Two FANUC cobots, one 1,418 mm arm: the stronger one is the only cobot in the range that never speeds up

FANUC sells two collaborative arms with exactly the same 1,418 mm reach, and the specification tables on its own product pages show the stronger one giving up something the rest of the range keeps: its high-speed mode. The CRX-10iA/L, launched in December 2019, carries 10 kg and weighs 39 kg. The CRX-20iA/L, announced on 1 March 2022 and shipping from that April, carries 20 kg and weighs 41 kg. Same reach, same six axes, same R-30iB Plus controller, same IP67 sealing, same mounting options. Twice the payload for two kilograms of extra arm, and the heavier model is the more accurate of the two at +/-0.04 mm against +/-0.05 mm. On every line a buyer normally reads, the 20 kg arm is simply the better machine. The exception is the speed row. Every other arm FANUC lists in the CRX family runs at 1,000 mm/s in collaborative mode and doubles to 2,000 mm/s in high-speed mode, the setting used when the cell is fenced and no operator is standing inside it. For the CRX-20iA/L, FANUC publishes 1,000 mm/s in both modes. The strongest mid-size cobot in the range is capped at human-safe speed permanently, so in a fenced cycle the older, weaker CRX-10iA/L will complete more moves per hour on any job it can physically lift. That matters because most cobots do not spend their lives working next to people. A great many end up behind a fence doing palletizing or machine tending, where the collaborative rating is an installation convenience rather than a daily operating mode. For those cells the missing high-speed mode is a throughput ceiling, and it is not visible in the payload, the reach or the price. The same tables settle a question this catalogue has now asked of four cobot makers in a row. Reach does not predict payload. Techman numbers its arms so that a TM5-700 lifts more than a TM5-900; Universal Robots gives its strongest and its mid-range arms an identical reach; KUKA and now FANUC repeat the pattern. In FANUC's case two arms of the same length differ by a factor of two in what they will carry. The number in the name and the number on the drawing are not the same kind of fact, and only one of them is in the datasheet. wujec.ai has added the CRX-10iA, CRX-10iA/L, CRX-20iA/L and CRX-30iA to the catalogue. All figures come from FANUC America's own product specification tables.