{"id":316,"date":"2026-07-16T18:53:56","date_gmt":"2026-07-16T16:53:56","guid":{"rendered":"https:\/\/recostock.pl\/?p=316"},"modified":"2026-07-16T18:53:57","modified_gmt":"2026-07-16T16:53:57","slug":"czesci-z-nadwyzek-magazynowych-vs-regenerowane-vs-uzywane","status":"publish","type":"post","link":"https:\/\/recostock.pl\/en\/2026\/07\/16\/czesci-z-nadwyzek-magazynowych-vs-regenerowane-vs-uzywane\/","title":{"rendered":"New parts from surplus stock (new-old-stock) vs refurbished vs used \u2014 what to choose for a production machine?"},"content":{"rendered":"

A failed frequency inverter (VFD), power supply, or safety relay can bring an entire production line to a halt \u2014 and if the manufacturer has already discontinued the series, the standard distribution channel is no longer an option. Buyers and maintenance engineers are then left with three routes: brand new surplus stock parts<\/strong> (known as new-old-stock, NOS for short), refurbished components, and used parts. Each of these options has its place, but they differ in risk level, warranty, and certainty of origin. We compare them fairly \u2014 with no marketing spin.<\/p>\n

What are surplus stock parts (new-old-stock)?<\/h2>\n

New-old-stock components are brand new<\/strong>, never installed and never powered up. Where do they come from? Manufacturing plants and automation integrators buy more parts than they ultimately need: for projects whose scope later changed, as spares for machines that were subsequently upgraded, or as a stock buffer for the maintenance department. When a company clears out its warehouse or decommissions a line, these new, unused parts enter the secondary market \u2014 often still in their original packaging.<\/p>\n

On the surplus market you can therefore find, for example, drives from the SINAMICS or IndraDrive families, PNOZ safety relays, programmable safety controllers such as Flexi Soft, or power supplies from the PROmax series \u2014 exactly the same products that once sat on an authorized distributor's shelf. The difference lies in the route the part took to reach the buyer, not in its technical condition.<\/p>\n

The key distinction: new-old-stock is not the same as a refurbished or used part<\/strong>. These categories are often mixed up in listings, which is why it pays to know what to ask the seller.<\/p>\n

Three categories on the secondary market \u2014 definitions with no sugar-coating<\/h2>\n

Refurbished parts<\/h3>\n

These are components that have run in a machine and were then repaired: capacitors, fans, power transistors, bearings, or contacts were replaced. The quality of refurbishment depends entirely on the workshop \u2014 from the scope of replaced components, through load testing, to the repair documentation. A proper refurbishment by a specialized service center is a fully legitimate solution; an anonymous \u201crefurbishment\u201d limited to cleaning the housing is a different story altogether.<\/p>\n

Used parts<\/h3>\n

Components removed from running or scrapped machines and sold \u201cas is\u201d. No wear parts have been replaced, and the operating history \u2014 running hours, ambient temperature, overloads, short-circuit events \u2014 usually remains unknown. This is most often the cheapest option, but also the biggest unknown.<\/p>\n

Surplus stock parts (NOS)<\/h3>\n

Brand new (factory new), unused parts sourced from plant and integrator surplus. Their technical condition matches that of parts from regular distribution; the only points to check are storage conditions and \u2014 for electronics with electrolytic capacitors kept in storage for very long periods \u2014 the possible need for capacitor reforming, which is worth asking the seller about before first power-up.<\/p>\n

Comparison: surplus stock parts vs refurbished vs used<\/h2>\n\n\n\n\n\n\n\n\n\n
Criterion<\/th>\nNew from surplus (NOS)<\/th>\nRefurbished<\/th>\nUsed<\/th>\n<\/tr>\n<\/thead>\n
Certainty of origin and condition<\/td>\nHigh \u2014 the part has never been in operation; its condition can be verified against the nameplate number and photos of the specific unit<\/td>\nDepends on the service provider \u2014 requires repair documentation and a test report<\/td>\nLow \u2014 load and failure history is usually unknown<\/td>\n<\/tr>\n
Warranty<\/td>\nProvided by the surplus seller (at RECOSTOCK: 12 months)<\/td>\nDepends on the refurbishing company and the scope of repair<\/td>\nOften none, or only the seller's statutory liability<\/td>\n<\/tr>\n
Operational risk<\/td>\nComparable to a part from official distribution<\/td>\nModerate \u2014 depends on the quality of refurbishment<\/td>\nHighest \u2014 wear components are closer to end of life<\/td>\n<\/tr>\n
Availability<\/td>\nAlso covers discontinued series, as long as they circulate in surplus stock<\/td>\nGood for popular, high-value components (drives, spindles)<\/td>\nWide but random \u2014 depends on machine teardowns<\/td>\n<\/tr>\n
When to choose<\/td>\nCritical machines, safety systems, parts discontinued by the manufacturer<\/td>\nHigh-value components when NOS is unavailable and the service provider is credible<\/td>\nNon-critical machines, test rigs, limited budget<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

When surplus stock parts win<\/h2>\n

In two situations, the advantage of NOS is particularly clear.<\/p>\n

First: discontinued components.<\/strong> A machine's lifecycle is usually longer than the lifecycle of the electronics controlling it. The manufacturer ends support for a series and announces a successor \u2014 yet the machine still has to keep running. Replacing a drive with a newer generation often means changes to wiring, parameterization, and sometimes the supervisory software as well. A brand new (factory new) part from surplus stock, identical down to the part number (MPN), allows a true one-to-one replacement \u2014 with no modifications and no compatibility risk. This applies especially to drives and servo drives<\/a>, where firmware version compatibility and matching motor parameters genuinely matter.<\/p>\n

Second: safety system components.<\/strong> Safety relays and safety controllers \u2014 families such as PNOZ or Flexi Soft \u2014 are responsible for the effectiveness of a machine's safety functions. In devices with relay outputs, the switching endurance of the contacts (described by the B10d parameter) is consumed with every operation. With a used part, you never know how much of that service life is already gone; with a new part from surplus stock, the counter starts at zero. That is why, for safety circuits, it is sensible to choose brand new (factory new) components \u2014 you will find them among our safety controllers<\/a>.<\/p>\n

It is also worth adding to this list any machine whose downtime generates high costs: process bottlenecks, continuously running lines, machine tools with CNC electrospindles. There, saving money on a part with an unknown history rarely pays off.<\/p>\n

When used or refurbished parts make sense<\/h2>\n

To be fair: you do not always have to buy new. A used part can be a rational choice when:<\/p>\n