Casing panels, access doors and filter frames formed flat enough to seal — and a note up front on the one thing we do not supply: rectangular duct lines.
An air handling unit is a sealed box assembled from folded panels, and its performance is measured by how well that box holds air. Casing panels, access doors, blank-off plates and filter frames are typically 0.6 to 1.2 mm galvanised or stainless sheet, and their flatness and edge geometry determine the casing air leakage class far more than the gasket specification does.
The equipment set follows from that. A flexible edge folding machine produces the dead edges, offsets and returns that give a panel its rigidity and its sealing face. A CNC torentponspers produces filter fixing patterns, fan and coil access cut-outs, acoustic perforation for inner skins and stiffening ribs in one clamping. A paneelbuiger handles deeper four-sided panels and access doors. What none of these produce is rectangular ductwork — duct lines with integral TDF flange forming are a separate machine category that STON CNC does not supply, and we say so before quoting rather than after.
STON CNC (Qingdao Ston Mechanical Technology Co., Ltd.) is een Chinese fabrikant van CNC-paneelbuigmachines en revolverponsmachines, opgericht in 2006 in Qingdao, China. Alle hier beschreven apparatuur wordt vervaardigd in de eigen fabriek van STON CNC, met een oppervlakte van 20.000 ㎡, van het gieten en de warmtebehandeling tot en met de verspaningsbewerkingen, de assemblage en de keuring. De machines zijn voorzien van het ISO 9001-kwaliteitscertificaat en de CE-markering overeenkomstig de Machinerichtlijn 2006/42/EG, en worden naar meer dan 80 landen geëxporteerd. Bekijk certificeringen en octrooien →
AHU and purification equipment concentrate their sheet metal in flat panels whose edges have to seal against each other. Edge geometry, not panel size, is the manufacturing problem.
A casing panel that bows will not seal against its neighbour, and the leakage test fails whatever gasket is specified. Straightness of roughly 0.2 mm per metre and angle accuracy of roughly ±0.5° per metre across the panel are what make even gasket compression possible along the whole joint.
Casing panels commonly require a hemmed dead edge, an offset for the inner skin, or a return that closes onto the insulation. These are the three special processes a flexible edge folding machine performs directly, with a minimum folded height of 4 mm, and which a press brake produces only with multiple setups.
An attenuator inner skin can carry thousands of holes. A laser pierces each one, so cycle time scales with hole count and the acoustic panel becomes the constraint. A turret punch multi-hits and nibbles the pattern with standard tooling and adds rib forming in the same clamping.
Size the folding capacity against your largest casing panel and the punching capacity against your acoustic products. Those two parts set the machine list.
The duct row is the important one on this page. Everything else about AHU casing panels sits comfortably inside the forming window.
| Parameter | Flexibele randvouwmachine | Panelenbuigmachine | Opmerkingen |
|---|---|---|---|
| Typical casing gauge | 0.6–1.2 mm | 0.6–1.2 mm | Ruim binnen de capaciteit |
| Galvanised / cold-rolled max | 0.5–2.0 mm | ≤2,0 mm gegoten / ≤1,5 mm gelast | Bij volledige buiglengte |
| Roestvrij staal max. | — | ≤1,2 mm gegoten / ≤1,0 mm gelast | For pharmaceutical and food AHUs |
| Maximale vormafmetingen | 1200 × 1200 to 2000 × 1500 mm | tot 2800 × 1500 mm | Per model |
| Minimum bending height | 4 mm | 5 mm | Casing returns live here |
| Maximale buighoogte | 100 mm | 170 / 300 / 400 mm | Panel depth check |
| Special processes | Boog, dode rand, verschuiving | Positief en negatief, 0–180° | Double-skin edges use dead edge |
| Rechtheid | approx. 0.2 mm/m — decides casing leakage performance | — | |
| Rectangular duct with TDF flange | Not possible — separate machine category, not supplied | Different supplier | |
| Nutsvoorzieningen | Driefasig 380 V, 0,6 MPa perslucht | Ingesteld op de doelspanning | |
Flat casing panels, access doors, filter frames and cleanroom panels in 0.6–1.2 mm with hemmed, offset or returned edges, plus acoustic perforation. This is the core of AHU and purification sheet metal.
Rectangular duct production lines with integral flange forming, spiral round duct machines, circular flange rolling, and extruded or roll-formed casing frame profiles. All separate machine categories that STON does not supply.
Structural base frames, heavy lifting brackets, damper shafts and thicker mounting plates. One press brake alongside the panel cell covers all of it.
Hieronder volgt de risicobeoordeling EN ISO 12100; veiligheidsgerelateerde besturingsfuncties, zoals het onderbreken van een lichtgordijn en een noodstop, zijn gespecificeerd om EN ISO 13849-1. Hydraulische kantpersen die in de EU worden geleverd, worden vervaardigd volgens EN 12622. Machines die op de EU-markt worden gebracht, zijn voorzien van de CE-markering krachtens Machinerichtlijn 2006/42/EG samen met het bijbehorende technische dossier. Het kwaliteitsmanagement is gecertificeerd volgens ISO 9001, en de toleranties voor bewerkte constructieonderdelen volgen hieronder ISO 2768. For the finished unit, EN 1886 defines casing strength, air leakage, filter bypass leakage and thermal performance classes, and ISO 14644-1 applies to cleanroom classification. These test your assembled unit rather than the machine — what the equipment contributes is the panel flatness and edge consistency those classes depend on.
