The Comparison Between Horizontal Milling And Vertical Milling

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Milling is an all-round machining process which can be applied to various materials including metals, plastics and composites. The suitability of a material for milling is dependent on factors like machinability, toughness and the particular form of milling operation. 

The fabrication industry applies different types of milling machines depending on the application. Generally, milling can be classified as horizontal and vertical milling. These two are further subdivided into different categories.

In this article, we will give a comparison and differences of the aspects of horizontal and vertical milling. To unravel these key characteristics and help yourself in making the right decisions on the types of milling machines to use in your project, keep on reading.

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Horizontal vs Vertical Milling Machine (Image Source: Pinterest) 

Orientation of the Spindle

The major difference between horizontal and vertical milling machines is the spindle orientation. Let’s explore how the spindle differs within them.

1. Vertical Milling Machines

In vertical milling machines, the spindle is oriented vertically just as the name suggests, meaning that the cutting tool, usually a drill bit end mill, moves up and down along the Z -axis. 

Vertical milling machines are popular with tasks that require cutting and shaping materials in a vertical direction. They are specifically useful in creating holes, sots and pockets in a workpiece.

The main advantage of vertical milling machines is their ability to work with high precision on operations with various complexities. The vertically oriented spindle allows for greater control and accuracy when cutting intricate shapes and contours.

Oftenly these machines are equipped with a rotary table that enables the workpiece to be rotated at different angles. This feature is majorly instrumental for turning out curved surfaces or creating spiral patterns.

2. Horizontal Milling Machines

Horizontal milling machines have a spindle that is oriented horizontally along the X-axis. This means that the cutting tool moves along the axis, parallel to the workstation. These machines are recurrent with tasks that require cutting and shaping materials in a horizontal direction. They are particularly useful for modeling slots, grooves and flat surfaces. 

Horizontal milling machines’ have an upper hand in their ability to remove substantial amounts of material swiftly. The spindle’s orientation enables efficient chip evacuation resulting in faster machine operation times.

Equipped with multiple cutting tools, the type of machines can perform simultaneous operations. This feature is especially beneficial for production in high-volume, where time is a key factor.

Tool Geometry

The distinction in tool geometry between horizontal and vertical milling machines has a central role in their respective capabilities and applications. Tools used for horizontal milling are short and stout, enhancing its ability to remove large materials from the workpiece.

These tools are characterized by their robustness, allowing them to withstand the heavy-duty cutting operations.Due to their architecture, horizontal milling cutters ensure a high rate of rapid material removal making them ideal for tasks that require aggressive machining.

On the contrary, vertical milling machines have long and slender tools that are tailored for enhanced versatility and precision producing cuts with intricate and finer details.

The elongated nature of the tools enables them to reach deep into the workpiece enabling the vertical mill to achieve high accuracy in the execution of intricate contours and profiles. Additionally, the slenderness of the tools minimizes the chances of deflection thus ensuring consistent machining results.

Understanding the tool metrics between horizontal and vertical milling machines is vital since it reflects their specific strengths. Horizontal mills are best for rapid material removal while vertical mills excel in complex and precise milling operations. By leveraging these capabilities, selecting the appropriate machine for your given needs is simplified.

Cutting Specifications and Accuracy

The geometry of a milling tool is directly proportional to its cutting proficiency and the quality of the resulting workpiece. With their slender and elongated designs, vertical milling machines offer superior precision making them ideal for detailed and intricate results.

Having the ability to access tight spaces, vertical machines can execute fine cuts with high accuracy.However, despite their upperhand in precision, vertical tools have limitations when it comes to creating deeper cuts.

Furthermore, vertical milling machines are prone to vibration and deflection when exposed to heavy cutting loads. As the tool infiltrates deeper into the workpiece, it encounters increased resistance leading to vibration and digressions from the desired design. This limits the depth of the cuts made by vertical tools affecting their sustainability for certain tasks.

Horizontal tools feature a shorter and thicker geometry that provides stability and resistance to deflection.  This rigid design enables them to bear up against great cutting forces, thus creating deeper cuts with reduced risks of vibration inaccuracies.

