# Evaluation of Non-Planar Tool Interaction in Milling of Shaped Surfaces Using a Copy Milling Cutter
## 2 Materials and Methods  
To adequately illustrate the possibility of producing complex and free-form surfaces, the profile of a human face (Figure 1) created in the Rhinoceros 2020 graphics program was selected as a CAD model. The model was extracted from the Rhino environment into STL format and saved in STEP format using the STL2 STEP converter. This format is supported by the CAD system SolidWorks 2020, which forms the basis for the chosen CAM system SolidCAM 2022, which allowed us to define the necessary milling strategies for machining the desired shape and dimensions. An aluminium alloy was chosen as a semi-finished product AlCu4 Mg (Slovalco, a. s., Ziar nad Hronom, Slovakia), tensile strength = 420 MPa; yield strength = 240 MPa; hardness = 120 HB. A 3-axis milling machine was used to produce a test sample with dimensions of 100 \(\times\) 80 \(\times\) 40 mm EMCO Mill 155 ((EMCO MAIER Ges.m.b.H., Hallein, Austria) with a control system Heidenhain TNC 426. The maximum speed of the machine spindle is 5000 rpm. Production took place in six operations, where three types of tools were used as shown in Table 1. All tools were from the Korloy company, while the cutting conditions corresponded to the manufacturer's recommendations. Figure 1: CAD model of human face. Semi-finish and finish operation were tools clamped in a BT-40 clamping system by a mechanical collet chuck. Overhang of the tool was 40 mm. A mineral emulsion-based coolant was used for cooling during production. For the clamping of the specimen, a vise type KSX 125 (Schunk GmbH & Co. KG, Brackenheim, Germany) was used, with the specimen clamped in the middle of the vise jaws. The choice of finishing strategies was conditioned by previous studies, as well as the most frequent use in the production of the mentioned shapes. The milling strategies linear, constant step and constant Z in the simulation mode that SolidCAM 2023 includes were selected as finishing operations and compared with each other. This is the SolidVerify mode, in which, based on the consideration of the residual material after machining with the chosen strategy, the most suitable one for production was selected. The implementation of the experiment included the following sequence:  
* Roughing: face cylindrical cutter D18 mm with two interchangeable cutters plates marked APXT11T3 PDR-MA, axial depth of cut a\({}_{\text{p}}\) = 1 mm, radial depth of cut a\({}_{\text{e}}\) = 0.6 mm, tool path tolerance T = 0.1 mm, surface allowance P = 0.5 mm
* Semi-finishing--ball nose end mill D6 mm, cutting material solid carbide, number of teeth 2, coating AITiN, tool geometry \(\lambda\) = 30\({}^{\circ}\), \(\gamma\) = 12\({}^{\circ}\), machining strategy--linear, axial depth of cut a\({}_{\text{p}}\) = 0.5 mm, radial depth of cut a\({}_{\text{e}}\) = 0.5 mm, surface allowance P = 0.2 mm
* Finishing--ball nose end mill D4 mm, cutting material solid carbide, number of teeth 2, coating AITiN, tool geometry \(\lambda\) = 30\({}^{\circ}\), \(\gamma\) = 12\({}^{\circ}\), machining strategy--constant Z, radial depth of cut a\({}_{\text{e}}\) = 0.2 mm, tool path tolerance T = 0.01 mm  
The following sequences were chosen to evaluate the results of the experiment:  
* Comparison of machined surfaces between CAM system and real production
* Evaluation of the effective diameter of the tool Deff with respect to the contact of the tool and the workpiece
* Evaluation of tool surface area distribution using areal content and volume data extraction at the contact patch location
* Assessment of surface deviations by the 3D scanning method--scanner FARO Laser ScanArm V3 (FARO Technologies Italy S.r.I., Rezzato, Italy)  
Methodology for Evaluating the Effective Diameter of the Tool with Regard to the Contact between the Tool and the Workpiece  
The evaluation of the effective diameter of the Deff cutter was carried out directly in the CAD system, where it was possible to perform a measurement based on the contact surface of the tool with respect to the workpiece in a specific position.