WASTING PROCESSES

Machine wasting :

-          Wasting process, the process of taking something away from a material is called wasting

-          Machine wasting, almost any wasting technique can be mechanised

-          Common machines used for shaping by wasting – lathes, pillar drills, milling machines.

-          Computer Numerical Control (CNC) – CNC machine tools are programmable, automated means of machining components They are a development of a numerical control technique that first appeared in the 1950s which controls the actions of machines by the input of instructions in the form of a code. Drilling machines for drilling, lathes for all turning contouring operations, milling machines, most versatile operations for creating a wide range of complex contours as well as internal and external profiles, laser cutters for engraving and cutting sheet materials.

-          Milling machine involves the movement of the work piece against the rotating cutter, meaning it will be able to cut on its flanks as well as its tips. Used for complex shaping of metal, plastic or wood parts. Has rotating cutter which rotates about the spindle axis, a movable bed to which the material is clamped. The cutting tool remains stationary while the material on the bed moves. 2 forms which refer to the orientation of the spindle, vertical and horizontal.

-          CNC router is a machine which creates objects from various materials. It can be designed on the computer with a cad/cam program, and then cut automatically using a CNC router to produce a finished part, it is accurate and fairly quick.

-          Ultrasonic machining – high frequency electrical signal that is converted into oscillating mechanical motion through electric motors. The high frequency motion causes the cutting tool to expand and contract in a pulsating manner. Cutting takes place at the highest point of amplitude or expansion of the tool. Very hard materials such as glass, ceramics and precious stone.

-          Spark eroding -  an electrical current is discharged between two electrodes which are in the preence of a dielctric liquid, this produces the spark. It is the repeated action of this discharge which causes the removal of material from the workpiece and shapes the object in the desired accurate fashion. It is used in automotive and engineering industries.

 

PIERCING AND BLANKING PROCESSES:

• Sheet metals can be cut to a required shape using punches. These cut through the material using a shearing action, much in the same way that scissors cut through paper.
• A guillotine is usually used to cut sheet metal off a roll into useable sheet sizes. These sheets are then passed into either manually operated or automatic machines that will cut the material to shape and/or punch holes into it.