Palletizing and Stretch Wrapping Innovations for Greater Flexibility and Productivity

Clint Larson and Rick Sprouls, Brenton, and Becky Hensley and Craig Zelasko, Orion, both product brands of ProMach

Palletizing and stretch wrapping are two operations at the end of the packaging line where automation provides a cost-effective solution for a tight labor market. Automated palletizing and stretch wrapping also reduces the risk of repetitive motion injury, allows the plant to create higher pallet loads for better cube utilization, reduces the cost of stretch wrap consumables, and ensures optimum load stabilization and track and trace for every pallet.

To achieve maximum benefit, automated palletizing and stretch wrapping systems must:

• Fit available floor space;
• Offer maximum flexibility to accommodate shorter product lifecycles and product proliferation;
• Be easy to operate and cost effective to maintain; and
• Lower the cost of acquisition and overall risk.

Robotic palletizing provides cost effectiveness and flexibility

The most cost effective and flexible palletizing systems today, for a high mix of relatively low to medium volume products, are robotic palletizing cells. For safety reasons, cells are typically large fenced areas that ensure workers are safely outside of the robot’s range of motion. Footprint often becomes an acquisition issue for space constrained packing operations.

Two innovative solutions are gaining popularity for reducing the footprint for robotic palletizers. The first involves having the original equipment manufacturer (OEM) design cells that have multiple safety zones, and the second solution incorporates stretch wrapping within the palletizing cell.

In robotic cells, fencing, light curtains and other safety guards keep workers outside the range of motion of the robot. When an operator must enter the cell to reload corrugated, slip sheets, or pallets, they must follow a procedure. This involves the operator requesting entry into a restricted space. At that point, the robot arm ceases motion and will not resume operation until the operator has left the cell and resumes the robot.

In a multiple safety-zone configuration, the work zone of the robot and the work zones of the workers are delineated during the cell’s programming. When a worker enters a multi-safety-zone cell, the robot continues to move but in a more restricted manner. The robot’s motion may not be as efficient, but the palletizing process continues eliminating downtime. Once the worker leaves the cell, the robot regains its full range of motion. Multi-safety-zone configurations compress footprint without compromising safety.

Another effective means to conserve floorspace is to incorporate the stretch wrapper within the robotic cell and have the robot build the pallet load on the wrapper’s turntable. In addition to space savings, there are other advantages of building a pallet on the turntable. High unstable loads can be wrapped from the bottom up as each layer is laid. Higher pallet stacking improves cube utilization. Integrating the robot and stretch wrapper also facilitates automated corner board placement, which lowers labor while adding protection to the cases.

Stretch wrapping innovations

There are two areas of stretch wrapping innovation of interest to packaging operations, advancements in film performance and more intelligent wrappers.

Film advancements provide new options for improved load production, cube utilization, and lower overall consumption of stretch wrap. Pre-stretch of just under 300 percent is the norm from the leading stretch wrapper manufacturers. With 300 percent pre-stretch, for example, each roll of film goes three times farther. New films are being developed with a pre-stretch capability from 300 – 600 percent for even greater utilization of each roll of film and a consequent decrease in material cost. It is important to note that packagers will have to determine whether the film carriages on existing wrappers can be modified to achieve these increases.

New advancements in control of the carriage is resulting in less neck down – decreased drawing in from the edges of the film. Less neck down means greater film coverage. New high-performance films are also under development with the goal of improving bulk strength and providing greater puncture resistance.

Intelligent wrappers contribute to better production and operation

Intelligent wrappers can measure, record and report film usage per load. This information allows operations personnel to better understand and control costs, as well as fine tune wrap recipes and improve load protection. These smarter machines are easier to operate and  changeover between recipes, which helps maintain high throughput. More intelligent wrappers have the capability of independently generating and sending alert messages in regard to low film, a machine fault and required maintenance. In a tight labor market, these advancements maintain throughput with less worker involvement.

Lower lifecycle cost

Automated tracking and tracing of packaging relies on tight integration of automated labeling and bar code reading with palletizing and stretch wrapping. One way to ensure optimum integration is the turnkey automation project where an OEM is responsible for building, integrating and factory acceptance testing of the infeed, robotic palletizer, stretch wrapper and identification and labeling components/systems. In turnkey integration, the OEM assumes the risk for providing an operational system on time and within budget. With smaller internal engineering teams, packagers find it to their advantage to have a single point of contact during the development of their new end-of-line system. Furthermore, customers only have one acceptance test to attend. Another advantage is one point of contact for training, technical support and maintenance.

Assuring greater flexibility in the face of shorter product lifecycles and product proliferation

One of the motivations for utilizing robotic palletizers is the flexibility robots offer in handling diverse packaging and pack patterns. Robotic palletizers, however, are only as flexible as their end-of-arm tools (EOATs). Increasingly, automation customers are asking turnkey OEMs to design EOATs that will remain viable for long periods despite shorter product lifecycles and product proliferation.

The OEM is in the ideal position to pair the EOAT with an infeed system – an infeed system that changes over quickly and easily to accommodate various packaging and pack patterns.

Greater flexibility, smaller footprint, easier operation, better utilization of materials and lower risk solutions when acquiring automation are all available today for improving end-of-line operations.