Reverse Engineering Process Modeling for Cutting Insert Preparation in Laser Micro-Machining

Abstract

In simulations and certain manufacturing processes (such as additive manufacturing, laser ablation), STL models in the form of raw data from the digitization process can be used as direct input. However, to produce a model with the highest possible accuracy and quality, reverse engineering is often necessary to eliminate errors or defects, ensuring a geometrically precise and optimal model, in the case, when initial CAD data are missing. Based on practical experience, where the cutting insert was scanned using the smallest measuring volumes MV 38 and MV 100, we can conclude that the measurement method using optical 3D scanning is suitable for measuring the cutting insert as well as its wear. During the reverse engineering process, it is frequently required to adjust the models, such as aligning the coordinate system or modifying (reducing) the triangular mesh to decrease the size of STL models, if necessary. The reverse engineering process itself offers a wide range of methods that can be applied (e.g., surface fitting methods such as external, middle, or internal fitting), which can significantly impact the accuracy of the final CAD model, required as input for simulations or the manufacturing processes themselves. This research paper focuses on analyzing the accuracy of a CAD model of a cutting insert with chip-braker based on various techniques used in the Reverse Geometric Modeling process. The exact type or name of the cutting insert will not be disclosed for commercial and business reasons and will be referred to throughout the article simply as the cutting insert. The experiment also examines the impact of triangular mesh reduction on the final accuracy of the CAD model within the reverse geometric modeling process. For this experiment, a turning cutting insert with a chip-breaker was selected, and its physical model was digitized using the optical 3D scanner GOM ATOS II Triple Scan with a measurement volume of MV 100. The results of this experiment highlight the effects of individual reverse geometric modeling methods (surface wrapping using external, middle, and internal fittings) as well as the influence of triangular mesh reduction on the final accuracy of the CAD model, specifically in the case of the cutting insert. The aim of this experiment is to determine how specific process parameters of reverse geometric modeling affect the accuracy of the cutting insert, particularly how precise parameters of the cutting insert (e.g., IC, L, RE, ESPR, AN, and others) change with variations in reverse geometric modeling parameters and triangular mesh reduction. These findings are highly relevant not only for simulations of the machining process in advanced CAE software but also for the manufacturing of models using advanced production technologies such as additive manufacturing or laser micro-machining. The results of this experiment highlight the suitability of using non-contact data acquisition methods, specifically optical 3D scanning, for measuring the parameters of the cutting insert and digitizing its shape for reverse modeling purposes. However, for the digitization and measurement of the cutting edge rounding, this method proved to be inaccurate compared to the contact method and, therefore, unsuitable for use.