CNC deep-hole drilling, also known as CNC gun drilling, is a specialist machining process in which a computer-controlled machine uses a long, precision tool to drill very deep, straight holes. Unlike manual or conventional drilling, which are limited by shallow depth-to-diameter ratios, CNC gundrilling utilises high-pressure coolant and rigid tooling to achieve much greater depths.
However, the benefits of CNC gundrilling don’t stop here: the process plays a key role in improving overall product quality across a range of industries, as we’ll explain in this article.
Advantage #1: Speed
Pre-programmed, CNC deep-hole drilling significantly increases throughput. Because machines run continuously at optimum speeds and feeds with a constant coolant flow, operators don’t have to stop the machine to adjust or change set up, or to clear swarf. In practice, CNC deep-hole machines perform complex drilling patterns much faster than manual methods, with the ability to achieve significantly higher productivity compared to manual drilling.
At Hone-All, CNC gundrilling enables us to deliver rapid turnaround and exceptional quality, both critical factors that reduce cycle times and keep production schedules on track.
Advantage #2: Accuracy
CNC deep-hole drilling offers exceptional micron-level accuracy. Using advanced gun drill tooling and precise CNC controls, the process maintains perfect alignment throughout the cut, minimising drill wander and ensuring outstanding straightness. Bore tolerances of around ±0.002″ (±0.05 mm), even on deep and complex components, are routinely achieved . Exceptional drilling precision significantly enhances part fit, function, and performance, reducing dimensional errors and enhancing product quality and reliability.
Advantage #3: Repeatability
CNC deep-hole drilling delivers exceptional repeatability. Once a drilling program is proven, the machine consistently produces identical holes with minimal variation across each component. This dramatically reduces material waste, as parts reliably meet tight tolerances from one cycle to the next. In high-volume production, such consistency ensures that every component conforms to exact specifications, enhancing overall product quality, eliminating the need for any rework, and improving manufacturing efficiency.
Advantage #4: Consistency
CNC deep-hole gundrilling delivers consistently high output quality by maintaining precise feed rates and applying continuous high-pressure coolant. This controlled process produces smooth, uniform bore surface finishes, typically around 0,8μ.
In demanding applications such as aerospace, counter-rotation further enhances straightness and dimensional stability in deep, precision-critical components. A high level of process control significantly reduces the risk of tolerance variation, leading to more reliable component performance and fewer quality issues.
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At Hone-All, our CNC gundrilling machines routinely drill ø3 - ø25 mm bores up to 1500mm long with tolerances as tight as ±0.05mm, providing exceptional precision for the aerospace, automotive, and medical industries.
