What is Slitting Metal Machine -Function , types of Slitter

What is Slitting Machine ?

The machine used for roll slitting is called a slitter rewinder, a slitter or a slitting machine – these names are used interchangeably for the same machines. Roll slitting, also known as log slitting or rewind slitting, is a shearing operation that cuts a large roll of material into narrower rolls. The log slitting terminology refers back to the olden days of saw mills when they would cut logs into smaller sections. They would also use these saw mills to cut iron rods into smaller sections. By today’s definition, slitting is a process in which a coil of material is cut down into a number of smaller coils of narrower measure. Potential workpieces are selectively thin (0.001 to 0.215 in.) and can be machined in sheet or roll form. Slitting is considered a practical alternative to other methods due to its high productivity and the versatility of materials it can manage. Rewind slitting involves rewinding the material through a number of knives to form narrower rolls of materials

Slitting Process :

When the term “slitting machine” is used to describe the machine, the three parts are referred to as the unwind, the slitting section and the rewind. Slitter rewinders are normally used to slit plastic films, paper and metal foils. The unwind is normally braked to maintain accurate tension in the material. Some machines have a driven unwind which reduces the effect of inertia when starting to unwind heavy rolls or when the material is very tension sensitive. The slitting section has three main options: Rotary shear slitting, Crush cut slitting, and Razor slitting which is ideal for thin plastic film. The rewind section also has options. The main type is centre winding using differential rewind shafts.

Components of Slitting Machine :

Slitting is performed on slitting lines which consist of four basic devices:
• The uncoiler, or pay-off reel, which tightly grips the master coil on its inside diameter using an expandable mandrel. The coil is fed into the slitter by either rotating or jogging the mandrel.
• The slitter, which consists of two parallel arbors mounted with rotary cutting knives. These knives partially penetrate the coil stock causing a crack or fracture on both sides of the stock, separating the material.
• A tensioning device, which is placed between the slitter and the subsequent recoiler. A tensioning device is needed because the master coil is crowned or larger in diameter in the center of its width than at the edges. Without a tensioning device the slit material from the center of the master coil would take up more quickly while the outboard strips would hang loosely.
• The recoiler, which takes up the slit coils on a driven, expandable mandrel. The recoiler mandrel is fitted with separator discs which prevent interleaving of the narrower coil widths.

Other slitting line equipment can include:
• Scrap disposal machinery
• Edge conditioning equipment
• Packaging devices

Types of Slitting Machines :

There are two basic types of slitting lines:
• The pull-through slitting line
• The loop slitting line

On pull-through slitting lines the recoiler provides the power to pull the coil material off the uncoiler reel, through the slitter, and recoil the processed strips.

In loop slitting lines, a pit is incorporated into the line. The processed coil strips are looped into the pit which assists in absorbing the strip length differential within the slit coils. The slitter typically provides the power to both uncoil and slit the material, while the recoiler provides the power to rewind the material.