Abstract: The paper presents the influence of non-metallic inclusions on the multi-stage forging process and the mechanical properties of the dodecagon socket bolt used in the automotive industry. The detected metallurgical defect was so large that it directly influenced the mechanical properties of the bolt and resulted in failure to meet the requirements of the mechanical property class. In order to assess the defect, an X-ray examination and metallographic examination of the defective bolt were performed, showing exogenous non-metallic inclusion. The size of the defect on the cross section was 0.531 mm in width and 1.523 mm in length; the defect was continuous along the entire axis of the bolt. In analysis, a finite element method (FEM) simulation of the multi-stage forging process was designed, taking into account a non-metallic inclusion parallel to the sample axis, reflecting the studied case. The process of defect propagation due to material upset in the head area was analyzed. The final forging stage in shaping the dodecagonal socket and filling the flange area was particularly studied. The effect of the defect was observed to significantly reduce the effective cross-section as a result of the expansion of the defect perpendicular to the axis of the bolt. The mechanical properties of products with and without the defect were analyzed. In the first step, the hardness test confirmed that the required value for the mechanical class 8.8 of both bolt types was obtained. In the second step, the bolts were subjected to a static tensile test. The bolts without the defect gave a positive result, while all 10 bolts with the defect gave a negative result, achieving a tensile strength below the requirements. Tensile strength tests were confirmed by metallographic tests and FEM simulation with perpendicular inclusion spread in the area of the head. The bolts were damaged directly under the bolt head, which is inconsistent with the requirements of ISO 898-1. It has been shown that non-metallic inclusions with orientation in accordance with the axis of the bolt can directly cause loss of functionality and these defects should be detected even before assembling in the machine element.
Abstract: There is decagram of strategic decisions of operations
and production/service management (POSM) within operational
research (OR) which must collate, namely: design, inventory, quality,
location, process and capacity, layout, scheduling, maintain ace, and
supply chain. This paper presents an architectural configuration
conceptual framework of a decagram of sets decisions in a form of
mathematical complete graph and abelian graph.
Mathematically, a complete graph is undirected (UDG), and
directed (DG) a relationship where every pair of vertices is
connected, collated, confluent, and holomorphic.
There has not been any study conducted which, however,
prioritizes the holomorphic sets which of POMS within OR field of
study. The study utilizes OR structured technique known as The
Analytic Hierarchy Process (AHP) analysis for organizing, sorting
and prioritizing(ranking) the sets within the decagram of POMS
according to their attribution (propensity), and provides an analysis
how the prioritization has real-world application within the 21st
century.