Brass and zinc-aluminum alloy housings for road, landscape, and high-bay LED fixtures are typically poured from 500–2000 kg batches, and the dominant equipment for that throughput is a medium-frequency induction melting furnace coupled with a holding furnace for pour-line stability [S5].
Luminaire bodies must reproduce thin-wall geometry, tight tolerances, and consistent surface finish, so the furnace upstream of the die must deliver stable bath temperature, low slag carry-over, and reproducible melt chemistry across long campaigns running the same LEDSFOCUS-style or LEDSROAD-style housing families [S1].
Alloy families and their pour-temperature windows
Architectural and outdoor LED housings are predominantly cast in silicon brass (C87800, C87500) at 950–1050 °C pour window, while heat-sink bodies and reflectors run as A380 or A383 aluminum at 660–720 °C; a furnace that swings 300 °C between charges (e.g. dual-frequency or paired crucible furnace + holding furnace layouts) is the practical answer for shops running both alloy streams [S5].
Outdoor special-purpose lines such as LEDSHIGHMAST 460 W floodlights expose castings to harbor salt spray, so silicon brass with 14–16% Si is the default body alloy and demands a furnace capable of 1100 °C superheat without excessive silicon burn-out, a task that lines up with the SCR parallel intermediate-frequency topology used by Chinese suppliers Henghe Electric Technology and the furnacescn product family [S3][S5].
For a pure-jewelry or small-batch decorative trim path, 1–2 kg tabletop melting furnace units with ceramic chambers (e.g. Regal Ltd's casting-supply line) are appropriate, but they are 2–3 orders of magnitude below the throughput of any luminaire production line [S2].
Selection criteria: capacity, control, atmosphere, footprint
Pour rate sets furnace size: a 500 kg crucible delivering 8 pours/h needs a 400 kW medium-frequency supply, whereas a 2000 kg crucible at the same pour rate calls for 1200–1500 kW, with melt time per cycle typically 45–60 min for brass and 35–50 min for aluminum [S5].
Temperature control must hold bath within ±5 °C of the setpoint to keep the silicon-brass fluidity constant; PID plus SCR cascade control is the dominant Chinese OEM architecture, with furnace temperature usually measured by type-S thermocouple protected by an alumina sheath [S3].
Foundry footprint and indoor siting: gas aluminum melting furnace units with regenerator burners run at 35–45% thermal efficiency versus 60–70% for medium-frequency induction, but they are preferred where electricity cost exceeds 0.10 USD/kWh or where grid capacity is constrained; induction is preferred where silencer-grade silence and indoor air quality matter [S3][S5].
Comparing the main furnace types for lighting castings
Across four decision criteria, the comparison reads as follows. Capacity: medium-frequency induction handles 500–2000 kg per crucible; gas crucible furnaces typically 250–1000 kg; resistance crucible furnace units 50–300 kg; small tabletop units 1–5 kg [S2][S5].
Temperature control accuracy: induction with PID achieves ±5 °C; gas furnace with flue-gas trim achieves ±10–15 °C; resistance crucible ±8 °C; tabletop ±20 °C [S3][S5].
Energy efficiency: induction 60–70% electrical-to-thermal; regenerative gas 35–45%; resistance 40–50%; tabletop resistance 25–35% [S3][S5].
Best-fit alloy and product mix: induction suits brass and aluminum for road/high-bay floodlights; gas aluminum units suit dedicated A380 heat-sink lines; resistance suits zinc-aluminum decorative trim; tabletop units suit jewelry-scale decorative inserts only [S1][S2][S3][S5].
This criteria matrix is the practical decision tree a foundry engineer walks: pour weight, alloy, setpoint stability, and energy price each knock out one or two options before the shortlist collapses to one or two configurations.
Use cases matched to fixture families
Road and street LEDSROAD-class housings in C87500 brass, running 1000+ units/day, are best served by a 1000 kg medium-frequency induction furnace feeding two 500 kg holding furnace units on a continuous pour loop, with a tilt-pour ladle interface to the die-casting machine [S3][S5].
Landscape LEDSFOCUS and LEDSFOCUS GOLD line bodies, where surface finish drives the brand spec, are best served by resistance crucible furnace plus sealed holding, because the lower melt turbulence preserves dross-free skim before the shot sleeve, a metallurgical concern that mirrors the lighting equipment and electric lamps chain's demand for consistent photometrics downstream [S1].
High-bay LEDSHIGHBAY and outdoor LEDSHIGHMAST 340 W / 460 W floodlight bodies, often cast in A380 aluminum for thermal mass, are typically poured from regenerative gas aluminum melting furnace units where the foundry co-fires a holding loop for both body and reflector pours [S1][S3][S5].
Failure modes and constraints specific to lighting castings
Silicon brass is unforgiving on superheat: above 1080 °C the silicon phase coarsens and fluidity drops sharply, so a furnace that overshoots the setpoint on a SCR ramp-up can scrap a full crucible before the operator notices; that constraint alone rules out gas-fired units without closed-loop flue-gas trim for high-end LED body lines [S3].
Aluminum heat-sink castings demand iron contamination below 0.4–0.6% to preserve thermal conductivity, and a melting furnace changeover from iron-rich brass to aluminum must include a full crucible swap or reline to avoid iron pickup above 0.8%, which derates the heat sink by 10–15% [S5].
Sourcing, standards, and supplier signals
Chinese OEM Henghe Electric Technology lists precious-metal refining furnaces and electric melting furnace lines, with R&D and metallurgical chemistry support from a doctoral team at Anhui University of Technology, a useful technical-backstop signal for foundries specifying unusual brass or copper alloys [S3].
Suppliers such as the furnacescn portfolio publish medium-frequency SCR parallel induction models with steel-shell and aluminum-shell options, the latter favored for cost-sensitive aluminum-only lines where refractory life is the limiting maintenance factor at roughly 800–1200 heats per lining [S5].
Production-capacity signals in 2026: Henghe reports effective process schemes tailored per precious-metal enterprise, while furnacescn markets a "new energy-saving series" intermediate-frequency line, both of which indicate the Chinese supply chain is still pushing efficiency and control refinements rather than a new furnace topology [S3][S5].
For an adjacent decision on metals selection that often runs in parallel with furnace choice, see the nickel-alloy selection map for electronics and the titanium-alloy grade map; for a peer foundry application, the agricultural-machinery furnace selection brief covers similar capacity-versus-alloy trade-offs in a heavier-tonnage context.