Subscribe
PLANT

Palletizers: conventional or robotic?

Now that you have settled on purchasing new end-of-line equipment, which palletizing technology best suits your operation?


March 29, 2011
by Pat O’Connor

Now that you have settled on purchasing new end-of-line equipment, which palletizing technology best suits your operation? Will the conventional palletizer’s speed or a robotic arm meet your handling needs?

Choosing the right palletizing equipment starts with analyzing the range of products and packaging types running on your line. Take some time to determine how each item should be handled. For example, can the packaging support its own weight during transfer for a pick-and-place solution? How stable is the pallet load? Is there secondary packaging?

The Alvey 952 robotic in-line palletizer combines conventional and robotic technologies for higher-rate applications. These robots precisely turn and position the cases. Photo: Intelligrated

Consider these important factors:
• size, shape, weight of the product;
• stability and construction of the load;
• secondary packaging; and
• pattern forming capabilities.

Robotic arms are suited for difficult-to-handle items, such as pails and bags, that must be precisely placed. Pails stack on a pallet, each one nestling on the lid below, and bags must be gently and squarely placed without disturbing the contents. Robots also work well in confined spaces and dusty environments.

Because conventional palletizers never pick up the product, they’re more tolerant of packaging changes to cases, trays, film bundles or poly sacks. And they’re more flexible than robots when dealing with product packaging and stacking patterns, handling each case individually so pattern changes have little impact on rate.

The throughput capabilities of material handling systems vary greatly depending on the equipment used and the product being palletized. Determine an acceptable range of line speeds (cases per minute) to better evaluate equipment options.

Conventional palletizers are capable of very high speeds, handling more than 200 cases per minute, while inline, continuous-motion palletizers handle 20 layers per minute. Robots are intermittent motion machines that are appropriate for high-SKU, lower-speed operations.

But you can have the best of both worlds. Combining the handling of difficult loads while achieving higher speeds is now possible with new hybrid machines that integrate robotic arms for pattern forming with a conventional palletizer for layer forming in higher-rate applications.

With product mix and throughput requirements decided, consider staffing and maintenance capacity, which are different for robotic palletizers and conventional machines. Some considerations for your staff include:
• learning curve for robotic applications versus conventional applications;
• operation platform;
• inventory of parts;
• floor space considerations; and
• training time for programming.

Also consider the abilities of employees to perform maintenance on these machines, or how readily available your supplier will be to do so.

You’ll find staff are more familiar with conventional palletizers and consider them to be more accessible. Parts are likely already in inventory and the palletizers operate on the same control platform as hundreds of other pieces of equipment in the plant. Robots, on the other hand, can be intimidating. Some maintenance crews may hesitate when asked to perform routine or emergency maintenance on a robotic arm, especially if it involves the control platform.

A PLC-controlled robotic arm makes the palletizer more accessible, allowing staff to deploy new solutions while maintaining a standard control platform.

Of course, every application has different handling demands and rate requirements. Thoroughly analyzing the options will ensure new end-of-line palletizing or depalletizing systems handle your company’s needs.

Pat O’Connor is a St. Louis, Mo.-based product manager, palletizing systems, for Intelligrated, a manufacturer of material handling automation systems with Canadian offices in Mississauga and Oshawa, Ont. Call (905) 858-0088 or e-mail info@intelligrated.com. Visit www.intelligrated.com.

Comments? E-mail joe.terrett@plant.rogers.com.