Longitudinal Milling Research Articles

Longitudinal Milling and Fine Abrasive Finishing Operations to Improve Surface Integrity of Metal AM Components

Growing market of additive manufacturing and in particular, metal AM has allowed the manufacturers to produce a wide variety of complex designs with near-net shape in minimum time without the need for custom tooling. However, the application of additive manufactured components in various applications, e.g., biomechanical contacts, naval and aerospace components are limited due to its poor surface integrity and part feature tolerance limits. Traditional methods, e.g., milling, do provide solution to some of the post-processing needs, however, results in poor material utilization, requires custom tooling or may be completely infeasible for complex geometries. In the current work, we focus on developing a post-processing strategy by coupling traditional machining processes with non-traditional fine abrasive finishing (FAF) methods. Preliminary results on 316 L stainless steel components fabricated via laser powder-bed fusion suggests that the proposed post-processing strategy can be used to (a) selectively impart surface finish Sa < 25 nm, and (b) reduce the surface porosity by ∼89% when compared to the as-fabricated sample.

Effect of Process Parameters on Cutting Forces and Surface Roughness during Peripheral Up Milling of Bamboo Scrimber

The effects of milling process parameters on cutting forces and surface roughness were studied during peripheral up milling of bamboo scrimber. The study results indicated that the effect of feed rate on cutting force components Fx, +Fy, -Fy, and surface roughness Ra were the most significant compared to spindle speed and cut depth during longitudinal milling. Fx, +Fy, -Fy, and Ra decreased slightly with increasing spindle speed, but increased greatly with increasing feed rate. In addition, cutting direction had a great effect on the cutting force components Fx and +Fy, as well as the machined surface roughness Ra. Fx, +Fy, and Ra during longitudinal cutting were always larger than those during end-grain cutting. Decreasing the feed rate appropriately could greatly improve the quality of the machined surface.

Анализ неравномерности технологической нагрузки от малорезцовых торцово-конических фрез лесопильных агрегатов

The paper studies the process of uneven load at longitudinal milling by small tool cross-conical cutters of sawing machines. Non-uniformity of process load during milling by specified cutters was quantitatively evaluated by the indicator of the non-uniformity of the technological load during cycle of processing of logs and sawn timbers and wood chips. For small tool cutters, this figure is the ratio of the maximum total length of the cutting edges of cutters to the average length of their cutting edges simultaneously participating in a cutting cycle for processing of wood (turnover of cutters). Butt-tapered (conical) small tool cutters were conventionally considered as a discrete set of stepped cylindrical cutters, i.e. as often case of small tool cutter. The process of interaction of cutters with the wood for its processing cycle was divided into four zones (periods): I zone – time of insertion off all cutters of the group into the timber; II zone – the period of all cutters and serial outputs of them from the timber; III zone – period of successive outputs of cutters from wood; IV zone – period of approach of neighboring group cutters. The size and relative orientation of the time of these zones in the steady cutting defines the different nature of the interaction of cutters with the wood with varying intensity of process load. Mathematical relationships of these zones and taking it into account – dependence of the definition of the index of uneven process load per cycle of wood processing were obtained, calculations were made and a number of parameters cutters were substantiated. The effect on the rate of uneven width, height, milling, as well as the angle of rotation of cutters in the center plane of milling cutter was defined.