Converting Conversations | Episode 5 Recap: Understanding Slitting Shaft Types

In the precision-driven world of web converting, selecting the correct slitting shaft types is crucial for efficient winding, consistent edge profiles, and long-term performance. In this episode of Converting Conversations, Catbridge Machinery dives into the three most widely used shaft technologies: lock core, direct friction differential, and cam lock differential shafts.

Each shaft type has unique design characteristics, torque capabilities, and ideal applications. Here’s how they compare and where each excels.

Lock Core Shafts: Versatile Simplicity

Lock core shafts are a go-to for many converting operations due to their simplicity and effectiveness. They are available in multiple configurations such as:

• Leaf Shafts: These use expanding metal leaves that open concentrically when inflated, providing excellent core grip without “starring” the material. They are perfect for thin cores, narrow cuts (such as one-inch widths), and applications requiring minimal buildup variation.
• Multi-Bladder Shafts: These are lightweight and easy to maintain. Ideal for single-slit applications or where caliper consistency isn’t critical between slit lanes.

Catbridge demonstrates that lock core shafts are highly effective for stripping liners and running materials cast onto liners, especially when big diameters and limited slit lanes are involved.

Direct Friction Differential Shafts: Precision for Narrow Cuts

Direct friction shafts offer enhanced accuracy for narrower slit widths and are often used in applications requiring quick, repeatable core placement. One key advantage is the core strip system—a machined strip with preset widths (e.g., 1″, 2″, 3″) that allows fast setup without spacers or accumulated tolerances.

This shaft uses a segmented air pressure system to adjust torque per section. Catbridge pairs this with a proprietary mixed-mode tension control program, offering remarkable results for narrow cuts even with large roll diameters. These shafts shine when you’re working with products in the half-inch to two-inch range.

However, direct friction shafts are not as precise as cam lock differentials when dealing with high-caliper variation. They’re better suited for products requiring medium to high tension and not ideal for ultra-thin films.

Cam Lock Differential Shafts: Pure Precision and Load Capacity

Cam lock shafts are considered the most “pure” differential system. They are robust and capable of handling a wide range of materials—films, papers, and laminates—while delivering high tension accuracy.

Most cam lock systems are built on a 60mm base for 3″ diameter shafts. As machines get wider, shaft deflection becomes a concern. Catbridge notes that shaft deflection may mimic caliper variation and mislead troubleshooting unless center supports are used for wide or heavy rolls.

These shafts are best for cuts of 3″ and above. While narrower cuts are possible, they require precise core ring placement and setup. They’re ideal for runs that demand consistent tension, tight edge profiles, and wide format configurations.

Final Thoughts

There is no one-size-fits-all slitting shaft. That’s why Catbridge Machinery stocks and supports all major types—lock core, direct friction, and cam lock—so customers can get the best fit for each application. Their in-house lab and floor-testing capabilities ensure the recommended solution works before going into production.

For operators and engineers, understanding the differences in slitting shaft types can help reduce downtime, improve cut quality, and maximize performance.
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Watch the Full Episode

Want to see the breakdown in action? Watch the full episode for Understanding Slitting Shaft Types here!