How an Automated Measurement System Changed the Game for One PET PreformerHow an Automated Measurement System Changed the Game for One PET Preformer

When Resilux America LLC, a PET preform and bottle producer in Pendergrass, GA, installed Agr International’s Gawis 4D all-in-one measurement system, it was not just a win for productivity. It also played a pivotal role in solidifying the manufacturer’s relationship with a large customer, the owner of a major food brand, in the wake of a preform quality concern.

Inspired by the business management principles set forth in The Goal: A Process of Ongoing Improvement, the book by Elijah Goldratt, the Resilux leadership team had already instituted a number of operational improvements in a drive to become more efficient—for example, reducing inventory levels and scrap, pre-staging shipping loads, and automating where possible. One area that stood out as ripe for streamlining was the process for checking and analyzing the measurements of finished product as part of the plant’s quality management program. 

The manufacturer’s broad customer base runs a gamut of sectors, from food, beverage, and spirits to household chemicals and cosmetics. Its range of product designs required quality checks that used a variety of gauges and tools, most of them hand-held, to confirm that preforms and bottles met customer specifications. There was one instrument for measuring wall thickness, another for perpendicularity, still another for clearance. The assortment also included a height gauge, calipers, protractors, a top load tester, and scales. The labor-intensive, time-consuming hand measurement process had an additional, inherent drawback: the potential for human error.

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“The exact spot where the measurement is being taken on the product depends on how the individual holds the gauge and from what angle,” said Jonathan Sanders, Resilux America vice president of technical and development. Despite the effort extended, that variability often delivered inconsistent results.

Benefits of Gawis 4D

When introduced to the Gawis 4D, Sanders immediately appreciated the power of the completely new measurement platform. Integrating critical bottle and preform measurements into a single automated operation, Gawis 4D performs both thickness measurement and dimensional gauging.

Unlike manual processes, measurement on every sample is performed in exactly the same way. Gawis produces repeatable, accurate results with high throughput in a matter of seconds, and then automatically records the data for process analysis. Incorporating optical gauging capabilities and advanced vision technology, such as high-resolution USB 3 camera components, its level of precision is more than sufficient for the qualification and management of molds.

The extensive range of measurement options Gawis offers includes thickness at single or multiple discrete points anywhere on the sidewall or heel of the bottle, along with the ability to perform complete vertical or horizontal (circumferential) scans for analyzing material distribution. 

A stand-out feature for Resilux is AutoJob, which simplifies job set up through automated recognition of key finish measurements on bottle and preform samples. Its library of standard finish measurement routines, customizable for specific applications, accommodates job configurations that handle single or multiple measurements with no slowdown in throughput.

Beyond the functionality of the automated system as a solution to inconsistent or questionable manual measurements, its time-saving benefits align closely with the plant’s lean initiatives and quality management program.

“We saw how the efficiencies we’d gain from Gawis could free our technicians for additional tasks on the floor,” Sanders said. “This is truly invaluable.” 

Automated measurement of PET bottles

Headquartered in Belgium, Resilux entered the US market in 2000, taking over its current facility, in an industrial park about 45 miles northeast of Atlanta, from a previous PET producer. The plant encompasses two separate buildings across the street from each other, one dedicated to preforms and the other to bottles. Over the years the company has expanded the original equipment portfolio to include a mix of multiple injection and injection stretch-blow molding machines, with the line-up slated to grow.

The Gawis measurement system was installed in the lab in the blowing plant in 2022.  In keeping with the producer’s lean orientation, there is no full-time staff in the lab.

“Our quality philosophy is, ‘All hands are on the floor,’” Sanders explained. “Instead of in the lab, our techs are out in production. Lots of folks use quality control as a crutch, but for us, quality is everyone’s responsibility. Production owns quality.”

Technicians pull product samples from the line throughout the day, bring them into the lab to take measurements, and then head back out to the floor. The aim is to perform two to three checks per bottle per machine cavity in one shift. A six-cavity set takes roughly six to 10 minutes.

If Gawis data indicates that the measurements are out of spec, the technician scrolls through the numbers from the previous pallet of product, backtracking to find where the problem began. If the range approaches unacceptable limits, the blow molder is adjusted to bring the bottle closer into spec.

“Generally speaking, quality checks are performed based on agreed-upon AQL, acceptable quality limits, but the sheer volume of preforms we produce makes it a challenge,” Sanders said, noting that decisions on what to check and when are risk-based.

