What the HVAC OEM asked for
A European HVAC OEM asked for drawings of two standard plastic axial impeller models. Namely the LWA-ф401×115-03 and the larger LWA-ф450×155-04.
They sent only part numbers and a short note. Evidently this is a component purchase for a new or revised product line. Furthermore, they assemble in house rather than buying complete fan-motor units.
The constraints come from the impellers themselves.
- First, an 8mm stepped bore on the 401mm impeller.
- A 12mm bore on the 450mm impeller.
- Lastly, RoHS compliance, since the European market demands it.
Those bore sizes are the whole reason for the request. Their engineers need to confirm a proper fit onto motor shafts they already plan to use.
Beyond that, the drawings unblock the mechanical layout. Mounting clearances, orifice panel design and assembly tolerances all wait on this paperwork. Consequently the request arrived marked urgent.
Confirming the plastic axial impeller choice
Two named part numbers made this a check rather than a search. Our task was to confirm both suit a condenser, then get the drawings out quickly.
Why the material matters most
Both impellers are molded in ASG20, a glass-filled plastic. That choice is worth a word, since aluminum is the obvious rival.
Against a stamped aluminum blade, ASG20 resists rust far better, which matters outdoors where metal needs coating. Moreover, molding allows complex, efficient blade shapes that stamping either cannot produce or produces expensively.
It is also much lighter. Consequently start-up torque falls, and so does the load on the motor bearings over years of running.
The blade shape
Both use a sickle-shaped profile from our AcousticFlow approach, which targets low noise without losing airflow. In commercial HVAC that matters, because noise rules keep tightening.
Why two sizes
Offering a 3-blade 401mm and a 4-blade 450mm option lets the OEM build a tiered range. The smaller one suits a lower-capacity unit, while the larger suits a top model. Both sit inside a similar design.
The tolerance that matters
Our engineer paid particular attention to one line on the drawing: residual unbalance no greater than 0.3g at 1000 RPM.
That figure is tight, and it is not decoration. Unbalance makes vibration, vibration makes noise, and vibration shortens motor bearing life. Consequently the balance line protects the customer product long after the fan is fitted.
Once everything checked out, the approved PDF drawings went out. In short, precise data delivered quickly was all the customer needed to keep moving.
Technical Specifications
Two plastic axial impeller sizes appear below. Note the bore dimensions, since those decide whether it fits the motor you already stock.
| Parameter | LWA-ф401×115-03 | LWA-ф450×155-04 |
|---|---|---|
| Longwell Model Number | LWA-ф401×115-03 | LWA-ф450×155-04 |
| Outer Diameter | 401 mm | 450 ±1 mm |
| Impeller Height | 115 ±2 mm | 155 ±2 mm |
| Number of Blades | 3, evenly distributed | 4, evenly distributed |
| Material | ASG20 | ASG20 |
| Color | Blue | Blue |
| Product Weight | 440 ±13 g | 752.8 ±10 g |
| Bore Configuration | Stepped bore, Ø8 mm / Ø7 mm | Stepped bore, Ø12 mm / Ø10 mm |
| Direction of Rotation | Clockwise (C.W.) | Clockwise (C.W.) |
| Dynamic Balance Specification | Residual unbalance ≤ 0.3 g @ 1000±50 RPM | Residual unbalance ≤ 0.3 g @ 1000±50 RPM |
| Axial / Radial Runout | Axial runout ≤ 3 mm | Radial & Axial runout ≤ 2 mm |
| Compliance | RoHS | RoHS |
Technical Documentation
Here the following documents were provided to the customer to support their system design and integration efforts. All technical drawings are generated from our centrally managed PDM system to ensure accuracy and revision control.
The product image shows the 3-blade LWA-ф401×115-03 impeller, highlighting its sickle blade geometry.
Here the detailed mechanical drawing for the LWA-ф401×115-03 impeller includes all critical dimensions, tolerances, material specifications, and balancing requirements for OEM design engineers.
This image displays the 4-blade LWA-ф450×155-04 plastic axial impeller designed for higher airflow requirements.
Above, the complete engineering drawing for the LWA-ф450×155-04 impeller provides the necessary data for mechanical integration, motor shaft pairing, and quality assurance protocols.
Why OEMs buy components here
Choosing a component supplier matters as much as choosing a finished product vendor. In this case, four things counted.
- Parts, not just whole fans. Selling the plastic axial impeller alone lets an OEM tune their own build and parts list, using our molding and balancing skill without buying a full fan-motor unit.
- European engineering, Asian cost base. Making these in Ningbo puts each plastic axial impeller well below European rivals on price. Buying parts in volume, that is a direct saving on the finished product.
- A balance figure we commit to. The drawing calls for 0.3g residual unbalance. That is a commitment to low vibration, which in turn means lower noise and longer motor bearing life in the customer product.
- Responsive on custom work too. This was a fast turnaround on standard documentation. For genuinely custom requirements, our 90-day NPI process runs far shorter than the 12 to 18 months other major suppliers commonly quote.
Browse our impeller and fan blade range, or the axial fan section for complete assemblies. Balance grades are defined in ISO 21940.
Questions during component selection
What motor shaft suits the 450mm impeller?
Meanwhile the drawing specifies a 12mm bore with a tolerance of +0.15 to +0.05mm, intended for a nominal 12mm shaft. We usually suggest a shaft with a g6 or h6 tolerance class, whether you are using a press fit or a slip fit with a keyway.
Is ASG20 suitable outdoors in varied climates?
Yes, and that is why it was chosen. It shrugs off UV, and it cannot rust at all, unlike metal blades that often need a coating. The material is qualified from -40C to +60C. Being much lighter than an aluminum blade, it also cuts start-up torque and bearing load.
Can I have a P-Q curve for these impellers?
Not for the impeller alone, because it does not have one. Aerodynamic performance depends on the whole system: the impeller, the motor speed and the housing or orifice plate around it. We can supply curves for our complete axial fans using these impellers, tested to AMCA 210/211. Alternatively, through our NPI process we run CFD and lab testing against your specific motor and housing.
Why does an impeller need a balance specification if the motor is ours?
Because the plastic axial impeller is the largest rotating mass in the assembly, so its unbalance dominates. Your motor bearings then carry that force every revolution. In short, a tight balance figure is one of the few things a component supplier can promise that extends the life of parts they never supplied.
Technical Documentation & Resources
Have a fan requirement like this one?
Send the datasheet you are working against, or simply the duty point. Then our engineers tell you what fits and what does not. Meanwhile custom spec sheets and samples take up to 90 days. Since 1990 we have been building fans for OEMs worldwide.
Browse Related Products:
🏆 ISO 9001 / ISO 14001 / ISO 45001 | CE (TÜV) | UL/ETL | ATEX Zone 21/22 | AMCA 210/211 / ISO 5801 tested
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