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The total cost of ownership of a machine tool makes a case for automation as well. The pie chart here shows the relative sizes of various costs involved in using a particular machine tool over the course of its life. The initial purchase price accounts for 14 percent of the total cost. Over time, the personnel required to operate the machine will account for much more than this—40 percent. Numbers such as these will vary from machine to machine. Still, even if the investment slice gets a little bigger because of automation, the overall pie—the total cost—gets smaller as a result of the personnel cost being reduced.
An automatic part loader like the one shown here can make the machine operator far more efficient. In the photo on the facing page, the loader unit is to the right. The photo above shows the loader’s gripper. If two grinding machines are both served by loaders such as this, then one operator can stage parts for both loaders to keep both machines running. In other words, the shop does not have to add a second operator to run the second machine.
This is the case with almost any capital equipment purchase, and it’s the case with automation, too: When considering whether the purchase makes sense, price does not tell the whole story. Machine tool automation earns returns in various ways, some of which will be more or less valuable to different shops, and all of the returns on automation deserve to be figured into the analysis.
Of course, the
most obvious promise of automation hardware is the chance to run
unattended, or more specifically, the chance to keep producing with the
machine tool after all of the operators have left for the day. An
automated parts-loading system might make the machine tool seem
considerably more expensive if it adds 30 percent to the overall price.
However, what if that same parts-loading system allows the machine to
continue making parts through 12 hours per day when no operator is
present? The shop would therefore get twice the productive output of
the machine for just 1.3 times the price.
Even When Operators Are PresentJohn Richard is a sales director for grinding machine maker Fritz
Studer AG (represented in the U.S. by United Grinding). This company’s
grinding machines are used with various automation options in various
applications at various price ranges, but Mr. Richard says the scenario
of 30 percent more price for 100 percent more productive time is not at
all unrealistic. In fact, he says it’s common. However, he also says
that automation can pay its way even if unattended machining is not in
the cards for the shop or plant. The various other sources of return on
investment for automation include the following:
- Speed. Studer’s “easyLoad” system, which is shown on this page, can load a part into a cylindrical grinding machine in about 6 to 12 seconds, depending on a variety of factors including the size of the part. An operator loading workpieces into the machine by hand would take longer—about 10 to 15 seconds. This seemingly slight speed difference between automatic and manual loading may be meaningless if the grinding cycle time is long. However, if the grinding cycle time is short, the saved seconds may produce more output during the course of the production run. More significantly, the automatic loader does not get tired. Its speed remains the same, even late into the shift.
- Consistency. How valuable is it to be able to accurately predict how long the entire production run of a part will take? Knowing just the machining cycle time is not enough to make this prediction. The amount of time between each cycle—that is, the load and unload time—is a variable as long as it relies on human beings. This variable is influenced by which operator is doing the loading, how the operator is feeling at that moment and to what extent the operator gets distracted. By contrast, automation turns the load/unload time into a fixed and repeatable value (in addition to potentially shortening this time). Gaining certainty about the total time required for a production run makes it possible for the plant to schedule equipment more accurately, which in turn makes it more likely that the plant can get the most value from equipment by fully employing its machines.
- Increased output per operator. A plant that depends on operators to load its machines has to add both machines and people in order to increase its volume. However, a plant that uses at least some automation can add machines without necessarily adding people, making it that much easier to quickly respond to increasing demand.
Even When The Lights Are OnMr. Richard says grinding machine users he consults with consider either long- or short-cycle-time parts to be more appropriate for automation. That is, different shops have different opinions, believing that either the long-running parts or short-running parts are better able to be automated. The perspective depends on the shop’s experience and what return on automation that shop has come to expect. Both types of parts are potentially suited to automation—it’s just that the reason for automating varies.
For parts with short cycle times, the principle reason to automate is productivity. If the part is relatively lightweight, an automated system is likely to load and unload the part faster than a human being can, and this loading time advantage will accumulate over time. The consistency of part load/unload times will also allow the plant to schedule machines more effectively.
For parts with long cycle times, the reason to automate is unattended machining. Filling the staging area of the automated loading system with a run of long-cycle-time parts can be enough to let the machine keep producing without an operator for hours into the night, perhaps all the way through to the morning.
However, Mr. Richard stresses that unattended machining is something larger than just “lights-out” machining. Even if the shop is staffed around the clock, what happens to the machine tool when the operator takes a lunch break or steps away from the machine to ask a question about the next job? With automation, the machine doesn’t have to sit idle if the machining cycle ends before the operator makes his or her way back to the machine. This extra productivity during otherwise idle periods of each typical day can sum to significantly more output over the course of the year.