Horizontal Milling Machines Basics

Posted on Jun 26, 2020

Horizontal Milling Machine

The milling machine is one of the most important machine tools and the most common. A CNC milling machine is used for cutting and shaping workpieces made from various materials, in most cases some kind of metals. The milling machine is used in the formation of smooth and irregular surfaces, above all else. In addition to this main purpose, the milling machine may also perform other tasks such as drilling, routing, preparing, gear cutting, boring, and slot creation among others.

Several CNC milling machines perform particular tasks with the most efficiency. Distinguishing each type of milling machine helps identify the most appropriate milling machine to use. To identify the most suitable milling machine for you to use, we should take a look at the different types. There are generally just two categories of milling machines, the vertical milling machines, and the horizontal milling machines. In this article, we will focus on horizontal mills that use a spindle axis with a horizontal orientation.


What Are Horizontal Milling Machines?

Horizontal milling machines feature a similar design in which a spindle containing a rotating cutting tool presses against a part to remove material from it. They usually consist of a base, knee, column, table, X-axis, over-arm, and spindle arbor. Some horizontal mills also feature an integrated rotary table that allows milling operations at different angles, you might also hear people call this a universal table.

The real advantage of horizontal milling machines lies in arbor-mounted cutters, called side and face mills, which have a cross-section rather like a circular saw but are generally wider and smaller in diameter. But horizontal mills can also use endmills and the other types of tools available for their vertical counterparts. 

The most significant difference between these two types of milling machines is the spindle orientation. The spindle features a vertical orientation with vertical milling machines and a horizontal orientation with horizontal milling machines. In other words, horizontal mills mount the cutting tool on a horizontally oriented spindle that can remove material from the workpiece. Besides, horizontal milling machines usually use other cutting tools.

While vertical milling machines normally have long and fine cutting tools, horizontal milling machines have shorter and thicker ones; therefore they can perform heavier, deeper cuts compared to vertical milling machines. These are often used by manufacturing companies to cut grooves or slots into workpieces. 

:: Read more: Horizontal milling is the art of efficient production


How to Choose the Right Machine for the Job?

When choosing a horizontal mill, there are some important factors to consider. These include the direction of the milling feed, feed rates, cutting speed, and lubrication. The direction of feed is important since it affects performance and accuracy. The cutting speeds must match the type of material and cutter. Besides, cutting speeds should also match the kind of work the mill does, such as finishing. Suppliers usually provide a recommended list of feeding rates for the proper operation of the milling machines. It should be noted that the recommended feeding rates vary for each type of cutter used to fry. Lastly, proper lubrication is a must when milling metals and alloys.

There are all kinds of horizontal milling machines on the market today. Although some operators still prefer the traditional manual mill and, computer numerical control (CNC) milling machines have overtaken them when it comes to worldwide popularity.

Horizontal Milling Machine Operations & Advantages



The process of machining flat, curved, or irregular surfaces by feeding the workpiece against a rotating cutter containing several cutting edges is a milling operation. The machine consists of a motor-driven spindle that mounts and rotates the milling cutter, and a reciprocating adjustable worktable that mounts and feeds the workpiece. Milling operations can be divided into four groups:

● Face Milling: flat surfaces at a right angle to the cutter axis
● Angular Milling: flat surfaces at an inclination to the cutter axis
● Plain/Snab Milling: flat surfaces parallel to the cutter axis
● Form Milling: surfaces with irregular outlines

Besides, other special milling operations can be performed on horizontal milling machines that we will cover in another article. Let’s talk a bit more about the advantages of horizontal milling machines.


Horizontal milling machines are extremely sturdy and robust machines. There are a variety of cutters available for material removal and shaping which are normally fixated with a strong machine vice. For example, if the removal of a lot of material in a short time is prioritized over milling accuracy, a horizontal milling machine is selected.
Horizontal milling machines do not use a fixed spindle, as opposed to the vertical milling equipment. Rather they use cutting heads similar to small circular saws mounted on a horizontal arbor. In some situations, for example, when the arbor stretches across the entire length of the bed, it might be a good idea to install multiple cutters. While some milling machines have bed movement restrictions on the horizontal axis, some models incorporate a rotating bed. On those horizontal milling machines, you can perform milling operations at different angles.

Several machining operations are ideally on horizontal milling machines:

● Cutting one or more grooves on a workpiece
● Slot machining 
● Multi-side or multi-plan milling operations 
● Machining jobs with extremely heavy workpieces and material 

Overall, horizontal milling machines are generally a better choice for complex projects. 
Often these machines can complete tasks faster, though projects requiring this kind of precise and complex work may require greater financial investment than projects that can be worked on vertical mills.

:: Read more: What are the pros and cons of Horizontal Milling Centers?


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