increases splay at the gate land. The standard natural and black colours are suitable for technical applications but are not specified for food-contact service under FDA 21 CFR unless a dedicated compliance package is validated. RoHS compliance and REACH registration apply to the standard product forms, but downstream converters must confirm the compliance status of bonded seals, lubricants, and colour concentrates added during processing.