International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 12 | Dec 2025
p-ISSN: 2395-0072
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A Topology Optimization Approach for Lightweight Design of CNC Tool Holder Assemblies Kesavdarshan M1, Velmurugan C2, Akash S3, Kamalika M4 1,3,4 UG Scholar, Department of Mechanical Engineering, Kumaraguru College of Technology, Coimbatore, India 2 Professor, Department of Mechanical Engineering, Kumaraguru College of Technology, Coimbatore, India
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Abstract - Conventional CNC tool holders are typically overdesigned, leading to unnecessary weight, higher spindle loads,
and reduced energy efficiency. This study focuses on the design and optimization of a BT40–ER32 CNC tool holder assembly through topology optimization and Design for Additive Manufacturing (DFAM) strategies to achieve lightweighting while preserving mechanical integrity. A redesigned collet nut incorporating a groove for chip deflector integration and dualwrench operation was developed using SOLIDWORKS and structurally analyzed in ANSYS Workbench. Finite Element Analysis (FEA) was performed under realistic loading conditions—comprising preload, axial, radial, and tangential forces—to evaluate stress distribution, deformation, and safety factors. The optimized model achieved a 5.6% mass reduction relative to the conventional design, maintaining a safety factor above 2.2. A prototype was fabricated using Fused Deposition Modelling (FDM) to assess fit, functionality, and manufacturability. The outcomes demonstrate that targeted material removal and functional redesign can significantly improve performance, energy efficiency, and production sustainability. This research validates a complete digital workflow consistent with Industry 4.0 principles and sustainable manufacturing practices
Key Words: CNC Tool Holder, Topology Optimization, FEA, Lightweight Design, BT40-ER32 1. INTRODUCTION Computer Numerical Control (CNC) machines represent a cornerstone of modern manufacturing, offering automated and precise control over machining operations through pre-programmed computer commands. Compared to conventional manually operated machines, CNC systems deliver superior accuracy, repeatability, and productivity in material removal processes. Operating typically along three to five axes, these machines are capable of producing complex geometries with minimal human intervention [1-4]. In CNC milling, a rotating multi-point cutting tool removes material from the work piece as it follows programmed tool paths, enabling high-precision face milling, slotting, contouring, and pocketing operations. Similarly, CNC drilling employs rotating single-point tools to produce accurately positioned holes. Advanced process control features—such as adaptive feed rate adjustment, spindle speed modulation, and optimized tool paths— further enhance cutting efficiency while ensuring dimensional precision [5-7]. The performance and reliability of these machining operations depend significantly on the rigidity, concentricity, and balance of the tool-holding assembly. Even minor deviations in tool alignment or excessive vibration can lead to poor surface finish, accelerated tool wear, and geometric inaccuracies [8-10]. Consequently, the design of the tool holder and collet nut assembly plays a crucial role in ensuring smooth force transmission between the spindle and the cutting tool, thereby maintaining dynamic stability during high-speed machining [11-13]. Within the framework of Industry 4.0, CNC machining has evolved toward greater integration of optimization, automation, and digital twin technologies to improve process reliability, energy efficiency, and material utilization. Recent research efforts have increasingly focused on developing lightweight, high-stiffness, and dynamically stable tool holders using computational analysis and topology optimization techniques. Such advancements contribute to sustainable manufacturing by enhancing performance while minimizing energy consumption and material waste [14,15]. Among the various standards, the BT40 tool holder is one of the most widely used configurations in modern CNC machining centres due to its balanced design and suitability for high-speed operations. When combined with the ER32 collet system, it offers versatile clamping capabilities across a range of tool diameters while maintaining high concentricity and stability. Optimization of this tool holder assembly—particularly through topology optimization and additive design—presents a promising pathway for improving machining accuracy, extending tool life, and achieving overall process efficiency in advanced manufacturing environments [16,17]. In conventional CNC tool holders, excess material in non-critical zones leads to unnecessary weight, resulting in higher rotational inertia that negatively impacts spindle acceleration, dynamic balance, and overall energy efficiency. For high-speed machining applications, achieving an optimal stiffness-to-weight ratio is essential to minimize vibration and deflection during operation. By applying Design for Additive Manufacturing (DFAM) principles in combination with topology optimization, tool holders can be re-engineered to remove low-stress regions while maintaining the required structural integrity [18,19]. The optimized BT40–ER32 tool
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