Lost Foam Casting

Abstract

Lost foam casting is a sand casting process in which the mold consists of an evaporative polystyrene foam pattern embedded in sand. It is especially well suited for making complex parts with convoluted features such as engine blocks, transmission cases, and cylinder heads. This article describes the lost foam casting process and its primary advantages, including the elimination of flash and parting lines, the relative ease of prototyping with foam, and the ability to incorporate multiple metals, whether in sections or layers, through sequential pours. It illustrates an entire process cycle from mold filling to fusion, cooling, and part ejection. The article also provides information on casting quality, discussing dimensional tolerances, fold defects, and porosity.

Surface topography investigation during nanosecond pulsed laser engraving of SAE304 stainless steel

“…Given that usually, in laser engraving, pulsed lasers are utilized, each layer of material is removed by the overlap of the generated craters that are formed due to material ablation [4]. As it was aforementioned, pulsed lasers are most commonly utilized since, although they have lower nominal power, through their pulsed operation extremely high-power peak and power density can be achieved [5]. In laser engraving, minimum power density of 10 8 W/cm 2 is required and laser pulse durations in the order of nanoseconds are usually utilized.…”