Supply Chain Reliability and Quality Traceability in Critical Applications

Sesco Industries has built its reputation on a simple principle: small components often carry enormous responsibility. In many mechanical systems, a single set screw secures rotating shafts, locks critical adjustments, and ensures that assemblies maintain alignment under load. When those fasteners fail, the consequences can range from costly downtime to complete system failure.

In recent years, manufacturers across industries have been reminded that where fasteners are made matters just as much as how they are made. Domestic fastener manufacturing continues to play a critical role in ensuring supply chain reliability, quality traceability, and consistent engineering performance.

The Supply Chain Reliability Advantage

The global supply chain disruptions experienced over the past several years exposed vulnerabilities in relying exclusively on overseas sourcing for critical components. Shipping delays, port congestion, geopolitical tensions, and raw material shortages all created uncertainty for manufacturers dependent on imported fasteners.

Domestic suppliers like Sesco Industries help mitigate these risks by offering:

• Shorter Lead Times: Manufacturers can access set screws and specialty fasteners without waiting months for international shipments. Domestic production allows companies to respond quickly to production demands and engineering changes.
• Greater Supply Stability: Local manufacturing reduces exposure to transportation disruptions, tariff changes, and international logistics complications.
• Inventory Flexibility: Domestic suppliers can often provide smaller batch production or rapid replenishment, allowing manufacturers to maintain lean inventories while avoiding production stoppages.

For industries that operate on tight production schedules—such as automation, packaging equipment, marine systems, and heavy machinery—this reliability is invaluable.

Quality Traceability: A Growing Requirement

Quality traceability has become increasingly important in industries where documentation and compliance are essential. Engineers and procurement teams often need detailed records of materials, manufacturing processes, and inspection protocols.

Domestic manufacturers are typically better positioned to support these requirements.

Working with a supplier like Sesco Industries allows companies to maintain clear documentation regarding:

• Material certifications
• Heat treatment records
• Dimensional inspection reports
• Lot traceability for each production run

This level of documentation ensures that fasteners meet specified standards and can be traced back through the production process if necessary.

For applications in regulated industries—such as defense, aerospace, energy, and transportation—traceability is not optional; it is mandatory.

Engineering Consistency and Process Control

Domestic fastener manufacturers also provide an advantage in process transparency and engineering collaboration.

When design engineers work with a domestic supplier, they often gain direct access to technical expertise. This collaboration can help address issues such as:

• Selecting the correct set screw point style
• Determining proper hardness and material specifications
• Preventing shaft damage or vibration-related loosening
• Improving holding power in high-load environments

Because the manufacturer is geographically accessible, engineering teams can communicate more effectively and resolve issues faster than when working through international supply chains.

Supporting American Manufacturing

Choosing domestic fasteners does more than improve reliability—it supports the broader industrial ecosystem. Domestic manufacturers sustain skilled labor, maintain production capabilities, and invest in modern equipment that strengthens the overall manufacturing base.

Companies like Sesco Industries continue to play an important role in ensuring that high-quality industrial fasteners remain available from trusted domestic sources.

The Bottom Line

Fasteners may be small components, but their role in mechanical reliability is significant. When engineers and procurement teams evaluate suppliers, factors such as supply chain resilience, quality traceability, and engineering support should weigh heavily in the decision.

Domestic manufacturers offer a clear advantage in all three areas.

By partnering with experienced suppliers like Sesco Industries, manufacturers gain not only a reliable source of precision set screws but also a trusted partner committed to quality, transparency, and long-term supply stability.

On July 5, 2020, the bulk carrier Atlantic Huron was approaching the Soo Locks (Sault Ste. Marie, Michigan) when the crew ordered astern to slow the vessel. Instead, the ship’s propulsion system experienced a failure that caused it to move ahead with increasing speed, ultimately resulting in a $2.2 million accident.

The National Transportation Safety Board (NTSB) traced the event back to a deceptively small component: a set screw in the vessel’s controllable pitch propeller (CPP) pitch-control mechanism. According to the NTSB, the set screw backed out and post-accident examination found no evidence of manufacturer-required thread-locking fluid—a detail that set off a chain of mechanical failures.

