The aim of this investigation is to study the performance of the new generation of the PVD coated grade and to map the influence of cutting conditions on the tool life in milling of ADI
The aim of this investigation is to study the performance of the new generation of the PVD coated grade and to map the influence of cutting conditions on the tool life in milling of ADI (Austempered Ductile Iron). The results show that chipping is the main wear mechanism which determines the tool life in dry condition and notch wear in wet condition for this application. This due to the different stress mechanisms and preexisting cracks in the coating. The wear development shows clearly that the new PVD coating (C20) has the best ability to delay the chipping growth. It was also found that a high content of Al in the new coating (C20) was especially favorable compared to a TiAlN multilayer with lower Al content (C30) or CVD coating. This is due to fine grains and low compressive stress level in the coating which increase the coating ability to withstand the mechanical and thermal impact. It was also found that the use of coolant decreases the tool life with 70-80% compare to dry milling. Keywords—Austempered Ductile Iron (ADI), coating, chipping, milling, tool performance.
Successfully Machining Austempered Ductile Iron (ADI)
Austempered Ductile Iron (ADI) is a relatively new material to the industrial marketplace. Many have tried to machine ADI as if it were steel, or as-cast Ductile Iron, and have been unsuccessful. Because of this, a myth has developed that ADI is not machinable. When the material properties and metal matrix of ADI are taken into consideration, ADI can be successfully machined.
Can fly-ash extend bentonite binder for iron ore agglomeration?
There is great incentive to reduce bentonite use in iron ore pelletization by improving its effectiveness. In order to make bentonite more effective, it is necessary to understand the actual binding mechanisms so that they can be properly taken advantage of. Bentonite use could also be reduced by replacing bentonite with even lower-cost binders, such as high-carbon fly-ash based binder (FBB). While FBBs can be used alone as binders, it was considered possible that mixtures of FBB and bentonite could exhibit superior binding properties. In this study, it was found that bentonite bonds by a physical mechanism, while FBB bonds by a chemical mechanism. These mechanisms were determined to be incompatible. Mixtures of the two binders resulted in reduced dry magnetite concentrate pellet compressive strengths below the industrially acceptable value of 22 N (5 lbf). Activators and accelerators, which were necessary components of the FBB, deactivated the bentonite. The compatibilities and mechanisms of the two binders are explained in this paper. The classical theory of the binding mechanism of bentonite binder is challenged by the bentonite fiber mechanism that was recently identified by the authors.