Lighting-fixture enclosures split into two process families: high-pressure die casting for aluminum LED housings and resin-bonded sand molding for iron pole bases, decorative brackets, and large reflector bodies, with selection driven by annual volume, surface class, and dimensional envelope rather than by part shape alone [S1][S2][S3][S5].
The die-casting route for lighting parts converges on a small alloy set (ADC12, ADC14, A360, A380, AlSi9Cu3), LKM C50 + P20 mold bases, and H13, 8407, 1.2344, or Dievar steel inserts hardened above HRC45, with T1 sample lead times of 3-10 weeks and production runs shipping in 2-5 weeks [S1][S2][S3].
Process Boundary: When Die Cast Wins, When Resin Sand Wins
Aluminum die casting is specified when wall thickness sits in the 2.5-4 mm band, annual volume per part exceeds roughly 5,000-10,000 pieces, and the housing must double as a heat sink for the LED engine, a configuration that drives the choice of ADC12 and A380 for their thermal conductivity and cast flow behavior [S2][S3]. Resin sand molding is specified when the lighting casting exceeds 500 mm in any dimension, when surface class is allowed to be Ra 12.5 or coarser, and when pattern variety per SKU is high with annual volumes per pattern in the 500-5,000-piece band [S5].
The boundary case is the high-bay and street-light housing, where one OEM may run a 1,200×1,000 mm flask on a resin sand line for pole-base and bracket castings while sourcing the same fixture's heatsink housing from a die-casting tool with an LKM C50 + P20 base, a useful reminder that the casting mold decision is per-SKU, not per-program.
Die-Cast Mold Stack-Up for Lighting Enclosures
Standard die-casting tooling for LED panel, downlight, track-light, and street-light enclosures pairs an LKM C50 + P20 mold base with cavity inserts in H13 (the most common choice, 50,000-120,000 shot life on Quanxing lighting tooling), Dievar for higher thermal-fatigue loading, or 8407 / 1.2344 for hot-work endurance at hardness above HRC45 [S1][S2][S3][S4]. The same H13 grade is documented in GB/T 1299-2000 chemistry (0.32-0.45% C, 4.75-5.50% Cr, 1.10-1.75% Mo) and a working hardness of 205-245 HB on one verified lighting-housing tool [S4].
Alloy choice tracks the cast section and the corrosion environment: ADC12 and A380 dominate indoor and commercial-grade housings for their die-cast flow and surface finish, while AlSi9Cu3 (the European near-equivalent) is preferred for outdoor IP-rated luminaires where anodizing and powder-coat adhesion are specified [S2][S3]. A360 sits between them for thinner-wall heat-sink housings where the lower iron content of A360 improves ductility, a useful pointer when the same die cast mold will run a mixed-portfolio program.
Resin Sand Line Sizing for Lighting Hardware
Lighting foundries run resin-bonded furan or phenolic molds on flask sizes from 600×500 mm up to 1,200×1,000 mm with a 50-100 mm clearance per side for riser placement, and select automatic molding when annual volume per pattern exceeds roughly 3,000-5,000 moulds and pattern changes are infrequent (fewer than 2-3 per shift) [S5]. Automatic lines hit 30-60 s cycle times with 1-2 operators per shift, while manual benches run 120-240 s with 4-6 operators; pattern amortization favors aluminum patterns (30,000-80,000 RMB) over wooden (8,000-20,000 RMB) once a single pattern holds for 12-18 months [S5].
Working mould hardness of 80-90 on a typified Chinese iron-foundry scale (versus 70-80 for green sand) reduces sand shift on the 3-6 mm walls typical of thin-wall lamp housings, and is the single mechanical reason the sand casting mold process keeps winning decorative and pole-base work over shell molding despite a coarser surface [S5].
Alloy Targets: Iron, Aluminum, Ductile
Gray iron HT200 (ASTM A48 Class 30A, tensile 200 MPa) and HT250 (Class 35A, 250 MPa) cover the majority of decorative and pole-base lighting castings because they machine cleanly, damp pole-top vibration, and accept paint or powder-coat finishes without surface rework [S5]. A356-T6 aluminum (tensile roughly 240-275 MPa, elongation 6-10%) is specified for weight-sensitive high-mast and solar-integrated luminaires, with section thickness held above 4 mm to avoid misrun and cold-shuts on heat-sink fins [S5].
