Nibbling
The nibbling is the punching and shearing related manufacturing processes for cutting and editing sheet . In contrast to conventional punching and shearing, this method is characterized by a parting line and free shaping or a cutting path that is independent of the tool. This is achieved by periodically moving up and down a punching tool open on one side with simultaneous continuous feed - a kind of nibbling, which is why the hand tools are colloquially referred to as nibbling . To cut out complex shapes, the tool rotates and can therefore be moved in all directions.
In addition to hand-held, manually or electrically driven nibblers, CNC- controlled machine tools are also used, usually combined with punching machines. While with hand-held nibblers the two cutting edges are usually directly next to each other like scissors and are connected to each other by a common axis of rotation, a nibbling machine tool usually performs the same movement as a punch. The difference is that the punching tool performs many movement steps in succession while nibbling, while the sheet metal is slowly moved past the tool in order to be able to produce longer cutouts.
Advantages and disadvantages
Like a punch, the parting tool for nibbling consists of a punch and a die. This allows cutouts to be cut out of sheet metal without distortion. However, when nibbling, waste is generated as a cutting track is punched out of the sheet metal.
The cutting out of complex shaped cutouts is also called notching . Round punches also enable tight curves, resulting in sickle-shaped waste. The shape and width of the cutting track results from the type and dimensions of the punch.
When making interior cutouts with hand-held nibblers, a pre-drilling is required in order to be able to insert the cutting edge. Especially with hand-held nibble, nibblers and rodents can be also corrugated and trapezoidal sheets edit. In contrast to the scissors, the cutting track is largely free of warping.
In contrast to water jet and laser cutting , forming processing steps can be carried out with the same processing machine that also uses the nibbling tool. In many cases, not only cutouts have to be made in sheet metal, but also partial areas are deformed in order to insert elements such as (ventilation) gills, passages, etc. Modern nibbling machines , whose tool holder has a rotation axis , can even form threads . (In thread forming, the thread turn is created without cutting, as material is displaced. Compared to cut threads, formed threads can be subjected to higher loads and there are no chips during production that could hinder subsequent processing.)
Standard tools
Hand-held tools are nibblers , nibbler or rodents called.
The standard equipment of a machine tool for nibbling includes punches with the most important, simple geometric shapes, such as B. circle (round punch), square, rectangle or oval ( slot punch ). To cut out larger openings, arched punches are also used, which can, for example, produce a circular cutout with several strokes.
Frequently recurring sheet metal blanks, such as B. Openings in computer housings for D-Sub and other plug connections are usually made with punching tools that were made for the specific application.
Special tools
In (large) series production , e.g. B. of control cabinets , special tools are often used that can cut complete contours with just a few tool strokes.
One form of the special tool is the so-called multitool. Several punching tools are attached to one head and can be addressed by turning (so-called indexing).
machinery
Modern, NC-controlled punching and nibbling machines are characterized by high productivity at (compared to laser cutting) lower unit costs. However, no arbitrary contours can be cut.
Combination machines
In order to combine the advantages of nibbling with those of laser cutting , the various manufacturers also offer combined machines that enable both forming operations with the punching head and the laser cutting of any contours.
Another design of the nibbler combines this with the technology of the guillotine shears in order to be able to carry out the often straight long cuts in an optimized way.
