The spec comparison table
Flexible and semi-rigid round duct is a different product family from rigid spiral or rectangular duct: instead of heavy galvanised sheet, these machines work thin aluminium foil, aluminium strip or thin-gauge stainless, and they run as a small dedicated cell separate from the rigid-duct workshop. This table compares the four SBKJ machines that make round flexible and semi-rigid duct, from light foil flex through self-supporting semi-rigid to thin-wall stainless. Every value is taken from the model's own product page. For how flexible duct fits into the wider production picture, see how HVAC duct is made.
| Machine / makes |
Model |
Material |
Foil / sheet thickness |
Diameter |
Length per piece |
Speed |
Power |
Weight |
| Foil flexible duct former (double station) |
SBLR-600 |
Non-woven fabric, PVC film, aluminium foil |
0.02–0.08 mm |
Φ80–Φ600 mm |
up to 36 m |
65 m/min |
7 kW |
680 kg |
| Aluminium-foil flexible duct former (single station, drying oven) |
SBLR-600A |
Aluminium foil |
0.02–0.08 mm |
Φ80–Φ600 mm |
30–40 m |
70 m/min |
Mainframe 1.5 kW + drying oven 7.5 kW + decoiler 1.5 kW |
980 kg |
| Semi-rigid aluminium corrugated former |
SBLF-500 |
Aluminium strip (60 mm wide) |
0.08–0.15 mm |
Φ80–Φ500 mm |
— |
0–25 m/min (feeding) |
2 kW |
260 kg |
| Thin-wall stainless round-duct former |
Stainless Duct Forming Machine |
Stainless steel |
0.05–0.1 mm |
Φ100–Φ500 mm |
— |
— |
Main 2.2 kW + decoiler 1.5 kW |
750 kg |
Source: SBKJ Product Catalog 2026, manufacturer nameplate specifications, drawn from each model's product page. A dash (—) means the value is not published on that machine's page: the SBLF-500 page does not state a length per piece, and the Stainless Duct Forming Machine page does not state a length per piece or a forming speed. The SBLF-500 figure is a feeding speed; the SBLR figures are forming speeds. All units run 380V 3-phase 50Hz (60Hz on request) where stated. Round flexible and semi-rigid duct conforms to EN 1506 / SMACNA duct construction.
The three duct types
These four machines make three distinct products, and the difference is in the material and how self-supporting the finished duct is.
Foil flexible duct is the soft, fully flexible duct used for residential and light-commercial branch runs. The SBLR-600 Flexible Duct Forming Machine is the double-working-station former: it builds aluminium-foil duct on a steel-wire frame from Φ80 to Φ600 mm, works non-woven fabric, PVC film and aluminium foil at 0.02–0.08 mm, runs PLC fully automatic cutting at a forming speed up to 65 m/min, makes lengths up to 36 m, and weighs 680 kg on a 7 kW, 380V/50Hz/3-phase supply. The SBLR-600A Aluminum Flexible Duct Forming Machine is the single-station aluminium-foil version, fitted with a drying oven for production quality: same Φ80–Φ600 mm range and 0.02–0.08 mm foil, but a 70 m/min forming speed, 30–40 m lengths and a heavier 980 kg frame because of the oven. Its power splits across a 1.5 kW mainframe, a 7.5 kW drying oven and a 1.5 kW decoiler.
Semi-rigid aluminium duct sits between flexible and rigid. The SBLF-500 Semi Rigid Aluminum Duct Forming machine rolls 60 mm-wide aluminium strip into a corrugated, self-supporting round tube that holds its shape but can still be bent by hand. A custom-built moulding wheel forms the rigid tube so it will not easily fall off, working Φ80–Φ500 mm duct from 0.08–0.15 mm strip to a 6-corrugation standard, with a double-decked tabby / twill lockseam, at a feeding speed of 0–25 m/min. At 2 kW and 260 kg it is the lightest and lowest-power machine in this group.
Thin-wall stainless round duct is the corrosion-resistant option for kitchen exhaust, fume and process air. The Stainless Duct Forming Machine produces stainless steel round duct from Φ100 to Φ500 mm in 0.05–0.1 mm stainless, supplied as a 2.2 kW mainframe forming unit plus a dedicated 1.5 kW decoiler for continuous production, at 750 kg.
SBLR-600 vs SBLR-600A
The two foil flexible duct formers cover the same diameter and foil-thickness window, so the choice is about throughput, materials and finish:
SBLR-600 (double station). Two working stations, so it is the higher-throughput machine, and it is the more versatile on material — non-woven fabric, PVC film and aluminium foil. It forms at 65 m/min and makes the longest pieces in this comparison, up to 36 m, at 680 kg.
