What is a Boring Machine?
A boring machine is a device for producing smooth and accurate holes in a workpiece by enlarging existing holes with a bore. The bore may bear a single cutting tip of steel, cemented carbide, diamond, or maybe a small grinding wheel.
Single-point tools, gripped in a boring head attached to a rotating spindle, are moved circularly against the sides of the existing holes. The diameter of the hole swept out by the tool is controlled by adjustment of the boring head.
Grinding-wheel cutters have a planetary motion, rotating rapidly about their axes, which in turn slowly rotate with the boring head about the spindle axis; the hole diameter is controlled by adjusting the distance between the wheel and spindle axis.
The spindles on boring machines may rotate about vertical or horizontal axes.
Boring machines used in toolmaking shops have one vertical spindle and a work-holding table that can be moved horizontally in two directions perpendicular to each other so that holes can be accurately spaced.
On some machines, the spacing error is less than 0.002 percent. In mass-production plants, special boring machines with multiple spindles are common.
History
Before boring machines were invented, carpenters used hand-powered augers to boreholes. Most common were T-handled augers.
The shape of the drill bits changed over time, with the spoon bit and shell bit being common before the invention of the spiral or twist bit in 1771 which removes the cuttings as it turns.
The exact origin of this invention is not known, but the earliest patent is in the United States in 1830 by J. Beckwith and was as tall as a man and operated by a large wheel from the side.
Boring machines use twist auger bits usually ranging in size from 7⁄8 inch to 2 inches. The machines hold the bit perpendicular (square) to the face of the timber and are operated with both hands while the operator sits on the base to keep the machine from moving. Some machines can be set at an angle.
Types of Boring Machines
Examples include:
- line boring machines
- tunnel boring machines
- horizontal boring machines
- directional boring machines
- cylinder boring machines
- jig boring machines
- portable boring machines
- vertical boring machines
- coupling boring machines
What Is Boring Machining?
Boring machining is a precise and accurate process that involves enlarging a pre-existing hole in a workpiece using a single-point cutting tool or boring bar.
This technique is employed to achieve high levels of dimensional accuracy and surface finish, making it essential in industries where precision is critical.
Unlike drilling, which creates initial holes, boring enhances the accuracy and size of existing ones. The process is carried out using a boring machine, which can be configured for horizontal boring or vertical boring, depending on the requirements.
This versatility makes boring an indispensable machining technique in today’s manufacturing landscape.
How Does Boring Machining Work?
Boring machining is a precision-driven process used to enlarge or refine existing holes in a workpiece, often involving high levels of accuracy and dimensional consistency.
Unlike drilling, which creates the initial hole, boring machining focuses on enhancing the size and surface finish of pre-existing holes.
The process utilizes various boring machines and tools, such as the boring bar and cutting tool, to achieve desired outcomes in machining tasks.
This technique is fundamental in manufacturing, where precision and accuracy are paramount, ensuring that machining processes meet industry standards and specifications.
Through the application of CNC machining and advanced technologies, boring machining can produce highly precise and accurate results that are crucial in the manufacturing of engine components and other critical parts.
Types of Boring Machining
The three main types of boring machining are listed below:
- Horizontal: As the most common type, this is done on either a lathe or a horizontal milling machine. In horizontal boring, the boring bar moves parallel to the axis of the workpiece, and is used for boring holes in longer workpieces.
- Vertical: This is done on a vertical milling machine, CNC router, or drill press, and the process sees the boring bar moving perpendicularly to the floor. Vertical boring is best suited for heavy workpieces and for large holes, up to 24” in diameter.
- Precision: These machines are designed particularly for boring and are smaller than lathes or milling machines. Because of their small size, precision boring machines are best for boring small parts that require great surface finishes and extreme precision. For example, watch components are typically bored using a precision boring machine called a watchmaker’s lathe.
Applications of Boring Machine
A line boring machine bores holes in heavy construction equipment, such as cranes and end loaders, and is a very economical piece of equipment. A tunnel boring machine is capable of drilling a bore in everything from hard rock to sand and produces a smooth tunnel wall.
A horizontal boring machine is a time-saving machine used to bore holes in a highly rigid construction. A directional boring machine includes a frame and a drive mechanism that is slide-able and is mounted on the frame.
A cylinder boring machine is mainly used for reboring engine cylinders in automobiles. A jig boring machine is used to accurately enlarge existing holes and make their diameters highly accurate. They perform operations such as drilling, boring, and counter-sinking holes in metal workpieces.
A portable boring machine is a flexible, powerful, and easy-to-use machine that is available with a pneumatic or hydraulic drive. A vertical boring machine is designed for manual vertical drilling and it has a drill chuck. A coupling boring machine is designed to bore precision couplings. Other boring machines are commonly available.