In a high-pressure system, the smallest flaw can become the biggest risk. For Schneider Electric’s Foxboro differential pressure transmitters, stainless steel plugs may appear to be simple hex-shaped parts with a vent option. However, they play a critical role in ensuring safety, accuracy, and reliability in tough operating environments like refineries, chemical plants, and power stations.

Schneider Electric provides an economical pressure transmitter designed for applications demanding an accuracy of ±0.075% of span and featuring SIL2 certification as standard. This robust design also boasts exceptional stability, with drift of less than ±0.05% URL/Yr for 5 years.

Inside these transmitters, every component has a job to do. For these precision plugs, this means:

  • Safety in Assembly: Avoiding sharp edges that could injure operators or complicate installation.
  • Integrity in Sealing: Ensuring that even the tiniest flaw doesn’t compromise the seal, which is vital for high-pressure measurements.
  • Reliability in Operation: Eliminating machining burrs that could result in sliced sensor wires, preventing accurate function and causing unwanted downtime.

The Foxboro line also leverages FoxCal dynamic technology, which includes 11 calibration curves in a single transmitter. This allows the device to automatically switch to the most accurate curve based on input, enhancing performance. Furthermore, the combination of enhanced turndown and FoxCal technology can reduce inventory stock by two-thirds—a significant logistical and cost benefit. These transmitters are also designed for easy integration, compatible with both Field Device Tool (FDT) and Field Device Interface (FDI) technology.

Early Hurdles: When Sharp Edges Create Risk

When Schneider Electric approached MES with their new plug design, expectations were clear: deliver flawless parts, produced at scale, with zero margin for error. They required high-volume production across eight different part numbers, with absolute confidence in quality.

But early production runs revealed hidden burrs in two critical locations. These defects raised immediate concerns about the final product’s ability to maintain its TÜV SIL2/SIL3 safety certification and overall operational reliability.

What followed was a story our team knows well. It’s a story of collaboration, innovation, and rapid problem-solving that turned a machining challenge into proof of MES’s ability to deliver precision without compromise.

The Challenge: Eliminating Risk

From the start, our quality and engineering teams knew that the machiningwould be demanding.

Working with 3/16-inch stainless steel hex stock on a Tsugami Swiss Lathe meant burr control would be a constant battle. And in this application, perfection wasn’t option – it was mandatory.

Two details required immediate attention:

  • Vent hole burrs: The 1/8-inch side hole left a burr in the plug’s center. Though small, it was dangerous because the sharp edges could slice wires during assembly and affect performance.
  • Thread-start burrs: The requisite cutoff left a sharp edge at the start of the outside diameter thread. This could lead to both operator safety issues and possible seal failures.

As our Matthew Perry, MES Quality and Engineering, put it: “These weren’t cosmetic issues. They were showstoppers.”

The Solution: Rethinking Processes

At first, inspection was manual. Operators spotted burrs by eye and cleaned them up on a belt grinder. It worked, but only in the short term. It was slow, inconsistent, and not sustainable for thousands of parts. What we needed was a fix we could trust at value.

So we went back to basics: Own the problem, rethink the process, and scale the solution.

Reordering the Machining Sequence

First, we solved the vent hole problem by simply flipping the cut order. Instead of drilling the large interior diameter hole first, we started with the 1/8-inch vent hole and then followed with the larger drill. That single change let the bigger tool wipe out the burr so we were left with a smooth surface (and no more sensor wire cuts).

Redesigning the Cutoff Path

Next, we fixed the thread burr by fixing the coding in the machine. We reprogrammed the cutoff to create a smoother handoff instead of a sharp break. That small change removed the edge and improved both safety and sealing.

Optimizing the Swiss Lathe

Once tuned, the Tsugami Swiss Lathe became a true advantage. We dialed in feed rates, tool paths, and engagement. Six-foot hex bar went in, two-inch blanks came out, and parts came out fast and consistent.

Modernizing Inspection

We already knew that manual checks weren’t the answer, so we introduced an optical comparative vision system. This system is much like a digital camera, in that it flips the part into a negative, checking dimensions instantly. This meant that operators could validate parts in real time. As a result, inspections sped up, and both consistency and confidence soared.

Sharing Knowledge Globally

Because MES is committed to delivering value-added solutions to organizations worldwide, once we proved these changes, we didn’t keep them local. Instead, we shared our revamped processes from Mexico to India to China. Every facility working on similar parts benefits, giving our customers supply chain continuity they can rely on.

The Results: Safety, Confidence, and Scale

These changes paid off immediately:

  • Eliminated burrs: Assemblers could handle parts safely. Seals held under pressure.
  • Sped up inspection: The vision system cut time and removed operator guesswork.
  • Scaled production: Output jumped to meet demand without sacrificing precision.
  • Reinforced customer trust: On a joint call, Schneider’s engineers even suggested extra checks on the fly, which is a clear sign of collaboration among our team and theirs.

 As Matt explains, “We didn’t just patch a problem. We engineered a trusted system we can replicate.”

The Impact

For Schneider, the result was far more than just burr-free plugs. It was confidence in MES as a partner who responds quickly and takes responsibility.

For us, the project further sharpened our capabilities. We refined stainless hex stock machining, fine-tuned Swiss Lathe programming, and modernized inspection.

Those lessons now fuel other high-volume, high-precision projects for customers with demanding needs.

“It was a new product, a new material, and a new machine,” says Matt. “We had every reason for this to be difficult. Instead, we turned it into a success story that now benefits Schneider worldwide.”

5 Lessons Learned

  1. Order matters: Changing the cut sequence solved a major issue.
  2. Code counts: Small path changes can drive big gains.
  3. Inspection must evolve: Manual checks don’t scale. Digital systems do.
  4. Sharing multiplies value: Once a revised process works, replicate it.
  5. Responsiveness builds trust: Owning the problem strengthens partnerships.

Conclusion

What started as a burr problem became proof of what happens when engineering know-how and customer collaboration align. By reworking machining processes, enhancing programming, and upgrading inspection, MES delivered parts that met Schneider’s highest standards for safety, consistency, and scale.

For Schneider, it means a reliable supply of a critical part. For MES, it reinforces our belief that persistence and ownership turn challenges into best practices.

Ready to raise the standard for critical components? Contact MES today.

Key Metrics

Parts involved: 8 unique part numbers across the plug family

Material: 3/16-inch stainless steel hex stock

Equipment: Tsugami Swiss Lathe with optimized programming and tool paths

Volumes: Doubled the scale

Inspection: Optical comparative vision system implemented for digital, real-time checks

Global reach: Process improvements shared across facilities in Mexico, India, and China

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