Ductile iron QT450-10 and QT500-7 (EN-GJS-450-10, EN-GJS-500-7) are reserved for load-bearing spigots and adjustable knuckle joints where elongation above 10% and impact resistance are required, a material change that does not alter the line selection but tightens melt-handling discipline around the magnesium treatment and inoculation step [S5].
Mold Standard, Surface Finish, and Tolerance Stack-Up
Die-casting lighting tooling on the three Moldie product sheets is built to HASCO, DME, and MISUMI standards, with PUNCH listed as an additional standard on the lamp-enclosure SKU, a useful compatibility shorthand for buyers porting tooling between China and EU mold shops [S1][S2][S3]. Surface finish is selectable from sandblasting, powder coating, painting, and anodizing on the same tool without re-cut, which lets one mold base serve indoor, outdoor, and architectural-finish SKUs [S1][S2][S3].
Resin-sand lighting castings hold ±1.0 mm across a 300-500 mm envelope at Ra 12.5 or better, which is the working tolerance cited on pole-base and luminaire-housing work; the die-cast route tightens that band to roughly ±0.1-0.3 mm on critical LED-jig dimensions because the steel mold reproduces the cavity repeatedly with the same thermal cycle [S1][S5].
Decision Matrix: Process by Lighting-Fixture Family
For LED panel, downlight, track-light, and bulb housings with thin walls (2.5-4 mm), high annual volume (above 5,000 parts), and tight tolerances, die cast in ADC12 or A380 on an LKM + H13 tool is the default [S1][S2][S3]. For street-light, tunnel-light, high-bay, and flood-light pole bases and brackets, where envelope exceeds 500 mm and surface is allowed to be Ra 12.5, resin sand in HT200 or HT250 is the default [S4][S5].
For weight-sensitive high-mast and solar street-light housings, A356-T6 on the same resin sand line (section > 4 mm) competes with die-cast A360 heat-sink bodies, and the deciding factor is usually annual volume versus weight budget [S2][S5]. For decorative cast-iron brackets, bollards, and heritage luminaire parts, gray iron on a manual or semi-automatic resin sand bench with a wooden pattern (8,000-20,000 RMB) is the economic choice at 500-1,000 pieces per SKU per year [S5].
Who This Process Fits, and Who It Does Not
Die-cast lighting tooling fits programs that can amortize a 50,000-120,000-shot tool over 12-24 months of continuous production, where the LED housing doubles as a heat sink and surface finish must be IP-rated outdoor [S1][S4]. It does not fit program profiles below roughly 3,000 parts per year, where the per-piece mold cost cannot be recovered, and it does not fit pole-base or large bracket castings that exceed the practical die-casting envelope of 600-800 mm in any dimension [S5].
Resin sand fits programs that need pole bases, large brackets, or decorative castings in the 500-1,000-piece-per-SKU band with surface class Ra 12.5 and tolerance ±1.0 mm, and it tolerates pattern changes at 2-3 per shift on a manual bench [S5]. It does not fit programs that need <3.2 Ra surfaces, which push the choice to shell mold tooling, and it does not fit programs that need 100,000+ parts per year on a single SKU, which justify the capex of an automatic line with 30-60 s cycle [S5].
Adjacent Process Considerations: Ladles, Aux, and Downstream Finishing
Lighting foundries running mixed iron and aluminum programs should size the casting ladle fleet to the higher-temperature alloy on the line; a 1,200°C iron pour needs ladle refractories rated for sustained gray-iron service, while a 720°C A356 pour can run on a lighter ladle lined for aluminum, and mixing the two on a single ladle is the most common source of iron-contamination defects in aluminum lighting castings [S5]. Pour-basin design, riser placement, and feeding distance for thin-wall LED housings are part of the casting aux check that should be scored on the same one-page checklist as flask size and cycle time, because the lighting fixtures stack the geometry risk (thin walls, large flat faces for heat-sink fins) onto the auxiliary equipment first [S5].
For buyers who also need downstream surface treatment, anodizing and powder-coat lines for die-cast aluminum lighting parts are commonly co-located with the casting cell, which shortens the per-piece logistics chain and keeps the mold base selection aligned with the finish specification rather than with a remote paint shop [S1][S2][S3].
Trackable signals to watch: H13 versus Dievar pricing for >HRC45 inserts in 2026 Q4, and any shift in the 3-10 week T1 lead-time band as Chinese mold shops report capacity utilization into the autumn peak.