EMS-Grivory Grilamid LKN-3H is a 30 % glass-bead-filled polyamide 12 injection-molding compound supplied in a dry state. The dry designation refers to residual moisture below 0.10 % by weight, not to a permanently immobilized condition; once the packaging is opened, ambient moisture ingress progressively shifts the resin toward a conditioned state. The grade is classified as PA12-GB30 under ISO 1043-1 and is intended for rigid molded components that require lower warpage than short-glass-fiber PA12 grades and lower moisture uptake than PA6 or PA66. The spherical filler geometry changes the deformation behavior relative to unfilled PA12 by raising stiffness while reducing large-strain elongation. Because the polymer base is polyamide 12, the material inherits a relatively low equilibrium water content and good resistance to aliphatic fuels, oils, and many automotive greases. The product is not positioned for structural replacements of glass-fiber compounds where ultimate tensile strength is the controlling requirement.

What Property Shifts Result from 30% Glass Bead Loading?

The following representative values are consolidated from public supplier literature for dry-molded specimens. Lot-specific certificates may vary with color, regenerated material content, and post-mold conditioning; the current EMS-Grivory technical datasheet remains the controlling specification.

At 30 % filler loading, tensile modulus rises substantially above unfilled PA12, but notched Charpy strength remains below the values obtainable with short-glass-fiber reinforcement because spherical particles do not bridge crack fronts effectively. Stress at yield is limited by matrix adhesion at the bead interface; therefore, parts under constant tensile load require creep data from ISO 899-1 rather than short-term tensile strength. The heat deflection temperature under 1.8 MPa is a deflection parameter and must not be interpreted as a continuous-use temperature for loaded parts. Melting point remains that of PA12 because the filler does not alter the crystal lattice. The melt volume-flow rate at 275 °C/5 kg is sufficient for thin-wall sections, but the viscosity increase from bead packing requires larger gates and higher packing pressures than unfilled PA12. Weld-line strength is generally lower than in unfilled PA12 because the filler interrupts molecular diffusion across the melt-front boundary; mold designers should locate gates so that weld lines are placed in low-tensile-stress zones.

In geometrically complex connectors, the low aspect ratio of the filler limits melt-phase orientation, but it also increases low-shear viscosity and can promote bead settling in hot-runner manifolds operating with long residence. On hydraulic injection-molding machines with 25 mm screw diameters and closed-loop melt-pressure control, cushion position should remain below 2 mm shot-to-shot to avoid insufficient packing and localized sink marks near inserts. Back pressure in the range of 0.5–1.0 MPa is used during plastication to homogenize bead distribution without excessive shear heating; higher back pressure increases cylindrically generated melt temperature and can push barrel zones above 260 °C. Screw recovery speed should be set so that the material is not starved in the feed section, because starved feed can produce bead-rich and matrix-rich regions that alter local shrinkage. Regrind addition up to 20 % is common on production lines, but regrind generated from hot-runner drops with long thermal history may reduce impact strength; therefore, regrind ratio must be validated by ISO 179/1eA measurements at 23 °C. Gate blush and silver streaking observed after 2 h of open-air storage above 60 % RH indicate that the material has exceeded the safe moisture threshold and must be re-dried before reuse.

When Low-Warpage Geometry Stability Is Specified Over Maximum Tensile Strength

Glass-bead-filled PA12 is selected when tolerance across a long flow path must be maintained after ejection and during subsequent humidity exposure. In short-glass-fiber PA12, fiber alignment in the flow direction can create a shrinkage differential of several tenths of a percent; the spherical filler in Grilamid LKN-3H reduces this differential by avoiding high-aspect-ratio orientation. Components such as rigid sensor housings, terminal blocks, and electrical connector shells are therefore processed with lower post-mold distortion. The mold shrinkage values obtained from ISO 294-4 plaques must be adjusted for cavity thickness; sections below 1.5 mm freeze before full packing and exhibit higher shrinkage than thick sections. For a nominal 50 mm dimension specified at ±0.05 mm, cavity-to-cavity pressure balance in a multi-cavity tool becomes the dominant source of variation; runner sizing and gating symmetrical to the fill flow reduce this error more effectively than raising hold pressure. The material should not be used for living hinges because the strain required for hinge flexing exceeds the reduced elongation at break. Snap-fit designs using this grade must incorporate rounder corner radii than unfilled PA12 because stress concentration at sharp inner corners accentuates notch sensitivity.

Because the filler does not act as a nucleating agent in the same way as high-surface-area talc, PA12 crystallization is governed by mold temperature and cooling rate. At mold temperatures below 40 °C, rapid skin formation traps molecular orientation and can increase post-mold dimensional instability; at 80 °C, cycle time increases while crystallinity approaches equilibrium and improves dimensional stability. The glass beads do not significantly reduce the melting point, but they alter thermal conductivity by increasing heat transfer through the melt and therefore shorten cooling time compared with unfilled PA12. Differential scanning calorimetry under ISO 11357-3 should be used on molded parts to detect unmelched granules or inconsistent cooling across thick and thin sections. This grade is not suitable for annealing above 160 °C because the close approach to the melt point can distort thin walls and cause bead-rich zones to settle.

