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Shaftless drive technology increases profitability of existing presses

Posted: 03 Oct 2005 ?? ?Print Version ?Bookmark and Share

Keywords:shaftless? press? technology? flexographic? rotogravure?

Today, shaftless-driven presses are available in all printing subsegments, including label printing, package printing, commercial printing, newspaper printing and converting. This technology not only fixes the fundamental flaws of traditional mechanical drive train, but also provides unmatched flexibility. Printers benefit from improved quality, reduced make-ready, infinitely variable repeats and greater flexibility.

While most new technologies monitor and control the inconsistency of a process, shaftless drive technology reinvents the mechanical drive system, eliminating inconsistency while increasing flexibility and quality.

As shaftless drives continue to gain acceptance, more companies are finding creative uses for this technology. This is not new, as servo drive technology has had the same effect in other industries. In packaging, most machinery now uses servo drive technology. In automotive manufacturing, there are production facilities with over 3,000 servo drives controlling all aspects of production.

In the converting portion of our business, servo drives are now appearing on platen and rotary die cutters, coaters/laminators and paper converting machinery. Shaftless drive technology is also appearing in many retrofit and add-on applications. With the large installation base of existing equipment, it is impossible to justify the replacement of all our manufacturing machinery. Retrofits become feasible because the basic printing process has not changed. Reviewing advances in flexographic printing technology, we see that the plate, anilox and impression cylinders haven't changed. Other advances have been made in mechanical timing mechanisms and programmable-logic controllers used for automating the setup.

Innovative printers have performed shaftless retrofits on flexographic, rotogravure and lithographic offset printing presses.

Let's look at the retrofit of a wide-web flexographic press. This could be a common impression or stack press. As we evaluate what machine is right for a shaftless upgrade, we find that age is not necessarily the deciding factor. In fact, older machines were typically built with thicker sideframes and more iron. Consider a 20- or 30-year-old press. These machines are mostly mechanical in design, so we don't have to try to salvage electrical components.

Many servomotors

Before starting a retrofit, we need to evaluate the machine. When determining the planned maximum speed, we also need to review the overall process. Are the dryers sized to handle additional machine speed? Do any converting processes limit our speed? Another consideration is the machine's ability to readily accept the mounting of the servomotors. Some print-deck designs are not rigid enough or do not have a surface area that can accommodate the mounting of a bracket to support the servomotor. In these cases, we need to determine if we can use the existing print deck or if modifications are required.

Once we have decided that our printing press is worthy of a shaftless upgrade, we start by removing the existing mechanical drive train, including the bull gear. Since cylinder technology has not changed, we can use our existing plate, anilox and impression cylinders. We can even remove any mechanical timing devices, such as those used for retiming plate cylinders when changing repeat sizes. Fundamentally, all that remains are the side frames and cylinders.

Each plate, anilox and impression cylinder will receive its own servomotor. Also, all web transport rolls such as tension rollers and chill stands will receive independent servomotors. All servomotors are connected with fiber-optic cable to a common motion controller. The motion controller provides synchronization and functionality for the entire system. The motion controller can command each drive independently or as a whole system.

In removing all mechanical drive elements and electrical control systems from the press, we removed some setup functions. As a result of the shaftless retrofit, the machine is less complex in design and requires less maintenance.

The return-on-investment for a shaftless press is quickly achieved. Reduced setup time by using electronic setup and timing provides more time for manufacturing and makes the machine more competitive for short-run jobs. Precision presetting and elimination of machine windup reduce make-ready waste. Faster machine speeds provide more production without increases in labor, floor space and overhead.

Non-stop improvement

Having a press that is driven with independent motors also provides for simultaneous job setup procedures. Previously, mechanical drive systems prevented printers from performing make-ready if any part of the machine required maintenance.

When a drive shaft connected the entire machine, it was a safety hazard to set up and perform maintenance on the same machine. With independent drives, press operators can rotate any part of the machine while maintenance works on a different part. This same independent control allows for simultaneous setup of all machine modules. Because there is no mechanical link, each print deck and machine module can be set up simultaneously. Compare this to the sequential process of setting up one module at a time and you will clearly see a reduction in make-ready time and an increase in productivity. After setup, the machine automatically retimes itself.

Many converting processes can benefit from shaftless drive technology. Platen die cutters can double in speed, making them competitive for longer run lengths. The increase in flexibility also minimizes the risk of in-house development projects.

With the ability to achieve higher speeds in your converting methods, it becomes more feasible to combine processes. This eliminates the costs associated with scheduling, staging and storage of jobs that require multiple processes. Since our converting processes are no longer connected by a mechanical drive shaft, we can now relocate the module in various locations within a line, or move the module to another line.

Today, the printing industry faces challenges such as shorter runs, more competition and increased job complexity. Whether you are purchasing new or upgrading existing equipment, shaftless drive technology can help face these challenges.

- Jim Hulman

Business Development Manager

Bosch Rexroth Corp.




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