Short answer
With spare parts the right question is not "original or aftermarket" but "which property is critical on this part". On some parts the dimension decides, and any part that holds the dimension will do the job; on others material and heat treatment decide, and the wrong material finishes early even when the dimension is right; on others geometry is critical, and a part that looks identical behaves differently. Separating those three categories makes the decision easy and moves the argument off brands and onto technical ground. The measure is always the same: not the price of the part but how many hours it lasts and how much downtime its replacement creates.
Three categories
These three are not rivals but answers to different situations. On the same breaker one part can be original, another aftermarket and a third remanufactured, and that is not an inconsistency; the critical property differs from part to part.
- Original: the part from the company that makes the attachment. Dimension, material and geometry match the design; uncertainty is lowest.
- Aftermarket: a part made by another manufacturer to serve the same function. The quality range is wide; a good aftermarket part gives life close to original, a poor one finishes early.
- Remanufactured: a used part brought back to dimension and returned to service. Chrome plating a piston is the commonest example. What decides it is whether the dimension is preserved after the work.
What is critical on each part?
- Where the dimension is critical: pins, locks, washers and some bushings. Where the dimension holds and the material is reasonable, an aftermarket part is used comfortably.
- Where material and heat treatment are critical: tools, bushings, piston. A part of the same size but different hardness finishes sooner than expected or breaks. Here a cheap part turns out expensive.
- Where geometry is critical: the valve and its sleeve, the diaphragm. Gallery geometry and flexing characteristics cannot be seen; a matching dimension is not enough to decide on.
- Sealing elements: material and temperature rating decide. A seal of the right dimension in a different material degrades quickly under heat.
When does a remanufactured part make sense?
Remanufacturing makes sense where the surface of the part is damaged but its body is sound. The piston is the typical example: a scored surface can be ground and re-plated and the part returns to dimension.
The decisive question is: is the dimension preserved after the work? A piston ground too far falls outside its dimension and the clearance grows; a grown clearance means internal leakage. So the quality of the remanufacture lies not in the thickness of the plating but in dimensional control.
The second question is who did the work. The difference between a workshop that measures and records and one that says "looks fine" is larger than the difference between parts.
A cheap part fitted twice is not cheap
Comparing by price tag misleads. The right measure is cost per hour for the part: price divided by the hours it lasts, plus the downtime lost while changing it. A part bought at half price that gives half the life breaks even; if it gives a third of the life, it is expensive. We covered how to build that calculation in the cost per hour guide.
What to ask when assessing an aftermarket part
- Is material and hardness information given? A supplier who will not give it is guaranteeing nothing beyond the dimension.
- Is the model compatibility stated by model code, or is it just "it fits"?
- Is there a reference who has used the same part before, and how long did it last?
- What is the lead time? A cheap part waited on for three weeks is expensive once downtime is counted.
- Who is accountable when there is a problem? Who takes responsibility for the part matters as much as the price.
Do and don’t
Do
- Decide part by part; different categories can coexist on the same breaker.
- Ask for documentation on parts where material and heat treatment are critical.
- Start an aftermarket trial on a non-critical part and record its life.
- Ask whether dimensional control was carried out on a remanufactured part.
- Compare on cost per hour rather than on the price tag.
Don't
- Do not decide on dimensions alone for parts where material is critical, such as tools and pistons.
- Do not change a valve or diaphragm because "the dimensions match"; geometry is invisible.
- Do not use an over-ground remanufactured part on the grounds that "a little clearance is fine".
- Do not run the first trial on an attachment that is on the critical path.
- Do not take an aftermarket decision without recording the life; otherwise the same argument repeats next time.