Moisture Uptake, Drying Parameters, and Melt Residence Limits

For dry-molding logistics, the glass-bead phase suppresses equilibrium moisture gain relative to unfilled PA12, and polyamide 12 itself absorbs less water than PA6 and PA66. At 23 °C/50 % RH, the measured water absorption of the glass-bead compound is generally below 0.3 %; water saturation is higher but the filler phase suppresses equilibrium mass gain relative to unfilled PA12. Processors must dry the material in a desiccant dryer with dew point −40 °C or lower. For material that has remained sealed, drying at 80 °C for 4–12 h is specified. If ambient relative humidity exceeds 60 %, open hopper residence must be limited to 2 h unless the hopper is blanketed with dry air. Melting wet material above 0.10 % moisture initiates hydrolytic chain scission, producing splay, gate-area delamination, and measurable loss in notched Charpy strength. Melt temperature is maintained at 220–260 °C and mold temperature at 40–80 °C. The lower mold-temperature boundary is controlled by skin solidification and gate blush; the upper boundary is often limited by increased cycle time rather than thermal degradation. Barrel residence time should not exceed 8 min at 260 °C. Because glass beads raise melt viscosity, screw recovery settings must avoid excessive shear heating; barrel set points may underreport actual melt temperature when high back pressure and low screw speed combine. Production startup after color change should include a purge sequence and melt-temperature verification with an insertion probe to prevent residual degraded polymer from contaminating the first shots.

Fluid-contact performance is governed mainly by the PA12 matrix. The compound resists aliphatic hydrocarbons, diesel and gasoline blends with moderate alcohol content, lubrication greases, and oil mists; however, resistance must be confirmed by immersion testing under ISO 175 for each fluid mixture. Swelling data from unfilled PA12 cannot be directly transferred because the rigid glass beads limit volumetric expansion but may increase internal stress at the matrix interface. Strong mineral acids, phenols, chlorinated solvents, and high-polarity solvents should be avoided. In under-hood locations, exposure to road de-icing brines containing zinc chloride can produce environmental stress cracking; molded-in stress in thick sections increases this risk and should be minimized through annealing. Continuous hot-water service above 80 °C is not recommended because combined hydrolytic and oxidative processes accelerate molecular-weight loss, and published data for this specific configuration is limited. Parts that contact potable water or food require separate migration testing under the applicable national regulation; the grade does not self-certify. Compliance statements for RoHS Directive 2011/65/EU and REACH SVHC should be requested from the supplier; they are not part of standard technical data packages.

Differentiation Against Unfilled PA12 and Glass Fiber Reinforced PA12

Relative to unfilled PA12, the 30 % glass-bead filler raises density, increases tensile modulus, reduces elongation at break, and lowers notched Charpy energy. It also reduces mold shrinkage and post-mold dimensional change after moisture uptake. Relative to a 30 % short-glass-fiber PA12, this grade has lower tensile strength and modulus because spherical beads transfer stress less efficiently than high-aspect-ratio fibers. The advantage appears in isotropy and surface quality. Short glass fibers align during filling and produce flow-direction-dependent shrinkage, whereas spherical beads remain nearly unoriented and produce a more uniform shrinkage field. The surface of bead-filled moldings does not expose raised glass-fiber ends, which improves seal contact in connector bodies and reduces wear on mating surfaces. Screw, barrel, and mold wear are generally lower with spherical glass beads than with milled glass fiber, although wear-rate comparisons depend on tool steel composition and filler surface chemistry. In applications where chemical resistance and low moisture absorption are secondary, PA66 glass-bead grades may offer higher temperature capability, but the PA12 matrix of Grilamid LKN-3H provides a different balance of hydrocarbon resistance and moisture stability.

In fuel vapor management, PA12 is selected for its combination of low permeation and resistance to sour gasoline. Glass bead addition may reduce aromatic permeation by replacing polymer volume, but permeation depends on wall thickness, filler-matrix adhesion, and weld-line integrity. Validation should follow SAE J1737 or the vehicle-specific hydrocarbon loss specification; published data for this specific configuration is limited.

Automotive quick connectors, vapor line clips, and pneumatic distribution blocks demand roundness and fit retention across seasonal humidity changes. Unfilled PA12 components can exhibit measurable dimensional shift after moisture conditioning; short-glass-fiber PA12 components can exhibit gate-to-weld anisotropic shrink that compromises bore roundness. The glass-bead-filled PA12 is therefore specified when bore diameters must remain within 0.05 mm after conditioning and when sealing faces cannot tolerate fiber protrusion. Molding trials on 80-tonne hydraulic presses with two-plate cold-runner tools indicate that polished sprue bushings and generous cold-slug wells reduce bead agglomerations and gate defects; hot-runner nozzle tips should be sized to avoid dead spots and bead settling during extended cycle interruptions. Load-bearing snap-fit geometries should be validated by insertion–extraction cycling under ISO 16750-5 for engine-compartment thermal shock. For parts machined after molding, carbide-tipped tools are preferred because glass beads increase tool wear compared with unfilled PA12.