This is exactly the type of high-consequence scenario where fastener selection, installation discipline, and retention strategy matter—and where companies like Sesco Precision, as a supplier of industrial screws and set screws, can help customers reduce risk by specifying the right retention approach for the application.

What the NTSB Found: How a Set Screw Failure Became a Propulsion Control Failure

In a CPP system, blade pitch changes direction and speed. The NTSB report explains that a set screw intended to secure a locking pin in the feedback mechanism backed out, allowing the locking pin to also back out and damage components inside the oil distribution (OD) box.

Two key details from the investigation stand out:

1. The original equipment manufacturer required thread-locking fluid when installing the set screw (to prevent it from backing out).
2.  Technicians found no evidence that thread-locking fluid had been applied the last time the set screw was removed and reinstalled (maintenance records indicated that work occurred years prior).

The result wasn’t just a loose screw—it was a system-level failure where the vessel could command astern while propulsion behavior effectively went the opposite direction, complicating decision-making on the bridge.

The Real Lesson: Fasteners Don’t “Fail” in Isolation—Processes Do

Most maintenance teams understand torque values, locking compounds, and best practices. The challenge is consistency—especially across:

• Shipyard periods with many trades touching the same equipment.
• Time gaps measured in years between disassembly and “the day it matters.”
• Vibration, thermal cycling, and oil exposure that can degrade retention over time.

 The NTSB’s probable cause statement points directly to not following the manufacturer’s requirement to use thread-locking fluid during installation.
That framing is important: in high-consequence systems, installation method is part of the design.

Where Set Screw Retention Commonly Breaks Down

Here are the most common “failure pathways” seen across industrial and marine environments:

1) Threadlocker is specified—but not applied (or applied incorrectly)

Threadlocker is process-sensitive: surface condition, oil contamination, cure time, and correct grade all matter. If it’s skipped—or applied to contaminated threads—it may not perform as intended.

2) The application needs more than one retention method

Some assemblies benefit from redundancy: mechanical locking + chemical locking, witness marking + inspection intervals, etc. (Always align to OEM guidance and class requirements.)

3) Procurement substitutes “equivalent” fasteners without an equivalent retention strategy

A set screw can match thread size and material and still be wrong if it lacks the retention feature the design assumed (patches, pellets, locking elements, point style, etc.).

How Sesco Precision Can Help Reduce Risk with the Right Set Screw Options

Sesco Precision (as a fastener supplier) can support customers by providing set screws and retention-ready configurations that align with demanding applications—especially when the maintenance reality is “high vibration + limited access + long intervals.”

Examples of retention strategies that are commonly used to help resist loosening (application-dependent):

Pre-applied locking features

• Pre-applied threadlocker coatings/patches (helps standardize application and reduce “missed step” risk in the field).
• Nylon pellet / nylon patch style locking (prevailing torque style retention).

Point style and engagement considerations

• Cup, cone, dog, and flat points each behave differently in how they bite/seat and how they resist motion under load and vibration.
• Matching point style to the mating surface can improve holding performance and reduce fretting.

Material and corrosion compatibility

In marine environments, galvanic corrosion and material compatibility matter. The “right” screw is not only about strength, but also about how it behaves over time in the actual service environment.

Important note: No supplier can honestly promise a single product would have prevented a specific accident—because prevention depends on correct specification, installation, verification, and maintenance practices. But selecting retention-ready fasteners and standardizing the locking method can materially reduce the probability of loosening-related issues in many real-world applications.

A Practical Prevention Checklist for CPP and Other Mission-Critical Mechanisms

If you want a simple, field-usable way to turn this lesson into action:

1. Treat threadlocker as a controlled step: Confirm the OEM requirement, specify the product/grade, and define surface prep.
2. Standardize the fastener + retention method: Reduce “tribal knowledge.” Use controlled part numbers and kitting where possible.
3. Add verification, not just installation: Witness marks, torque stripe, second-person check, or sign-off steps for critical assemblies.
4. Document what was used: Not just “installed,” but “installed with ____ threadlocker / ____ locking feature.”
5. Source the right fastener the first time: Work with suppliers like Sesco Precision to ensure the screw, locking method, material, and point style match the application.

