Robots or People? Balance the Costs

Jan. 1, 2002
Labor is both fast and flexible, while robots are dependable and precise. here's help for your decision.

Robots or People? Balance the Costs

Labor is fast and flexible. Robots are dependable and precise. Sometimes you can afford the best of both.

When comparing the cost of a material handling robot vs. manual labor, you should consider not just the hourly rate but the total cost of that labor. Your calculation should include workers’ compensation insurance, costs of vacations and other benefit packages, turnover, and the associated costs of recruiting and training replacement workers.

You will also want to consider intangible benefits such as the ability to transfer workers out of dangerous/harsh environments and/or drudge work into more pleasant/meaningful assignments. This translates into:

• Reduced injuries and/or sickness and, thus, fewer workers’ comp claims.

• Making the workplace more attractive for those hard-to-recruit-and-retain skilled workers.

Further, you will want to look at both immediate and potential downstream implications of using a robot in place of an operator. For example, robotic palletizing might afford you not only more efficient and consistent stacking on pallets (e.g., by tiers vs. discrete cartons or cases), but also fewer lift truck trips between the palletizing and storage/shipping areas.

In your calculations, don’t limit yourself to labor savings alone. Consider cost-avoidance. For example:

• Some plants have found that by having their robots load/unload from above (vs. from the side), they were able to eliminate some conveyor sections. (Note that some robots can have their bases mounted vertically — as against a wall — or even upside down, from a ceiling or girder. Top-loading, of course, can be done with floor-mounted robots as well.)

• Auto manufacturers have started using some heavier-duty robots now available to load/unload and even manipulate engine blocks. (Compare that to using a chain hoist and overhead trolley.)

• Material handling robots in high-temperature or freezer areas do not require frequent breaks.

• Cost containment, quality consistency and worker safety were drivers behind a large robotics investment by the U.S. Postal Service in 1999.

Finally, remember to consider that while a robot may not be able to do a specific task (e.g., loading/unloading/stacking) faster than an operator, it’s consistent work — without breaks. That can translate into greater total output over a shift. Even small shops have run their robot(s) around-the-clock. Consider how a robot might boost your shop’s output and revenue.

Experience indicates payback expectations of 18 to 24 months are reasonable.

Affordability alternatives

If your company has never purchased a new robot due to the high initial cost, consider either buying a used one or leasing. Just remember to consider the source.

• In the early 1980s, many robots were installed unsuccessfully, and then just sold at a loss. That situation is now rare. Instead, you may find projects/orders being dropped/canceled for various reasons — sometimes in mid-contract. Sometimes the robots have been paid for; sometimes not. Such “orphaned” robots can be among the best to be found.

• Many large companies dump hundreds of used robots onto the market every year. Even though many are in great physical shape, the companies choose to buy new robots rather than retool the old ones. If you are purchasing 100 robots, you can expect robot manufacturers to compete fiercely for your business. This partly explains how/why they can release so many robots into the used market regardless of condition.

Doesn’t used mean abused? Not necessarily. Present-day robot arms are robust. Heavy-duty robots in production applications frequently go 50,000 hours between major overhauls. (12.5 man-years for a 2-shift operation; 8.3 man-years for a 3-shift operation.) Some newer models built since 1992 are actually seeing 70,000+ hours between overhauls (corresponding to 17.5 and 11.7 man-years for 2- and 3-shift operations, respectively.)

Note here that while the arms have long, useful lives, their (proprietary) controls have tended to become obsolete about every four years — equivalent to some three to four new “generations” between major mechanical overhauls. Consequently, many robots have been retired prematurely to allow their owners to take advantage of newer controllers with better diagnostics, better path control, networking capabilities and/or other technical advances.

Given the basic robustness and longevity of the arms, upgrading a low-hour used “arm” with a new control (from an independent source) can be a frugal and sensible “first buy” — not exclusively, but especially for firms with limited capital. (A good used robot may be available at as little as half the price of a new one.)

* A portion of this text appeared earlier on, and is reproduced here by permission of the copyright owner, Robotics Institute of America. For more information on material handling robots and their applications, go to our Web site at Go under news and click on “Robot Update.” MHM

Robots That Palletize

The CGS-1000 robot spans many palletizing locations, and handles 2,000-pound payloads. It is designed to receive product at two cases per minute and strategically position the cases labels-out onto pallets. The system will accommodate 117 different palletizing locations, a product conveyor pickup location, and a pallet rack under one gantry structure. A supervisory computer handles product allocation. The C5 control center features a color graphic operator interface and coordinates all aspects of a robotic work cell. Robot motion is integrated with fork and clamp end effectors, conveyors and other auxiliary equipment. C&D Robotics Inc.,

Robo-Pall is an integrated system to automatically build, stage and stretchwrap pallets for inbound storage or outbound shipments. The robotic system will build pallets with the same size cases, with individual layers of the same size case, and with many different sizes and weights of cases. Cases can be delivered by conveyor from a pick line, crossdock or reserve storage system. Systems can control and apply labeling, and ID and manifest pallet contents. It operates at eight seconds per case. KeyOneSource,

This robotic orderpicking system was installed in a beverage distribution facility to pick layers of containerized products and build mixed palletloads to be placed on delivery trucks. It performs at 1,400 to 1,900 cases/hour, depending on the product mix. The linear gantry services 20 pallet locations for orderpicking. PaR Systems,

This palletizing robot is pedestal-mounted for efficient reach and carton placement. Note large gripper for carton lifting and placement. Columbia Okura,

FANUC Robotics' M-410iWW robot does layer palletizing of products such as beverage trays, bricks/tiles, building material, steel and bundle wire. The system can operate at up to 760 cycles-per-hour with a 1,000-pound payload capacity, depending on the product mix and the end-of-arm tooling.

Here's an example of multiple-SKU, full-layer robotic palletizing from ABB Inc. This application includes automatic slip sheet placement.

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