VMC vs. HMC

As technology progresses, CNC machine tools are capable of more than ever before. While this is an incredible nod to the advancements that have been made in the industry, it also reinforces an added pressure when choosing the right machine for your shop. The bells and whistles can create gray areas, and understanding whether a machine is right for your business can be tricky… especially when it comes to the larger and more popular categories of machines, such as vertical and horizontal machining centers. These days there are so many options out there, the differences can get lost. This blog post covers the differences between verticals and horizontals. While they have certain similarities, they ultimately serve quite different purposes.

Today, VMCs are used in great capacity. Even if a shop has invested in a 5-axis machine, they’ll likely still have a 3-axis vertical on their shop floor. They’re the least expensive of the two machines and typically require less fixturing and toolholders. The way they operate also tends to be more familiar to the average machinist. VMCs come in a wide variety of types and sizes; big enough to create the largest parts on a diesel engine, and others small enough to produce a medical bone plate. They’re generally all-purpose, tried-and-true machines.

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 tombstones or fixtures are often 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. This feature is great for a multitude of reasons – a major one being that it limits operator intervention compared to working on a VMC, lessening the possibility for human error and massively improving productivity. Spindle utilization is greatly improved. Other benefits of HMCs include a larger tool magazine (some can carry hundreds of tools) and improved chip flow (the spindle orientation allows gravity to do the work). Not to mention, HMCs come automation ready, which is a huge plus.

Both types of machines have their benefits, and the choice between the two depends entirely on the application. This means taking a look at the number of sides on which a piece needs to be worked, as well as the shape and size of the piece. One- or two-sided workpieces can be produced just fine on a vertical, while items with multiple sides would benefit from a horizontal. If you’re looking to start small and add peripherals as you see fit, a vertical would be a good place to start.

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If your application has the following concerns, you may want to consider a horizontal:

• Multiple operations
• Quantity of parts
• Compounded/complex angles
• Part size
• Lack of skilled operators
• Maintaining consistent accuracy
• Cycle time
• Automation

When looking into what’s best for your shop, it can also help to look at the ROI of an HMC vs. VMC. There are compelling productivity, cost, and quality reasons to consider an HMC where you might have initially thought a VMC would be the machine of choice.

Need help deciding VMC vs HMC? Talk to your local distributor for a specialized evaluation.