Horizontal Machining Centers

1. What is a Horizontal Machining Center?

A horizontal machining center is a drilling and milling machine where the main spindle is equipped on the horizontal axis in relation to the worktable. Horizontal machining is used for the mass production of metal components in all kinds of industries. There are NC and CNC-controlled machines with different cutting capabilities. However, nowadays all modern machine tools feature rapid tool change, high cutting efficiency, and high precision permformance.

 Machine Base
Fig.1 Base Structure of HMC with horizontal spindle (courtesy of Quaser)  

HMCs have critical components but also optional equipment. Examples are swing heads, high-end spindles (spindle taper SK,BT,HSK-A etc.), cradle-like 4th axis, electric cutters, etc. The spindle rpm (revolutions per minute) can range from a few thousand up to 50,000 rpm, depending on the machine size and the type of metal removal required (though even most advanced models usueally top aut around 20,000). HMCs can also be combined with automation equipment such as robotic arms and pallet changers, which makes them essential for today’s manufacturing industries relying on CNC machining.

2. How does a Horizontal Machine work?

Generally speaking, the metal removal procedure with a horizontal machining center is very similar to other machin tools. By advancing the tool on one or several workpieces, the spinning cutter is able to remove the materials. As the additional functions of the equipment are involved within this mechanism, it gives horizontal machines a higher level of versatility. Here is a video we filmed where you can see a professional CNC horizontal machining center:

How the cutting tool machines on the workpiece indicate how the profile on the product is presented. One of the considerations about this principle is in the design of the worktable. With the general arrangement, the cutting tool does lateral movement on the workpiece. As the blades protrude through the surface of the workpiece, the removed materials, which are the chips, are naturally discarded.

3. The Development from NC Lathe to HMC

HMCs feature horizontally mounted cutters and specialize in automatic tool-changing functionality. In addition, multiple cutters are available, which ensures optimal production efficiency. Before discussing the structure of a horizontal machining center let's explore the origin of the machining center.

NC lathe
Fig.2 Traditional NC Lathe

The Origins

The invention of the machining center can be derived from the NC lathe, which is a machine based on a conventional milling machine. An NC lathe removes materials by advancing spinning tools through the surfaces of the workpieces, which ais called turning. While with the fixed tool position and limited tool choices, the metal removal operations this machine makescan perform are rather limited as well.

Although the NC system enables more precise control regarding the machining process, it still has to rely on the maneuver of operators. This takes not only time but also excessive labor expenditure, which isn't profitable for manufacturers. To pursue maximum practicality more advanced cnc machines appeared: vertical and horizontal machining centers.

4. Advantages and Capabilities of Horizontal Machines

There are many advantages to having a horizontal machining center in your shop. Let us talk about some of the most striking features and characteristics of horizontal machining centers.

Generally speaking, CNC Horizontal machining centers are much better suited for workpieces that need to be machined on multiple sides. HMCs are normally designed with two integrated pallets, to which fixtures are attached. This not only allows access to the front and sides of a workpiece but also allows the operator to stage a part in the setup station. Horizontal machines give you the ability to machine with high accuracy as they significantly reduce the risk of human error simply by automating and limiting the setup process.

Increased productivity & flexibility

In addition, HMC machines will provide you with a huge productivity boost. You can have eight setups in one operation on a horizontal machining center—a 4-sided workpiece on one pallet and another one on a second pallet.  That is because HMCs have pallets with a large, square metal column that is usually referred to as a tombstone. Vises or custom fixtures are bolted to each side of this block and workpieces are attached to it. At the very least, an HMC with a tombstone loaded up densely with parts can be loaded up and run unattended for significant periods of time

HMC Machines also grant you a lot of manufacturing flexibility. You can load one group of parts onto the four sides of one tombstone and accomplish producing complete sets with every machine cycle. But conversely, you can also just use two sides for one component that needs to be manufactured while using the other two to clamp up totally different parts for another machining job you need to get done.  This is especially hassle-free with an HMC as they usually include a very large tool magazine (40, 60, or even over a hundred different tools). With the right program and setup, HMC machines are possibly the most flexible machine tool out there.

Horizontal vs. Vertical

Horizontal machining centers and vertical machining centers are all popular metalworking solutions widely used in shops. Both styles which different from the orientation of the spindle have their benefits. When selecting from the two, the numbers of the sides that you are going to cut, and the shapes of the product are the keys. In short, if the products require to be machined on more than jsut two planes, a HMC will be a better choice than a VMC.

Horizontal machining centers are successful high-end machine tools for two main reasons. Firstly, the convenient and rigid worktables can handle many different machining tasks in a shorter time. Secondly, the collection of chips from the workpieces is easier thanks to the construction and of course the help of gravity. In additon, they allow vor easy workpiece access and provide a large work envelope. This explains why horizontal mills are often picked over their vertical counterparts.

When it comes to the arrangement of components, it is key to differentiate between a horizontal and a vertical machining center. The vertical machining center has perpendicular cutters. In contrast, the horizontal ones are parallel to the worktable or the ground.

Vertical vs Horizontal Machining Center
Fig.3 Vertical vs. Horizontal Type

The worktable on horizontal machining centers helps position the workpieces and allows for angular cuts with special arrangements. The rigid work table enables the device to operate on a wide range of workpieces, from small parts to heavy-duty applications. Furthermore, if the worktable is equipped with tilting or rotary features, the tools can cut the workpieces from multiple angles. Some machine shop owners attach one or multiple pallet changers (pallet size depends on the workpieces to be cut) to furhter automate and speed up the production cycle.

Power Turret and And Automatic Tool Change

Besides, with the assistance of the power turret as well as the stable clamping force of the worktable, the use of cutting tools on this machine can be even more effective. The power turret provides the space for tool storage and the automation of tool replacement. By setting up the tools necessary for the machining works beforehand, it helps smooth the process of the operation. As a result, the cycle time can be shortened, and more complicated profiles can be achieved. Furthermore, the computer numerical control system ensures the most precise and standardized control regarding the multiple tasks without possible failures.

5. Multi-Axis Machines

Machined Part
Fig.4 Workpiece machined with a multi-axis HMC

In the past, horizontal machine tools were mostly designed with three axes, namely x, y, and z-axis. Nowadays, due to the need for more intricate procedures with shorter cycle time, the machining centers are designed with a fourth axis or even the fifth axis. With the availability in adjusting the worktable and the additional functions of the equipment, they ensure increased efficiency, better product quality and overall machining performance, which is what the manufacturing industry really needs.

6. Industries and Applications

Horizontal machining centers are especially effective on heavy parts as well as those that require machining from multiple sides. In addition to more efficient chip management, horizontal configurations typically offer faster processing times due to the ability of operators to change pallets. They are also usually associated with lower prices due to the overall reduced manpower and machining time. Horizontal MCs by well-known brands such as DMGMori, Mazak, Hurco, Toyoda or Quaser are used for the production of heavy parts and components used in many industriessuch as:

• Commercial Applications

• Construction and maintenance

• Electronics

• Medicine

• Security

• Recreation

• Transport

• Automotive

• Industrial and O.E.M.


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