Cost-benefit analysis for disruption prevention in low-volume assembly

Manufacturing companies face rising pressure due to increased competition. Traditionally, companies have merely concentrated on offering impeccable, cost-efficient products. Today, however, flexibility and on-time delivery are additional requirements to satisfy the customers. At the same time, disruptions in production, especially in low-volume assembly, still frequently occur, leading to economic losses and delayed customer deliveries. The approach proposed in this paper strives for improving the disruption situation in low-volume assemblies. A detailed disruption management methodology has been developed, aiming at realizing an efficient reduction of disruptions, while at the same time considering the specific characteristics of low-volume assembly. The methodology is supported by a catalog of pre-emptive measures. These measures are known to reduce the disruptions’ occurrence or to diminish their consequences. In general, the approach pursues the basic idea to implement particularly those measures, which have the best cost-benefit-ratio. Based on the analysis of the cost-benefit-ratio of each measure, the developed methodology aims at improving the disruption situation in assembly and thus providing a high on-time delivery rate. The usability of the methodology for the low-volume assembly context has been confirmed by assembly experts on the basis of an application of the methodology in an exemplary case study.     

Aktuelle Aktivitäten zu den europäischen Rohstoff-Initiativen

The European Initiatives manifested in the Communications of the European Commission on Raw Materials, in the Strategic Implementation Plan of the European Innovation Partnership on Raw Materials and in the 2014 Call of the European Institute for Innovation & Technology (EIT) for a Knowledge and Innovation Community (KIC) on Raw Materials lead to manifold Austrian activities on Government level and on level of the Montanuniversitaet Leoben. The ESEE Region, thus East- and Southeast Europe has a special role.     

Rumination activity of dairy cows in the 24 hours before and after calving

Monitoring rumination behavior serves multiple purposes in feeding and herd management of dairy cows. The process of calving is a major event for cows, and a detailed understanding of alterations in behavioral patterns of animals in the time around calving is important in calving detection. The objective of this study was to describe the short-term changes in rumination patterns in dairy cows immediately before and after parturition. In total, 17 cows were fitted with rumination sensors that were able to monitor rumination time, number of rumination boli, and number of rumination jaw movements. Rumination time was decreased in the last 4 h antepartum and in the first 8 h postpartum. Cows stopped ruminating 123 ± 58 min (mean ± standard deviation) before calving and resumed ruminating 355 ± 194 min after calving. The number of rumination jaw movements and boli per day were decreased in the 24-h period postpartum. Rumination rate, the number of rumination jaw movements per rumination minute, and the number of boli per rumination minute changed little around calving. The calving event primarily influenced the duration and frequency of various rumination characteristics but not rumination intensity. Among detected characteristics, rumination time showed the greatest potential for monitoring of calving events.     

Filler Wetting in Miscible ESBR/SSBR Blends and Its Effect on Mechanical Properties

The selective wetting behavior of silica in emulsion styrene butadiene rubber (ESBR)/solution styrene butadiene rubber (SSBR) blends is characterized by the wetting concept, which is further developed for filled blends based on miscible rubbers. It is found that not only the chemical rubber–filler affinity but also the topology of the filler surface significantly influences the selective filler wetting in rubber blends. The nanopore structure of the silica surface has been recognized as the main reason for the difference in the wetting behavior of the branched ESBR molecules and linear SSBR molecules. However, the effect of nanopore structure becomes more significant in the presence of silane. It is discussed that the adsorption of silane on silica surface constricts the nanopore to some extent that hinders effectively the space filling of the nanopores by the branched ESBR molecules but not by the linear SSBR molecules. As a result, in silanized ESBR/SSBR blends the dominant wetting of silica surface by the tightly bonded layer of SSBR molecules causes a low‐energy dissipation in the rubber–filler interphase. That imparts the low rolling resistance to the blends similar to that of a silica‐filled SSBR compound, while the ESBR‐rich matrix warrants the good tensile behavior, i.e., good abrasion and wear resistance of the blends.

     

Thermal stability of modified end‐capped poly(lactic acid)

The influence of functional end groups on the thermal stability of poly(lactic acid) (PLA) in nitrogen‐ and oxygen‐enriched atmospheres has been investigated in this article using differential scanning calorimetry, thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Functional end groups of PLA were modified by succinic anhydride and l ‐cysteine by the addition–elimination reaction. PLA was synthesized by azeotropic condensation of l ‐lactic acid in xylene and characterized by nuclear magnetic resonance. The values of the activation energies determined by TGA in nitrogen and oxygen atmospheres revealed that the character of functional end groups has remarkable influence on the thermal stability of PLA. Moreover, DMA confirmed the strong influence of functional end groups of PLA on polymer chains motion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41105.