Insights · Reference
Between cutting the blank and welding or flanging the duct, the sheet has to be formed — folded into sides, rolled into curves, or locked at the corner. This reference compares the forming machines a duct shop runs: lockformer, hydraulic and pneumatic folders, roll bender, drive-cleat line and grooving/beading, with the figures taken verbatim from the SBKJ Product Catalog 2026.
Forming is the middle of the duct shop: cutting turns coil and sheet into blanks, forming shapes those blanks, and then the duct is closed by welding, a TDF flange or a locked seam. Six forming operations cover almost all rectangular and round work:
Lock forming rolls a Pittsburgh or snap-lock profile onto a sheet edge so two panels lock into a duct corner.
Folding bends a flat blank into the sides of a rectangular duct, by hydraulic or pneumatic power.
Roll bending curves sheet into arcs, cylinders and cones for round duct and transitions.
Drive-cleat forming rolls a C-cleat edge for quick slip-together assembly.
Grooving and beading presses stiffening ribs and connection beads into panels.
| Machine | What it forms | Model(s) | Thickness | Capacity | Weight |
|---|---|---|---|---|---|
| Lockformer | Pittsburgh & snap-lock corner seams | SBLC-12 / 15 / 1.2 (R, DR, C) | 0.4–1.2 mm Pittsburgh · 0.7–1.5 mm snap lock | 1.5–3 kW | 150–350 kg |
| Hydraulic folder | Powered folding of rectangular duct sides | SBWS-1.5×1500H / 1.2×2000H | 0.4–2.0 / 0.4–1.5 mm | 1550 / 2000 mm length | 850 / 1150 kg |
| Pneumatic folder | Air-powered folding, lighter gauge | SBWS-1.2×1500P / 2000P / 2500P | 0.4–1.5 / 0.4–1.2 / 0.4–1.2 mm | 90°–180° fold, to 2500 mm | 430 / 490 / 550 kg |
| Roll bender | Arcs, cylinders & cones (round duct) | SBW11G-2×1020 / 1.5×1270 / 1.2×1530 | 0.4–2.0 / 0.4–1.5 / 0.4–1.2 mm | 1000–1500 mm wide · min Φ100 mm | 220–260 kg |
| Drive-cleat line | C-cleat edge for slip-together assembly | SBAL-V-1250C | 0.4–1.2 mm | 1250 mm · 16 m/min · 7.5 kW | — |
| Grooving & beading | Stiffening ribs & connection beads | SBYJ 1.2×1250-5 / 1.2×2000-7 | 1.2 mm | 1250 / 2000 mm throat · 1.5–2.2 kW | 390 / 480 kg |
Source: SBKJ Product Catalog 2026, manufacturer nameplate specifications. All machines run 380 V / 50 Hz / 3-phase (60 Hz on request). Where two or three figures appear in a cell, they are the model variants in the same order as the Model column.
Lockformer is the cornerstone of rectangular-duct corner assembly. If you build Pittsburgh-lock or snap-lock duct, it is not optional — it forms the locking edge that closes the duct without welding. The SBLC range covers 0.4–1.2 mm Pittsburgh and 0.7–1.5 mm snap lock, with R/DR/C variants for reinforced and combination profiles.
Hydraulic vs pneumatic folder. Both fold the blank into duct sides; the difference is power and gauge. The hydraulic folder handles heavier gauge (to 2.0 mm) and longer 1550–2000 mm folds with consistent force. The pneumatic folder is lighter and lower-cost, for thinner material to 1.5 mm in lengths to 2500 mm. Heavy gauge and long sides point to hydraulic; light gauge and budget point to pneumatic.
Roll bender is what makes anything round — arcs, cylinders, cones, transitions. The SBW11G rolls 0.4–2.0 mm across 1000–1500 mm widths down to Φ100 mm minimum diameter. A round-duct or fittings shop needs one.
Drive-cleat line suits markets where the C-cleat (drive slip) connection is standard rather than TDF or Pittsburgh — it rolls the cleat edge for quick slip-together assembly. Grooving and beading adds stiffening ribs to large panels and connection beads to round fittings; it is a finishing detail rather than a primary former.
Tell us your seam type and gauge for a forming-machine recommendation →
It rolls a locking profile onto a sheet edge so two panels lock into a duct corner. The Pittsburgh lock is the classic interlocking seam; the snap lock is a faster press-together seam. The SBKJ lockformer (SBLC-12/15/1.2, R/DR/C variants) forms Pittsburgh on 0.4–1.2 mm and snap lock on 0.7–1.5 mm.
Hydraulic is more powerful — to 2.0 mm, 1550–2000 mm lengths. Pneumatic is lighter and cheaper — to 1.5 mm, lengths to 2500 mm. Heavy gauge and long folds: hydraulic. Light gauge and lower cost: pneumatic.
It curves flat sheet into arcs, cylinders and cones for round duct and transitions. The SBW11G handles 0.4–2.0 mm across 1000–1500 mm widths down to Φ100 mm minimum diameter.
Hydraulic folder and roll bender reach 2.0 mm; lockformer 0.4–1.2 mm Pittsburgh / 0.7–1.5 mm snap lock; pneumatic folder to 1.5 mm; drive-cleat line 0.4–1.2 mm; grooving/beading 1.2 mm. All 380 V / 50 Hz / 3-phase.
Tell us the seam type, gauge and duct sizes you build and an SBKJ engineer will spec the forming machines you need — within 12 hours, and not a salesperson.
Ask an engineer