Considerations when Retrofitting, Rebuilding or Remanufacturing Machine Tools

Adapted from a white paper written by Mark Brownhill, CNC product manager for GE Fanuc

Without question, your machine tools are among the most vital – and costly – pieces of equipment on your plant floor, and represent significant capital investments.

They must therefore maintain their viability for many years.

Keeping them updated with the latest control technologies through a CNC retrofit is one way companies are doing that successfully.

A CNC retrofit is the process of replacing the CNC, servo and spindle systems on an otherwise mechanically sound machine tool to extend its useful life. Rebuilding and remanufacturing typically include a CNC retrofit. The anticipated benefits include a lower cost investment than purchasing a new machine and an improvement in uptime and availability.

A retrofit, rebuild or remanufacture will cost somewhere between 1/3 to 2/3 the cost of purchasing a new machine, and reduce or eliminate the additional costs of any new tooling requirements, transportation and rigging, modifications or replacement of special foundations, modification of part programs and processes, and the associated training for the operators and maintenance personnel.

Here are some of the key considerations you should keep in mind before implementing a CNC retrofit project on your machine tool.

Performance
A significant portion of the benefits will actually be delivered by upgrading the servo and spindle system to a high-speed, digital interface. It does not matter how fast the CNC can process blocks of part program data, if the servo and spindle systems cannot keep up.

Energy savings
Machine electricity costs can be reduced by as much as 50 percent, easily justifying the investment in the new servo and spindle drive technology during a retrofit.

Improved mean-timebetween- failures
CNCs are much more reliable today than those that were produced just a few decades ago. The differences are compounded by the fact that the aged electronics integrated into older machines are now into the high-failure rate section at the end of their life cycle curve, and many retrofit candidates are mission-critical or bottleneck machines.

Improved mean-timeto- repair
Though improving mean-time-betweenfailures is important, there is even more of an opportunity to improve uptime by focusing on the time it takes to recover from a failure. Today’s operators typically run multiple machines, and assets often sit just waiting for attention.

If the downtime cannot be predicted or prevented, advanced diagnostic tools can be used, locally or remotely, over Ethernet, to reduce meantime- to-repair.

Data accessibility and customization
Manufacturers have determined that they need robust, high-speed communications and the ability to create custom screens for specialized processes.

For the past decade, GE Fanuc CNCs have supported an optional or embedded Ethernet port that provides standard TCP/IP data transfers, and a comprehensive public FOCAS2 API for data collection and control applications. And, because the CNC does not use a public domain operating system such as Microsoft Windows, it is not susceptible to attack by viruses and hackers.

Improved support
Technical and training support may be limited on your older CNC. Even if the original manufacturer is still in business, they may not have resources available that are experienced with your particular control vintage.

Standardization
Many machining operations use a wide range of machine types for a variety of applications including turning, machining, grinding, gear cutting, punching, laser cutting and other specialized applications. There are a few machine tool builders that can offer a comprehensive line of machine tools that cover a significant portion machining applications, but typically the end-user may consider that there is a best-in-class manufacturer available for each type of application.

Control standardization is an important factor to simplify operation, part programming and maintenance, allowing more agility in applying labor resources.

Features for lean manufacturing
There have been many CNC technology advances in the last twenty years to support the evolution of machining processes. The CNC is now a relative supercomputer when compared with the technology that is currently integrated into older machine tools.

With multiple, faster, and distributed microprocessors, and with a magnitude increase in system memory, the CNC can now incorporate advanced software algorithms that can model the machine mechanics, and dynamically compensate for inherent, undesirable mechanical characteristics.

Numerous features have been added to the CNC to reduce setup, minimize downtime, increase processing speeds, minimize minor stoppages, and improve setup and production part yields. Many of these new features address issues that are critical success factors for lean manufacturing environments, and they typically cost less if implemented with a new CNC purchase, including during a retrofit.

Mark Brownhill, CNC product manager for GE Fanuc (www.gefanuc.com) delivered a web seminar on retrofitting machine tools. The hour-long, archived seminar and its question and answer session is available at www.americanmachinist.com, and can be viewed free of charge.

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