OEM vs Aftermarket vs Remanufactured Industrial Parts

When a machine needs a spare part, the original part is not always the only option. Suppliers offer OEM parts, aftermarket parts, remanufactured units, refurbished stock and used parts, often for the same application. The terms are used loosely in the market, which makes comparison difficult. This article explains what each category usually means and how to decide which one fits your situation.

What the terms mean

OEM parts

OEM stands for original equipment manufacturer. In industrial maintenance the term is used in 2 ways, which causes confusion:

• The machine builder's part: the part sold by the company that built the machine, often under its own part number.
• The component manufacturer's part: the same part bought directly from the company that actually makes it, such as a bearing, drive or valve manufacturer.

Machine builders rarely make every component themselves. A machine builder's part number may refer to a standard component from a known brand. Identifying that underlying component can open more supply channels, as long as it is truly the same part and not a modified version.

Aftermarket parts

Aftermarket parts are made by a third party to fit or replace the original. Quality varies widely. Some aftermarket manufacturers specialize in particular part families and produce to the same standards and dimensions as the original. Others compete mainly on price. For standardized parts, such as many bearings, seals, filters and pneumatic cylinders built to ISO standards, aftermarket alternatives are common and often perform well.

Remanufactured parts

A remanufactured part is a used unit that has been disassembled, cleaned, inspected and rebuilt, with worn or failed components replaced, then tested. The goal is performance comparable to a new part. Remanufacturing is common for hydraulic pumps and motors, gearboxes, servo motors, spindles and some electronic assemblies. The quality depends on the remanufacturer's process, the parts used and the testing performed.

Refurbished, repaired and used parts

These terms overlap with remanufactured and are used inconsistently:

• Repaired usually means the specific fault was fixed, without a full rebuild.
• Refurbished often means cleaned, checked and possibly repaired, but the depth of work varies.
• Used or pulled means removed from another machine and sold as is or after a basic test.
• New surplus or new old stock means unused parts from excess inventory, sometimes many years old.

Always ask the supplier what work was actually done and what testing was performed.

Comparing the options

Note that new surplus parts are not automatically perfect. Rubber seals, capacitors and lubricants can degrade during long storage, even in unused parts.

How to choose

There is no single right answer. The decision depends on the part and its role in the machine. These questions help:

1. How critical is the part? A failure that stops a whole line or affects safety justifies a more conservative choice than a part on a non critical auxiliary unit.
2. Is the part standardized? Parts built to recognized standards are easier to replace with an equivalent from another manufacturer.
3. Is the original still available? For obsolete parts, remanufactured, surplus or aftermarket options may be the only ones. See how to source obsolete industrial parts.
4. What does the warranty cover? Compare warranty terms and what they actually include, not just the label on the part.
5. Are there safety, certification or contractual requirements? Safety components, certified equipment and machines still under the builder's warranty may require original parts. Check the documentation and, if in doubt, the machine builder.
6. Can the alternative be verified? Dimensions, ratings, materials and test reports should be available before purchase.

Tip: For a critical machine, consider keeping 1 original part in stock as a reference and safety net, and using qualified alternatives for routine replacements once they have proven reliable.

Practical examples by part family

• Bearings: standardized dimensions make alternatives from established bearing manufacturers common. Check the full designation, including suffixes for clearance, cage and seals.
• Hydraulic pumps: remanufacturing is widely used, and alternatives are possible when displacement, flange, shaft and control match. See hydraulic pump replacement.
• Servo motors and drives: repair and remanufacturing are common, but replacements from another manufacturer usually need parameter or software changes.
• PLC modules: for legacy systems, new surplus, refurbished and repaired modules are often the practical route until a migration is planned.

Avoiding risk with non original parts

The main risks are poor quality, wrong specification and counterfeit parts presented as original. Reduce them by buying from traceable sources, asking for photos of the actual unit, requesting documentation and test results, and inspecting parts on arrival. A sourcing agency such as LiteHard can compare OEM, aftermarket and remanufactured options and clearly state the condition of each offer, so the choice stays with your maintenance team.

Key takeaways

• OEM can mean the machine builder's part or the original component maker's part.
• Aftermarket quality varies, but standardized parts often have reliable alternatives.
• Remanufactured, refurbished, repaired and used are different levels of work: always ask what was done.
• Choose based on criticality, standardization, availability, warranty and safety requirements.
• Verify condition, origin and specification before accepting any non original part.