The horizontal milling machines are highly applicable in areas where substantial material removal and machining of large workpieces is required due to its stability and rigidness.


Vertical milling machines have outstanding adaptability for a wide range of machining operations, making them a popular choice in many workshops. Due to their capability in precise depth and angle control of the drill, vertical mills excel not only in traditional milling tasks but also drilling operations.

Moreover, vertical mills’ flexibility in adjusting workpiece position along multiple axes, enables them to execute complex cuts with ease resulting in sleek surface finishes and contours.

The upright orientation of its(vertical mill) spindle allows for easily integrating rotary tables or indexers thus enhancing their capabilities for complex machining i.e gear cutting or engraving.

Horizontal milling machines, on the other hand, are especially equipped for handling heavy workpieces and specific complex projects. Their robust construction and short, thick tools provide the stability and rigidity necessary for machining large components with precision. 

The horizontal mills are excellent for tasks that demand substantial material removal rates, such as roughing operations on heavy-duty parts. Additionally, their horizontal spindle orientation facilitates efficient chip evacuation, contributing to extended tool life and improved surface finish. 

While horizontal milling machines may have limitations in terms of flexibility compared to vertical counterparts, they are necessary for certain applications that require high productivity and accuracy in machining heavy workpieces.

Cost of the Machine

For smaller workshops and businesses, cost considerations associated with vertical milling machines are usually preferred. Mostly because they have a lower initial investment compared to horizontal milling machines and the overall expenses related to operation and maintenance is more economical. 

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Vertical Milling Machine (Image Source: Shutterstock) 

Below are some of the factors that make vertical mills affordable: 

  • Simpler Design: They have simple designs with few movable parts resulting in reduced maintenance requirements and associated costs.
  • Availability: Compared to horizontal mills, vertical mills are less expensive thus they have lower operational expenses.
  • Low training costs: Manufacturers save a lot on training costs since there is an availability of operators skilled on working with vertical mills allowing them to easily integrate new equipment during transitions.
  • Low overhead costs: 
  • The ease of operation and reduced learning curve associated with vertical machines not only make them more accessible but also contribute to lower operational expenses by minimizing the potential for errors and downtime. 

Generally, vertical mills are preferred over horizontal mills in many small shops and manufacturing facilities because of their cost advantages.

Material Removal Rate

Some of the core factors that determine the removal rate of materials in milling operations include stability and cutting tool geometry. Horizontal milling machines, outperforms their counterparts vertical mills in material removal rates since they are stable and produce deeper cuts.

Since they are constructed with a horizontally oriented spindle, horizontal mills are more stable allowing aggressive machining with minimal vibration and deflection. This stability feature also enables horizontal mills to sustain higher cutting forces hence the faster material removal rate. 

With its precise and limited depth of cuts, vertical mills are often preferred for operations such as facing and grooving. The vertical orientation of the spindle facilitates smooth access to the workpiece surface enhancing accuracy of the operations. However, its limit to cutting potential, especially when it comes to the depth of the cut, clearly restricts their material removal rate.

Despite their precision advantages, vertical mills may not yield high productivity when it comes to large scale material removal which is done rapidly.  While vertical machines excel in precision tasks, their lower removal rate makes them less suitable for high volume material removal applications.

Overarm and Arbor Support

Horizontal milling machines have various unique components. For instance, plain horizontal milling machines have a column that contains the drive motor and gearing. They also have a fixed-position horizontal milling machine spindle. 

An overhead arm  (overarm) that is adjustable and contains one or more arbor  supports projects forward from the top of the column. The arm and arbor supports are used to stabilize long arbors. 

Depending on the position of the milling cutters, the supports can be shifted along the overarm to support the arbor where support is desired. The horizontal milling machine’s knee rides up or down along the column on a rigid track.

They also have a heavy, vertical positioning screw beneath the milling cutter. This makes horizontal mills excellent for forming and fluting milling cutters and reamers, flat surfaces, cutting dovetails and keyways, cutting gears etc. 

With different attachments available for use, horizontal milling machines offer many special operations. For instance, the saddle rests upon the knee supporting the worktable. Moving in and out of the dovetail, the saddle controls the crossfeed of the worktable.

