Horizontal Boring Mills vs. Vertical Boring Mills
Both vertical and horizontal boring mills are capable of performing a variety of drilling or boring operations both manually and automatically. The tool head and workpiece typically move along 3 axes known as the X-axis, Y-axis and Z-axis.
The X-axis is the cross travel, the Y-axis is the vertical travel, and the Z-axis is the main axis which drives the work piece toward the spindle. Additional axes include the C-axis, which is the work spindle itself and the B-axis, which is the centerline of the rotary worktable, if equipped.
The main difference between a vertical boring mill and a horizontal boring mill is the machine setup, workpiece setup and the machine’s tooling configuration.
Vertical Boring Mill
Vertical boring mills are also called vertical turret lathes. They operate very similar to an engine lathe if it were turned up on end, and can perform almost all common lathe operations. The machine can perform operations including turning, boring, facing, tapering, and cutting of external and internal threads.
Parts are formed in a vertical boring mill by the workpiece being rotated around its Y- axis while the boring head moves linearly, very similar to that of a vertical lathe.
Characteristics unique to a vertical boring mill include:
- The workpiece is held by a horizontal table that rotates around a vertical axis
- Non-rotating tools can be fed either horizontally or vertically with the use of the cross rail mounted turret slide
- A side head which can be fed both horizontally or vertically
Vertical boring mill applications include machining: water turbine runners, turbine casings, ring gear blanks, large pipe flanges, locomotive tires, and machine tool tables.
Horizontal Boring Mill
Horizontal boring mills are capable of performing many different machining functions including facing, boring, shaping, tapping, reaming, drilling, contouring and milling.
They are used primarily for boring out large parts with the use of a horizontal spindle. This means that the machine’s spindle is parallel to both the ground and the work table.
One advantage of this style of machine tool is that very large parts can be placed on the machine’s worktable using an overhead crane. Parts larger than the table can still be milled, even if the part hangs off the sides of the table. The only requirement is that the part is stable on the worktable to prevent potential operator injury or machine damage.
The setup of horizontal boring millwork and tools are similar to those found in lathe and standard milling machines. Parts are fabricated by the work-piece being placed on a worktable while the boring head rotates around the X-axis, similar to a horizontal milling machine. In fact, horizontal boring mills have often been confused with horizontal turret lathes and the terms have been used interchangeably.
Boring Mill Types
The first boring mills were designed to create a rough cut of the part, which required a second machine tool to finish the part. Newer machine tools, known as precision boring mills, are capable of creating very detailed, finished parts.
The table type of boring mill, also known as the universal boring mill, is the most common as well as the most versatile.
Boring mills can be mechanically operated, but most modern machines use computer numerical controls (CNC), which deliver very precise and accurate machined parts.