Characterization ofCapacitive Sensors andMonitoring ofMetalFill inLost FoamCasting

Thefilling characteristics inLostFoam Casting needtobemonitored tominimize thefill- related defects. Capacitive sensors, basedonthechange inthecoupling capacitance withthepresence of grounded metalinitsproximity, provide asimple non- destructive methodofacquiring filling information. In thecurrent work,thepreviously proposed capacitive sensor design isoptimized forresponse sensitivity for metalfill insimple andcomplexfoampatterns. The response fromthemulti-electrode sensor isdetermined forvarious locations ofthemetalpiece. An ANFIS (Artificial NeuralFuzzyInference System) numerical modelisdeveloped forthenonlinear sensor response andusedtofindthesensor responses forvarious metal fill conditions. Further, aleast square error approach is suggested toestimate thesensor response formultiple pieces infront ofthesensor. I. INTRODUCTION Lostfoamcasting (LFC)isa highly attractive technique amongthemetalcasters because ofits significant costandenvironmental advantages. It enables manufacturers toreduce machining, minimize assembly operations, produce patterns of high complexity, andeliminate theneedforsandcores and binders (1). Inlost foamcasting technology aprototype ismade using afoammaterial toserve asapattern andplaced inasand-filled container. A hotmolten metal isthen poured intothepattern. Thehotmetaldecomposes thefoamandreplaces itresulting inacasting ofthe shapeoftheprototype. A highlevel ofprocess control isthekeyforasuccessful lost foamcasting. InLFCmetal filling process, avariety ofproblems arelikely tooccur, resulting inpoorquality casting. Someoftheproblems include: imperfect pattern generation duetoimperfect fusion andcontraction of beadsinEPSfoamsresulting inanimproper surface finish andpattern distortion, caused bystructurally weakfoampattern; internal casting defects andcold shuts, caused bythemerging ofliquid metal streams or thetrapping of foamproducts. The filling characteristics inLFCneedtobemonitored to