Accessories · roll protection
Core plugs and end walls: what they do and how to choose them
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What core plugs and end walls are for
A finished roll must reach the customer with a round core, sound edges and a clean surface. During storage and transport it takes knocks, vibration and concentrated loads. Plugs and end walls move those loads away from the weak points:
- They protect the bore: an inserted plug supports the core from inside. If a heavy roll rests on the bare core, warm plastic or damp cardboard goes oval.
- They protect the roll edges: a knock on the edge of a roll of film ruins tens of metres of material. An end wall wider than the roll diameter takes the knock instead.
- They suspend the roll: with end walls or suspension plugs the roll stays raised and touches neither the pallet nor the rolls next to it. This is the solution for delicate films and printed surfaces.
- They allow handling: plugs with a centre bore take a bar for lifting or unwinding the roll.
Types of core plugs
| Type | Design | When it is used |
|---|---|---|
| Solid plug | closes the core; ribbed cylindrical body | protection of the bore and against dust |
| Bored plug | centre bore for a bar or pin | lifting, unwinding, hanging on racks |
| Flanged plug | outer rim resting on the face of the core | precise stop; protection of the core end |
| Suspension plug | shaped outer part taller than the roll, or made to sit in a cradle | rolls suspended on a pallet, without contact |
| Double plug | two-sided plug that joins the cores of two rolls standing one on top of the other | stacking rolls vertically on a pallet |
| Expanding plug | locks by expanding inside the core | cores with wide tolerances, high loads |
The plug must fit correctly: too loose and it falls out, too tight and it splits a plastic core that is brittle in the cold, or delaminates cardboard. That is why it is chosen on the real inside diameter, with its tolerances.
End walls and flanges
End walls (also written endwalls, and called reel ends or flanges in many plants) are discs or plates fixed to the ends of the roll, usually through a hub that enters the core. The main shapes:
- round, wider than the roll, to protect the edges;
- square or flat-based, so the roll can rest without rolling and can be stacked;
- with a suspension seat, to keep the roll off the surface;
- bored for a lifting bar or for strapping.
The right end wall has a diameter larger than the maximum roll diameter, with a margin for deflection under load.
Materials
| Material | Advantages | Limits |
|---|---|---|
| Polystyrene (PS, HIPS) | stiff, precise, cheap to mould | brittle on impact and in the cold |
| Polypropylene (PP) | tough, light, recyclable with the polyolefins | less stiff |
| Polyethylene (PE) | very tough, takes knocks and cold | flexible under high loads |
| ABS | stiff and tough | cost |
| Cardboard, wood, metal | very high loads (metal, wood); recycled with paper (cardboard) | weight, hygiene, moisture depending on material |
For recycling, an accessory in the same polymer as the core, or easy to separate, is best. The PPWR requires all components of a packaging unit to be compatible with collection and recycling and not to hinder recycling of the main body (Art. 6(9)). In the UK, each plug or end wall is a separate component for the Plastic Packaging Tax.
How to choose: the right questions
- Inside diameter of the core and its real tolerance.
- Weight and maximum diameter of the roll: they decide material, ribbing and end wall diameter.
- How it travels: upright or lying down, on a pallet, in a crate, suspended.
- How it is handled: with a bar, with a forklift, by hand.
- Environment: cold (avoid brittle materials), heat, humidity, clean area.
- Life cycle: one-way, or returned together with the core.
On the pallet: plugs, end walls, cradles and chocks
A roll lying down tends to roll and concentrates its weight on a line. Solutions can be combined:
- cradles or saddles that hold the roll and spread the load;
- chocks (wedges) that stop the roll from rolling;
- square end walls that rest on a flat side;
- suspension plugs that hang the roll on supports.
For rolls on plastic cores stored in the heat, suspending them or resting them on cradles prevents the core from going oval over time. Outdoor and hot storage.
Reuse and end of life
Plastic plugs and end walls are often easier to reuse than cores: they do not carry the roll pressure. In returnable loops they come back with the cores and are checked for cracks and distortion. At end of life they follow the packaging waste code of their material (15 01 02 for plastic): separating them from the core before disposal avoids mixing different polymers. Recycling plastic cores.
Transparency: ROLL, the publisher of this guide, designs and supplies core plugs and end walls for rolls. The advice on this page applies to any product in the same category.
Frequently asked questions
What are core plugs for?
They protect the core bore from crushing and knocks, let you lift the roll with a bar and, in suspension models, keep it raised so that it does not touch the pallet.
What is the difference between a core plug and an end wall?
The plug goes into the core and is about its diameter. The end wall, or flange, is a disc wider than the roll that protects its edges and keeps it raised.
What are roll core plugs made of?
Usually polystyrene, polypropylene, polyethylene or ABS; for very high loads also wood or metal. For recycling, the same polymer as the core or an accessory that is easy to separate is best.
How do I choose the size of a core plug?
On the real inside diameter of the core, with its tolerance, and on the roll weight. A plug that is too loose falls out; one that is too tight can split the core, especially in the cold.
Further reading
Sizes and tolerances
Plastic core sizes: diameters in inches and mm, walls, ISO 13542 tolerances, ovality, TIR, smooth or ribbed bore, shafts and how to measure cores properly.
Strength
Radial strength of plastic cores: roll pressure, Lamé, buckling, creep, temperature, the ISO 9969 test and how plastic differs from cardboard under load.
Packaging film
Plastic cores for packaging film rolls: stretch, BOPP, PET. Pressure from elastic films, creep, returnable cores, hygiene, a sample specification and PPWR.
Moisture and outdoors
Plastic cores for moisture and outdoor storage: water, containers, condensation, UV, frost, heat and thermal expansion. Which polymer to choose and why.
Recycling
Recycling plastic cores: waste codes, keeping PVC separate, PP and PE with the polyolefins, residual film, who collects, UK duty of care and PPWR.
Sources
- Regulation (EU) 2025/40 (PPWR), Art. 6(9) (components of the packaging unit), EUR-Lex
- ISO 13542:2006 (internal diameters and tolerances, for plug–core fit)
- Decision 2000/532/EC, European List of Waste (15 01 02)
- HM Revenue & Customs, Plastic Packaging Tax: packaging components, GOV.UK
- ROLL Lab analysis
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