Reproducing a damaged part on a 1:1 basis simply replicates the flaw that caused it to fail in the first place. Root Cause Analysis (RCA), combined with advanced reverse engineering, makes it possible to identify and eliminate a component’s weak points—for example, by changing the fillet radius or using a more ductile grade of steel. As a result, the improved part can last up to three times longer than the original, providing a lasting solution to production downtime.

Table of contents

• Why is “making an identical replacement part” an engineering trap?
• What is Root Cause Analysis (RCA) in replacement-part manufacturing?
• From photocopying to Value Engineering: 40 years of EDBA experience
• The most common causes of failure in hydraulics and the rail industry
  • Geometric notches—the silent killers of shafts and axles
  • Selecting the wrong material for the actual operating conditions
• How does EDBA improve on the original? Real-life examples
• Comparison: 1:1 reproduction vs. Value Engineering with EDBA
• Tangible benefits for maintenance departments
• Frequently asked questions about RCA and reverse engineering

Why is “making an identical replacement part” an engineering trap?

When a sudden failure occurs at a manufacturing plant, time pressure is immense. A maintenance manager will often arrive at a service provider’s workshop carrying a cracked shaft, a stripped gear or a ruptured hydraulic-cylinder component and repeat the familiar words heard across the industry for years: “Make me an identical one.” Although the intention is understandable—the goal is to get the machine running again as quickly as possible—this approach is one of the most common engineering traps.

A famous quote attributed to Albert Einstein says: “Insanity is doing the same thing over and over again and expecting different results.” If the original part cracked after only six months in service, an exact copy—made from the same materials and replicating the same design flaws—will almost certainly fail after a similar period. At EDBA, we do not treat machining as a basic craft service or a “metal printer”. When we see a damaged component, the first question we ask is not “How quickly can we turn it?” but the more fundamental one: “Why did it fail?”

What is Root Cause Analysis (RCA) in replacement-part manufacturing?

Root Cause Analysis (RCA) is a structured, methodical process used to identify the underlying causes of design problems or overload events. Its purpose is to prevent a failure from happening again, instead of merely reacting to its immediate consequences. In the context of machine reverse engineering and component remanufacturing, RCA allows us to provide a much more advanced level of service.

While conventional reverse engineering focuses on accurately measuring a worn component with a micrometer, RCA seeks broader answers. It examines the component’s operating mechanics, the forces acting upon it, its working environment and the characteristics of the fracture itself—for example, fatigue cracking, shear failure or severe abrasive wear. This article is intended not only for veterans of the metalworking industry but also for people taking their first steps in maintenance planning and procurement. Put simply, RCA is a form of “detective investigation” that identifies the main culprit behind a failure so that it can be permanently eliminated when the new part is manufactured.

From photocopying to Value Engineering: 40 years of EDBA experience

With 40 years of experience in the industrial market, we know that genuine added value is created in the engineering department and in the engineer’s mind—not only at the spindle of a CNC machine. We transform straightforward component reproduction into Value Engineering. We determine whether precision turning with a redesigned fillet radius can protect a component from destructive material fatigue, or whether a modified heat-treatment method could radically increase its service life.

Industry engineering studies and machine-design literature indicate that as many as approximately 70% of mechanical failures affecting high-speed shafts and heavily loaded axles are caused by material fatigue at points of stress concentration. Understanding this makes it possible to eliminate a defect at the drawing-board stage, before the machining program for the replacement part is created.

The most common causes of failure in hydraulics and the rail industry

Components operating in uncompromising, extreme industrial conditions—such as rail infrastructure exposed to vibration or advanced hydraulic systems operating under enormous pressure—are subjected to constant dynamic loads. Below are two key reasons why original factory-made parts most often fail.

Geometric notches—the silent killers of shafts and axles

In mechanics, a notch is any abrupt change in a component’s cross-section. It may take the form of a sharp undercut, a keyway, a thread or a lubrication hole. Stress becomes concentrated around these features. If the original manufacturer designed a sharp right-angle transition instead of a smooth fillet radius that distributes the forces, it is only a matter of time before a fatigue crack begins at that point and ultimately causes the component to fracture.

Selecting the wrong material for the actual operating conditions

Engineering offices designing mass-produced machines often select steel based on standardised, theoretical calculations for ideal conditions. In doing so, they may overlook micro-vibrations, random impacts, contamination or operator error. Using a very hard but brittle steel for a component subjected to bending is a mistake. Under such conditions, steel with slightly lower core hardness but considerably greater ductility is often a much better solution.

How does EDBA improve on the original? Real-life examples

We always look for a better solution. The following examples show how our approach to Value Engineering and Root Cause Analysis translates into tangible success on our partners’ production floors.

Example 1: Reducing stress by changing the radius and removing the notch

Several years ago, a processing plant approached us with a thick, fractured drive shaft. Every 8–10 months, on average, its failure brought an entire section of the plant to a standstill and required a costly replacement. A visual examination of the fracture surface revealed classic fatigue lines and a final overload fracture zone radiating from a very sharp change in shaft diameter.

We resolved the problem by redesigning this critical area. Instead of retaining the sharp, right-angle transition, we calculated and introduced a smooth fillet radius. Producing it required advanced multi-axis CNC milling with precisely profiled cutting tools. The engineering outcome? Smoothing and removing the sharp notch distributed the stress across a much larger surface area. The new, improved part has now been operating continuously for nearly three years without a single failure. It has lasted more than three times longer than the “catalogue original”.

Example 2: Changing to a more ductile grade of steel

While remanufacturing components for advanced hydraulic systems, we encountered the problem of cylinder-mounting pins that repeatedly cracked. The original parts were made from case-carburised, extremely hard—and therefore very brittle—steel. During the operation of excavators and presses, the system transmitted aggressive impact loads. The hard steel responded like tempered glass struck with a small hammer: eventually, it snapped in two.

Our engineering team completely revised the material assumptions. We replaced the steel with a grade offering very high core ductility and resilience. At the same time, we achieved the required surface finish and protective properties through precision CNC grinding performed after specialised surface induction hardening. Only the outer layer, a fraction of a millimetre thick, was hardened. The pin regained the flexibility and capacity to absorb micro-impacts without the risk of sudden fracture.

Comparison: 1:1 reproduction vs. Value Engineering with EDBA

Feature or parameter	Replicating the original’s mistakes—the “photocopy” method	Value Engineering with EDBA using RCA
Failure-cause analysis	None. Machining begins on the basis of the old dimensions.	Detailed diagnosis of the fracture type, loads and wear.
Component geometry	Defective features and sharp notches are reproduced.	Sharp transitions are redesigned with appropriate radii, and the profile is optimised to reduce stress.
Material selection and treatment	The same steel—or simply the first available grade—is used.	The grade is deliberately selected, for example for greater ductility, and combined with modern heat or surface treatment.
Service life and total cost of ownership (TCO)	Short service life and recurring costs caused by major production downtime.	Service life extended by up to three times. A one-off engineering investment delivers long-term maintenance savings.

Tangible benefits for maintenance departments

When you contact an external partner as a maintenance manager to reproduce an emergency replacement part, you are not simply buying a piece of metal. You are buying machine availability, peace of mind and maximum production-line uptime. By treating a machining company as an engineering centre, you can deliver substantial financial and operational benefits to your plant:

• Higher MTBF (Mean Time Between Failures): New parts are free from the original design flaws, so they operate reliably for noticeably longer and extend the interval between failures.
• Substantial cost savings: You avoid buying five identical shafts that will fail repeatedly over the years. Instead, you invest once in a component with improved specifications, quickly reducing one of a plant’s largest expenses—the cost of unplanned machine downtime.
• Time for prevention instead of constant firefighting: When critical machine assemblies are fitted with components you can trust, your skilled maintenance team finally has the capacity to focus on preventive and predictive maintenance instead of repeatedly dismantling the same gearbox in a rush.

Frequently asked questions about RCA and reverse engineering

1. From a technical perspective, how does reverse engineering with RCA differ from simply reproducing a component?
   Conventional reproduction involves measuring the damaged part—as accurately as its deformation allows—and transferring those dimensions to a lathe. Reverse engineering combined with Root Cause Analysis examines why the part failed and deliberately changes its dimensions, such as by increasing an internal radius, or modifies the manufacturing technology to eliminate the original’s hidden defect.
2. Does improving a part on the basis of RCA significantly extend the delivery time?
   An engineering diagnosis, force analysis and selection of a new material grade naturally take slightly longer than making a “blind copy” of the component, so the first replacement may require more time. This should, however, be viewed strategically: the modest additional lead time pays for itself several times over by preventing further downtime in the months ahead.
3. Is using a different material from the original safe for the rest of the machine?
   Yes, provided the change is handled by an experienced manufacturing engineer. At EDBA, we always verify friction pairs and mating components. If we change the material used for a pin, we make sure that the new structure will be more durable without aggressively wearing or damaging the mating seats or bearings. Maintaining the right hardness balance is essential in Value Engineering.
4. Which industries benefit most from improving replacement parts?
   Companies dealing with heavy loads, vibration and impact achieve the fastest return on this investment. These include the rail and extractive industries—such as mining and aggregates—as well as heavy-duty hydraulic applications, where standard solutions fail under real-world operating loads.