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Laminates, Rigid
Published in Martin W. Jawitz, Michael J. Jawitz, Materials for Rigid and Flexible Printed Wiring Boards, 2018
Martin W. Jawitz, Michael J. Jawitz
One of the major differences between fabricating paper-based laminates and fabricating laminates made with reinforced fiberglass is in the hole-forming and routing process. With paper-based laminates, all the holes, slots, and contours are usually punched at one time. Glass-based laminates require that each hole be drilled individually and then routed. Punching of paper-based laminates is much easier, produces cleaner holes, and is less troublesome if the part is preheated to approximately 100°F (38°C) even if the laminate is classified as “cold punch.” Since punch tooling is relatively expensive, punched boards are usually used in highvolume applications where tooling costs can be amortized over long, or multiple, product runs.
Magnetorheological finishing of micro-punches for enhanced performance of micro-extrusion process
Published in Materials and Manufacturing Processes, 2019
Manpreet Singh, Anant Kumar Singh
The present process setup which is employed in nano-finishing the outer surface of the micro-extrusion punches as depicted in Fig. 4(a). An experimental setup has two main components, the first one is the finishing electromagnetic tool with horizontal X-axis slider and another one is the modified workpiece holding fixture. In the MR finishing setup, three programmable servo motors (S1, S2, and S3) are utilized. S1 and S2 servo motors are used to provide the rotation and reciprocation motion to the electromagnetic tool core tip surface as depicted in Fig. 4(b). The third servo motor (S3) is used for providing the rotary motion to the micro-punch workpieces as depicted in Fig. 4(b). The micro-punch workpiece is held in a straight line with the help of drill chucks. Further, the workpiece holding fixture is fabricated. The fixture has a wooden base, four plumber blocks, two cylindrical shafts to hold the drill chucks and nut and bolts to clamp the plumber blocks to the wooden base. The drill chucks are screwed with the cylindrical shafts and these shafts further locked to plumber blocks. The rotary motion is provided to the cylindrical shaft through the belt pulley drive as depicted in Fig. 4(a). The coolant is supplied to the electromagnetic tool to cool down the electromagnetic coiling as depicted in Fig. 4(a).
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
As observed in Fig. 5, the diameter of drilled hole was greater than drill diameter, and yet the diameter of punched holes (exclusive of d3) was less than the diameter of punches. This was due to the difference in cutting principle that drilling was based on the rotation of drill bit, while electromagnetic punching relied on acting force derived from punch and cavity die. Therefore, directions of cutting forces were distinct from each other. That is, cutting force of drilling (torque for its main movement) was along the tangent of hole, whereas cutting force of electromagnetic punching (blanking force) was toward the axial direction of holes. Furthermore, the drill bit was in the semi-closed state during drilling process. Meanwhile, high speed, large stock removal, difficulty to evacuate chips, and severe friction caused cutting process unstable (e.g. drill bit jitter). Thus, multiple cutting and unstable cutting jointly led to drilled hole diameter being enlarged. For electromagnetic punching, the main reason for d1 and d2 less than punch diameter was the presence of uncut fibers (incomplete punching owing to once cutting along the axial direction of holes) and elastic recovery of fibers and epoxy resin matrix after completing electromagnetic punching process. As for the exit diameter (d3), it was slightly larger than the cavity die diameter (dc). The reason of this result was that the fiber layer at exit was mainly subjected to shear load (tearing) without bending so that exit diameter (d3) was very close to cavity die diameter (dc).
3D CAD modeling of deep drawing tools based on a new graphical language
Published in Computer-Aided Design and Applications, 2018
Sergej Koch, Bernd-Arno Behrens, Sven Hübner, Robert Scheffler, Gregor Wrobel, Matthias Pleßow, David Bauer
After the parameterization of the counterbore hole, the pin diameter is defined as a quarter of the punch diameter. Such simple relations are defined by a formula created and saved in the formula editor of CATIA. The distance between dowel hole and central axis is also described by a formula and amounts to half of the punch diameter. Thus, the risk of the dowel hole being positioned outside the punch or inside the pin is eliminated.