A horizontal machining center is a machine tool in which the spindle axis is set parallel to the worktable. It can process larger parts and can perform indexing and rotary machining. It is best suited for multi-process machining of parts with multiple working surfaces, such as milling, drilling, boring, reaming, tapping, and two-dimensional and three-dimensional curved surfaces. It has the excellent performance of completing the machining of box-shaped holes and planes in one clamping. It is also particularly suitable for turning and boring of box-shaped holes. It is widely used in the automotive, internal combustion engine, aerospace, home appliance, and general machinery industries.
Horizontal machining centers are classified into fixed-column and movable-column types based on whether the column moves.
I. Fixed-column type
- The worktable moves in a cross motion, with X and Z axes, and the spindle head moves in the Y axis. The spindle head can be mounted on the column in either a front or side configuration. Suitable for multi-process machining such as boring and milling of medium-sized complex parts.
- The spindle head moves in a cross motion, with X and Z axes, and the worktable moves in the Y axis. Suitable for multi-process machining such as boring and milling of small to medium-sized parts.
- The spindle head is mounted on the column side, with Y and Z axes. This layout is similar to a planer-type horizontal milling and boring machine, with the worktable moving in the X axis. Suitable for multi-process machining such as boring and milling of medium-sized parts.
II. Movable-column type
- Planer-type: The bed is T-shaped, the worktable moves in the X axis on the front bed, and the column moves in the Z axis on the rear bed. 1. Spindle Headset Type: The spindle headset has two mounting configurations on the column: upright and side-mounted, moving in the Y-axis. Suitable for medium to large parts, especially long parts, in multi-process machining such as boring and milling.
- Column Cross Motion Type: The column moves in the Z and U (parallel to the X-axis) directions, the spindle headset moves in the Y-axis on the column, and the worktable moves in the X-axis on the front bed. Suitable for multi-process machining of medium-sized complex parts, such as boring and milling.
- Spindle Ram Feed Type: The spindle headset moves in the Y-axis on the column, the spindle ram moves in the Z-axis, and the column moves in the X-axis. The worktable is fixed or equipped with a rotary table. Multiple worktables can be configured, suitable for machining multiple small to medium-sized parts, where workpiece loading/unloading and cutting times can overlap.
Differences between Vertical and Horizontal Machining Centers
I. Worktable
Vertical machining centers typically have a T-slot worktable with a cross-slide structure. Two motion mechanisms handle perpendicular table movement, with the X-axis feed table overlapping the Y-axis feed guide rail. Horizontal machining centers only move in the X or Y direction. Their worktables are generally rotary tables with a dot-matrix screw hole surface, and are relatively easy to equip with interchangeable dual worktables.
II. Spindle
Vertical machining centers have a vertical spindle, while horizontal machining centers have a horizontal spindle.
III. Machining Objects
Vertical machining centers, limited by column height and tool changer, cannot machine very tall parts. They are suitable for machining discs, sleeves, and plates, and the workpieces are relatively small. To machine the side of the workpiece, an angle head or CNC rotary table must be added. Installing a rotary table rotating along a horizontal axis on the worktable allows for the machining of helical parts.
Horizontal machining centers can machine four surfaces (excluding the mounting surface and top surface) in a single setup, making them ideal for machining box-shaped parts. With the addition of an angle head, they can perform five-sided machining.
IV. Column
The column of a vertical machining center generally does not move and is made as robust as possible to ensure rigidity. There are also moving-column vertical machining centers, where the worktable only moves in the X or Y direction, and the column moves accordingly in the Y or X direction. This design places high power requirements on the column’s drive motor.
The column of a horizontal machining center is always moving. A T-shaped horizontal machining center’s column moves along the X-axis, while an inverted T-shaped horizontal machining center’s column moves along the Z-axis. The structure of a moving column requires it to be as lightweight as possible while maintaining rigidity. Foreign machine tools often use welded steel plate structures to address this issue.
V. Chip Removal
When machining cavities or concave surfaces, vertical machining centers often experience difficulty in chip removal, which can damage the cutting tools, ruin the machined surface, and hinder the smooth progress of machining.
Horizontal machining centers, on the other hand, facilitate chip removal and result in relatively ideal machining conditions.
VI. Operation
Vertical machining centers are easy to clamp, operate, and observe the machining process, and program debugging is straightforward.
Horizontal machining centers typically handle larger workpieces, making clamping difficult, monitoring the machining process challenging, and operation and debugging relatively difficult.
