TL;DR

Slit width variation is most often caused by slitter blade lateral play or dull blades. Verify blade holder torque, replace worn blades, and check the web tension profile.

What you might see

slit width varying beyond specification
edge quality inconsistent across slit rolls
blade chattering during cutting
web tension meter showing variation at the slit zone

Likely causes

Tap to mark as ruled out

Slitter blade holder clamp undertorqued allowing lateral blade movement
Dull or chipped slitter blade deflecting under cutting load
Web tension variation causing the web to weave through the blade zone
Top blade engagement depth incorrect for the material caliper

Required tools

Torque wrench for blade holder clamps
Calipers for slit width measurement
Cut-resistant gloves (blade-rated)
LOTO kit

Safety first

Slitter blades are razor sharp. Use cut-resistant gloves rated for blade handling at all times near the slit head.
Web under tension stores energy. Reduce web tension to zero before any blade or holder work.

Procedure

7 steps · ~45 min

1
Measure slit width on at least 10 consecutive rolls at three MD positions per roll. Identify whether the variation is MD, CD, or random.[1]
2
Stop the machine and lock out before touching blades or blade holders.
Warning: Slitter blades are extremely sharp. Use cut-resistant gloves rated for blade handling whenever touching or adjusting blades.
3
Check blade holder clamp torque on all holders. Undertorqued holders allow blade movement under web tension. Re-torque to specification.
4
Inspect each blade for chips, nicking, or visible dullness. Replace any blade with edge damage.[1]
5
Check the top blade engagement depth (overlap) against the specification for the material caliper. Incorrect overlap causes blade deflection.
6
Verify the unwind web tension setpoint against the grade recipe. Tension variation above 5% of setpoint widens slit width tolerance.
7
Run a test set after corrections and measure slit widths before releasing to production.

Sources

Atlas Converting Atlas CW1000 / 5000 Slitter Rewinder general technical documentation, Atlas Converting
Slitter rewinder blade setup and slit width control, general converting machinery practice (general)

More guides for Atlas Converting Atlas CW1000 / 5000

How to fix telescoping rewind rolls on an Atlas CW5000 Slitter Rewinder

Telescoping rolls are caused by incorrect rewind tension taper or misaligned rewind cores. Check the tension taper profile, core alignment, and unwind brake for the current material.

~45 min7 steps

How to reduce web breaks at the slit zone on an Atlas CW1000 Slitter Rewinder

Web breaks at the slit zone are caused by dull blades, excessive web tension, or nicks in the web guide rolls. Inspect blades, reduce web tension by 10%, and check all rolls in the web path.