Laser Cutting

When the 2D model of the part is made available by the unfolding module, job preparation for laser cutting can begin. This preparation also requires 4 step:

Flat parts are nested so that several parts can be produced from a single, standard sheet. The system strives for optimal use of the sheet during the nesting. A cutting sequence having a minimal production time, is fixed. The complete job can be simulated on the computer.
Finally, all information is converted into a machine compatible code.

Laser technology is in direct competition with punching technology especially in thin materials up to a thickness of 6 mm. The table illustrates the justification process in determining the most suitable technology for the application. The laser is the superior choice for small series parts and parts with difficult contours. The punch press remains the best choice for medium to large batches of parts with straight angles and forming operations.

Shearing

The first step in manufacturing simple sheet metal parts is producing a flat blank. This is usually performed using a guillotine shear to cut the sheet material to size in square or rectangular shape.

A basic machine tool used to shear sheet metal or plate has two cutting blades, a fixed bottom blade and a top blade mounted to the vertically moving cutting beam which can be positioned at an angle and the larger rake angle, the less power or force is needed to shear the plate.

however, a larger rake angle can reduce the accuracy of the cut part. Therefore, the rake angle should be adjusted to the smallest angle possible within the capacity of machine.

Bending

The 4 steps of job preparation for bending include::

Punching

Punching is similar to shearing. In punching, the shearing line follows the circumference of the punch tooling

The punch is performing the function of the upper blade, while the die acts as the lower blade. The stripper replaces the plateholders.

To minimize set up time, the alignment between the punch and the die is achieved through the use of keys and keyways located in the tool holders. The die is fixed to the lower part of the frame while the punch, concentric with the die, is fixed to the upper part of the frame. The punch assembly consist of several elements: the punch, adjustable punch head, punch guide, stripper and stripper ring. The inside diameter of the stripper ring is slightly larger than the punch body and its over the punch between the adjustable punch head and the punch guide. The complete punch assembly is located on a spring-support mechanism attached to the upper frame.

To punch a hole in a sheet, the sheet is first located on the die. This process can be divided into six phases. In the first frame, the striker attached to the hydraulic ram hits the top of the punch head, causing the punch assembly to move down and overcome the spring support mechanism. Contact is quickly made between the bottom of the punch guide / stripper and the material. To minimize set up time, the alignment between the punch and the die is achieved through the use of keys and keyways

As the striker continues to push down, the stripper spring forces the punch guide / stripper against the sheet. This fulfils the function of a plate-holder applying a holding force of 10% to 15% of the punching force on the sheet around the location of the punched hole. As the punch continues its downward motion, the stripper spring forces the punch guide / stripper against the sheet. This fulfils the function of a plate-holder applying a holding force on the sheet around the location of the punched hole.

As the punch continues its downward motion, the stripper spring will further compress, allowing the punch to penetrate the surface of the material, shearing the profile of the punched hole. The detached material is called the slug. To ensure that the slug does not return with the punch, the punch travels further than the thickness of the material. The distance the punch travels in the die is called die penetration. This concludes the downward motion.

The ram and striker then return upward, the stripper spring ensures that the punch also return upward and remains in contact with the striker, while the stripper remains in contact with the sheet.

When the punch is back in the highest position of the punch guide, the spring support mechanism keeps the punch in contact with the striker. The full punch assembly then travels upward allowing the sheet to relocate for the next punch operation. The striker releases the upper tool when it returns to the top of its stroke, the machine is then ready for a tool change.