“Please send the CAD drawing for your filter design.” If you’re building a private label air purifier or vacuum filter line and you’ve never touched mechanical drafting, that one line can stall a project for weeks. You might have a nice product photo, a rough sketch, or a competitor’s filter sitting on your desk. None of that is a CAD drawing, and a factory can’t quote tooling, size a mold, or lock your MOQ without one.
This isn’t about becoming an engineer overnight. It’s about knowing which details actually matter, so someone, you or the factory’s own design team, can turn them into a real file in a day instead of a month.
Why the Factory Won’t Move Without One
A HEPA filter or vacuum cartridge looks simple from the outside. Inside, the frame, the pleat pack, the gasket, and the mounting tabs all have to line up inside someone else’s housing, often to the millimeter. Quote a mold or set up a pleating line off guesswork, and the first sample batch is usually the wrong batch.
That mistake is expensive in time, not just money. Sample delivery after a mold opening typically runs 30 to 35 business days. A drawing missing one critical dimension, a gasket position, a tab location, can trigger a second mold opening and a second month-long wait. The drawing is the one document that turns a filter idea into a part number a factory can actually build against.
What a Complete Filter CAD Drawing Needs to Show
The dimensional basics
- Overall dimensions with tolerance. Length, width, and height, or outer diameter and height for round cartridges, plus wall thickness. Add a tolerance line, such as ±0.5mm. Skip it, and the factory defaults to its own standard tolerance band, which may not match the housing you’re building for.
- Filtration media and class. “HEPA” alone isn’t a specification. State whether it’s H13 or H14 under EN 1822, or a MERV rating, plus any activated carbon or pre-filter layer. An H11 media captures roughly 95% of 0.3-micron particles; true H13 media is closer to 99.95%. Mixing those up changes the entire quote.
- Pleat count and depth, for pleated designs. This pair sets the usable surface area and how much resistance the filter adds to airflow.
- Frame or housing material and color. Cardboard, ABS, PP, or foam, plus any color visible from outside the appliance.
The details most private label brands miss
- Gasket or seal type and position. Foam density, thickness, and exact placement. A gasket sitting even 1-2mm off can create a bypass leak that fails an efficiency test even though the filter media itself is fine.
- Mounting features. Tabs, clips, handle cut-outs, or locking notches, measured from a fixed reference edge rather than described as “centered.”
- Airflow direction. A simple arrow marking which face is the dirty-air side.
- A reference model or OEM part number, if this is a replacement or compatible design. A vacuum model name can cover several housing revisions; a part number points the factory to one exact fit. We broke this down in more detail in our Dyson, Bosch, and Gtech filter compatibility guide, since the wrong reference is one of the most common causes of a bad first sample.
- File format and units. DXF or STEP for direct CAD-to-CAD transfer, or a fully dimensioned PDF if that’s all you have. State millimeters or inches up front. A factory defaulting to the wrong unit system is common, and entirely avoidable.
No CAD File Yet? Three Realistic Starting Points
Most private label brands don’t keep a mechanical engineer on staff, and that’s fine. A finished drawing isn’t the only way in.
- Send a physical sample. Note what should change: color, logo placement, a thicker gasket. A factory’s engineering team can measure and reverse-engineer the rest.
- Send the OEM part number or a link to the original filter, along with your requested changes, rather than just a product name. Our OEM air purifier and vacuum parts catalog shows the range of frames, gaskets, and media combinations a factory can work from as a starting reference.
- Fill out a plain-language spec sheet covering the items above, with photos instead of formal drawings. A factory’s own design team, like the one behind Hifine’s OEM/ODM engineering solutions, can convert that into production-ready CAD.
Two Standards Worth Knowing Before You Sign Off
Two separate testing standards define what counts as HEPA, and they’re not interchangeable. The European EN 1822 standard classifies filters from E10 through U17 based on how much of the hardest-to-catch particle size they actually capture. The U.S. Department of Energy’s DOE-STD-3020 sets its own bar: 99.97% efficiency at 0.3 microns. A filter tested and labeled under one standard doesn’t automatically qualify under the other, and mixing them up on a spec sheet is a common source of compliance headaches down the line.
For mechanical tolerance, most factories default to the general ISO 2768 standard unless a drawing says otherwise. If your filter needs a tighter fit than that general standard allows, put the exact number on the page. Don’t assume the factory will guess correctly.
A 60-Second Check Before You Hit Send
- Dimensions and tolerance are both on the page
- Filter media and class are named
- Gasket size and position are marked, not implied
- Mounting features are measured from a fixed edge
- Units are labeled, mm or inch
- File format is confirmed with the factory (DXF, STEP, or dimensioned PDF)
- A reference sample or OEM part number is attached, if this is a replacement design
If you’re still staring at a blank template, you don’t need to become a CAD drafter overnight. Hifine’s engineering team reviews samples, part numbers, and rough sketches every week for private label brands starting their first OEM run, and can turn them into a production-ready drawing as part of your quote request. Get that conversation started before a mold gets cut, and the first sample run is far more likely to be the only one you need.
