Light-Duty Casters at 30–100 kg: What They Cover, and When to Step Up to Medium Duty

The light/medium boundary is a catalogue label, not a technical limit

Two suppliers place the light/medium split at 350 lb (≈159 kg) per caster, while a third places it at 70/71 kg 2 , 4 , 24 . The 30–100 kg band therefore sits on both sides of the line depending on whose catalogue you read.

A 100 kg per-caster application is 'medium duty' under the 70/71 kg segmentation and comfortably 'light duty' under the 350 lb segmentation 2 , 24 . Because these are catalogue segmentations rather than technical limits, no source establishes that a 100 kg caster must be medium duty 2 , 4 , 24 .

The practical consequence is that the buyer should size on the actual load and duty, and confirm the supplier's own class definition, rather than rely on the label 'light duty'.

What safety factor to apply — and why the sources disagree

One industry source treats a 2x safety factor as a marketing minimum that fails within 6–12 months under real duty cycles, and 4x as the industrial standard for 3–5 year service life 1 . Other sources give much lower guidance: ≥1.5 recommended, 1.25–1.5 common, or a 30% margin 9 , 15 , 17 .

The disagreement is material, and no source establishes a mandatory safety factor for 30–100 kg light-duty casters 1 , 9 , 15 , 17 . Load capacity is also not a single number: static, dynamic, side and impact load are distinct, and static capacity is calculated as (equipment + payload)/(N−1) 19 .

The buyer should require the supplier to state whether the published rating is static or dynamic and what safety factor it embeds, rather than assume a figure.

Plain-bore bearings rule out frequent starts, long travel and shock

Plain bore bearings are positioned for light-duty, low-speed, intermittent equipment; annular ball for general industrial frequent starts/stops; roller for heavy/shock; precision sealed for long runs and powered equipment 3 , 11 .

Bearing mis-specification is reported as more common than wheel mis-specification, with a 1,000 lb die cart on plain bearings wearing out its axle in under 90 days 3 .

Neither source gives a bearing recommendation specific to the 30–100 kg per-caster band, nor a duty-cycle threshold at which plain bearings must be replaced by ball or roller bearings 3 , 11 . For any application with frequent starts/stops, long travel or shock, the buyer should rule out plain-bore bearings and specify ball, roller or precision-sealed bearings instead.

Wheel material is bounded by temperature and chemistry

Wheel material choice is bounded by temperature and chemistry, and the ranges differ by material 13 . Polyurethane is stated to handle 800–2,000+ lb per caster and last 3–5x longer in industrial environments, while rubber tops out around 500 lb and is 5–8 dB quieter on tile 5 .

That is a genuine trade-off: PU carries more load and lasts longer, rubber is quieter and gentler on delicate floors 5 , 13 . The buyer should choose a material that survives the actual temperature and chemistry of the application, and accept the load, life and noise trade-off that comes with it.

Duty cycle forces a derate or an upgrade

Capacity ratings are stated for intermittent service only; for 24/7 use the guidance is to derate by 25–33%, and bearings should be re-greased every 3–6 months normally and monthly under heavy duty cycles 23 . Light commercial casters can last three to five years, while high-cycle industrial environments commonly see annual replacement of standard-grade wheels 34 .

Across sources, duty cycle rather than nominal load class is the recurring driver: continuous or multi-shift use shortens life, requires derating, and shifts the cost balance from purchase price to labour and downtime 7 , 23 , 34 . No source quantifies the duty-cycle threshold at which a 30–100 kg application should move from light duty to medium duty 7 , 23 , 34 .

The buyer should check continuous or multi-shift use against the intermittent-service basis of the published rating.

Whether purchase price or labour and downtime will dominate the total cost

On light-duty, low-failure fleets purchase price dominates TCO; on multi-shift, heavy or high-failure fleets labour and downtime dominate 7 . The higher safety factor carries a 20–30% upfront cost delta that the source says pays back 3–5x in avoided replacement labour 1 .

The buyer should decide which bucket will dominate their fleet before choosing between a cheaper light-duty caster and a longer-life upgrade.

What to confirm on the quote before treating two quotes as comparable

Quotations are only comparable when load, wheel diameter, brake mode, mounting dimensions, tread requirement, quantity and documentation request are normalized; sample cost, tooling/customization charges, packaging, test reports and lead time should be clarified 26 , 33 . No source states which standard or certification applies to light-duty 30–100 kg casters, or what load testing they require 6 , 8 , 14 , 30 , 31 .

• ✓Normalize load, wheel diameter, brake mode, mounting dimensions, tread requirement, quantity and documentation request across all quotes.
• ✓Ask about sample cost, tooling or customization charges, packaging, test reports and lead time.
• ✓Confirm the order quantity used for the quoted unit price.
• ✓Ask which standard or certification the supplier applies to this band, and what load testing it requires.

The two figures the sources state differently

These are the two places where the sources give different figures for the same thing, and the buyer cannot treat either as settled from these sources alone 1 , 2 , 4 , 9 , 15 , 17 , 24 .

What the sources do not establish

• No source states a published dynamic vs static load rating, or the manufacturer's own safety factor, for a specific 30–100 kg light-duty caster.
• No source gives wheel hardness or rolling-resistance figures specifically for 30–100 kg light-duty wheels.
• No source describes swivel raceway or kingpin design for light-duty swivel rigs in this band.
• No source maps a specific top-plate size or bolt-hole pattern to the 30–100 kg band.
• No source gives a light-duty-specific temperature or chemical rating.
• No source states which standard or certification applies to light-duty 30–100 kg casters, or what load testing they require.
• No source gives unit price, volume discount thresholds, tooling cost or replacement frequency for 30–100 kg casters.
• No source gives a standard lead time or MOQ for light-duty 30–100 kg casters.
• No source quantifies the duty-cycle threshold at which a 30–100 kg application should move from light duty to medium duty.