A CMM machine's probe being used to measure a precision machined component

Navigating the complexities of Inconel 718 is a well-known challenge in the manufacturing sector. This high-strength nickel-chromium alloy is prized for its exceptional resistance to extreme temperatures and corrosion, making it a staple in aerospace and other high-tech industries. However, its machinability is another story. A leading aerospace technology firm learned this the hard way when their precision-machined Inconel 718 parts displayed unexpected dimensional discrepancies. Despite leaving Lampin Corporation’s facilities meeting all specifications, the measurements didn’t align upon arrival at the client’s site.

The Challenges of Precision Machining Inconel 718 

Inconel 718 is a nickel-chromium alloy known for its exceptional high-temperature strength, corrosion resistance, and ability to withstand extreme environments, making it indispensable in aerospace, power generation, and chemical processing industries. Its unique composition includes niobium, molybdenum, and titanium, which contribute to its strength via precipitation hardening. This hardening process enhances the material’s mechanical properties at temperatures up to 700°C (1290°F), allowing it to maintain integrity under high stress and in corrosive environments.

Machining Inconel 718 involves navigating several challenges due to its work-hardening properties and high shear strength. These characteristics can lead to significant tool wear and tear, making conventional machining practices inefficient and costly.

  • Tool Wear: The high hardness and strength of Inconel 718 cause rapid tool wear, necessitating the use of carbide or ceramic tools that can withstand the material’s abrasive nature. Advanced coatings on tools, such as titanium aluminum nitride (TiAlN), can further extend tool life by minimizing wear.
  • Work Hardening: Inconel 718 work-hardens rapidly during machining, which can lead to increased cutting forces and a higher risk of tool failure. Adopting slow cutting speeds and heavy, constant feeds can help mitigate work hardening and maintain consistent machining conditions.
  • Heat Generation: The machining of Inconel 718 generates considerable heat, which can affect the tool’s life and the material’s surface integrity. Effective cooling strategies, such as high-pressure coolant systems, are crucial to dissipate heat and prevent thermal damage to both the workpiece and the tool.

Strategies for Machining Inconel 718

To address these challenges, precision machining of Inconel 718 requires a strategic approach:

  • Optimized Tool Selection: Utilizing tools made from robust materials such as polycrystalline diamond (PCD) or cubic boron nitride (CBN) with appropriate coatings can significantly reduce wear and improve machining efficiency.
  • Controlled Machining Parameters: Adjusting cutting speeds, feeds, and depths of cut to optimize the balance between productivity and tool life is critical. Lower speeds and higher feeds can reduce work hardening and extend tool life.
  • Advanced Machining Techniques: Techniques such as high-speed machining (HSM), cryogenic machining, and ultrasonic-assisted machining (UAM) can improve the machinability of Inconel 718 by reducing cutting forces, minimizing heat generation, and enhancing surface finish.

Lampin Gets Hands-On In A Technical Deep Dive

The parts were meticulously machined and measured, quality checked, and confirmed. But by the time the components arrived, something had changed. The customer’s receiving inspections produced different, sometimes drastically different, measurements. What could be causing this sudden, seemingly impossible shift in part dimensions? This mystery needed a solution ASAP, so Lampin’s engineers went to work. 

Lampin Corporation didn’t just give these parts a once-over; they delved deep into the details to understand every step of the process. Their reevaluation of the parts was an exhaustive exercise in precision measurement, ensuring each piece adhered to micron-level accuracy. Lampin’s meticulous approach reaffirmed that the parts were flawless as per the specifications, indicating the problem lay elsewhere. 

Collaborative Problem-Solving On-Site

The journey to resolution led Lampin’s team to the client’s facility to witness the measurement process in action. This collaborative approach was key in diagnosing the issue. The culprit? The client’s internal measurement process, specifically how the parts were held during the inspection. Even a fraction of a millimeter can cause measurement discrepancies, so the team resolved to collaboratively correct the inspection process to ensure accurate results every time.

Once the cause was identified, the customer welcomed Keith, Lampin’s Director of Operations and a seasoned precision manufacturing expert, to their facility to consult on the inspection. Keith’s approach wasn’t just theoretical; he worked hands-on with the client’s engineers, sharing insights on advanced fixturing and metrology techniques, crucial for accurately measuring complex components. His evaluation of the production line led to process optimizations that significantly enhanced efficiency without compromising quality.

Engineering Excellence and Partnership

This story is a masterclass in problem-solving and client partnership for anyone in engineering and manufacturing. Lampin showed that they’re not just about making parts; they understanding the nuances of materials like Inconel 718 and how to work with them under the strictest tolerances. Their commitment to troubleshooting and optimizing their client’s processes shows a level of dedication that’s rare in the supplier world.

This story is a reminder of the immense value a supplier like Lampin brings. They are more than just a provider of parts; they are a source of expertise, training, and process improvement. This experience underscores the importance of choosing a manufacturing partner with the expertise to tackle challenges head-on. Lampin isn’t just a supplier; they’re a pivotal part of your team.

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