Small Parts, Big Consequences

The Atlantic Huron accident is a sharp reminder that a low-cost fastener can sit upstream of multi-million-dollar consequences when it’s part of a control mechanism. The NTSB’s findings reinforce a truth every maintenance and reliability team already knows—until they’re forced to relearn it:

In critical systems, fasteners are not “hardware.” They’re engineered risk controls.

If you’re reviewing your own propulsion control mechanisms, steering systems, or other safety-critical assemblies, Sesco Precision can be positioned not just as a seller of screws—but as a supplier that helps you spec the correct set screw and retention strategy so “small” never becomes “catastrophic.”

In the high-flying world of aviation, where a single miscalculation can have catastrophic consequences, every component is critical. We often marvel at the powerful thrust of a jet engine, the sleek design of a fuselage, or the complex avionics in the cockpit. But beneath the surface, a vast network of smaller, often unseen parts works in perfect harmony to ensure a safe and successful flight. Among these, the set screw stands out as a true unsung hero.

From Mach Speed to Mach Precision

Jet engines, whether powering a jumbo jet on a transcontinental flight or a fighter jet at supersonic speeds, are engineering marvels. They operate in a brutal environment, subjected to extremes of temperature and pressure. The combustion chambers can reach temperatures of over 3,000°F, while the turbines spin at tens of thousands of revolutions per minute (RPMs). This incredible rotational speed generates immense vibration—a constant, rhythmic assault on every part within the engine.

This is precisely why a simple fastener like a set screw takes on monumental importance. Unlike a standard bolt or screw that joins two separate parts, a set screw is designed to hold a single component relative to another. It typically has a headless design and is threaded into one part to apply pressure against the surface of a second part, locking it in place. In an engine, this function is used to secure critical components like:

• Sensors: Ensuring they remain in precise alignment to provide accurate readings on everything from temperature to pressure. A loose sensor can give false data, leading to engine performance issues.
• Fuel control modules: Maintaining the exact position of these parts is vital for regulating the flow of fuel, which directly impacts efficiency and power.
• Balancing weights: Used to fine-tune the balance of rotating parts to minimize destructive vibration. If a set screw holding a balancing weight loosens, the resulting imbalance can lead to catastrophic failure.

Engineered to Endure: The SESCO Precision Difference

At SESCO, we understand that a standard screw won't cut it in the aerospace industry. Our set screws are not mass-produced; they are meticulously engineered to perform under the most demanding conditions. This process begins with material science. We select high-strength alloys that can withstand the extreme temperatures and corrosive environments found inside a jet engine.

The journey from a raw piece of metal to a flight-ready component involves a series of advanced manufacturing techniques:

• Heat Treatments: We use specialized heat treatment processes to alter the material's properties, increasing its hardness and resistance to wear and fatigue. This ensures the screw can handle the constant stress without deforming or breaking.
• Precision Machining: Each screw is machined to incredibly tight tolerances. The precision of the threads is crucial for creating a secure, vibration-resistant connection.
• Thread-Locking Features: To combat the relentless vibration, we incorporate advanced features like specialized coatings or pre-applied thread-locking patches. These features create additional friction and adhesion, ensuring the set screw remains locked in place, even under the most punishing conditions.

In aviation, there is no room for compromise. A mission's success, and the safety of everyone on board, depend on the reliability of every single part. The humble set screw, designed and built for absolute endurance, is a testament to this principle. At SESCO, we're proud to be part of the mission, one small, yet vital, component at a time.

Ready to elevate your engineering standards? When precision, durability, and safety are non-negotiable, trust the experts who treat every detail like a mission-critical component. Discover how SESCO's aerospace-grade set screws can transform your next project from reliable to remarkable.

Contact us today to learn more or request a custom solution—because in aviation, there’s no such thing as “just a screw.”

Set screws may be small, but they play an outsized role in securing components across industrial, mechanical, and aerospace applications. Their performance—and the reliability of the system they support—depends heavily on the type of locking mechanism selected. The right locking feature prevents loosening, reduces maintenance, improves safety, and ensures long-term stability under load and vibration.

