Converting Conversations | Episode 4 Recap: Understanding Cam-Lock Differential Shafts

When it comes to slitting and rewinding, rewind shaft selection can significantly impact roll quality, tension control, and overall production efficiency. In Episode 4 of Converting Conversations, we explore three key types of rewind shafts used on slower or center winders—and take a closer look at the features and functionality of cam-lock differential shafts.

The Three Main Types of Rewind Shafts

In many converting applications, rewind shafts typically fall into one of three categories:

• Locked-Core Shafts – These mechanically grip the core and rotate at a fixed speed.
• Pure Differential Shafts – These allow for variable speeds across slit rolls, accommodating differences in tension or diameter buildup.
• Friction-Style Differential Shafts (e.g., Cam-Lock) – These offer slip control through mechanical friction, ideal for specific materials or varying web tensions.

Each shaft type has a role depending on the material, slit width, buildup ratio, and other application-specific variables.

Why Use a Cam-Lock Differential Shaft?

A cam-lock differential shaft is a type of friction-style differential rewind shaft. Unlike locked-core shafts, which treat every roll the same, cam-locks allow for slight variances in roll behavior—without sacrificing overall consistency. This makes them an excellent choice for applications where even small tension differences across rolls can lead to issues like telescoping or poor edge quality.

Key advantages of cam-lock differential shafts include:

• Slip control across multiple slit rolls
• Better adaptability for varying materials and roll widths
• Improved tension balance during rewinding
• Ease of switching between product types without changing shaft hardware

“We have customers who switch between differential and locked-core shafts depending on the product they’re running,” notes Michael Pappas in the episode. “There’s not one shaft that’s always right—it really comes down to the application.”

Flexibility Is the Key

One major takeaway from the episode is that no single rewind shaft fits every scenario. Many converters benefit from having multiple shaft types available, using locked-core for consistent runs and cam-lock differential shafts when greater flexibility or tension control is needed.

For operations handling diverse products, cam-locks offer a reliable middle ground—balancing the structure of locked-core shafts with the adaptability of full differential systems.

Watch the Full Episode

Want to see the breakdown in action? Episode 4 of Converting Conversations explains how these shaft types differ and when each might be the right fit for your production line.