Contract slitting is the cutting of web materials on behalf of a customer: a provider slits films, papers, laminates, nonwovens or foams to the width the customer needs for production. The decisive specifications are cut width, width tolerance and core diameter. For contract slitting at GOBA these are 5 to 1,600 mm, ±0.1 mm and cores of 25, 55, 76 or 152 mm. This page shows when outsourcing pays off against running your own slitting line and provides the grid for comparing providers.
When contract slitting pays off
Material producers deliver in standard widths, often 1,000 mm and more. Few production lines can work with that. Anyone winding a slot insulation 38 mm wide or processing a 12 mm tape needs the material at exactly that width, cleanly wound and on a core that fits their own unwind shaft.
On the way from master roll to slit roll, the customer supplies the material or has the provider source it, and the provider slits and rewinds. The economic point lies in utilisation: a slitting machine only amortises with continuous throughput. Anyone slitting occasionally mainly pays for downtime when running their own line.
Five specifications decide whether a slitting provider suits you
Quotations often state only that the work is precise. That says nothing. Ask for these five values instead and providers become comparable. The right column shows what we deliver.
| Specification | Why it matters | GOBA |
|---|---|---|
| Cut width | Sets the narrowest and widest roll you can source | 5 to 1,600 mm |
| Width tolerance | Decides whether the roll runs in your next machine without rework | ±0.1 mm |
| Core diameter | Has to match your unwind shaft, otherwise adapters are needed | 25, 55, 76 or 152 mm |
| Material groups | Nonwoven, film and foam each demand a different cutting approach | Films, papers, laminates, nonwovens, foams, composites |
| Cutting method | Determines edge quality and dust generated in the cut | Slitting with counter-rotating circular blades |
Collecting these five details from three providers gives a sound basis for a decision. If a provider cannot answer the tolerance question, that says more about their production than any self-description. Our values are stated in full on our slitting and contract slitting page.
Slitting separates with two counter-rotating circular blades
The web runs from the master roll through the cutting station and is divided across several winding shafts. Separation is done by two circular blades moving past each other, much like scissors with rotating edges. The achievable width tolerance of ±0.1 mm follows from this principle, because the cutting point is fixed geometrically and does not wander.
Web tension is the critical variable. Too little pull and the roll telescopes, too much and thin films stretch permanently. Tension is therefore regulated through the winding shafts and set per material. More on the setup is in the articles on slitting and on the winding shaft.
The core diameter determines your downstream processing
The core is easily overlooked during purchasing and causes most of the later problems. If it does not match the unwind shaft, adapters are needed, and adapters introduce runout errors into a process designed around ±0.1 mm.
We wind onto inner core diameters of 25, 55, 76 or 152 mm. The choice follows the downstream process: small cores keep the roll compact and suit manual processes and short runs. Large cores hold more material and reduce roll changes in automated lines. Anyone supplying an existing line should therefore state the core with the enquiry, not with the order.
Which materials can be slit under contract
The material has to be web-shaped, meaning it unwinds from a roll. Within that limit we process the groups needed in electrical insulation and industrial converting.
- Polyester and polyimide films, thin and dimensionally stable
- Aramid papers and pressboard for thermal classes in motor manufacturing
- Technical laminates, where the composite must not delaminate in the cut
- Nonwovens and filter media, which distort easily under blade pressure
- Foam tapes and self-adhesive build-ups on a liner
- Copper foils and composites for shielding and battery applications
Individual material groups have their own pages with application-specific data, for instance on battery film slitting or on filter fleece. Which material suits which thermal requirement is covered in the article on thermal classes of insulation.
Nonwoven, film and foam behave differently in the cut
The material group determines how the machine is set up. Anyone slitting only film never notices. Anyone placing both nonwoven and film with the same provider should ask about it.
Nonwovens are compliant and have no firm edge. Under blade pressure the material gives way sideways, cut width scatters more than with film, and the edge frays if the blades are not sharp. With filter media there is the added point that the web must not be compressed during winding, otherwise permeability changes. Nonwoven is therefore run at lower web tension and lower speed than a film of the same thickness.
Thin films behave the other way round: they need tension to run flat through the cutting station, but stretch permanently once tension gets too high. Polyimide films in Kapton quality are so thin that small tension differences across the roll already produce visible wrinkles. Foam tapes in turn spring back after the cut, so their width is measured in the relaxed state rather than directly at the blade.
When in-house slitting capacity pays off
The fair objection from purchasing is that you could slit in-house. With continuous demand that holds. A slitting machine with winding shafts, blades and tension control amortises when it runs several shifts and the material variety stays low.
Three situations argue against running your own. First, demand spread across many materials and widths, because every change costs setup time and blade wear. Second, a tolerance band below ±0.2 mm, which demands experience in tension control. Third, fluctuating call-offs that leave the machine idle most of the time. In those cases contract slitting is the cheaper calculation, because you do not co-finance setup time and downtime. On request we also supply with stockholding, see customer-specific products.
What belongs in a contract slitting enquiry
With these details a quotation can be calculated without a follow-up question.
- Material with trade name and thickness, or a sample of the master roll
- Required cut width with tolerance, and whether trim strips are acceptable
- Core diameter and maximum outer diameter of the slit roll
- Running metres per roll and annual quantity, since both drive the price per metre
- Whether you supply the material or we source it
The maximum outer diameter is the detail most often forgotten. It depends on the unwind station at your end and determines how many running metres fit on a roll. Supplying it late often means a new calculation, because the number of rolls and therefore the setup effort changes.
GOBA conclusion: ask for numbers, not for precision
Contract slitting providers all describe themselves in much the same way. The difference shows as soon as you ask for cut width, width tolerance and core diameter. A provider who cannot name those three straight away probably does not control them in production either. Our values are published: 5 to 1,600 mm cut width, ±0.1 mm width tolerance, cores of 25, 55, 76 or 152 mm. State the core diameter and the maximum outer diameter with your enquiry and you save a calculation loop. The service in detail, including material supply and sourcing, is on our slitting and contract slitting page.
