Industry Applications / Air Handling & HVAC
Metal Fabrication for Air Handling Equipment: Precision Sheet Metal for HVAC OEMs
Metal fabrication for air handling equipment requires precise flat cutting and tight-tolerance bending: housing panels and enclosures, fan scroll sections, transition ductwork flanges, filter frames, coil casings, and custom equipment enclosures. Dimensional accuracy matters because seam gaps affect airflow efficiency and acoustic performance. Paragon serves HVAC OEMs and air handling equipment manufacturers with in-house laser cutting, forming, welding, and finishing.
What Parts Go Into Air Handling Equipment?
Air handling units (AHUs), industrial fans, HVAC rooftop units, and commercial ventilation equipment use dozens of fabricated sheet metal parts: housing sidewalls and end panels, fan scroll housings, inlet bells, transition sections, drain pan assemblies, filter track frames, access door frames, coil section casings, and internal structural supports and brackets.
Each of those parts has a dimensional requirement that ties directly to equipment performance. A fan scroll that’s 0.10″ undersized on the cutoff gap changes the fan curve. A housing panel with seams that don’t close tightly leaks air, reducing system efficiency. Transition sections that don’t match the designed cross-section disturb airflow and add static pressure. Precision fabrication is not just an aesthetic preference in air handling work: it’s a functional requirement.
Production HVAC OEMs run these parts in volume. An AHU manufacturer might need 500 scroll housings per quarter, all to the same drawing. A custom commercial contractor might need one set of custom transition sections for a specific project geometry. Paragon handles both: production runs with consistent quality and lead times, and one-off custom parts from submitted drawings.
Internal structural supports and brackets are often overlooked in discussions of air handling fabrication, but they’re critical. Fan mounting plates, motor support frames, drain connections, and coil support channels must all align precisely with the sheet metal housing they mount to. When all parts come from the same fabrication source, tolerances stack consistently. Sourcing housing panels and internal hardware from two different shops often leads to fit-up issues during assembly.
What Materials Do HVAC and Air Handling OEMs Specify?
Galvanized steel is the standard for most commercial HVAC and AHU construction: corrosion-resistant, cost-effective, and readily available in the gauges common in air handling work (22 gauge through 14 gauge). Stainless 304 or 316 is required for food processing, pharmaceutical, and clean-room air handling where cleaning protocols and sanitary standards apply. Aluminum is used where weight is a constraint or where moisture and corrosion exposure is severe.
Galvanized steel’s zinc coating provides cathodic protection that outlasts paint in the humid, condensate-prone environment inside an AHU. Standard mill-galvanized sheet in G90 coating weight is the common commercial HVAC spec. G60 appears in indoor, lower-exposure applications. Hot-dip galvanized structural members are used where corrosion exposure is more severe.
Stainless steel introduces fabrication considerations. The laser cuts stainless cleanly on nitrogen assist gas, producing a bright, burr-minimal edge. Bending stainless requires adjusting for higher springback compared to mild steel: the press brake operator compensates by overbending slightly. Welding stainless requires TIG process and appropriate filler metal to maintain corrosion resistance at the weld joint. Paragon’s team handles all three consistently on air handling fabrication orders.
Aluminum air handling components are common in marine, coastal, and outdoor applications where condensation and salt exposure make galvanized steel marginal. 5052-H32 is a typical HVAC aluminum grade: good formability, decent corrosion resistance, and readily available in sheet. 6061-T6 appears in structural components where higher strength is needed. Both cut and form well on Paragon’s equipment.
Why Precision Matters in Air Handling Fabrication
Tight-tolerance flat cutting and accurate bend angles reduce assembly time and improve performance. Housing panels that are consistently cut to ±0.005″ positional accuracy align with mating panels without shimming or rework. Scroll housings with accurate cutoff geometry perform to the fan curve. Filter frames that close tightly eliminate bypass leakage. Precise parts lower assembly cost and improve delivered performance.
The cost of imprecise fabrication in air handling assembly is invisible in the quote but visible in the labor hours. Panels that don’t align require hand fitting, drilling new holes, shimming flanges, or pulling seams tight with fasteners that weren’t in the design. Those extra assembly hours often cost more than the difference in fabrication quality that would have prevented them. Precision fabrication from the start is cheaper at the system level.
Paragon’s laser cutting holds ±0.005″ positional accuracy on flat profiles, and the press brake holds ±0.5-degree bend angle on standard material thicknesses. For production HVAC OEMs, those numbers mean parts that stack consistently from piece to piece and unit to unit.
Finishing Options for Air Handling Equipment Parts
Most galvanized AHU parts ship raw, relying on the zinc coating for corrosion protection. Where additional protection or specific color is needed, Paragon’s powder coating applies a durable baked finish. Stainless parts typically ship mill-finish or brushed and need no additional coating. Aluminum parts may receive clear anodize (typically by outside process) or powder coat for color. Specify finish requirements in the RFQ.
Powder coating is not always appropriate for galvanized HVAC parts. The coating can peel from the zinc surface if the outgassing during cure isn’t managed properly, and not all powder coat formulations adhere well to galvanized steel without pretreatment. When powder coat on galvanized is specified, Paragon uses proper pretreatment chemistry. If you only need primer for field paint, that’s a simpler and more reliable option. Clarify finish requirements up front to avoid surprises.
For stainless air handling components destined for food or pharmaceutical environments, mill finish (2B) is often the spec. In some clean-room applications, a ground or electropolished finish is specified to reduce surface roughness and microbial adhesion. Paragon can supply 2B mill-finish stainless parts; electropolishing is an outside process that we can coordinate. Include the finish standard on your drawings.
See our powder coating page for finish options and our overview of fabrication services for the full capability list. For information on the specific process steps involved in finishing, see powder coating process steps.
Precision Sheet Metal for HVAC and Air Handling OEMs
Galvanized, stainless, and aluminum. Laser cutting, forming, welding, and powder coating under one roof. 40+ years, Northern Kentucky and Greater Cincinnati.
Frequently asked questions
What materials are used in air handling and HVAC equipment fabrication?
Galvanized steel (G60 or G90 coating weight) is the standard for commercial HVAC and AHU construction. Stainless 304 or 316 is required for food processing, pharmaceutical, and clean-room air handling. Aluminum 5052-H32 is used in marine, coastal, and outdoor applications where galvanized steel’s corrosion resistance is marginal. Specify the grade and coating weight on drawings, not just ‘galvanized steel.’
Why does precision matter for sheet metal air handling parts?
Dimensional accuracy affects both assembly cost and equipment performance. Housing panels that don’t align require hand fitting and rework, adding assembly hours. Fan scroll housings with incorrect cutoff geometry perform off the fan curve. Filter frames with seam gaps allow air bypass. Precise fabrication from the start lowers total system cost even if the per-part price is slightly higher than a lower-tolerance source.
Can Paragon handle production volume for HVAC OEM parts?
Yes. Paragon handles production runs for HVAC OEM programs alongside prototype and custom work. Nesting files and programs are retained for repeat orders. Consistent lead times and quality on production quantities are standard. Call 1-800-467-0121 or contact us to discuss your volume requirements and set up a blanket order or scheduled release program if that fits your production schedule.
What finish is standard for galvanized air handling fabrications?
Most galvanized AHU parts ship raw, relying on the zinc coating for corrosion protection. Where color or additional protection is required, powder coating can be applied with appropriate pretreatment for adhesion to galvanized steel. For parts that will receive field-applied paint, a primer coat is a simpler and more reliable option. Specify finish requirements in the RFQ to avoid surprises.
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