CNC Vertical Machining Center

The Boring Machine Process in Manufacturing

Nov 17, 2023

In the intricate world of manufacturing, raw materials go through a fascinating transformation, undergoing a series of cutting processes before emerging as the final product. One common requirement in this journey is the creation of holes within the material, and that's where boring machining takes center stage.

While various methods, such as drilling, can indeed punch holes in a workpiece, CNC boring stands out as the go-to technique for crafting spacious, wide-diameter cavities with a remarkable focus on dimensional precision.

In today’s article, we will unfold the depths of boring machining, shedding light on its intricacies. So, let’s begin a journey to understand the art and science of boring machining and its significance in modern manufacturing.

What Is Boring In Manufacturing?

Boring is an essential subtractive manufacturing technique designed to achieve two primary goals: first, to enlarge pre-drilled or casted holes, and second, to elevate their dimensional accuracy. This process employs a single-point cutting tool, a true artisan in the world of machining, to meticulously remove material from the interior of a workpiece.

The beauty of boring lies in its versatility. Depending on the specific requirements for hole size, precision, diameter, and positional constraints, boring emerges as the ideal solution. It excels particularly when it comes to crafting holes of considerable dimensions, and its innate precision sets it apart from traditional drilling methods.

Regardless of the specific tool or machine used, boring operations always encompass three fundamental tasks:

  • Widening Holes to Precise Perfection: Boring tools excel at enlarging holes to their exact and accurate dimensions while providing an impeccable finish.

  • Straightening the Path: Boring steps in to rectify the course of pre-drilled or threaded holes and smooth out any imperfections in castings, ensuring a flawless outcome.

  • Creating Concentric Harmony: Boring achieves the impressive feat of crafting concentric holes, aligning their internal and external diameters in perfect harmony, a feat of precision that's indispensable in manufacturing.


How Does Boring Machining Work?

The magic of boring machining takes place on a stage set by either a lathe or a CNC milling machine, where a specially designed tool, the star of the show, is none other than the renowned boring bar, boasting its precision-cutting insert. However, before this captivating process can commence, it requires a preliminary act – the presence of an initial hole, whether it’s from drilling or casting.

In the theater of lathe-based boring, the head of the boring bar takes center stage as it elegantly enters the pre-existing hole. The lathe, with a graceful twirl, sets the workpiece in motion, while the stationary boring tool delicately trims the inner edges of the hole. As it performs its artistry, the hole gracefully expands, inch by inch, growing closer to its intended dimensions.

On the other hand, in the ballet of a milling machine, the workpiece assumes the role of the stationary performer. The spinning boring tool, like a maestro with a baton, takes the lead and, with calculated precision, enlarges the hole to perfection. The workpiece remains poised, allowing the tool to perform its enchanting dance of material removal.

No matter which stage this symphony unfolds on, the principle of boring remains consistent and unwavering. The boring tool’s graceful interaction with the workpiece slowly but surely augments the hole’s dimensions until it reaches the precise size and attains the desired surface finish, leaving us with a workpiece that’s been transformed with meticulous precision.

Types of Boring Machines

When it comes to the world of boring machines, the stage is shared by an array of versatile performers, each tailored to specific tasks and workpiece characteristics. Here, we'll unveil the stars of the show, and the various types of boring machines that grace the manufacturing arena.

Floor-type Horizontal Boring Machine (HBM)

These majestic machines are ideal for the grand stage, reserved for long workpieces.

  • They can gracefully accommodate workpieces as tall as 144" (3657.6 mm).

  • The table, often mounted on the floor, may also take its place on the machine runway.

  • Floor-type HBMs wield boring bars ranging from 6" (152.4 mm) to 10" (254 mm) in diameter, boasting similar geometries to those found in table-type HBMs.

  • Line boring machines, akin to the floor-type, are tailored for precision.

Table-type Horizontal Boring Machines

  • These dependable workhorses find their calling with medium to large-scale workpieces of prismatic shapes.

  • They wield a single-point cutting tool, with diameters ranging from 3 in (76.2 mm) to 6 in (152.4 mm), held by a spindle parallel to the work table.

  • The table-type HBMs exhibit a sturdy configuration, capable of delivering robust cutting forces to tackle even the heaviest stocks.

  • Clamps and bolts secure the workpiece, while the ribbed table structure gracefully supports the load.

  • Boring bar rotary speeds range between 15 and 1500 RPM, while the feed rate follows a harmonious rhythm, typically set between 0.1 to 40 IPM.

Vertical Boring Machine (VBM)

  • The VBMs take a different stance, with a horizontal table and a vertical-moving spindle-borne boring bar that elegantly enters and exits the workpiece.

  • They are sturdy enough to support hefty workpieces and craft holes as vast as 24" (609.6 mm) in diameter.

  • Jig borers, a subtype of VBMs, boast high-precision bearings and come in diverse sizes and specifications, with CNC variants rising in popularity.

  • The world of CNC mills and CNC routers also features VBMs of varying sizes and specifications, catering to an array of applications.

Precision Boring Machine

  • These delicate, yet precise machines are suited for intimate tasks, catering to the needs of small workpieces.

  • Precision boring machines are entrusted with the responsibility of crafting miniature components, such as those found in the intricate workings of a watch, where impeccable surface finish and extreme precision are of paramount importance.

  • Even high-powered CNC lathes, like the Haas ST-30, occasionally step into this role, expertly crafting precise holes in robust materials like steel and titanium.

With this cast of characters, the manufacturing world can tailor its boring operations to the unique demands of each workpiece, ensuring that precision, accuracy, and efficiency reign supreme.


Operations of Boring Machines

Let’s explore together the various operations that can be accomplished using these machines:

Boring Operation

  • Holes are bored using specialized boring bars.

