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The article summarizes an experimental study on the abrasive wear behavior of particulate filled glass‐epoxy (G‐E) composites. The two fillers investigated were graphite and alumina. The wear behavior was assessed by rubber wheel abrasion tests. The tests were carried out for 270, 540, 810, and 1080 m abrading distances at 22 and 32 N loads. The worn surfaces were examined using scanning electron microscopy (SEM). The results showed varied responses under different abrading distance because of the addition of fillers in G‐E composites. Graphite filler, however, performed poorly resulting in significant deterioration in wear performance while the alumina filled G‐E composite showed improved abrasion resistance. Selected mechanical properties such as hardness, tensile strength, and elongation at fracture were analyzed for investigating wear property correlations. The SEM studies indicate the reasons for failure of composites and influencing parameters. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Higher damping with higher static stiffness is essential for improving the static and dynamic characteristics of machine tool structures. The structural vibration in conventional machine tools, which are generally made up of cast iron and cast steel, may lead to poor surface finish and the dimensional inaccuracy in the machined products. It leads to the investigation of alternative machine tool structural materials such as concrete, polymer concrete, and epoxy granite. Although epoxy granite has a better damping capacity, its structural stiffness (Young's modulus) is one-third as compared to cast iron. Therefore, the present work represents optimization of the structural design of the vertical machining center column by introducing various designs of steel reinforcement in the epoxy granite structure to improve its static and dynamic characteristics using experimental and numerical approaches. A finite element model of the existing cast iron vertical machining center column has been developed and validated against the experimental data obtained using modal analysis. Furthermore, finite element models for various epoxy granite column designs have been developed and compared with the static and dynamic characteristics of cast iron column. A total of nine design configurations for epoxy granite column with steel reinforcement are evolved and numerical investigations are carried out by finite element analysis. The proposed final configuration with standard steel sections has been modeled using finite element analysis for an equivalent static stiffness and natural frequencies of about 12–20% higher than cast iron structure. Therefore, the proposed finite element model of epoxy-granite-made vertical machining center column can be used as a viable alternative for the existing column in order to achieve higher structural damping, equivalent or higher static stiffness and, easy and environmental-friendly manufacturing process.

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Nowadays, natural fibre-reinforced composites find applications in almost all engineering fields. This work is an attempt to realise improvement in dynamic characteristics of micro lathe bed using Himalayan nettle (Girardinia heterophylla) polyester (NP) composite as an alternate material. In order to study and validate the improvements envisaged, a cast iron micro lathe bed is considered as reference. Numerical (FE) model of the cast iron micro lathe bed was developed and validated through experimental static and modal analysis. Finite element analysis of the micro lathe bed with the existing cast iron material as well as with nettle-polyester composite as alternate material was also carried out using worst case cutting forces, and based on the relative performances, the need for form design modification for the proposed material was identified. To enhance the bending and torsional stiffness of the nettle-polyester composite lathe bed, various cross sections and rib configurations were studied and the best among them was identified and the same was implemented in the nettle-polyester composite micro lathe bed design. Finite element analysis of the newly designed nettle-polyester composite micro lathe bed was performed and the improvements in dynamic characteristics were evaluated. The newly designed nettle-polyester composite micro lathe bed was fabricated and the predicted enhancement in static and dynamic characteristics was verified experimentally. The studies indicated that nettle-polyester composite could be considered as a suitable alternate to cast iron structures in machine tools.

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Vibrations transmitted into the machine tool structure made of cast iron cause chattering and develop positional errors between the components during machining operations, causing dimensional inaccuracy and poor surface finish for the products manufactured from them. As an alternate material for cast iron, mineral cast epoxy granite structures are found to exhibit good mechanical properties such as high stiffness and damping ratio at a lesser weight. This study attempts to fabricate an epoxy granite lathe bed having same stiffness as that of a cast iron microlathe bed, and the dynamic characteristics of both the beds are compared. The dimension for the epoxy granite bed is obtained through analytical and finite-element method analysis such that it has same stiffness as that of a cast iron microlathe bed. Modal analysis is conducted to determine the dynamic characteristics of the lathe fabricated. It is found that the damping ratio is improved by 2.2 times for the fabricated epoxy granite bed. In addition, a weight reduction of about 38.64% is observed for the epoxy granite lathe bed in comparison with same-stiffness cast iron bed. To verify the dimensional stability of the fabricated epoxy granite bed, oil and water immersion tests are conducted on test specimens and no change in the dimensions is observed. It is observed that epoxy granite is a promising alternative material for fabrication of advanced machine tool structures.

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