Retrofit or Replace?
Retrofitting by design can maximize machining center value.
Nothing lasts forever. But when it comes to replacing machine tools, whether in standalone production, cells or entire production lines, the choice of whether to retrofit or replace is a critical one to consider.
Heller Machine Tools (www.heller-us.com) believes in adopting a retrofit mindset at the time of specifying new machine tool purchases. “It requires a different way of thinking,” says Tracy Ellis, Heller account executive. “Not everyone gets past that first order of business, that production tools are required to make parts. It may be subtle, but what you’re really buying is the ability to make parts, and that depends on many factors regarding the machine tool and beyond.”
Heller has a few terms for this mindset where its equipment choices are concerned. One is “designing for a second life.” Another is “lifetime productivity.” “It really depends on use,” Ellis says. There can be really brutal applications in cast-iron diesel engine blocks for heavy-equipment manufacturers or lighter-gauge automotive transmission lines that run 24/7, he says. The decision to upgrade existing equipment or replace with new goes beyond figuring the per-piece price. Is the machine tool a standalone unit, part of a cell, or needs integrating into a production line? What are the downtime considerations? Do part design or part volume considerations reveal the possible advantages of flexible, multi-axis processing?
The company relates the example of a German tractor manufacturer and a cell for machining steering knuckles. Robust and straightforward machine design, including flat bedways, emphasized process stability and machine dependability. At the same time, part volumes were 800 to 900 pieces annually, while other knuckles were made only two or three time a year. This made upgrading the circa 2002 machine tools with new controls good retrofit candidates.
Keeping up with new electronics and plant connectivity can be very important in the emerging Internet of Things, but scraping new ways and re-establishing alignment and positioning are important, as well. Stability and rigidity along with improved workholding also can mean taking advantage of innovations in modern cutting tools and cutting techniques, Ellis adds.
Heller's emphasis on reliability and maintainability (R&M) has also had an influence on its Lifetime Productivity approach, in that driving to make machine components robust and reliable with long mean time between failure (MTBF), the company has developed some machine components that last significantly longer than former designs, such as guideways, way covers, ball screws, couplings, seals and O-rings. Robust and reliable also means they are replaceable/repairable in a short time resulting in a low mean time to repair (MTTR). This makes rehabilitating/rebuilding a machine tool easier and cost effective, for example, thanks to cartridge-type spindles and zero-point clamping elements.
Improved energy use is another benefit achievable with retrofitting, such as via new motors and controls for hydraulic and coolant systems that are more energy efficient, constant filter media monitoring, and optional on/off or sleep modes for the machine tool control and peripherals including pumps, chip conveyors, loaders, lights, and more.
The tools go a whole lot faster—40,000 rpm, perhaps—but the advantage is not parts per hour but in the ability to make precise parts with less induced stress
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