# Expert System Based on Integrated Fuzzy AHP for Automatic Cutting Tool Selection
## 2 Proposed Methodology  
### Cutting Tool Selection Procedure  
The proposed cutting tool selection process is carried out in five main steps based on Sandvik's selection guidance, as described in Figure 1.  
Step 1: The first step is to determine the optimal cutting tool type using an integrated fuzzy AHP method. The selection is based on the machining features, including the related machining operations, basic dimensions, quality, and stability, in the evaluation of the material removal capacity, tool cost, power requirement, and flexibility. The alternatives are all possible cutting tool types for machining of this kind of feature. Figure 2 shows the most popular cutting tool types used for many types of milling operations, according to Sandvik's catalogue [18]. This classification can be applied for other cutting tool manufacturers. Tools are not divided as is normal into general types, such as face mill, end mill, side mill, etc. Instead, other characteristics are considered, such as whether there is a solid mill or insert mill, the entering angle of the cutter, and the holder type. Thus, the process is more detailed and specific, which makes the next selection step easier and more accurate. A hierarchy tree of multicriteria and alternatives is also constructed. The experts' experiences are utilized to judge the importance of criteria and the priority levels of alternatives through pairwise comparisons. Then, the final priorities are calculated for each of the decision alternatives to determine the ranking of M cutting tool types. M is the number of cutting tool types that have high priority in the ranking list. In that case, if the priority value between two alternatives is quite different, the next alternative should not be added into the ranking list. The rules for determining the cutting tool type ranking list according to all given initial conditions are automatically generated and stored in the database as default data for the next step.  
Step 2: In the second step, some main dimensions for each machining feature are preliminarily determined through a calculation model. The input variables correspond to the main dimensions of specific machining features, such as the minimum width, maximum width, length, and depth, so as to determine the cutting tool's diameter range by considering the toolpath number.  
Step 3: Based on the cutting tool type, the specific cutter is determined from the cutter database.  
Step 4: The search process is performed in a cutting tool database to determine the specific cutting tool following the preliminary cutting diameter range.  
Figure 1: Cutting tool selection procedure. Abbreviations: AHP = analytical hierarchy process.  
Figure 2: The cutting tool types used for the milling process.  
Step 5: This step deals with the selection of other characteristics, such as the insert size, edge geometry type, and insert grade. The rule-based method is applied to choose these characteristics based on the recommendations collected from different cutting tool manufacturers' technical guides, machining handbooks, and research results [19; 20]. Cutting data are also collected from the manufacturer's catalogue in addition to correction factors. The loop continues with the next cutting tool type until loop \(i\) is larger than the number of cutting tool types \(M\). The loop should be paused, and a warning is given to stop the selection process or introduce the proper cutting tool based on the optimal cutting tool type for purchasing.  
In this procedure, cutting tool type selection is the first step and is very important. The results of this step affect the next selection steps. For each type of machining feature, there are different types of tools that can be used. Without the prioritization of these cutting tool types, it is difficult to determine the time and quality of the results in the next steps. In the next selection, we primarily describe the proposed method for cutting tool type selection as a key factor of the whole procedure.