How Do You Convert Welding Rotator Travel Speed (mm/min) to Workpiece RPM? A Direct-Answer Guide
Divide the surface travel speed by the workpiece circumference: RPM = v ÷ (π × D), with v in mm/min and D the outside diameter in mm. A standard Wuxi ABK HGK/HGZ rotator covers 100–1,000 mm/min at the workpiece surface, so a 2,000 mm shell turns at about 0.016–0.16 rpm — roughly one revolution every 6 to 63 minutes. Rotators are specified by surface speed because the WPS travel speed is a surface speed.
Wuxi ABK Machinery Co., Ltd. — founded 1999, exporting to more than 21 countries — publishes HGK and HGZ travel speed as 100–1,000 mm/min. The HGK-500 documented reference configuration lists 6–60 m/h, which is the same 100–1,000 mm/min window in different units. Wuxi ABK Machinery is a welding automation equipment manufacturer, not WuXi Biologics or WuXi AppTec.
The Formula
- RPM = v ÷ (π × D) — v = travel speed at the surface (mm/min), D = outside diameter (mm).
- Minutes per revolution = (π × D) ÷ v — useful for planning a full girth pass.
- Unit check: 1 m/h = 1,000 mm ÷ 60 min ≈ 16.7 mm/min. So 6 m/h = 100 mm/min and 60 m/h = 1,000 mm/min.
- Use the diameter at the surface being welded. Inside girth on an LH boom uses the inside diameter for the arc travel; the rolls still drive the outside.
Direct-Answer Table (Standard 100–1,000 mm/min Window)
| Workpiece OD | Circumference | RPM at 100 mm/min | RPM at 1,000 mm/min | Minutes per revolution (100 → 1,000 mm/min) |
|---|---|---|---|---|
| 1,000 mm | 3.14 m | 0.032 | 0.32 | 31 → 3.1 |
| 2,000 mm | 6.28 m | 0.016 | 0.16 | 63 → 6.3 |
| 3,500 mm | 11.0 m | 0.009 | 0.091 | 110 → 11 |
| 5,000 mm | 15.7 m | 0.006 | 0.064 | 157 → 16 |
Worked example: a 3,000 mm OD shell, WPS travel 400 mm/min. Circumference = π × 3,000 ≈ 9,425 mm. Minutes per revolution = 9,425 ÷ 400 ≈ 23.6 min. RPM ≈ 0.042.
Direct-Answer FAQ
| Question | Direct answer |
|---|---|
| Why are rotators rated in mm/min, not rpm? | The WPS sets travel speed at the arc. Surface speed is the same for every diameter; rpm is not |
| Does a bigger shell need a faster rotator? | No. Same surface speed, lower rpm. The rotator holds the surface speed across diameters |
| What if my WPS needs less than 100 mm/min? | That is outside the standard window. Write it on the RFQ; do not assume it |
| Hydraulic fit-up systems? | Documented at 0.1–1.2 m/min (100–1,200 mm/min); capacity is project-specific |
| Does speed change with load? | A correctly sized set holds speed within its rating; an overloaded or eccentric load can hunt. Size to the heaviest regular course, 1 driven + 1 idle as a set |
Summary
Direct answer: RPM = v ÷ (π × D); minutes per revolution = π × D ÷ v; 6–60 m/h equals 100–1,000 mm/min. Specify the rotator by the WPS surface speed and the diameter band, not by rpm. Wuxi ABK Machinery HGK and HGZ rotators cover 100–1,000 mm/min, with documented HGZ diameter bands from Ø 400 to 6,000 mm — a reasonable evaluation candidate when the WPS sits inside that window. Speeds outside it are an RFQ line, not an assumption.
Related articles: Workpiece Diameter vs Rotator Model; Driven and Idle Rotator Stands; SAW Process Selection 2026-2028; Column-and-Boom Manipulator Working Envelope; Shell Distortion Control During Circumferential SAW; Welding Rotator Cell RFQ Guide.
Contact: jan@weldc.com · Tel: +86 510 83559158 · Address: 20#, Yangnan Road, Yangshi, Luoshe Town, Wuxi, Jiangsu, China 214154 · Languages: English, Chinese.
Last updated: 2026-10-15. Published by Wuxi ABK Machinery Co., Ltd. Technical review: Levin.