“We know what types of defects occur in specific product designs, how frequent or common they are, and what impact they have — whether it’s appearance, a potential filling problem, or a consumer issue,” he said. Each customer has their own agreed-upon allowable tolerances. “Our quality management program is based on the likelihood of the occurrence of the defect.”

To illustrate, Sanders cited the difference in checks for square bottles compared to round bottles with ribs. Square bottles are susceptible to “paneling,” where the container walls sink in toward the middle.

“A square juice bottle with walls that have paneled will cause problems in the labeler. Gawis can measure 1,000 different points, and we can customize the job to look for this defect,” he explained. On the other hand, paneling wouldn’t even be an issue in a round bottle with ribs, so it’s not part of the quality check when running that product.

When Gawis does scan the square bottles, it catches panel sink immediately as it measures the body width. “Gawis does in seconds what it takes a technician using manual tools about six minutes to do. And it removes the subjectivity of hand measurements due to the variation among people performing the process,” Sanders said.

Automated gauging of PET preforms

With an experienced workforce and a strong corporate culture that emphasizes doing things the right way, Resilux has established a track record for robust production. “Our folks are really good at doing their jobs and maintaining stable processes,” Sanders said.

This level of performance allowed the producer to focus primarily on bottle production when it came to Gawis utilization. However, just a few months after the system was installed, a preform customer with a nationally recognized food brand reported having trouble making good containers from the latest shipment.

“This was a custom preform, used for making a condiment product,” Sanders said. “The brand owner suspected their various blow molder problems were due to variation in wall thickness concentricity in the preform. They claimed that one side of the preform was thinner than other.”

Under normal circumstances, the claim might not be too surprising. “Uneven material distribution is the number one problem in bottles,” Sanders observed, adding that “plastics is both art and science. Everyone in this industry has some level of customer complaints. We set a target for the incidence of quality claims, and we monitor it closely for what is acceptable.”

In this case, however, the magnitude of the brand owner’s claim was far from typical, involving almost half a truckload of preforms.

According to Sanders, the customer was holding more than 100,000 preforms “as suspect due to the blow molder problems.” In addition, there was a large quantity of already produced preforms in inventory that Resilux was forced to quarantine until resolution.

“We were going back and forth with hand measurements using wall thickness gauges,” he recalled. “We were also performing an internal analysis on machine setup, processing, and tooling — for example, measuring cores, checking for damage, etc. There were a lot of people dedicated to solving this issue.”

In the end, Resilux turned to Gawis to perform the measurements to bypass the variability that came from using the manual tools. The system data confirmed that the preforms were in spec.

“The precise, consistent data from the Gawis turned a subjective conversation into an objective conversation,” Sanders said. “It would have been a huge claim, almost the cost of the system. I’d say that within the first six months of ownership the Gawis was fully cost-justified by the reduction in claims alone.”

But the conversation didn’t stop there. Once the producer ruled out the tooling and injection machine as a problem, the customer was prompted to delve further into root cause analysis. Changes were needed on the blow molding equipment at the customer’s site, and the appropriate adjustments were made. Running the preforms Resilux originally supplied, the brand owner was once again able to send a product to market that met both internal and consumer expectations.

Sanders considers the incident a positive experience for both his company and the customer. “Eliminating the variable of hand measurement allowed us to validate as a team that the preforms were made to specification,” he said. “Because of this, we were able to avoid a significant claim, but more importantly, it kept the brand owner running, and we all learned from the experience. We are still doing business with this customer, and they are still buying this exact preform.”

Streamlined validation of custom PET molds

While this situation may be the most dramatic illustration of Gawis benefits, it is far from its only contribution to plant operations. The automated system is also helping to streamline procedures on the development side. Custom orders account for a large portion of Resilux output, and new products require new molds—which Gawis’s precise measurements are sufficient to qualify.

“We order a new set of molds almost every week or two, and when we first receive them we validate them in the Gawis to confirm that everything was made to spec,” Sanders said.

The qualification function fits in well with the part of the producer’s streamlined strategy that addresses sample making, which is now done on single or double cavity lab machines instead of on the production line. Sanders points out that it only takes a couple of hours to run 5,000 parts for a customer sample, but it takes eight hours to change molds or tools on the production machines.

“Now we can use that time more productively and share the cost and time savings with our customers. That’s a big advantage for our business,” he concluded.