Automation reduces scrap for plastics manufacturer

A pre-engineered six-axis robotic system for blow-molded bottle handling improves operator safety and manufacturing efficiency.

07/01/2009


The Robotic SUBTA system uses different robotic units depending on the type of machine being unloaded. Acting as a takeaway unit, the robot grabs and sets the bottles standing up on a conveyor. Source: Motion Controls Robotics

A national manufacturer of stock and custom plastic packaging solutions for the food packaging, chemical, automotive, and household industries needed to improve the safety and ergonomics associated with a manual system of unloading a Nissei Bottle Making Machine at its manufacturing facility. The plastics manufacturer also wanted to reduce scrap and increase productivity.

The manual take-out system used with the bottling machine had been in use for nearly 20 years, but had several pitfalls including a large amount of scrap. The manual system also lacked reliability and increased the chances for injuries.

Being one of the largest blow molders of high-density polyethylene (HDPE) and polyethylene terephthalate (PET) plastic bottles and containers, with several manufacturing sites throughout the U.S., the manufacturer sought to automate the process to help increase production of quality products while making the plant safer for its employees. The company also hoped to increase its sales by improving manufacturing process efficiencies through automation, as the company’s lack of automation had forced it to turn away opportunities to increase its business due to capacity limitations.

The company contacted Motion Controls Robotics to help develop a solution that would automate the bottle take-out process and alleviate the safety and ergonomic issues related to repetitive stress injuries. They also wanted to reduce scrap, which ultimately would increase sales revenues without having to produce more product than it did in the past.

The manufacturer preferred the idea of using robotics because of their production flexibility and, if needed, the robot could be reallocated to another part of the facility if the workload changed.

The plastics manufacturer had considered a vendor with a fixed automation system that included a simple slide, but decided that system was not reliable enough for its needs. In addition, every time the mold tooling changed, the slide also had to be changed to accommodate the new product. This created a higher cost to change tooling, which was not acceptable. In addition, the facility already had one machine with such a fixed automation system, leading them to consider a more flexible and reliable solution.

Grabbing plastic

The plastics manufacturer installed Motion Controls Robotics’ Robotic SUBTA system, a pre-engineered system designed for PET blow-molded bottle handling. The Robotic SUBTA system uses different robotic units depending on the type of machine that is being unloaded. Acting as a takeaway unit, the system grabs and sets the bottles on a conveyor, standing up.. Due to its high reliability and uptime, as well as cycle times faster than most mold machine rates, the system provides increased throughput. It also requires a minimum of floor space.

The system handles any mold configuration (single or double row) and provides quick changeover using quick change tooling. A programmable built-in operator pendant has stored recipes and menu selection for patterns, and allows for on-the-fly adjustments. The 20-part recipe maintains data such as part description, pick/place locations, and vacuum pattern. The system uses straightforward tooling, eliminating the need for multiple hoses that can develop leaks or become damaged. Rugged welded tubular construction and low-maintenance components create a system with a mean-time-between-failure rate of five years.

Employee acceptance, improvements in manufacturing

Employees and management have been receptive to the Robotic SUBTA system. To ward off any concerns from employees about potential layoffs within the plant, management presented the new system as an opportunity to ramp up its technology and said that new business would be available if it were added.

“We are proud to say that we have not lost a single employee after adding the new robotic systems,” said the plant manager. “Instead of layoffs, employees have been allocated to other parts of the facility. This success has created new business, which creates secure jobs. Overall, the addition of the Robotic SUBTA systems has created a more positive and productive environment within our facility.”

The system has cut employee bending movements by 50%, and increased productivity of the system has led to an increase in sales. For those reasons and more, “employees are asking when we will add another Robotic SUBTA,” says the plant manager.

The robotic systems have also created unexpected improvements in the manufacturing process. The company noted a net reduction of .5% of scrap, effectively adding 500,000 bottles per year to its output simply by virtue of not dropping any. Also, since fewer products need to be reground, the company saves money, considering the cost to run the regrind machines had increased with the cost of oil.

“Compared to other take-out systems, the six-axis robots give us an option to pack the bottle or bring it to a leak detection machine,” said the plant manager “Now we have dwell time at the robot to look at secondary operations, and an opportunity to potentially add some value to our customer’s process. We can present it to our customers as a benefit.”

Overall efficiency at the facility also has been affected by the addition of the robotic units. “Everything in the plant runs much more smoothly,” says the plant manager. “More bottles are being produced, but the pace seems slower since there was a reduction in the complexity of the system. We have seen a reduction in the commotion and activity, since employees can now work at a constant pace and succeed without as much physical effort. We also have a greater chance to understand the bottlenecks in the manufacturing process.”

Improvements downstream

The company plans to rigorously examine each step along the way in the manufacturing process, including leak detection, printing, and labeling. Now that that the process runs more smoothly, each step can be looked at as a potential bottleneck. The engineering department can now work on making improvements downstream from the blow molding machine.

The company also conducted time studies to make planned improvements to the machines, so eventually the machine rate, and therefore the production rate, can be increased.

The company now has four Robotic SUBTA systems installed in one facility. The facility has 10 machines, half of which are now being unloaded with automation.

The company believes the new systems have helped to bring a new level of technology to its operations, and plans to add more automation with Motion Controls Robotics in the future. “We are reviewing to see where we can make an economic justification for adding automation,” said the plant manager. “We chose the [places] that are simple to execute first—that run one mold all day—as well as the systems with the highest stress strain or ergonomic safety issues. We are looking for future automation as soon as we can.”



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