Three cobots, three cleanroom ratings — and two of them come with an asterisk

Reading three collaborative arms' data sheets side by side turns up the same sentence written three different ways, and the differences decide whether the number on the brochure survives contact with a real production line. ABB launched its PoWa cobot family from Zurich on 22 April 2026, and the flagship PoWa 13 is the fastest thing in the class: 5.8 m/s at the tool with the full rated payload on the flange, 8.3 m/s with a kilogram, and pose repeatability of 0.03 mm while doing it. The company also certifies the arm for ISO 14644-1 Class 4 cleanrooms. The condition sits one line further down the data sheet: Class 4 applies at 50 percent of rated speed. At full speed the arm is Class 5. The same construction appears at Universal Robots. The UR15, shown at Automate in Detroit in May 2025 and the fastest arm the Danish company has built at 5 m/s, is likewise rated for Class 4 — with a footnote tying the rating to velocity and payload held at or below 80 percent. This catalogue noted that clause when the UR15 profile went up. ABB's derating is the steeper of the two, which is the arithmetic consequence of the faster arm: more speed means more particles shed, so more speed has to be given back. KUKA answers the question differently. Rather than derate the standard machine, the German company builds separate cleanroom variants: the LBR iisy catalogue lists an 11 R1300 CR and a 15 R930 CR next to the standard models, and rates the cleanroom build up to ISO Class 3 — a cleaner class than either rival claims — with no published speed condition attached. That is the more expensive answer for the buyer, because it means purchasing a different robot rather than turning down the one already installed, and it is the one that holds up when the line runs at rate. The practical reading is simple. A cleanroom class printed on a cobot brochure is not a property of the robot; it is a property of the robot at a stated speed. Two of these three tell you that in a footnote, and the third tells you by selling you a second part number. All three arms are now in this catalogue: ABB PoWa 13, KUKA LBR iisy 15 R930 and Universal Robots UR15. Figures are taken from each manufacturer's own data sheet or product page — ABB's PoWa CRB 1910 sheet of 27 May 2026, Universal Robots' technical specification of April 2026, and KUKA's LBR iisy product pages.