What is Tool Deflection in CNC Machining and How to Reduce Them?

March 12, 2021

One manufacturing process that is now being maximised by a lot of industries is computer numerical control (CNC) machining. This manufacturing process utilises pre-programmed computer software to effectively control the movement of industrial tools. From simple to complex activities, CNC machining can certainly perform all of them quickly and efficiently.

While computer software does not truly make errors and mistakes throughout the CNC machining process, the tools controlled by the software can still generate problems and issues. A prominent issue with CNC machining is the occurrence of tool deflection.

An Overview of Tool Deflection

Generally, tools that are used for CNC machining are typically gripped between the chuck in a specific location, making one of their ends to be inside the chuck while the other end is free. As these tools start to perform their intended functions, they would consistently exert a force against a given workpiece. The workpiece, however, would also generate a resisting force, which somehow contradicts the force given by the CNC tools. As the CNC machining continues, the tools might not be able to withstand the external forces from the workpiece, which ultimately leads to their deflection from their initial alignment.

The deflection of the tools from their predetermined alignment is known as tool deflection. Once this incident occurs, it can result in numerous issues and problems for the entire CNC machining process. Some of these issues include total failure of the tools or workpiece, depletion of the tools’ overall life cycle, the occurrence of dimensional inaccuracy, and the formation of rough surface finish or damages.

Minimising Tool Deflection

Tool deflection can happen anytime, even with the presence of preventive measures and strategies. However, minimising this problem can still provide significant and much more valuable benefits to the operators of the CNC tools and their entire businesses.

One best strategy to minimise tool deflection is to reduce the distance between the clutching point of the CNC tool and the operating tip of the tool. A CNC tool often experiences bending stress as it is mounted as a cantilever beam. To lower the impact of the bending stress and minimise tool deflection, the distance between the two points or the overhang length must be reduced.

Enhancing the tool’s core strength can likewise help in minimising tool deflection. The core strength of a tool can be easily determined by its flute length and reach. Obtaining the difference between the aforementioned elements will then help identify the rigidity of the tool’s core. If the diameter of the core is maintained thick, then the tool can easily absorb shear stress and obtain greater strength and rigidity.

The stiffness of the tool must also be enhanced to minimise tool deflection. Even though CNC tools that are made from high-speed steel can be durable, their continuous exposure to high-stress load can still break them in the long run. Opting for carbide tools, alternatively, can be great in minimising tool deflection since they are three times more rigid than high-speed steel.


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