How do you design and implement effective chip evacuation strategies in CNC drilling and tapping operations?

1 Chip formation

The type and shape of chips formed during drilling and tapping depend on the material, tool geometry, cutting parameters, and coolant. Generally, ductile materials produce long, continuous chips, while brittle materials produce short, fragmented chips. The ideal chip shape is curled or helical, as it reduces the contact area with the tool and the workpiece, and facilitates chip removal. To achieve this, you need to select the appropriate drill or tap design, with features such as chip breakers, flutes, and coolant holes.

2 Chip removal

The main methods of chip removal in CNC drilling and tapping operations are gravity, air blast, and coolant flow. Gravity is the simplest and cheapest method, but it is only effective for vertical or inclined holes, and for short chips. Air blast is a common method that uses compressed air to blow the chips out of the hole, but it can be noisy, messy, and require additional equipment. Coolant flow is the most effective and versatile method, as it not only removes the chips, but also lubricates and cools the cutting zone. However, it requires a high-pressure coolant system, and a proper balance between the coolant flow rate and the chip formation rate.

3 Chip disposal

The final step of chip evacuation is chip disposal, which involves collecting, transporting, and recycling or discarding the chips. Chip disposal can affect the productivity, cost, and environmental impact of the machining process. Therefore, you need to consider the following aspects: the volume and weight of the chips, the type and size of the chip conveyor or bin, the frequency and ease of chip removal, and the value and recyclability of the chips.

5 Chip optimization

The ultimate goal of chip evacuation is to optimize the machining process, by reducing the cycle time, improving the hole quality, extending the tool life, and minimizing the waste and energy consumption. To achieve this, you need to apply the following principles: select the optimal material, tool, and cutting parameters for your application; use a suitable coolant type and delivery method; design and maintain a reliable and efficient chip removal and disposal system; and monitor and adjust your chip evacuation strategy as needed.

6 Chip challenges

Despite the best efforts and practices, chip evacuation can still pose some challenges in CNC drilling and tapping operations, especially for deep, small-diameter, or blind holes; hard or abrasive materials; high-speed or high-feed machining; or complex or irregular geometries. In these cases, you may need to use some special techniques or tools, such as peck drilling, reaming, thread milling, through-spindle coolant, or minimum quantity lubrication.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?