Strip Memory Not Removed by Leveler – Causes, Inspection, Repair & Prevention Guide for Roll Forming Machines

Strip Memory Not Removed by Leveler

Roll Forming Machine Troubleshooting & Repair Guide

Strip memory not removed by the leveler occurs when the leveling or straightening unit fails to eliminate the natural curvature that steel strip retains from being stored in coil form. This curvature is commonly referred to as coil memory or coil set.

Steel strip is wound tightly into coils during manufacturing and transportation. When the strip is unwound during roll forming production, it naturally attempts to return to this curved shape. The leveler is designed to remove this curvature by applying controlled reverse bending cycles.

When the leveler fails to remove the strip memory, the strip may enter the roll forming machine with residual curvature.

If this issue is not corrected, it may lead to several production problems including:

• Strip curl entering the roll forming machine
• Feeding instability at entry guides
• Uneven forming pressure across the strip
• Profile dimensional inconsistencies
• Strip tracking drift
• Increased roller wear

For manufacturers producing metal roofing panels, cladding sheets, structural decking, purlins, trims, and other roll formed products, removing coil memory before forming is essential for stable feeding and consistent product quality.

This guide explains the causes of strip memory not being removed by the leveler, inspection procedures, corrective actions, and preventative maintenance strategies used by experienced roll forming technicians.

Causes of Wear or Failure

Strip memory problems usually occur when the leveling unit does not apply sufficient corrective bending to the strip.

Insufficient Leveler Roller Penetration

If the leveling rollers are set too lightly, they may not apply enough bending force to remove coil curvature.

Incorrect Setup for Material Thickness

Leveler settings designed for thinner material may not apply sufficient force to thicker steel strip.

High Yield Strength Material

High-strength steel requires greater leveling force to remove coil set.

Standard leveling settings may be insufficient.

Worn Leveler Rollers

Rollers that are worn or polished may not grip and bend the strip effectively.

Leveler Roller Misalignment

Misaligned rollers may apply uneven forces that fail to eliminate curvature.

Excessive Coil Set

Coils stored for long periods or wound under high tension may develop severe coil memory.

Why It Happened and What Caused It

From a mechanical standpoint, levelers remove coil memory by applying repeated reverse bending cycles to the strip.

During proper leveling:

1. The strip enters the leveler with curvature.
2. Rollers bend the strip alternately above and below its neutral axis.
3. The repeated bending gradually neutralizes internal stresses.
4. The strip exits flat.

If the bending force is insufficient:

• The strip never exceeds its elastic limit.
• Internal stresses remain in the material.
• Coil curvature persists.

This residual curvature may cause instability when the strip enters the roll forming machine.

How to Inspect the Problem

Inspection Procedure

Proper inspection helps determine whether the leveler is failing to remove strip memory.

Step 1 – Observe Strip Shape After the Leveler

Watch the strip immediately after it exits the leveling unit.

Signs of coil memory include:

• Upward or downward strip curl
• Visible curvature along the strip length
• Strip lifting from the entry table

Step 2 – Inspect Entry Guide Behavior

If the strip is curling upward or downward, entry guides may struggle to keep the strip centered.

Step 3 – Inspect Leveler Roller Settings

Check roller penetration and leveling pressure settings.

Light roller settings may indicate insufficient leveling force.

Step 4 – Inspect Material Thickness and Strength

Verify that leveler settings match the strip thickness and yield strength.

Step 5 – Inspect Coil Condition

Check whether the coil has severe coil set before entering the leveler.

Step-by-Step Technician Guide – How to Fix

Several corrective actions can improve leveler performance and remove strip memory.

Method 1 – Increase Leveler Roller Penetration

Gradually increase roller penetration until the strip exits flat.

Method 2 – Adjust Leveler Settings for Material Type

Ensure settings match the material thickness and yield strength.

Method 3 – Recalibrate the Leveler

Follow manufacturer setup procedures to properly configure the leveling system.

Method 4 – Replace Worn Leveler Rollers

Worn rollers may reduce leveling effectiveness and should be replaced.

Method 5 – Run Test Material Through the Leveler

Before full production, run test strip to verify that coil memory is removed.

Preventative Maintenance Tips

Routine inspection and proper setup help prevent coil memory problems.

Adjust Leveler Settings for Each Coil

Different materials require different leveling adjustments.

Inspect Leveler Rollers Regularly

Check for wear or surface damage that may reduce effectiveness.

Monitor Strip Flatness During Startup

Operators should observe strip shape when beginning a new coil.

Maintain Leveler Adjustment Systems

Ensure adjustment screws and mechanisms operate smoothly.

Inspect Incoming Coil Quality

Severely curved coils may require additional leveling adjustments.

FAQ Section

What is strip memory in roll forming?

Strip memory refers to the natural curvature steel retains after being stored in coil form.

Why must coil memory be removed before roll forming?

Residual curvature can cause feeding instability and profile dimensional problems.

How does a leveler remove coil memory?

Levelers use alternating rollers to apply reverse bending cycles to the strip.

What happens if strip memory remains?

The strip may curl, drift sideways, or feed unevenly into the roll forming machine.

Can high-strength steel cause leveling problems?

Yes. High-strength materials may require stronger leveling force.

Should leveler settings be adjusted for each coil?

Yes. Different coils may require different leveling adjustments.

Machine Matcher Technical Support

If your roll forming line is experiencing strip curl, leveling problems, or feeding instability, Machine Matcher technical specialists can help diagnose and resolve the issue.

Support services include:

• Roll forming machine troubleshooting
• Leveler and strip preparation diagnostics
• Strip flatness analysis
• Production line performance evaluation
• Remote technical assistance

Submit your issue through the Machine Matcher Technical Support Desk:

Include the following information:

• Machine type
• Coil width, thickness, and material type
• Photos or videos showing the strip curvature
• Leveler settings and production speed

Our technicians will review the information and provide step-by-step recommendations to restore stable production.