Log / Lathe Slitting Method Overview
Learn more about log aka lathe slitting method
Slitting is a crucial step in the converting industry's processing flow. Roll slitting is the process of converting large rolls of flexible materials—like paper, film, foil, tapes, plastic, and textiles—into thinner rolls, allowing further processing including printing, laminating, coating, and others.
Converters and roll material processors use 2 types of slitting: rewind/unwind slitting and log/lathe slitting. Rewind cutting is performed on cutting machines called slitter rewinders and is the main slitting method of the roll-to-roll processing industry. In this article, we will focus more on the second slitting method - log slitting.
What is Lathe / Log Slitting?
A large roll of flexible material, for example, pressure-sensitive adhesive tapes (PSAT), is spun rapidly around its axis on a mandrel during the log or lathe slitting. On an automated log slitter machine, a circular slitting knife is used to cut directly the master roll into smaller finished slit rolls without unwinding it. The operator of the automatic log slitters for converting logs controls the desired cutting breadth, speed, and direction of the knife.
Materials to Process on Lathe Slitting Machines
Lathe slitters and log-slitting machines may cut a variety of materials, including papers, tissues, foams, films, foils, adhesives, and many more. Despite the potential of cutting numerous flexible materials wound on a roll, the log cutting method is most commonly employed for the processing and conversion of adhesive tapes and wraps.
An example list of materials for the log slitting method:
- adhesive tapes, e.g. masking tape, acrylic foam tape, transfer tapes, single and double-coated tapes, rubber tapes, polyester tapes, duct tape and others
- release liners
- adhesive films, plastic films, surface protection films
- foams, polyurethane foam, silicone cellular and sponge foams, EPDM / Neoprene / XLPE foams
- rubber, silicone rubber
- paper, tissues etc.
Advantages & Disadvantages of Log Slitting Method
Like all methods of processing, converting, and slitting roll materials, log slitting has its pros and cons. We will highlight some of them.
Advantages of the lathe slitting method:
- Inexpensive cutting technique
- Cutting of flexible roll materials without the unwinding procedure
- Quick installation and change of logs with cut material
- Superior cutting quality over other roll-to-roll slitting techniques for difficult-to-cut materials like tape and sticky films
- Advanced log slitters deliver highly precise roll cut widths. The specific width of the rolls can be easily set in a range from a minimum width of 1-2 mm to quite wide options.
Disadvantages of the lathe slitting method:
- The log cutting process is solely used for cutting roll materials
- Frequent blade replacement or regular sharpening is necessary. Adhesive tapes can cause knife fouling from adhesive residue, requiring regular cleaning or the utilization of special knives
- The diameter of the roll that can be processed is limited
- Log cutting is not suitable if you need a smooth and precise cut edge
Log Slitting vs. Rewind Slitting
Log slitting and rewind slitting are two main slitting methods for material converting, when each suited to specific material conversion needs. Let's do an overview on these 2 slittig methods and compare them.
Aspect | Log Slitting | Rewind Slitting |
|---|---|---|
Slitting process | Simple and streamlined; cuts the roll directly without unwinding or rewinding. | Involves unwinding, cutting, and rewinding, adding complexity. |
Slitting speed | Faster due to fewer steps, ideal for high-volume production. | Slower but allows simultaneous multi-roll creation and added customization. |
Roll width range | Achieves extremely narrow widths (as small as 1 mm). | Typically handles wider cuts; can create multiple widths at once. |
Material to cut | Best for stable, uniform materials; less suited for sensitive or composite types. | Accommodates delicate or composite materials and allows laminating or trimming. |
Waste and dust | Minimal waste; uses the entire roll. | Can produce additional waste from edge trimming and leftover material. |
Setup | Easier setup with no need for tension control. | Requires precise tension management to avoid material damage. |
Applications | Typically used for pre-work and to create rolls for later processing. | Delivers ready-to-use rolls tailored for specific end-user needs. |
In terms of process complexity, log slitting is simpler as it slices the roll directly without the need for unwinding or rewinding, making it faster and ideal for high-volume production. Rewind slitting, on the other hand, involves multiple steps—unwinding the material, cutting, and rewinding onto cores.
When it comes to production speed, log slitting has an edge due to its streamlined process, making it a preferred choice for rapid, uniform cuts. Rewind slitting is comparatively slower but compensates by offering flexibility to handle multiple cuts and additional features like laminating or edge trimming during the process. Log slitting can produce extremely narrow cuts, as small as 1 mm, while rewind slitting typically manages wider strips but can create multiple rolls simultaneously.
In terms of material handling, log slitting performs well with stable, uniform materials but is less versatile than rewind slitting, which can accommodate delicate or composite materials. Rewind slitting also provides options to laminate or modify materials during the slitting process, which log slitting cannot.
Regarding waste, log slitting is more efficient, generating minimal waste as it uses the entire roll. Rewind slitting, however, may produce additional waste due to edge trimming and leftover material.
Customization is another key difference. Rewind slitting offers more options, such as varying roll lengths, diameters, and core sizes, making it suitable for delivering ready-to-use rolls. Log slitting is more limited in this regard, often creating rolls for further downstream processing. Machine setup is simpler with log slitting since no tension control is required, whereas rewind slitting demands precise tension management to avoid damaging the material.
Order Knives for Log Slitting & Rewind Cutting
For over 97 years, Sollex has been manufacturing and providing cutting tools in Sweden and internationally, successfully helping clients overcome different cutting challenges by selecting right knives and blades.
Sollex supplies the widest range of premium rewind slitting knives in the form of coated slotted razor blades, razor blades with 3 holes, injector blades, crush-cut knives, perforating knives, top and bottom shear slitting knives, but can also manufacture converting circular knives for your log slitter machine.
Email us at order@sollex.se with detailed information about which machine knife or industrial razor blade you need, and we will give you the best offer.