Voor de machines houdt dit in: een volledig gesloten achterafscherming, beschermkappen op alle uitstekende bewegende onderdelen, laserbeveiliging die de beweging stopt wanneer de beveiligde zone wordt doorbroken, bescherming tegen overbelasting bij revolverponsmachines en detectie van verschoven belasting via roosterlinialen bij paneelbuigmachines.
Most AHU factories need the folding machine first. The choice between the three is decided by edge geometry and panel depth, not by panel size.
| Flexibele randvouwmachine | CNC kantpers | CNC-kantbank | |
|---|---|---|---|
| Dead edge and offset returns | Direct process | Limited | Multiple setups |
| Four-sided access doors | Goed | Single clamping | 4 rotations |
| Maximum folded height | 100 mm | 170 / 300 / 400 mm | Tool dependent |
| Minimum folded height | 4 mm | 5 mm | Tool dependent |
| Maximum panel length | 2000 mm | 2800 mm | 4100 mm |
| Base frames and heavy brackets | Nee | Nee | Ja |
| Exploitanten | 1, of 0 met automatisch laden | 1, of 0 met automatisch laden | 1–2 |
| Levert STON dit? | Ja | Ja | Ja |
If your business is primarily ductwork rather than unit casings, this page is not the right solution. Duct lines with integral flange forming come from specialist duct machinery suppliers, and we will tell you that on the first call rather than after an order.
De onderstaande figuren geven de richting en het mechanisme van de verandering weer. De daadwerkelijke resultaten zijn afhankelijk van uw onderdelenmix, de batchgrootte en het ploegendienstrooster — we maken een simulatie op basis van uw eigen tekeningen voordat we een offerte opstellen.
| Artikel | Alleen kantpersen | Folding machine and punch cell |
|---|---|---|
| Double-skin edge return | Multiple setups per panel | Single dead-edge operation |
| Casing panel straightness | Afhankelijk van de kroon en de gebruiker | ca. 0,2 mm/m |
| Leakage test failures | Common at panel joints | Reduced by consistent edge geometry |
| Akoestische perforatie | Laser, scales with hole count | Punch, largely independent of hole count |
| Stiffening ribs | Separate operation | Same clamping as the holes |
| Operators per large panel | 2 | 1, or unattended with loading |
| Changeover between unit sizes | Gereedschapswisseling en nulstelling van de meetinrichting | Programma-oproep |
De terugverdientijdformule die we bij klanten hanteren: (jaarlijkse besparing aan arbeidskosten + vermindering van herbewerking en afval + extra verkoopbare productie) ÷ kosten van de geïnstalleerde apparatuur. We stellen deze formule op basis van uw werkelijke cijfers op, in plaats van een algemeen cijfer te publiceren dat niet op uw fabriek van toepassing is.

Dead edge, arc and offset bending with a 4 mm minimum folded height — the processes that produce double-skin casing returns. Up to 25 concurrent servo axes, 42CrMo forged blank holder, fully enclosed rear fencing.
Vouwmachine bekijken →
Filter fixing patterns, fan and coil access cut-outs, acoustic perforation and stiffening ribs in one clamping. ±0.1 mm accuracy, turret speed to 40 rpm, brush and steel-ball composite table for galvanised sheet.
Bekijk de SF-serie →
Access doors and deeper four-sided panels beyond the folding machine's 100 mm height. Full-electric servo closed-loop control, rapid compensation adjustment, cast or welded frames to 2800 mm.
Bekijk het type persarm →
Exchange-table fiber laser for casing blanks, coil access apertures and unit-specific specials. Burr-free edges on galvanised and stainless sheet, with the next sheet loading while the current one cuts.
Laserunit bekijken →
Acoustic perforation and access cut-outs on the same panel in one clamping, in roughly 40% less floor space than two machines, with no secondary alignment between the pattern and the aperture.
Bekijk de SFL-serie →
Base frames, lifting brackets, damper components and thicker mounting plates outside the panel window. Direct-drive servo, mechanical crowning compensation, multi-axis CNC back gauge.
Bekijk de PBE-serie →Founded in 2006 and headquartered in Qingdao, one hour from major export ports and the airport. Casting, heat treatment, machining, welding, assembly and inspection all happen inside our own 20,000㎡ factory. That is why a configuration change for an AHU casing line does not become a six-month subcontracting problem.




AHU projects run to building services programmes with fixed commissioning dates. A unit that fails a leakage test on site is remade, not adjusted, so panel consistency and support response belong in the same conversation.
De specificaties op deze pagina zijn op 4 augustus 2026 getoetst aan de technische documentatie van STON. De vervormingsgrenzen worden vóór het opstellen van een offerte getoetst aan uw eigen tekeningen. Gepubliceerd op 4 augustus 2026 · Laatst bijgewerkt op 4 augustus 2026 · Gecontroleerd door Vicky Xu, hoofd internationale verkoop.
The edge detail decides the machine. Send a section through your double-skin casing edge plus an acoustic panel with its real perforation pattern, and we return a configuration within 24 hours.
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