Polyurethane bonded to an aluminum hub is the corrosion-proof alternative to polyurethane on cast iron. Same non-marking tread, same capacity range at the same wheel diameter, but the aluminum hub won’t rust under washdown — the spec for food processing, beverage production, pharmaceutical clean rooms, marine applications, and any wet or chemical environment where a cast-iron hub would corrode and fail. 29 styles in stock from 4″ through 8″ wheels, 1,000-4,800 lb capacity per caster.
The decision tree is simple: does the caster ever see water, sanitizer, cleaning chemicals, salt, or persistent humidity? If yes, the cast iron hub will rust within 12-36 months and the caster fails. Poly-on-aluminum solves that. The most common applications are dairy and beverage production (daily caustic washdown), pharmaceutical manufacturing (regular sanitizer cycles), seafood and meat processing (continuous moisture + salt), marine equipment (salt air), and commercial laundry (steam + detergent). For purely dry indoor industrial use, poly-on-iron is the cost-effective spec and the aluminum hub doesn’t buy you anything beyond weight reduction.
| Wheel Size | Standard Capacity | Heavy-Duty Variant | Common Use |
|---|---|---|---|
| 4″ x 2″ | 1,000 lb | Sirius HD 4,000 lb | Food prep tables, washdown carts |
| 5″ x 2″ | 1,200 lb | Sirius HD 4,800 lb | Pharma transport, dairy production carts |
| 6″ x 2″ | 1,250 lb | Available on request | Beverage production, heavy washdown carts |
| 8″ x 2″ | 1,250 lb | Available on request | Floor seam crossing, larger washdown facility carts |
Typically 20-30% premium. A 5″ x 2″ polyurethane on cast iron caster runs $35-55 depending on brand and configuration; the same wheel on aluminum runs $45-75. The cost differential narrows at heavier capacity tiers because the iron core itself becomes more expensive at 6″ and 8″ sizes.
Aluminum forms a thin oxide layer (aluminum oxide) on its surface that protects it from further corrosion in salt air and most marine environments. Standard aluminum holds up indefinitely in coastal humidity and washdown. For continuous submersion or saltwater spray, anodized aluminum or stainless steel is the higher-grade spec — available on request.
Sirius HD is CasterHQ’s heavy-duty polyurethane-on-aluminum series — reaches 4,800 lb capacity per caster on the 5″ x 2″ wheel and 4,000 lb on the 4″ x 2″ total lock variant. Used where the corrosion-resistance requirement of aluminum combines with a heavy capacity requirement that standard poly-on-aluminum can’t hit. The orange tread color (visual marker for HD spec) is the standard finish.
The polyurethane tread itself is NSF-listed food-grade material. The aluminum hub doesn’t make contact with food. For full NSF certification documentation on a specific product, email info@casterhq.com with the part number — we’ll send the manufacturer cert. For applications requiring full stainless-steel construction (not aluminum), see our Stainless Casters S304 Grade collection.
Solid polyurethane (no metal hub at all) eliminates the bonding-adhesive failure mode entirely — the whole wheel is one piece of polyurethane. Trade-off is capacity: solid poly maxes around 1,000 lb per caster vs. 4,800 lb for Sirius HD poly-on-aluminum. For chemical-aggressive environments where the bonding adhesive is at risk, solid poly is the safer pick. For most washdown applications, poly-on-aluminum holds up fine.
Stock poly-on-aluminum casters ship same day from Mansfield, TX before 3 pm Central. The heavier 8″ and Sirius HD variants typically ship UPS Ground or LTL freight depending on quantity. For washdown application sizing questions, call 844-439-4335 or email info@casterhq.com.
