Boring Machinery: Key Machine for Your Shop

Posted on Jul 3, 2020

Boring Machinery

In machining, boring is the process of enlarging a hole that has already been drilled (or cast) by means of a single-point cutting tool (or of a boring head containing several such tools), such as in boring a gun barrel or an engine cylinder. Boring is used to achieve greater accuracy of the diameter of a hole and can be used to cut a tapered hole. Boring can be viewed as the internal-diameter counterpart to turning, which cuts external diameters.

There are various types of boring. The boring bar may be supported on both ends (which only works if the existing hole is a through-hole), or it may be supported at one end (which works for both, through holes and blind holes). Line boring (line boring, line-boring) implies the former. Back boring (back boring, back-boring) is the process of reaching through an existing hole and then boring on the "back" side of the workpiece (relative to the machine headstock).

Due to the limitations in tooling design due to the fact that the workpiece mainly surrounds the tool, boring is inherently somewhat more difficult than turning, due to the reduced rigidity of the tool attachment, increased clearance angle requirements (limiting the amount of support that a cutting edge can be given) and the difficulty of controlling the resulting surface (size, form, surface roughness). These are the reasons why boring is seen as a separate area of ​​machining practice, regardless of turning, with its own tips, tricks, challenges, and extensive expertise, despite the fact that they are identical in some respects.

The first boring machine was invented by John Wilkinson in 1775.

Boring and turning have abrasive counterparts in internal and external cylindrical grinding. Each process is selected based on the requirements and parameter values ​​of a particular application.

A horizontal boring mill showing a large boring head and a workpiece sitting on a table.

Boring head on Morse taper shank. A small boring bar is inserted into one of the holes. The head can be moved to the left or right with a slight gradation using a screw, adjusting the diameter of the circle through which the cutting tip moves, thus controlling the size of the hole, up to 10 micrometers, if all processing conditions are good.

The boring process can be performed on various machine tools, including universal or universal machines, such as lathes ( turning centers) or milling machines ( machining centers) and on machines designed for specialization in boring as a basic function, such as boring and boring equipment or boring machines, including vertical boring machines (the workpiece rotates around a vertical axis while the boring machine/head moves linearly; essentially a vertical lathe) and horizontal boring mills (workpiece sits on a table while the boring bar rotates around a horizontal axis; essentially a specialized horizontal milling machine).

:: Read More: What is a Horizontal Boring Machine?



Boring and milling machines

The dimensions between the element and the tool bit can be changed around two axes to cut both vertically and horizontally on the inner surface. The cutting tool is usually single-point, made of M2 and M3 high-speed steel or P10 and P01 carbide. A conical hole can also be made by turning the head.

The boring machine is available in many different sizes and styles. Boring small objects can be done on a lathe, while larger objects are machined on boring equipment. Workpieces typically have a diameter of 1 to 4 meters (3 feet 3 to 13 feet 1 inch) but can be as large as 20 meters (66 feet). The power demand can be up to 200 horsepower (150 kW). The cooling of the holes takes place through a hollow passage through the boring bar, in which the coolant can flow freely. Tungsten alloy discs are sealed on the strap to counteract vibration and vibration when boring. Control systems can be computer-based, allowing for automation and greater consistency.

Since drilling is intended to reduce the product's tolerance to pre-existing holes, there are a few design considerations to consider. First, large-diameter lengths for the hole are not preferred due to the deflection of the cutting tool. Then, through-holes are preferred over blind holes (holes that do not pass through the workpiece thickness). It's best to avoid broken internal work surfaces - in which the cutting tool and surface have discontinuous contact. The boring bar is the protruding machine arm that holds the cutting tools and must be very stiff.

Due to these factors, drilling and deep hole drilling are by their nature difficult areas of practice that require special tools and techniques. Nevertheless, technologies have been developed that produce deep holes with impressive accuracy. In most cases, they relate to many cutting points, diametrically opposed, whose deflection forces cancel each other out. Typically, they also include supplying cutting fluid pumped under pressure through the tool into holes near the cutting edges. Drilling pistols and drilling cannons are classic examples. These machining techniques, developed for the first time for the production of firearms and artillery barrels, are now widely used in production in many industries.

Various constant boring cycles are available on CNC controllers. These are programmed subprograms that move the tool through successive cuts of cut, retract, feed, cut, retract, return to the starting position, and so on. They are named using G codes, such as G76, G85, G86, G87, G88, G89; and also by other, less common codes, specific to specific control designers or machine tool designers.

Some people think machine drilling is the same as drilling, but this is not necessarily true. The purpose of drilling is to enlarge or enlarge the hole in the workpiece. Machine boring does not create the initial pilot hole. Rather, it widens the pilot hole, making it wider with extraordinary precision.

If a manufacturing company needs to create a hole with a specific diameter in the workpiece, it can use a machine boring. First, the manufacturing company must create the initial pilot hole, which is usually done by drilling. After creating the pilot hole on the workpiece, you can use a boring machine. The machine drill bits into the pilot hole, forcing it to enlarge to the desired size of the manufacturing company.

:: Read More: Boring & Milling Machines Achieve Faster Machining

Line-Boring vs Back-Boring: What's the Difference?

There are two types of machine boring: linear boring and back boring. For linear drilling, the boring bar is fully supported at both ends of the workpiece. For reverse drilling, it is operated only at one end of the workpiece.

Boring machines

Of course, boring machines are heavy machines used to drill holes in a workpiece. They usually contain a sharp tool that is pressed into the workpiece hole.

Like boring machine boring processes, there are two types of boring machines: general-purpose and boring specific. General-purpose boring machines consist of lathes and milling machines. Although they can perform boring processes, they are also able to perform other machining processes, which is why they are called "general goals". On the other hand, boring machines are designed specifically for boring. Typical examples of boring specific machines include horizontal boring machines and vertical boring machines.

Regardless of whether this is the general purpose of boring, most drills are equipped with a diamond, steel, or carbide tip. After setting and securing the workpiece in place, the drill is turned on. To widen the workpiece hole, the boring machine presses the rotating tooltip into the hole.


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