  • Multiple holes can be sequentially bored by adjusting the workpiece’s position to align with the boring bar.

  • The boring bar is fitted to the spindle, and the cutter is configured to the desired dimensions. A light cut is initiated.

  • The bore is measured, and speed and feed settings are adjusted as needed to complete the cut.

Forming Operation

This operation involves a cross-feed movement of the saddle to shape the workpiece.

Machining Flat Surface

  • The cross rail and the ram are locked in the desired position.

  • The saddle moves crosswise while the workpiece revolves on the table.

  • The depth of the cut is controlled by the ram.

Taper Boring Operation

  • Tapered and conical surfaces are shaped by swiveling the tool head to the required angle.

  • For conical surfaces with large included angles that surpass the tool head’s swiveling capacity, a combined cross and down feed is employed to cut the necessary taper.

Turning Cylindrical Surface

  • For this operation, the saddle is clamped to prevent horizontal movement of the ram.

  • The ram is fed downwards.

  • Larger diameter holes are bored by feeding the tool head directly into the work, while smaller diameter holes are shaped using a boring bar attached to the tool head.

Cutting Off and Necking Operation


Similar to the forming operation, this process is carried out through the cross-feed movement of the saddle.

Advantages and Limitations of Boring Machine Process



Superior Accuracy: Boring Machining is the embodiment of precision. While traditional drilling processes can attain a commendable accuracy of up to 0.02 inches, boring operations push the boundaries, achieving astonishing accuracies as tight as 0.0005 inches. To put this in perspective, it’s a remarkable 40 times more precise than standard drilling, ensuring that the final product meets the strictest dimensional requirements. Boring is your guarantee for meticulous precision.

Tolerance Challenges: Boring can typically hold tolerances greater than ±0.010 in (±0.25 mm) with ease. Tolerances down to ±0.005 in (±0.13 mm) are usually manageable even in deep holes. However, the challenge arises when striving for tolerances between ±0.004 in (±0.10 mm) and ±0.001 in (±0.025 mm). Achieving such tight tolerances, especially in deep holes, can be complex, often constrained by geometric limitations as much as size constraints.

Better Surface Finish: Boring Machining doesn’t just stop at accuracy; it’s an artist when it comes to providing superior surface finishes. With the remarkable capacity to achieve surface finishes as smooth as 32 micro inches (measured by the Ra value), it effortlessly outshines many other machining methods. This leaves workpieces with a remarkably refined texture, akin to a masterpiece in the world of manufacturing. Boring doesn’t just create holes; it crafts works of art.

Limited Precision in Deep Holes: In deep holes, maintaining ultra-tight tolerances, like ±0.0005 in (±0.013 mm), becomes challenging. Tolerances as tight as ±0.0001 in (±0.0038 mm) are possible in shallow holes but come at a high cost, necessitating 100% inspection and increasing the expense.

Versatility: Versatility is the hallmark of this machining process. It gracefully dances through a diverse range of materials, from the robust elegance of steel and aluminum to the soft subtlety of wood and plastic. But it doesn’t stop at material versatility alone. Boring transcends the conventional confines of creating round holes, extending its repertoire with the right tooling to craft slots, grooves, and keyways. It adapts effortlessly to the diverse symphony of manufacturing needs, never missing a beat.

Surface Finish Range: Boring machining may yield surface finishes ranging from 8 to 250 microinches. The typical range falls between 32 and 125 microinches, offering a good, but not exceptional, surface quality in some circumstances.

Customizable Hole Sizes: Unlike other machining processes that often adhere to the limitations of standard drill bit sizes, Boring Machining offers the freedom to create custom-sized holes. This flexibility is more than a mere convenience; it’s crucial in applications where uniqueness and precision are non-negotiable. Boring becomes the artisan, tailoring each hole to individual demands, ensuring a perfect fit every time.

Form and Size Accuracy: Boring may have limitations in achieving the highest accuracy of form and size. Variations in diameter across different sections of the bore are often in the range of 3 to 20 micrometers (.0001 to .0008 inches), which can be unacceptable for some applications. Taper, roundness error, and cylindricity error may fall outside acceptable limits for certain parts, requiring follow-up operations like internal cylindrical grinding.

Efficiency: In the modern age, efficiency reigns supreme. Advanced automated boring machines are the maestros in this regard, orchestrating operations with precision and speed. They significantly reduce production times, leading to a reduction in manufacturing costs and accelerated production. In high-volume industries, where every second counts, this efficiency is nothing short of a symphony conductor, ensuring every note is in harmony.

Workpiece Flexibility and Thermal Effects: Boring faces challenges when working with workpieces of extreme hardness and dealing with thermal effects. Workpiece movement due to temperature changes or even small cuts can lead to positional errors, which can be amplified over long distances. This reality can sometimes preclude finishing by boring and turning in favor of more precise methods like internal and external cylindrical grinding.


Choosing Precision with YANGSEN

In the world of manufacturing, precision and quality are non-negotiable. As we’ve explored the intricacies of boring machining, the need for impeccable accuracy becomes evident. That’s where YANGSEN steps onto the stage, ready to meet your precision manufacturing needs.

By working in this industry for more than 20 years, we have mastered our skills to perfection. Our state-of-art-facility which spans over 75k m2 that has more than 500 highly professional employees is proof of our commitment to excellence.


Contact us today and embark on a journey of precision and quality that will redefine your manufacturing experience. Join the ranks of those who demand nothing less than perfection, because, at YANGSEN, precision is not just a promise; it’s our legacy.

Leave A Message

Leave A Message
If you are interested in our products and want to know more details,please leave a message here,we will reply you as soon as we can.