The worktable, on the other hand, traverses to the right or left upon the saddle to feed the workpiece past the milling cutter. The table can also be moved manually or automatically.

Number of Sides for Machining

Horizontal milling machines boast of machining multiple sides of a workpiece due to their design and orientation. Horizontal mills easily access multiple sides of the workpiece without mobility because of their horizontal spindle configuration and the ability to set the workpiece on a rotary table or indexer.

The versatility of horizontal mills allows for efficient machining of complex geometries and enables the completion of operations in a single setup. Further features in horizontal milling machines include multi-axis capabilities that enhance their capacity to machine multiple sides of a workpiece with precision.

On the other hand, vertical milling machines face limitations in machining multiple sides of a workpiece since the spindle is oriented vertically making it difficult to access certain areas of the workpiece, thus repositioning is required or setting multiple setups to machine all sides effectively. 

Even though vertical milling machines achieve impressive accuracy and precision, the need for additional setups tend to increase machining time and complexity which impacts productivity and efficiency.

Compared to vertical mills, horizontal mills have a high capacity to machine multiple sides of a workpiece in a single setup contributing to its significant advantages in terms of versatility, efficiency and throughput. This makes it a preferred choice for tasks that require complex machining operations on multiple sides of a workpiece simultaneously.

Chip Evacuation

Chip evacuation is a critical aspect of machining processes, especially when cutting deep grooves or narrow cuts into workpieces. Chips generated from the cuts or between moving parts can accumulate and lead to various issues such as poor surface finish, tool damage, and even the machine could experience some downtime.

In such situations, horizontal milling machines are particularly advantageous due to their orientation that facilitates straightforward chip removal and helps in maintaining cleaner surface finishes. The horizontal orientation of the spindle in these machines allow gravity to aid in chip evacuation as chips will tend to naturally fall away from the cutting zone.

The horizontal layout also enables utilization of chip conveyors or augers to effectively remove chips from the work area thus preventing chip buildup and ensuring uninterrupted machining. This streamlined chi[ evacuation process minimizes the risk of chip recutting which can negatively impact the surface finish and the tool life.

The quality of the workpiece finish is highly attributed to the effective management of chip evacuation. Post-production, horizontal mills yield smoother surface finishes with fewer imperfections by preventing chip build up and recutting.

Additionally, the absence of chip-related issues such as chip packing or clogging allows for more consistent and predictable machining results. The orientation and chip evacuation capabilities of horizontal milling machines are significant in optimizing productivity in machining operations.

Choosing between Vertical and Horizontal

When it comes to choosing between horizontal and vertical milling machines, your final decision should be based upon the size and shape of the materials you will use, as well as the types of projects you wish to complete and your time frame for completing them. 

You should also consider how much you can afford in comparison to those factors. Let’s delve further into these factors below:

  • Size: Generally, handling projects that are large or involve heavy or bulky materials,  a horizontal milling machine is the most preferred option. The same is true of projects with parts that need cutting on multiple sides.
  • Shape: The shape of your project’s materials is a crucial factor to consider. If the material is bulky or oddly shaped, choose whichever machine is a better fit.
  • Projects:  if you have several different types of projects, choose a machine that is adaptable and can help you complete the broadest range of tasks- particularly if you want to save on the cost for purchasing several add-on parts or the work station space for more than one machine.
  • Time: a horizontal milling machine is ideal for projects that are to be completed on a daily basis or projects that require lon-g-term fast turnaround time. For lesser time-sensitive projects, a vertical milling machine is the preferred choice because it is simple to use and more affordable.

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Horizontal Milling Machine (Image Source: Shutterstock)


Vertical milling machines and horizontal milling machines have distinct differences that make each of them suitable for specific applications. While vertical milling machines excel in precision and versatility making them preferred for complex machining operations horizontal milling machines, on the other hand, excel in speed and efficiency, making them ideal for high-volume production runs. 

The choice between which milling machine to use is totally dependent on the specific requirements of the task at hand. By understanding the unique features and advantages of each type of machine, you can make informed decisions to optimize your machining processes. Your final derived decision of the type of milling machine should be based on the specific needs of your project. 


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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