Since 1955, Souhegan Wood Products has been a global leader in the production and distribution of winding cores. Also known as extruded shells, our rugged cores provide unrivaled strength and internal support for a broad range of rubber and industrial belt as well as woven and non-woven textiles during winding, unwinding, and transport.

Standard Cores
Sturdier than lumber or cardboard and lighter than steel, Souhegan Wood Products compressed wood particle cores have earned best‑in‑class status as the preferred core for the belt-winding industry. Our purpose-built cores are designed to transition easily through manufacturing, shipping, and installation, benefiting both your expectations and your bottom line.
SWP core strengths:
- Resist splitting
- Tremendous crush strength
- High impact resistance
- Lightweight
- Easy to implement
- Cut to desired length
- Materials can be quickly attached and wound at high speeds
- Suitable for sustained use
- Can be custom manufactured
(e.g. variable lengths, diameters, hole configurations) - Can be used as-is or enhanced
- See spec charts
Enhanced Cores
Based on customer requests, we’ve engineered, tested, and introduced a proven series of add-ons designed to enhance and customize the performance of our standard cores.
Paper-Wound
Versatile, high-strength reinforcement
- Paper sheath wrapped around standard core
- Available in a variety of thicknesses
- Adds beam and hoop strength without added weight
- Clean, dust-free surface
- Gives core a finished, presentable appearance
- See spec charts
Best for:
- Dust-sensitive products and facilities
- Repeat core use
Wooden Staves
Strength that rivals steel
- Laminated custom-cut softwood staves
- Won’t damage winding bars like steel can
- Added beam strength and durability
- Greater axial compressive strength
- Patented design
- See spec charts
Best for:
- Demanding situations
- Mid- to heavy-weight belting
- Repeat core use
Metal End Caps
Reinforcement for repeated use
- Galvanized steel
- Increased durability
- Protects core from abrasive and compressive damage
- Cap depth customizable from 1 to 4 inches
- Does not impede bar insertion
- Can be added to standard, paper-wound, and staved cores
Best for:
- Cores spun on a journal or roller cradle
- Product stored on an end-support rack
- Prolonged in-house use
Coated Finish
A smooth, dust-free seal
- Creates a clean, dust-free surface
- Provides a more finished appearance
- Adds lightweight protection
- Can be applied to standard or paper-wound cores
Best for:
- Dust-sensitive products and facilities
- Woven materials
- End-use customers that showcase product on the core
Notched
Prevent belting damage and waste
- Patent-pending design allows belting to wrap flush against core
- Prevents damage to first several feet of expensive materials
- Reduces product waste
- Linerboard-wound compressed wood rivals the strength of steel at a fraction of the price
- Smooth end holes won’t damage winding bars like rough-cut steel can
- Favored by end use customers
Best for:
- Winding heavyweight materials
- Manufacturers – offer this money-saving option to your customers
- Distributors – cut costs and waste

Core Member
A long-time member of the National Industrial Belting Association (NIBA), SWP understands the belt-winding process better than any other core supplier.

Talking Business
Hear SWP CFO Kathryn Dunn discuss family business on the premier episode of the Belt Friends podcast.
Belt-Winding Core Specifications
Standard Core |
||
|---|---|---|
| Outside Diameter | Square Inside Dimension | Safe Working Load (Based on Core Length) |
| 5" | 2.25" | 45 lb/inch |
| 6" | 3.25" | 35 lb/inch |
| 7" | 3.25" | 65 lb/inch |
| 8" | 4.25" | 50 lb/inch |
| 10" | 4.25" | 100 lb/inch |
| 12" | 6.25" | 79 lb/inch |
Paper-Wound Core |
||
|---|---|---|
| Outside Diameter | Square Inside Dimension | Safe Working Load (Based on Core Length) |
| 5.5" | 2.25" | 70 lb/inch |
| 6.5" | 3.25" | 57 lb/inch |
| 7.5" | 3.25" | 87 lb/inch |
| 10.5" | 4.25" | 135 lb/inch |
Staved Core |
||
|---|---|---|
| Outside Diameter | Square Inside Dimension | Safe Working Load (Based on Core Length) |
| 8.5" | 2.25" | 156 lb/inch |
| 9.5" | 4.25" | 140 lb/inch |
| 11.5" | 4.25" | 220 lb/inch |
| 13.5" | 6.25" | 186 lb/inch |




















