Used CNC Milling Machines – What to Look For

Age

Newer machines generally require less maintenance. If speed and maximum efficiency are not critical, a CNC mill that is 10 to 15 years old may still perform well, provided it is in good condition.

Size

Choose a machine based on the size of the parts you intend to make and the available space in your garage or shop. Allow clearance around the machine in addition to its stated dimensions.

A common machine may provide about 40 inches of X-axis travel and 15 to 20 inches of Y-axis travel. Smaller machines may offer approximately 30 inches of travel, while mini or tool-room mills may provide 15 to 20 inches in both directions.

Because price generally increases with size, buyers on a limited budget should consider the smallest machine that meets their needs. This may make it possible to purchase a newer machine.

Number of Tools

Determine how much automatic tool changer capacity you need. Tool changers may have 10, 20, 40, or more pockets. Smaller 10- or 20-pocket carousels are often located inside the enclosure. Larger or externally mounted systems generally cost more.

Spindle Hours

Spindle operating hours are an important measure when evaluating a used CNC milling center. Total machine-on time is less meaningful because the machine may have been powered on without the spindle running or the axes feeding.

The seller should be able to display the recorded spindle hours. If that information cannot be provided, investigate carefully before proceeding. A machine with fewer than 4,000 spindle hours may be a useful starting point for consideration, but its actual condition must still be inspected.

Options

Optional equipment may not add substantially to resale value, but finding a machine with the precise combination you need can take time. Common CNC mill options include:

• Chip auger
• Rigid tapping
• Tool setter or probe
• High-speed machining
• High-speed spindle
• Larger coolant tank
• Through-spindle coolant
• Fourth-axis capability
• Faster rapid movements

The right combination depends on the work the machine must perform. Waiting for a suitable machine may reveal better deals.

Controller

Consider whether you need a particular controller brand or model. Requiring a specific control may increase the price or extend the search. Fanuc, Yasnac, Fadal, and Mitsubishi are common CNC controls. Although they perform many of the same functions, their navigation and programming codes can differ significantly.

Research the available controls before buying so you understand their operation, programming requirements, and suitability for your work.

Noises and Operational Testing

Inspect the machine in person before purchasing it. If it is located too far away, arrange for a qualified professional or trusted person to inspect it. Some problems become apparent only while the machine is operating.

Run the spindle at several speeds and listen for unusual noises or humming. A geared machine may sound normal at high revolutions per minute but reveal problems at lower speeds or in low gear.

The most informative test is to run a part. Command rapid movements in every direction and listen for abnormal sounds from the head and ways. Test operations such as tapping, drilling, and heavier end-mill cuts. These checks can reveal components that may need immediate repair or replacement.

Shipping

Plan how the machine will be transported to your shop. CNC milling machines are large and can be expensive to ship, particularly across state lines. Research qualified machinery transport providers and include rigging, freight, unloading, and placement costs in the purchase budget.

Evaluating the Price

Compare current used-machine listings to understand how age, size, power, condition, and included options affect price. Remember to budget for inspection, shipping, installation, tooling, and any immediate maintenance in addition to the purchase price.