Investigation into Layered Manufacturing Technologies for Industrial Applications
Additive processes, which generate parts in a layered way, have more than 20 years of history can be defined as layered manufacturing. Layered manufacturing is gaining ground for rapid prototypes (RP), rapid tools (RT) and rapid manufacturing (RM) for production of functional parts. The paper describes which mechanism of layered manufacturing and definition and classification of rapid prototypes can be applied to complex geometries for long-term consistency. The paper demonstrates the application examples of layered manufacturing fulfilling the required physical, mechanical and geometrical properties. The most notable advantage is the integration of production planning and testing within the product development period.
Evaluation of grinding fluids in the grinding of a martensitic valve steel with CBN and alumina abrasives
Abstract In this paper the performances of different cutting fluids and grinding wheel types were analysed in the grinding of SAE HVN-3 workpieces. The resulting residual stress, wheel wear and roughness were evaluated. The influence of the cutting fluid jet velocity vj was also analysed. As a conclusion, the lubrication ability seems to be the governing factor in the cutting fluid performance. The use of CBN wheels can significantly reduce the thermal damage in grinding, leading to compressive residual stresses. The CBN wheel and the cutting oil give an optimum combination for performing this grinding operation.
Temperature control in CBN grinding
The main advantage of CBN grinding wheels is the long wheel life owing to the hardness of the CBN abrasive. Recent research has confirmed another advantage of CBN, which is cooler grinding. The new research allows the temperature in grinding to be predicted based on experimentally validated CBN thermal properties. This work also provides for in-process prevention of thermal damage in grinding. A well-documented feature of CBN grinding is the reduced risk of thermal damage to the workpiece. This advantage can allow a marked increase in removal rate whilst maintaining surface quality of the component compared to grinding with conventional abrasives such as aluminium oxide. The reduced risk of thermal damage in CBN grinding is sometimes attributed to the lower grinding specific energies. While lower specific energies when achieved are an advantage, this explanation ignores a fundamental advantage of the CBN abrasive. The experimental investigation has shown that a major advantage of CBN grinding is that a substantially lower proportion of the total grinding energy enters the workpiece compared to grinding with alumina wheels. The results further indicate that the effective thermal conductivity of CBN grains is considerably lower than its reported theoretical value of 1300 W(mK)−1.