Genuine parts and aftermarket: how to verify authenticity

Genuine, licensed aftermarket and counterfeit are three different things

These terms are often confused, and most disputed deliveries are built on that confusion.

• Genuine (OEM) — manufactured by the equipment maker or to its order, carrying factory marking and factory documentation.
• Licensed or certified aftermarket — made by another manufacturer to valid technical specifications, with its own certificate of conformity. It may be entirely suitable, but compatibility must be verified.
• Counterfeit — a part of unknown origin passed off as genuine. The marking is copied; documents are either absent or never checked.

The problem is not aftermarket parts as such — a properly selected aftermarket part does the job. The problem is paying for genuine and receiving the third option.

What documents the supplier must provide

The minimum set, without which a batch should not be accepted:

1. Certificate of origin or factory quality certificate stating the batch number
2. Packing list with the item list and factory part numbers
3. Product passport or declaration of conformity, depending on the type of part
4. Documents confirming the supply chain — from the factory to your warehouse

That last point is traceability. It answers the question of how many hands the part passed through and whether its route can be reconstructed. If the supplier cannot show the chain, you are buying a promise rather than a part.

What is visible before installation

Some discrepancies can be spotted at goods-in inspection if you know where to look.

Marking

On a genuine part the marking is applied by a durable method — engraving, stamping, laser. It is even, fully legible, and matches the part number in the documents. A sticker instead of a stamp, blurred characters, or a mismatch between the part and the packing list is grounds to stop acceptance.

Packaging

Factory packaging is normally preserved and carries its own batch marking. A part without preservation, in unmarked packaging or showing signs of repacking, is a question for the supplier.

Geometry and mass

Checking key dimensions with callipers and weighing the part often reveals a counterfeit immediately. A deviation in mass means a different material or a different wall thickness.

Surface quality

Coarse machining marks, burrs, uneven coating, cavities on cast parts — none of these survive factory quality control.

What to check before ordering rather than after

Most problems are eliminated at the requisition stage:

• verify the part number against the manufacturer catalogue, not against the description on an invoice
• specify the unit variant and serial number — a single model often has several revisions with different parts
• ask the supplier for the factory lead time: an implausibly short lead time on a rare item means the part is not from the factory
• agree claim terms in the contract before shipment

Price as an indicator

A significant deviation below market almost always has one of three explanations: it is aftermarket, it is refurbished, or it is counterfeit. Any of the three may be acceptable — but you should know which before purchase, not after the unit is opened.

The reverse holds too: a high price alone guarantees nothing. What guarantees authenticity is a verifiable supply chain.

If the part is already installed

Where authenticity of an already fitted part is in doubt, it makes sense to tighten condition monitoring: take vibration readings more often, shorten the interval between oil analyses, watch temperature more closely. Accelerated wear on a non-genuine part shows up in those parameters well before it shows up as a failure.