Buyers often start by comparing top speeds. That is the least useful number on a specification sheet. A slitter rewinder is right for you when it can hold your thinnest and your thickest material, take your largest parent roll, and wind finished rolls your customers accept, at an output your shifts can actually reach. Work through the sections below in order and you will have most of what a manufacturer needs to propose a model.
Start with the material
Everything else follows from the material, so describe it precisely:
- Material family and structure. "Film" is not enough. BOPP, PET, CPP, PE, metallized film, a PET/PE laminate and a coated optical film all need different knives, tension and roller surfaces.
- Thickness range. Give the thinnest and thickest grade you will run, not only the most common one. Each machine has a working thickness window; running at either end of it is where problems start.
- Surface sensitivity. Say whether the material is printed, coated, metallized, adhesive-backed or inspected under strong light after slitting. This decides roller surface treatment and how the web path is laid out.
- Behaviour. Note anything you already know: stretchy, brittle, static-prone, curls, dusty edges, blocks on the roll.
The KINYUN platforms show how much the thickness window varies by application. The SW4500 packaging-film slitter is specified for 6-75 μm, the SW3500 for special paper and laminates for 25-300 μm, and the SW2800 for electronic and optical film for 20-100 μm.
Web width and roll diameters
Four dimensions decide whether a machine physically fits your rolls:
| Dimension | What to check |
|---|---|
| Unwind width | Your parent roll width must sit inside the machine's unwind width range, including any future wider grades. |
| Unwind diameter | The largest parent roll you receive. A bigger unwind means fewer parent-roll changes per shift. |
| Rewind width | The usable width across all finished rolls after edge trim is removed from both sides. |
| Rewind diameter | The largest finished roll your customers accept, and whether you can lift it safely. |
Also give the narrowest slit width you need. Knife holders have a physical width, so very narrow slits can require a different knife arrangement or a second pass. Ask the supplier to confirm the minimum slit width for your knife type in writing.
Finally, give core sizes for both unwind and rewind. Cores determine the shafts or chucks the machine is built with, and changing them after delivery is expensive.
Speed versus real output
Maximum speed is the speed the machine can run when everything is going well. Your output depends just as much on how long each set of rolls takes to change. Roll length on a finished roll can be estimated from its diameters and the material thickness:
Roll length (m) = π × (D² − d²) ÷ (4 × t)
D = finished roll outer diameter (m), d = core outer diameter (m), t = material thickness (m)
For example, a 600 mm finished roll of 20 μm film on a core with a 90 mm outer diameter holds roughly 13,800 m. At 400 m/min, that set winds in about 35 minutes. If unloading, re-coring and threading take 10 minutes, the machine stands still for more than a fifth of the shift. Running the same job at 600 m/min saves about 12 minutes per set; halving the changeover saves 5 minutes per set without touching the speed.
So ask two questions: what speed can this machine hold on my material, and how long is a changeover with the loading, unloading and knife-setting options quoted? Speed matters most on long runs of thin film. On short runs with frequent slit-width changes, automatic knife positioning and unloading often pay back faster than extra speed.
Razor, shear or crush slitting
There are three basic ways to slit a web. Most machines can be configured for more than one; the choice depends on the material:
| Method | How it works | Typically used for | Watch for |
|---|---|---|---|
| Razor | A fixed blade cuts the moving web, either unsupported or over a grooved roll. | Thin plastic films such as BOPP and thin PET | Blades dull quickly; edge quality drops on thicker or laminated webs. |
| Shear | A rotating top knife overlaps a bottom knife, like scissors. | Thicker films, laminates, paper, metallized and coated materials | Knife overlap, angle and side pressure need correct setting; more setup time per slit. |
| Crush (score) | A round knife presses the web against a hardened anvil roll. | Some nonwovens, tapes and papers | Rarely suitable for film; edges can be deformed or dusty. |
If you run both thin film and laminates on one line, ask for both razor and shear stations and how long a changeover between them takes.
Tension and winding quality
Most complaints about finished rolls are winding problems, not cutting problems: wrinkles, telescoping, soft or hard rolls, and neighbouring rolls interleaving. Three things decide winding quality:
- Tension range. Specifications usually give tension in N/m, which is force per metre of web width. Multiply by your web width to get total force: 100 N/m on a 1.2 m web is 120 N. Your material should fall comfortably inside the range, not at its edge. The SW4500 is specified for 70-150 N/m and the SW3000 for 40-200 N/m.
- Taper tension. Reducing tension as the roll grows prevents the inner layers from being crushed. Ask how taper is set and stored per recipe.
- Rewind shaft type. When one finished roll winds slightly thicker than its neighbour, a plain shaft winds some rolls tight and others loose. Differential (slip) shafts let each roll run at its own tension. Ask which shaft type is quoted and why.
Mechanical precision also shows up here. KINYUN specifies radial runout below 0.05 mm on its high-precision rewinding chuck, which is the kind of figure worth asking any supplier for.
Automation worth paying for
Automation is priced per module, so buy the modules that remove your real bottleneck:
- Automatic knife positioning if you change slit widths several times per shift. On KINYUN machines that include it, each knife holder is driven by a linear motor with a positioning accuracy of ±0.1 mm, set from the touchscreen.
- Automatic unloading and shaft extraction if finished rolls are heavy or changeovers dominate your cycle time.
- AGV or robotic roll handling if rolls move between machines and warehouse in a larger automated plant. These are separate projects with their own layout and safety requirements.
See roll handling and slitter automation for how these modules connect to a slitting line.
Where the KINYUN range fits
The table below summarises the manufacturer's specification for the five KINYUN platforms we offer. Use it to shortlist, then confirm the configuration for your material in the quotation.
| Machine | Main use | Thickness | Max. speed | Unwind width | Max. unwind / rewind diameter |
|---|---|---|---|---|---|
| SW4500 | Packaging film: PET, BOPP, CPP, PE, metallized, laminates | 6-75 μm | 1000 m/min | 1200-10400 mm | 1500 / 1200 mm |
| SW3500 | Special paper and laminates | 25-300 μm | 600 m/min | 400-3300 mm | 1500 / 1500 mm |
| SW2800 | Electronic and optical film: PET, OCA, PI, TAC | 20-100 μm | 200 m/min | 1000-2650 mm | 1000 / 800 mm |
| SW3000 | Polarizers and PMMA optical film | Polarizers 100-200 μm; PMMA 20-80 μm | 80 m/min | 800-2800 mm | 1100 / 1100 mm |
| RW900 | Rewinding composite copper and aluminum foil | 3-12 μm PET/BOPP base, coated both sides | 250 m/min | 150-800 mm | 520 / 520 mm |
The two optical-film machines are slower by design: on polarizers and PMMA, surface quality and cutting accuracy matter far more than speed. If you are not sure which platform suits your material, the quote preparation guide lists what to send so the manufacturer can decide with you.
Figures quoted for KINYUN machines come from the manufacturer's published specification. Everything else is general guidance; the configuration for your material is confirmed in writing in the formal quotation.
