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Modern and traditional manufacturing processes
Published in Adedeji B. Badiru, Ibidapo-Obe Oye, Babatunde J. Ayeni, Manufacturing and Enterprise, 2018
Adedeji B. Badiru, Ibidapo-Obe Oye, Babatunde J. Ayeni
Sheet metal pieces are profiled by a number of processes based on shear fracture of the sheet metal. In punching, a shaped hole is obtained by pushing the hardened die (punch) through the sheet metal. In a similar process called perforating, a group of punches are employed in making a hole pattern. In the blanking process, the aim is to keep the part that is punched out, not the rest of the sheet metal with the punched hole. In the nibbling process, a sheet supported by an anvil is cut to a shape by successive bites of a punch similar to the motion of a sewing machine head.
Metalforming Applications
Published in Jerry P. Byers, Metalworking Fluids, Third Edition, 2018
There are many types of blanking classifications. Cutoff is a class of blanking that describes the use of a punch and die to make a straight or angular cut in the metal. This operation is basically a shearing operation completed in a forming press. Parting (Figure 5.4) is the opposite of blanking in that the scrap is “parted” from the original metal strip, leaving the desired finished piece.9 Punching (or piercing) is the making of a hole in metal, leaving a round slug of metal as scrap. Notching is similar to punching, only a slit is formed rather than a hole. Shaving uses a cut edge to remove rough edges for precision finishes. Trimming is also a type of blanking. Trimming removes excess metal from a formed part giving the final desired dimension. The Tool and Manufacturing Engineers' Handbook lists over 10 different blanking operations, and over 30 uniquely different metalforming operations.9
Machine Guarding Hazards
Published in Barry Spurlock, Physical Hazards of the Workplace, 2017
Punching operations employ the use of power and force to transform material into different shapes, to cut holes in the material, or to trim excess material. A single motion of a press may turn a blank sheet of material into several finished pieces. In other operations, the material may move from one press to another until the finished part emerges from the last press. The size of the hazard increases with the size of the parts processed and the size of the presses. The automobile manufacturing industry uses huge hydraulic presses to transform flat sheet metal into body panels. A careless person who has managed to bypass safety devices and comes in contact with the mating halves of a die during its operation would probably lose whatever body parts the die closed on. This is not meant to indicate that small presses are any less dangerous. Even a tiny press may exert several hundred pounds of pressure. Fingers, hands, and arms can be crushed or amputated by even small presses. Installation or removal of dies during changeover or maintenance are other opportunities for injury. One half of a large press die may weigh several hundred pounds.
Experimental investigations of electromagnetic punching process in CFRP laminate
Published in Materials and Manufacturing Processes, 2021
Liming Duan, Hao Jiang, Xu Zhang, Guangyao Li, Junjia Cui
Aforementioned work has mainly investigated the engineering applications of conventional methods. However, above-mentioned processing methods are likely to induce certain damages to carbon fiber composites, such as delamination, burrs, and so on. Specifically, in terms of machinability, it is unsuitable for CFRP composites to pierce holes by dint of flame cutting and plasma cutting. This is due to the surface burning and surface hardening caused by flame cutting and plasma cutting. For laser drilling, dimensional accuracy is affected by substantial radial swelling of fiber in the heat-affected zone adjacent to laser-drilled holes.[14] As far as drilling is concerned, the problems such as fast tool wear,[6,9] slow processing speed,[19] and high machining cost in the process of drilling are exposed. In addition, it is no picnic to drill irregularly shaped hole, because drilling rely on the rotation of the drill bit to accomplish piercing process. What’s worse, there is high damage in the exit region of drilled holes. Contrary to drilling, punching possesses higher working efficiency and lower machining cost. More importantly, its punch is not easy to wear and can be used to pierce noncircular hole. In particular, as a new type of punching process, electromagnetic punching (EMP) is in possession of faster processing speed and larger impact force as compared to traditional punching, which can reduce some damage caused by above-mentioned conventional methods. However, few studies on electromagnetic punching process in carbon fiber reinforced plastic laminate have been attempted to so far.