Why the Fan Factory vs Trading Company Question Matters

When you request a quotation for an industrial fan or a replacement impeller, the reply may come from a factory or from a trading company. Both can quote a price and a delivery date. Only one can tell you how the impeller was cast, how the rotor was balanced and what the test curve for that specific unit looks like. The difference usually appears after installation, when the fan has to hold its duty point in a real process.

These seven questions are a practical industrial fan manufacturer audit. They take one email to send and they are difficult to answer without a manufacturing floor behind them.

1. Where is your foundry, and what alloy do you pour?

Impeller performance and service life start with the casting. SINDFAN casts A356/LM6 aluminium in its own foundry and heat treats it in a T6 furnace. A reseller cannot describe melting, pouring, degassing and heat treatment in detail, because it does not run those steps. Ask for the alloy designation and the heat treatment condition in writing, and ask where the casting is poured.

2. Can you show the balance report for my impeller?

Unbalance is the main cause of vibration in industrial fans. Ask which balance grade the rotor will meet under ISO 1940, and ask for the report. G6.3 is typical for general industrial duty; G4.0 is specified for higher-speed or more sensitive machines. A supplier who cannot name a grade, or who offers "good balance" without a document, has not balanced your rotor on a dynamic balancing machine.

3. Will I receive a performance test curve for this unit?

Catalog curves are generic and describe a family of fans. A factory tests on a rig built to AMCA 210 or ISO 5801 and can issue a curve for the specific order, covering airflow, static pressure, shaft power and efficiency. Ask whether the curve comes from a test of your unit or from a datasheet. The distinction matters most when the fan runs near the edge of its range.

4. Who welds and fabricates the casing and frame?

Housings, inlet boxes and support frames are welded and fabricated. Ask whether this work is done in-house or subcontracted. It determines lead time and how quickly a non-standard dimension or a modified outlet arrangement can be handled.

5. Can I visit the factory, or join a live video call on the floor?

A real manufacturer welcomes a visit. If travel is not practical, ask for a live video call showing the foundry, the balancing machine and the test rig. A trading company can show you an office. It cannot walk a camera through a casting line for an impeller it claims to manufacture.

6. What is the minimum order quantity for a custom impeller?

Factories that design and cast their own impellers can often work from one piece. SINDFAN's custom impeller MOQ is 1 pc, with prototypes typically delivered in 2–4 weeks. A high minimum order quantity for a simple geometry or blade angle change is a signal that the supplier is placing your order with someone else.

7. Who handles a warranty claim?

Ask who inspects a failed fan, who determines root cause, and where the repair or replacement is carried out. If every answer routes through a third party, you depend on a company that does not control the process that produced the failure.

What the Answers Tell You

Two signals are the clearest indication of a factory: a stated balance grade and a test curve issued per order. A third is access — an invitation to the floor or a video call to the foundry and balancing area. When a supplier answers the casting, balancing and testing questions with documents and access, you are dealing with an industrial fan manufacturer. When the answers stay at price, delivery and catalog numbers, you are dealing with a reseller. Use the same questions to verify a fan supplier before every significant order, not only the first one.

Send your duty — airflow, static pressure, operating temperature, gas composition and arrangement — to SINDFAN and we will answer from the factory. Contact us on WhatsApp +852 9524 8434 or email info@sind-tech.com.