Avoiding roll damage: A guide for safer, smarter paper handling
Problems such as core damage and out-of-roundness frequently affect paper rolls during handling and transport. Causes include excessive clamping force, incorrect positioning, or deformation from contact with another object.
“To avoid this, operators should set the right clamp force using the pressure selection valve, pick the right friction surface on contact pads, or use automated paper roll clamps,” said Hansjörg Freund, Regional Sales Manager at Cascade Corporation.
Cascade offers attachments, forks, masts, and related tools to help improve productivity in the supply chain.
From the papermaking side, some rolls become out-of-round more easily during handling. Different paper grades serve different end uses and have specific characteristics.
What influences out-of-roundness
“One simple way to categorise paper is by its basis weight, measured in grams per square metre (gsm),” said Martin Schorn, Director of Technical Customer Service, UPM.
Newsprint is usually 40-45 gsm. Magazine paper ranges from 48 to 100 gsm. Premium papers for covers can go up to 150 gsm.
“The raw material and its properties impact winding hardness, which can range from soft to hard. Softer rolls deform more easily, especially during handling. The raw material mix also affects roll softness,” Schorn said.
Roll width influences out-of-roundness too, especially if narrow rolls are not clamped or lifted at the centre.
Properties such as brightness and print quality increase with grade. Softer wound rolls – especially in lower grades such as newsprint, machine-finished speciality paper (MFS), or supercalendered paper (SC) – are more prone to out-of-roundness, but all grades require proper handling, he added.
The bulk of the sheet is the major factor in out-of-roundness. Bulk refers to thickness at a given basis weight.
“Bulkier sheets are more compressible and usually softer when wound.
Raw material matters here too. Chemical pulp and virgin fibres are bulkier than recycled ones, making rolls softer and more vulnerable to deformation during handling,” he said.
Measuring out-of-roundness is complex
One method to measure out-of-roundness uses a device called the spider. The roll is placed on its side with the device centred in the core, while a laser arm circles it, measuring surface distance at several points.
It’s time-consuming, especially for wide rolls, and potentially hazardous, Schorn said.
A simpler method uses a mechanical device. The roll rests on its side while a spring-loaded gauge circles it, measuring radius deviations. This method only measures the edges, not the centre.
Another cause is eccentricity, which can happen during production, not just handling. If winding stations vibrate, the core may shift, causing eccentric rolls that act like out-of-round rolls in printing.
Though rare, eccentricity can occur in 100 percent recycled newsprint. Some mills use grooved cores to stabilise winding and prevent it.
Six key factors for clamp handling
Hansjörg Freund from Cascade Corporation explains the six interconnected elements that affect how a clamp handles a roll.
1. Clamp handling: A key factor is friction between the roll and the clamp’s contact pad. Friction allows the clamp to lift the roll. More friction = less clamp force = less damage risk. Different pad surfaces are used for different types of paper (steel herringbone, ripped steel herringbone, rubber).
2. Clamping force: Clamp force = pressure applied to the roll via the contact pad, spread over its area. It depends on cylinder size, hydraulic pressure, clamp geometry, and roll diameter.
3. Clamping force factor: This compares required clamp force to roll weight. Factors influencing it include pad friction, dynamic forces, and paper surface type. Lower friction (eg, waxy papers) means higher clamp force needed. Recommended/max clamp forces are often printed on rolls. Force can be measured (using a clamp force indicator) or derived from pressure readings
4. Hydraulic pressure: This generates force in the clamp cylinders. It’s measured in psi or bar.
5. Contact pad surface pressure: This is clamp force per unit area of pad surface. It helps minimise damage.
6. Dynamic forces: Handling generates forces (hoisting, braking, rough terrain, collisions) that affect the roll.
“All six factors influence handling. Correct clamp force is key: too much causes damage and deformation, while too little can lead to roll drops, injury, or telescoping,” Freund said.
However, Freund suggests three key steps to avoid handling damages.
- Set initial hydraulic pressure
- Verify and fine-tune pressure
- Perform daily equipment checks
Consequences of out-of-round rolls at the print shop
- Increased web breaks, especially during splicing.
- Web movement may cause breaks.
- Slower press speed means reduced efficiency.
- Wear and tear on press components: bearings, shafts, tension systems, drives
Best practices for efficient roll handling
Handling out-of-roundness is costly for everyone, according to Freund. Before each shift, the truck and clamp must be inspected for:
- Sharp edges and cleanliness
- Clamp force
- Oil and air leaks
- Pressure and contact pads (clean or replace as needed)
Paper handlers must always follow safety rules when handling rolls.
- Don’t stand under loads or reach through the mast.
- Keep the roll’s centre near the truck’s centre of rotation.
- Position the truck parallel and cantered to the roll.
- Adjust the short arm, move forward, clamp, lift, tilt.
- Lower with vertical mast position.
- Avoid clamping directly on the roll’s centreline.
As pressure increases, so does clamp force. Pressure must be controlled to avoid roll damage. These the three solutions:
