Understanding Vertical Machining and Its Uses
Milling machines have a wide range of uses in amateur and professional construction, including the cutting of slots, planing or drilling, and more complex tasks, such as contouring objects. They come in many sizes, from tiny units to benchtop machines found in many household garages. Some commercial milling machines can fill an entire room. These types of equipment have different classifications based on their size and how they are used. The two primary classifications are whether they perform the machining process vertically or horizontally.
The differences between vertical and horizontal machining are simply based on the orientation of the main spindle, which is the part of the machine that does the work. Vertical machining involves a spindle that moves in a perpendicular angle relative to the workpiece. The work is accomplished by either raising or lowering the spindle or the table that is supporting the object that is being machined. This differs from a horizontal milling machine, where the cutting tool, or endmill, is mounted on a horizontal support structure.
There are actually two types of vertical mills. A turret mill employs a stationary spindle. The table can be moved either parallel or perpendicular to the axis of the endmill. The most common of the turret types is distinguished by its sliding ram and rotating turret mounting. There is also a bed mill, where both the table and the spindle only move up and down relative to each other. A simple version of this type of equipment is the box mill, used by amateur machinists. It features a head that travels vertically. Another variant is the C-frame mill, which is used in industrial production and features a larger motor and a supplemental hydraulic system. Turret mills are considered more versatile, but larger units can be difficult to manipulate.
For this reason, large milling machines are normally of the bed type.
The advantage of vertical versus horizontal machining depends upon the size of the workpiece and the number of sides on the piece that is being drilled or shaped. Vertical machining is particularly useful in doing work where the cutting tool needs to be directly above the workpiece. This allows the operator to look down on the work and easily monitor the cutting action. Vertical machining is favored in die sinking work, which involves the shaping of a block of metal into a particular mold from which plastic or metal objects are cast. But when the workpieces are heavier and/or longer, a horizontal mill is more practical. Gear making normally involves horizontal machining.
Horizontal machining predates vertical milling, but the introduction of automated machine equipment led to the wider use of vertical milling machines in commercial manufacturing.