HFFR Compound Production

High Filler Loading. Precise Feeding. Reliable Compound Quality

HFFR cable compounds combine polymers such as EVA, PE or other suitable base resins with high levels of flame-retardant mineral fillers, primarily ATH and MDH, together with processing aids and functional additives. At these filler levels, the performance of the compounding line depends heavily on how accurately each ingredient is stored, transferred and continuously fed into the process. VOLDE develops complete raw material handling and feeding systems around the HFFR compounding line — from bulk filler storage and pneumatic transfer to Loss-in-Weight dosing, main and side feeding, automatic refill and compounder synchronization. Each system is engineered around the formulation, filler characteristics, extruder capacity and feeding architecture of the line

| Managing High-Load ATH & MDH

ATH and MDH are among the most demanding materials in HFFR production because large quantities of fine mineral powder must be delivered continuously and reliably to the compounding process. Bulk density, particle size, surface treatment and flow behavior directly influence silo discharge, conveying and feeder performance.

Rather than treating these fillers as conventional free-flowing powders, VOLDE designs the complete material path around their actual handling behavior. Storage silos, big bag discharge stations, intermediate bins and feeder hoppers can be equipped with suitable discharge aids and feeding geometries to reduce bridging, compaction and irregular flow.

For larger plants, ATH or MDH can be transferred from central storage to the dosing area through dedicated pneumatic conveying systems. Day bins and automatic refill systems maintain sufficient material availability above the gravimetric feeders.

Typical infrastructure may include central ATH/MDH silos, big bag discharge, vacuum or pressure conveying, intermediate bins, flow-assist equipment and local dust extraction.

| Gravimetric Feeding for Stable Formulation Ratios

HFFR compounding is typically a continuous process, making Loss-in-Weight feeding central to formulation accuracy. Polymer, mineral filler and additives are metered separately so that each component can follow its own mass-flow setpoint while maintaining the required formulation ratio.

The feeder continuously measures the reduction in hopper weight and adjusts the feeding rate accordingly. Feeder type, screw configuration and agitation are selected according to the ingredient — from polymer pellets to fine, cohesive mineral powders.

• Loss-in-Weight feeding for polymer, ATH/MDH and additives
• Single- or twin-screw configurations according to material behavior
• Continuous mass-flow measurement and correction
• Recipe-based ratio control between ingredients
• Target / actual feed-rate monitoring
• Automatic refill coordinated with feeder operation

This architecture allows the formulation to remain stable even when total compounding throughput changes.

| Main Feed, Side Feed & Compounder Integration

Not every HFFR ingredient needs to enter the extruder at the same location. Depending on formulation and compounding technology, polymer and part of the filler may enter through the main feed, while additional ATH/MDH or other components can be introduced further downstream through side feeders.

This approach is especially relevant in highly filled HFFR formulations, where dividing the mineral load between different feeding points can provide more suitable processing conditions. VOLDE designs the intermediate bins, Loss-in-Weight feeders and refill systems around the actual main-feed and side-feed locations of the compounder.

Feeder demand, refill timing and compounder throughput can be coordinated so that the material supply follows the extrusion process rather than operating as an independent upstream system.

| Automatic Refill & Continuous Material Supply

Continuous gravimetric feeding also depends on how the feeder is replenished. When a Loss-in-Weight hopper requires refill, the sequence must be completed quickly and consistently so that the feeder can return to gravimetric operation with minimal disturbance.

VOLDE integrates vacuum receivers, intermediate bins, refill valves and level monitoring directly with the feeding system. Refill timing is managed according to hopper weight, material demand and line status, ensuring that polymer, ATH/MDH and additives remain available throughout production.

This is particularly important on HFFR lines where several feeders operate simultaneously and formulation stability depends on each ingredient being available at the correct rate.

Where required, dust collection, grounding and suitable Ex/ATEX measures can be incorporated according to the actual materials present and the project-specific dust hazard assessment.

VOLDE combines filler handling, continuous gravimetric feeding, compounder integration and automatic refill into one process infrastructure developed specifically for highly filled HFFR cable compounds.