SBLR-600A (single station, drying oven). A single-station, aluminium-foil-only machine with an integrated drying oven that lifts finished-duct quality where solid adhesives need curing. It forms slightly faster at 70 m/min but makes shorter 30–40 m pieces, and the oven pushes the weight to 980 kg. If your product is specifically glued aluminium-foil flex and finish matters, the 600A's oven is the reason to choose it; if you want material flexibility and the longest runs, the 600 is the pick.
How to pick the right one
Two variables decide which flexible or semi-rigid machine you need, in this order:
1. Product type. Soft, fully flexible foil duct for residential branch runs comes off the SBLR-600 or SBLR-600A. Self-supporting corrugated duct that still bends by hand comes off the SBLF-500. Corrosion-resistant stainless round duct comes off the Stainless Duct Forming Machine. These are different products for different parts of the HVAC catalogue, not interchangeable settings on one machine.
2. Material and diameter. The foil machines run the thinnest material (0.02–0.08 mm) over the widest range (Φ80–Φ600 mm). The semi-rigid SBLF-500 steps up to thicker 0.08–0.15 mm aluminium strip but tops out at Φ500 mm. The stainless former works 0.05–0.1 mm stainless from Φ100 to Φ500 mm. Match the machine's material and diameter window to the duct you actually sell, and remember the power demand sits at the heater or oven, not just the main drive — the SBLR-600A's 7.5 kW drying oven is the dominant electrical load on that machine.
What this means for capital planning
A flexible-duct cell is small and low-power compared with a rigid-duct line. The SBLR-600 is a single 7 kW unit; the SBLF-500 needs just 2 kW; the stainless former is 2.2 kW plus a 1.5 kW decoiler. The exception is the SBLR-600A, where the 7.5 kW drying oven dominates the load and the oven adds both weight (980 kg) and floor space. Budget the cell around a foil decoiler, the forming station, an insulation-wrapping station for insulated flex, an end-shrinking machine and a packaging table — SBKJ can supply it as a turnkey package or as individual modules to drop into an existing flex line. For the full electrical picture across the catalog, see the duct machine power & electrical requirements reference; for the rigid-duct side, compare with the spiral duct machine spec comparison.
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FAQ
Which SBKJ machine makes flexible duct?
Flexible duct is made on the SBLR-600 Flexible Duct Forming Machine, an automatic former for aluminium-foil ducts with a steel-wire frame. It covers diameters from Φ80 to Φ600 mm, works non-woven fabric, PVC film and aluminium foil at 0.02–0.08 mm, runs a forming speed up to 65 m/min with fully automatic cutting, and produces lengths up to 36 m. The single-station SBLR-600A is the aluminium-foil version with a drying oven.
What is the difference between the SBLR-600 and the SBLR-600A?
The SBLR-600 is a double-working-station machine that handles non-woven fabric, PVC film and aluminium foil, forms at up to 65 m/min, makes lengths up to 36 m and weighs 680 kg. The SBLR-600A is a single-station aluminium-foil machine fitted with a drying oven; it forms at 70 m/min, makes 30–40 m lengths and weighs 980 kg. Both cover Φ80–Φ600 mm at 0.02–0.08 mm foil with fully automatic cutting on a 380V/50Hz/3-phase supply.
What is a semi-rigid duct former?
A semi-rigid duct former rolls aluminium strip into a corrugated, self-supporting round duct that holds its shape but can still be bent by hand. The SBLF-500 does this for Φ80–Φ500 mm duct from 0.08–0.15 mm aluminium strip, 60 mm wide, to a 6-corrugation standard, with a double-decked tabby / twill lockseam, at a feeding speed of 0–25 m/min. It draws 2 kW and weighs 260 kg.
What foil and material thickness do the flexible duct machines run?
The SBLR-600 and SBLR-600A run 0.02–0.08 mm aluminium foil (the SBLR-600 also takes non-woven fabric and PVC film). The semi-rigid SBLF-500 forms thicker 0.08–0.15 mm aluminium strip. The thin-wall Stainless Duct Forming Machine works 0.05–0.1 mm stainless steel. These are thin-foil and thin-strip ranges, far lighter than the galvanised sheet used on spiral or rectangular rigid-duct lines.
Can SBKJ make thin-wall stainless round duct?
Yes. The Stainless Duct Forming Machine produces thin-wall stainless steel round duct from Φ100 to Φ500 mm in 0.05–0.1 mm stainless steel. It comes as a mainframe forming unit (2.2 kW) plus a dedicated decoiler (1.5 kW) for continuous production, and weighs 750 kg.
What power supply do the flexible and semi-rigid duct machines need?
All run a 380V 3-phase 50Hz supply (60Hz on request). The SBLR-600 draws 7 kW. The SBLR-600A splits across a 1.5 kW mainframe, a 7.5 kW drying oven and a 1.5 kW decoiler. The semi-rigid SBLF-500 needs only 2 kW. The thin-wall stainless former uses a 2.2 kW mainframe plus a 1.5 kW decoiler. See the duct machine power requirements reference for the full catalog.