Below is a comprehensive, professional overview of the most common locking mechanisms for set screws, including the increasingly popular plastic strip locking mechanism, and how to determine the best option for your application.

1) Standard (Non-Locking) Set Screws

Standard set screws rely solely on thread friction and the geometry of the point type (cup, cone, flat, etc.) to hold position.

Advantages

• Cost-effective
• Widely available
• Suitable for static assemblies with minimal vibration

Limitations

• Most prone to loosening under vibration
• May require an additional locking method for dynamic equipment

2) Nylon Patch (Pre-Applied Coating)

A nylon or polymer patch creates prevailing torque by adding friction to the screw’s threads.

Advantages

• Excellent vibration resistance
• Clean, pre-applied solution—no additional hardware
• Suitable for high-volume production
• Partially reusable

Common Uses

• Industrial machinery
• Electronics
• Assemblies with moderate vibration

Considerations

• Increased installation torque
• Not ideal for high-temperature environments

3) Nylon Pellet (Radially Inserted Locking Element)

A nylon pellet is inserted into a drilled hole in the screw, providing consistent resistance throughout the tightening and adjustment process.

Advantages

• Highly repeatable and adjustable
• Does not damage mating threads
• Provides reliable prevailing torque

Common Uses

• Precision assemblies
• Valves and instrumentation
• Adjustable mechanisms

Considerations

• Higher cost than standard or patch screws
• Lower surface coverage than a full patch, but more consistent for repeated adjustments

4) Strip Locking Mechanism (Plastic Locking Strip)

The strip locking mechanism incorporates a plastic strip—typically made from engineered polymers—inserted longitudinally along the screw threads. As the set screw is installed, the strip compresses and creates continuous friction between the screw and mating threads.

Advantages

• Provides strong, consistent prevailing torque without adhesives
• Fully polymer-based, offering smooth adjustment without damaging mating threads
• More thermally stable than nylon patches in moderate heat ranges
• Highly reusable—strip returns to form after tightening
• Excellent for assemblies requiring frequent adjustments

Common Uses

• Aerospace and defense hardware
• Instrumentation and metering systems
• High-vibration environments
• Applications where nylon pellets do not provide enough surface engagement

Considerations

• Higher cost compared to standard locking features
• Requires precise installation during manufacturing
• Temperature limitations depend on polymer grade

5) Mechanical Locking Through Geometry (Cup, Cone, Knurled, Serrated)

These locking mechanisms rely on the point shape to physically engage the mating surface.

Point Types

• Cup Point: Balanced holding strength; most common
• Cone Point: Maximum penetration for secure engagement
• Knurled or Serrated Cup: Increased bite for vibration resistance

Advantages

• Strong mechanical holding force
• Ideal for torque transfer applications

Common Uses

• Collars, pulleys, gears
• Power transmission components

Considerations

• Can damage softer shafts
• Not ideal when frequent adjustments are needed

6) Chemical Threadlockers (Liquid Adhesives)

Liquid anaerobic adhesives cure between the threads, creating a chemical bond.

Advantages

• Strong resistance to vibration
• Seals threads against corrosion
• Available in low-, medium-, and high-strength formulas

Common Uses

• Field repairs
• Applications where pre-applied locking features are unavailable

Considerations

• Adds steps to the assembly process
• Requires curing time
• Less repeatable than pre-applied locking features

Choosing the Right Locking Mechanism

Consider Vibration Level

• High vibration: nylon patch, plastic strip, nylon pellet
• Low vibration: standard set screws may suffice

Adjustment Frequency

• Frequent adjustments: pellet or plastic strip
• Permanent setting: threadlocker or cone point

Material Compatibility

• Soft shafts: avoid aggressive mechanical points

Environmental Factors

• Temperature, chemical exposure, and installation torque all influence selection

Conclusion

Set screws may be fundamental components, but choosing the right locking mechanism is essential for ensuring performance, preventing loosening, and protecting critical assemblies. From nylon patches to plastic strip locking systems, each option serves a specific purpose—and selecting correctly can dramatically improve reliability and reduce long-term maintenance.