**1. Introduction**

Additive Manufacturing (AM), also known as Rapid Prototyping and 3D Printing is a three-dimensional fabrication process, executed by adding materials in layers. This is a revolutionary product development and manufacturing method, especially in the age when we are experiencing a mew industrial revolution. Small, relatively simple products may only make use of AM for visualization models, while larger, more complex products with greater engineering content may involve AM during numerous stages and iterations throughout the development process [1]. Among many different classes of AM processes, Direct Metal Laser Sintering (DMLS) is a widely used metal part manufacturing method. This process is carried on by using laser power to melt powder metal particles leading to a complete print of the part using the desired 3D solid CAD model data by a layer-by-layer process [2]. The key is to melt the material in a controlled fashion without creating a high accumulation of heat, so that when the energy source is removed, the molten material rapidly solidifies again. Recent involvement of large companies in developing metal AM processes have opened up the market significantly. As a result, machine accuracy, speed, cost, and quality of production have become apparent crucial factors in metal 3D printing nowadays. High quality metal parts with complex geometry can be produced in PBF process. At the same time the manufacturer needs to ensure part-quality, consistency, and competitive pricing to run and sustain a successful metal printing business. Here comes the requirement for deeper understanding of the process so that each and every step can be improved, optimized and controlled for higher efficiency, reliability, and production quality. The metal printing technology is in practice for more than a decade now, yet researchers are working till date to understand the physics of powder bed fusion process, and this is an ongoing pursuit. In this paper, a multiscale modeling technique is described which aims at correlating the PBF process parameter and their impact on single layer as well as subsequent printing defects on build part.
