What Is a Horizontal Machining Center?

Posted on Aug 18, 2020

Horizontal Machining Center

Cost always comes first; however, there is a huge difference between the initial cost and the total cost. For example, a vertical machining center (VMC) typically has a lower initial purchase price than a horizontal machining center (HMC). So if your workshop specializes in machining large, flat workpieces that require a single operation, high-quality VMC may be an excellent option. However, if you frequently work with different sizes of prism parts, the HMC is a better choice.

What about the Initial Price Difference?

This is where the Total Cost of Ownership comes in. You see, when it comes to machining parts from multiple sides, an HMC can save you a lot of time and money. How? By eliminating much of the handling of the VMC-related part. In fact, many studies, including those conducted by The University of Michigan and the American Machinist, show that average VMC usage, as measured by spindle run time, is only 25% versus 85% for HMCs.

:: Read more: Horizontal Machining Centers (HMCs) – Price, Costs, and Other Considerations


It's Not Hard to See Why

Machining a six-sided part, for example, on a vertical machining center typically requires the operator to move a part seven or more times – in and out, and from fixture to fixture.


This means:

• Increased labor cost

• Considerable spindle downtime

• Increased potential for mechanical or human error that can lead to scrap and rework


On the other hand

The horizontal machining center can handle the hexagonal part in no more than three touches by the operator. And as we know, in a manufacturing world where Lean translates into greater efficiency and profitability, the less you touch parts, the better. Moreover, all part movements are performed within the machining cycle, so no spindle time is wasted.


Of course, all this makes sense for long production runs. But what about short bursts?

In most cases, you find that one HMC replaces four VMCs because of its versatility. This means one operator instead of four, so your operators can be much more productive while reducing labor costs per part. It also means paying for less hardware and increasing throughput with less set-up time and more spindle usage. Plus, with reduced part handling there’s less room for error, so it’s easier to maintain product quality.

For all these reasons, it is worth taking a closer look at your applications and considering selecting a horizontal machining center as your next productivity tool. Manufacturing technology experts will help you find the right CNC machine for your unique job. They know all the facts about the HMC for general machining, heavy machining, and high-speed machining.


:: Read more: Horizontal Machining Center and Vertical Processing


Horizontal Machining Centers Benefits & Disadvantages

Chip evacuation: Due to the orientation of the horizontal mills, gravity aids the chip extraction process during the cutting process. This means that end products tend to have a cleaner surface finish and require less production or post-processing throughout the process.

Robust construction: Horizontal mills are built heavier and can handle larger production tasks. Each part of the machine is designed to withstand longer under the specified forces acting on the HMC. This rigid construction means that machines vibrate less, deflect less, and function more smoothly when compared to vertical mills.

Productivity: With the Tombstone 4th axis and integrated pallet changer, these machines increase productivity, a feature that is ideal for complex, large volumes of work. Due to its mechanical design, one HMC can handle up to three separate machining tools. It is optimal in terms of time and savings in production costs.


Horizontal Machining Center Disadvantages

Industry experts agree that the disadvantages of HMC consoles are actually good issues, and not all that bad.

Expensive: Horizontal Machining Centers cost much more than vertical mills. Usually, the manufacturers who own these machines have been around for a while and have worked their way up to owning these machines. You see, that's a good problem!

Chance of error: As with most things, there is a chance of error. Unlike VMCs, which introduce the risk of human error due to "eye chances", horizontal machining centers run the risk of errors because visibility can be limited due to the tombstone-spindle placement. Operators have less visibility to catch mistakes that might occur and correct them before they become disastrous.

Less trained operators: As HMCs are less common across the country (mainly due to upfront purchase and maintenance costs), less qualified operators are available to operate these machines. Fortunately, even this scam has an advantage. Because the pool of "experts" is smaller, those with HMC skills tend to be more experienced and knowledgeable, helping to ensure each project is done with precision.

Let's face it: the sticker shock on a new horizontal machining center (HMC) can be overwhelming, and stores need to make additional investments in PCs, software, tool management systems, and inspection equipment to get the maximum return on investment. Long-term efficiency gains compensate for these additional costs, but careful cash flow management is critical in the implementation phase. For a detailed list of the costs and benefits of horizontal machining, please scroll to the end of this article.

Many stores reduce upfront costs by searching for high-quality used horizontal machining centers through private sales and online CNC auctions. A good machinery broker can serve as your eyes and ears in this market, and the very few also guarantee the hardware.

Alternatively, the vertical machining center (VMC) costs about half as much as the HMC, and the shop that adds another VMC will be able to use their existing technology and tools in the new machine. When capital is tight or cash flow is slow, VMC is probably your best bet.

Overall, VMCs are faster to set up, so a store with many small customers ordering low-volume parts (or a store that frequently bids for prototype work) will be able to move on to the next job more quickly. These machines are also the best choice for large sheet metal processing.

HMCs have fewer setups, and can also tool multiple parts at the same time. The rotating palettes mean the machine never sits idle. Programming is complicated and setup takes longer, but complex parts can be produced quickly and accurately.  Shops bidding on long runs or complex parts will see the biggest gains from an HMC.

:: Read more: Why Horizontal Machining Center Wins in Certain Cases


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