## 1 Introduction
[PERSON] provided an investigation on the advantages of rapid tooling methods to build heating and cooling channels in order to enhance thermal control [12]. He also demonstrated how to seal such channels rapidly and inexpensively. [PERSON] et al. provided an insight on the conformal channel fabrication method, which is not possible using traditional drilling or machining processes [13]. They presented a technique for fabricating conformal cooling channels in an aluminum-filled epoxy mold using Rapid Prototyping (RP) techniques. An investigation of the automation of the preliminary design stage to the layout design stage of the cooling system design process was presented by [PERSON] et al., who provided a configuration of straight cooling channels based on the size and shape of the plastic part design, which does not necessarily require an additive manufacturing technique [14]. There have been a series of studies in the area of design and modeling of conformal cooling channels in injection molding tooling for a long time, yet the concept of simulating the designs cannot be traced back more than 10-12 years. Since then, researchers have been using different commercially available simulation packages to analyze the tool and channel designs. [PERSON] et al. found the best position of the runner in 2005, using Moldflow analysis in I-DEAST(tm) [3]. Two years later, [PERSON] and [PERSON] analyzed part cooling times using the ANSYS thermal analysis [15]. Two more years later, this research group demonstrated comparative part analysis using MPI simulation software for conventional and square section conformal cooling channels; they concluded that conformal channels render 35% less cooling time than conventional ones [16]. By incorporating a square sectioned conformal cooling channel system for injection mold dies, they provided comparative studies between conformal and traditional molds [17]. Finite element analysis using ANSYS was also presented for a mold with bimetallic conformal cooling channels. They compared the performance with a conventional mold, and provided experimental verification with two different plastic materials that were produced by a miniature injection molding machine [16]. [PERSON] and [PERSON] presented a quantitative guidance for tooling design in 2009. Their proposed methodology was tested on a 3D printed benchmark tool with truss support. In their study, preliminary tests demonstrated the technical feasibility of using a solid freeform fabrication process to create low thermal inertia tools [18]. Another finite element study was presented by [PERSON] et al. for the milled groove insert method for the cooling of plastic injection molds using a household iron plastic part [PERSON] et al. (2013). This analysis was based on a cooling and thermal stress modeling technique [PERSON] et al. (2013). [PERSON] et al. performed finite element analysis (FEA) to determine the mold temperature using ABS polymer as the molten material and water at 20 \({}^{\circ}\)C as the cooling fluid [PERSON] et al. (2013). [PERSON] and [PERSON] conducted a study to investigate the thermal effects of cooling channel design on injection molding using Moldflow Plastic Insight 3.1 [PERSON] et al. (2013). They proposed a novel scaffold for the design of uniform conformal cooling. A few years later in 2013, [PERSON] et al. identified that for cavities with irregular geometry, the distance between the cooling channels and the cavity would vary throughout the part, and would cause local heat accumulation and product defects such as sink mark, warpage, etc. They adopted a true 3D simulation technique to predict the cooling time and compare the results with traditional molds [PERSON] et al. (2013). [PERSON] and [PERSON] adopted an algorithm to calculate the temperature distribution through molds, and presented a conformal channel design with an array of baffles for obtaining uniform cooling over the entire freeform surface of the molded parts [PERSON] et al. (2013).