Knowledge-Based System For Computer-Aided Process Planning With Finite Element Predictions
The knowledge-based system COFEX (Cold Forging Expert) has been developed to assist in the planning of the cold forging of a wide variety of tubular steel components. Following user-input of the required shape and dimensions of the finished forging, together with as many different sequences as desired, each operation is examined by the system by consulting the knowledge-base process rules and data. Messages give the reason if any of the operations is unacceptable. If manufacture by cold forging is feasible, the dimensioned drawings of the finished and semi-finished forgings, together with the process parameters are displayed. Subsequently the suitability of existing presses are checked or new ones specified, the cost of the forging is computed and the sensitivity of the costs to various factors assesses. If heading is included in the sequence it can be checked by the finite element analysis whether or not plastic buckling and subsequent folding defect is likely to occur, and forging loads, stresses and strains predicted.
Cold Extrusion of Flanges on Cylindrical Hollows
Flanges on hollow cylindrical engineering components are often made by free upsetting when under certain conditions a bulge is formed in the unsupported portion, which on further deformation appears as a fold in the finished flange.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.