What the Cleat Does in a TDF Duct Joint
The TDF system (transverse duct flange, the standard recommended by the SMACNA association) closes a rectangular duct without angle iron and without welding. Each panel edge is roll-formed into an integral flange roughly 35 mm high; pre-crimped corner pieces lock the four corners; finished duct sections bolt flange-to-flange with a gasket in the joint.
The cleat — also called the clip — is the companion profile that locks the seam. In the standard Preda layout, one side of the machine forms the TDF flange profile while the other side forms the cleat: about fifteen stations shape the flange (using roughly 42 mm of material width) and about ten more stations form the clip (roughly 52 mm of width). A panel therefore leaves the machine with a flange on one edge and the matching cleat on the other, so the longitudinal seam between panels snaps together instead of being riveted or lock-seamed. On duplex machines the same job is done on both panel edges at once, and the cleat station doubles as the corner-notching station that cuts the reliefs needed for clean 90° corners.
Machine Layout: Flange Stations Plus Cleat Station
A TDF flange machine with cleat is not a flange former with an accessory bolted on — the cleat tooling is part of the roll train. Expect the line to be longer than a plain flange machine: 25 forming stations in total on the single-head design, mirrored on both sides for the duplex build. The infeed guide is hardened steel, the rolls run on turned-and-ground shafts in ball bearings, and the cleat position is set either by mechanical stops or — on CNC-equipped builds — by a servo-driven positioner that recalls notch patterns from a program.
That distinction matters when you order. "Cleat station fitted" on a quotation can mean anything from a fixed notching head to a full CNC cleat positioner. Get the configuration in writing, together with the notch pitch range and the repeatability figure — ±0.5 mm is the number to hold the factory to.
Specifications: T-12-2 and T-15-2 with Cleat Station
| Parameter | T-12-2 with cleat | T-15-2 with cleat |
|---|---|---|
| Material thickness | 0.5–1.2 mm galvanized | 0.6–1.5 mm galvanized |
| Functions | TDF flange + cleat/clip forming + corner notching | TDF flange + cleat/clip forming + corner notching |
| Flange profile | TDF and TDC on one frame | TDF and TDC on one frame |
| Forming speed | 15 m/min | 12 m/min |
| Motor power | 2.2 kW (duplex platform builds up to 4 kW) | 3 kW (duplex platform builds up to 5.5 kW) |
| Cleat station | Integrated / optional | Integrated / optional |
| Drive | Heavy-duty gear | Heavy-duty gear |
| Roll material | GCr15 / 9CrSi | GCr15 / 9CrSi |
Factory listings for the duplex platform quote main motors between 2.2 and 5.5 kW depending on the build, so confirm the nameplate power on your own quotation rather than trusting a catalog page. The cleat station itself adds little draw; the power difference is about the flange-forming duty.
Cleat station options to price
- Fixed mechanical notching head — lowest cost, one notch pitch.
- Adjustable stops — a small set of standard pitches, changed by hand.
- CNC cleat positioning — servo-driven with pattern recall from a program; the right choice if you run several flange sizes per shift.
Roll Tooling, Wear Parts and Service
The rolls are the machine. Specify GCr15 or 9CrSi, hardened after machining, and ask for the hardness range on the quotation — surface hardness in the high 50s HRC is the normal target for forming rolls. Ask whether the factory supplies replacement rollers and axles for the life of the machine; Preda lists this as standard, and it is worth more than a small discount on the base price. Ball-bearing roll mounts, hardened infeed guides and a heavy-duty gear drive are the three components that decide whether the machine still holds ±0.5 mm flange height after five years.
Separate Machines or One Combined Machine?
Price both routes before committing. Factory-direct FOB China estimates put single-head TDF flange formers at USD 3,000–5,000, duplex machines with an integrated cleat station at USD 6,000–10,000, and heavy-duty 1.5 mm builds at USD 10,000–15,000; corner making machines are separate at USD 1,500–4,000. A standalone drive-cleat bender (for example a CB-700-class machine, 0.5–1.2 mm, 700 mm width) is the budget alternative when cleat volume is low.
The combined machine wins on handling, not on forming speed. Every intermediate move between a flange former and a separate cleat machine is a handling cycle, a chance for edge damage, and floor space consumed. If your cleat demand justifies a dedicated operator, the split layout costs less up front; if cleats are a by-product of every panel, buy the integrated station.
Factory Acceptance Checklist
- Run your own coil: 0.5, 0.8 and 1.2 mm galvanized through the cleat station — not the factory's demo strip.
- Measure the cleat: check notch pitch repeatability against the quoted tolerance (±0.5 mm) at both ends of the bed.
- Assemble a test joint: clip two formed panels together — the cleat should engage with firm hand pressure, no hammering, no gaps.
- Corner relief: verify the notches are clean enough that the corner piece crimps without rework.
- Flange height: 35 ± 0.5 mm at three points per edge, on every gauge tested.
- Roll alignment: straightedge across the roll train; feel for any stand that sits proud.
- Electrical and certification: voltage and phase match, CE and ISO documentation, roller material certificates.
- Spares and warranty: replacement rolls and axles for machine life; warranty term in writing.
Common Faults and What They Mean
| Symptom | Likely cause | Fix |
|---|---|---|
| Cleat notch position drifts | Stop wear, or encoder/servo fault on CNC builds | Replace stops; recalibrate the positioner |
| Cleat engages too tight or too loose | Roll gap out of setting | Re-shim the cleat roll stand |
| Flange height varies along the panel | Roll wear or frame deflection | Re-shim or replace rolls; check leveling |
| Scratched coating | Dirty rolls or misaligned infeed guide | Clean rolls, re-set guides |
| Corner piece needs forcing | Corner relief notch worn or mispositioned | Renew the notching tooling |
FAQ
Is a cleat machine the same as a drive cleat bender?
No. The integrated cleat station forms the clip on the panel edge as part of flanging; a drive cleat bender (CB-700 class) forms separate S-cleats from strip for sliding onto assembled flange joints. Different machines, different jobs.
Can one machine run both TDF and TDC profiles?
Yes — the duplex platform carries both profiles on one frame. Confirm which profile set your market needs: TDF is the SMACNA standard, while TDC/GDF appears more often in UK and European specifications.
Does the cleat station slow the line down?
Marginally. The quoted 15 m/min (T-12-2) and 12 m/min (T-15-2) are with the cleat station working; the forming window, not the cleat head, is what sets the speed.
How much strip width does the clip use?
About 52 mm of material width for the clip against roughly 42 mm for the flange profile — worth knowing when you calculate coil consumption per panel.