USED OKUMA GI-20NII

The Okuma GI-20NII is a high-precision CNC internal grinding machine designed for medium-to-large bore grinding applications in demanding production environments. As part of Okuma’s GI series, this model is engineered to provide exceptional accuracy, stability, and flexibility for internal diameter (ID) grinding, making it suitable for industries such as automotive, aerospace, bearings, hydraulics, and heavy engineering.

The machine is capable of grinding bore diameters ranging from approximately 5 mm up to 300 mm, with a maximum grinding length of around 200 mm (extendable depending on configuration). This wide capacity allows it to handle a broad range of components, including bearing races, gear bores, valve bodies, and precision housings. The GI-20NII supports multiple wheel spindle configurations, including single, dual, and even four-spindle setups, enabling process integration and reducing setup time.

A major strength of the GI-20NII is its high-speed grinding capability. It offers belt-driven spindles up to 40,000 rpm and high-frequency spindles up to 150,000 rpm, allowing both efficient material removal and ultra-fine finishing. The machine is built with Okuma’s 5-surface hydrostatic guideways, which provide superior rigidity, vibration damping, and long-term accuracy.

Thermal stability is enhanced through Okuma’s Thermo-Friendly Concept, which minimizes dimensional variation caused by temperature changes and reduces warm-up time. Rapid traverse speeds of approximately 20 m/min improve efficiency by reducing non-cutting time.

Equipped with the OSP-P300GA control system and IGAP+ conversational programming, the GI-20NII simplifies operation and setup, even for complex grinding cycles. Overall, it delivers a strong combination of precision, speed, and flexibility, making it a reliable solution for high-production internal grinding applications.

OKUMA GI-20NII SPECIFICATIONS

WHY BUY USED OKUMA GI-20NII

Buying a used Okuma GI-20NII is a highly practical solution for manufacturers seeking advanced internal grinding capabilities without the cost of a new machine. Machines in the GI series are built with heavy-duty construction, high-speed spindle technology, and precision guideways, ensuring long operational life and making them well-suited for the used equipment market.

One of the main advantages of purchasing used is cost efficiency. Internal grinding machines with high-speed spindle configurations and multi-wheel setups can be expensive when new. A used GI-20NII provides access to the same advanced features—such as high spindle speeds, hydrostatic guideways, and flexible configurations—at a significantly lower cost, making it easier for manufacturers to expand capacity.

Grinding time (spindle hours) is the most critical factor when evaluating a used machine. Machines with lower grinding hours generally maintain better spindle condition and accuracy. For example, a machine from the early 2010s with moderate grinding time may offer more reliable performance than a newer unit that has been heavily used in continuous production. Since internal grinding requires extremely tight tolerances, wear on the spindle and guideways must be carefully assessed.

Another advantage is process integration. The GI-20NII’s ability to support multiple grinding spindles allows it to combine roughing and finishing operations in a single setup, improving efficiency even in a used condition. Additionally, Okuma’s global support network and strong parts availability reduce the risks associated with purchasing older equipment.

From a financial perspective, buying used allows for faster return on investment. With lower upfront costs and the ability to maintain high grinding time utilization, a used GI-20NII can quickly contribute to productivity and profitability in precision manufacturing environments.

HOW MUCH DOES A USED OKUMA GI-20NII COST?

The cost of a used Okuma GI-20NII depends on factors such as manufacturing year, machine configuration, condition, and most importantly, grinding time (spindle hours). As a larger and more capable internal grinding machine than smaller models like the GI-10NII, it generally commands a higher price in the used market.

Machines built before 2000 (or earlier-generation internal grinders with similar capacity) typically range from $10,000 to $30,000. These machines are the most affordable but may include outdated controls and higher wear levels. Grinding time is especially important—machines with high spindle hours may require refurbishment, while low-hour units can still be suitable for lighter production applications.

Models produced between 2000 and 2010 generally range from $30,000 to $80,000. This segment often offers the best balance between price and performance, with improved control systems, better spindle technology, and enhanced rigidity. Units with low to moderate grinding time are particularly desirable, as they can deliver reliable accuracy with manageable maintenance costs.

Machines from 2010 to 2025 typically range from $80,000 to $180,000 or more, depending on configuration, spindle type (standard vs high-frequency), number of wheel spindles, and automation integration. These newer machines benefit from advanced CNC controls, improved efficiency, and better consistency in high-volume production environments.

Grinding time remains the most critical pricing factor. A newer machine with excessive spindle hours may be less valuable than an older machine with minimal use. Buyers should carefully evaluate spindle condition, maintenance history, and machine accuracy to determine true market value and ensure long-term operational reliability.