THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Material issues in additive manufacturing: A review

Additive manufacturing (AM) or 3D printing has revolutionized the manufacturing world through its rapid and geometrically-intricate capabilities as well as economic benefits. Countless businesses in automotive, aerospace, medical, and even food industries have adopted this approach over the past decade. Though this revolution has sparked widespread innovation with single material usage, the manufacturing world is constantly evolving. 3D printers now have the capability to create multi-material systems with performance improvements in user-definable locations. This means throughout a single component, properties like hardness, corrosion resistance, and environmental adaptation can be defined in areas that require it the most. These new processes allow for exciting multifunctional parts to be built that were never possible through traditional, single material AM processes. AM of metals, ceramics, and polymers is currently being evaluated to combine multiple materials in one operation and has already produced never-before-produced parts. While multi-material AM is still in its infancy, researchers are shifting their mindset toward this unique approach showing that the technology is beginning to advance past a research and development stage into real-world applications. This review is intended to highlight the range of 3D printed polymer-based, metal-metal, and metal-ceramic applications while discussing advantages and challenges with additively manufactured multi-material structures.

Additive manufacturing of multi-material structures

On-line and indirect tool wear monitoring in turning with artificial neural networks: a review of more than a decade of research

Due to the widespread use of highly automated machine tools in the industry, manufacturing requires reliable models and methods for the prediction of output performance of machining processes. The prediction of optimal machining conditions for good surface finish and dimensional accuracy plays a very important role in process planning. The present work deals with the study and development of a surface roughness prediction model for machining mild steel, using Response Surface Methodology (RSM). The experimentation was carried out with TiN-coated tungsten carbide (CNMG) cutting tools, for machining mild steel work-pieces covering a wide range of machining conditions. A second order mathematical model, in terms of machining parameters, was developed for surface roughness prediction using RSM. This model gives the factor effects of the individual process parameters. An attempt has also been made to optimize the surface roughness prediction model using Genetic Algorithms (GA) to optimize the objective function. The GA program gives minimum and maximum values of surface roughness and their respective optimal machining conditions.

A genetic algorithmic approach for optimization of surface roughness prediction model

Compositionally graded yttria-stabilized zirconia coating on stainless steel using laser engineered net shaping (LENS™)

Effects of grit blasting on surface properties of steel substrates

Effects of cryo-cooling in grinding steels

In the present study, WC–12Co coating has been deposited using plasma spray and high velocity oxyfuel spraying (HVOF) and wear performances of these coatings have been compared with electroplated hard chrome. Bearing steel and WC–Co balls have been used as rubbing counterparts. The wear is predominantly adhesive for the atmospheric plasma spray (APS) and the electroplated coating. For HVOF coating, wear has been found to occur by localised microfracture. A careful choice of plasma spray parameters yields a coating more wear resistant than the electroplated hard chrome. However, the HVOF coating has always offered the highest wear resistance.

Plasma and HVOF sprayed WC–Co coatings as hard chrome replacement solution

During plasma spraying of alumina with the stable α phase in the starting powder, metastable phases tend to form in the final coating. This is attributed to the rapid quenching associated with the process. In this paper the weight fraction of metastable phase formed, i.e., stable phase retained, and has been estimated using Rietveld refinement of X-ray diffraction data. This weight fraction depends on the process parameters like standoff distance, primary and secondary gas flow rate, nozzle size, etc., which in turn control particle melting. Under favourable melting conditions the weight fraction of the metastable phases approaches 1.

Partha Pratim Bandyopadhyay

Papers

Compositionally graded yttria-stabilized zirconia coating on stainless steel using laser engineered net shaping (LENS™)

Effects of grit blasting on surface properties of steel substrates

Effects of cryo-cooling in grinding steels

Plasma and HVOF sprayed WC–Co coatings as hard chrome replacement solution

Analysis of phase transformation in plasma sprayed alumina coatings using Rietveld refinement