As thousands of cans and bottles whiz through manufacturing equipment, their structural integrity, fill levels, decoration and other features are tested by precise inspection equipment. But, as packages get lighter and designs become more complex, inspection equipment also must evolve to meet the needs of the changing industry.

Lightweighting of plastic bottles poses several challenges for inspection equipment. Laser equipment that codes onto the bottle can puncture a thinner bottle, and achieving an optimal amount of pressure inside the bottle is paramount to avoid crunching or bloating, inspection equipment manufacturers say.

“As the container becomes lighter and lighter, it also becomes less stable than the earlier packages,” says Jim Kearbey, vice president of sales and marketing for Teledyne Taptone, North Falmouth, Mass. “…What we’re seeing most recently is really an effort to take weight out and get some of these packages down under 9 grams.”

Kearbey says he has seen packages as light as 6 grams, which was akin to a standing bag, but that “many markets haven’t evolved to that level.”

Teledyne Taptone offers equipment that can measure a bottle’s internal pressure. With too little pressure, Kearbey says that case and tray packers will crunch bottles and cause jams, or the bottles will not have enough column strength to hold up stacked pallets. Overfilled bottles can become too big for case packers or bow on the bottom, making it difficult to transport, he says.

Many beverage manufacturers target 2 to 4 psi in a pressurized bottle, and Kearbey says Teledyne Taptone can provide equipment that can measure the amount of pressure inside the container to within 0.5 psi.

Teledyne Taptone’s Force line of inspection equipment includes both an entry-level and a high-end machine, Kearbey says. The T4000-F, an entry-level inspector of pressure and fill level, is designed for liquid nitrogen gas-dosed teas, juices and bottled water; carbonated beer and soft drinks; retorted dairy drinks in cans and lightweighted plastic containers under liquid nitrogen gas pressure. The machine can measure pressure up to 45 psi in as many as 1,500 containers per minute, the company says.

To measure pressure, conveyors carry containers past a sensor that records tension on the sidewall of the container. If the pressure is outside of the range the beverage company defines, the container is rejected, the company says.

The T4000-F system also uses X-ray technology to measure fill level in steel, aluminum, glass, plastic or cardboard containers, the company says. A low-energy X-ray beam is focused to look through the container in the defined fill level. A detector on the other side of the container measures the beam’s intensity. If the intensity is higher or lower than the defined range, the system will reject the container, the company says.

Teledyne TapTone’s Compression line of inspection equipment can detect pin-hole leaks in plastic containers and can be combined with optional sensors to inspect fill level, caps and labels, the company says. Made from aluminum and stainless steel, the 4000-C system can detect leaks as small as 0.2 inches at speeds up to 1,200 containers per minute, the company says.

“We build up pressure in the headspace, and we measure pressure decay in that package as it’s compared to the overall population of product that’s being produced,” Kearbey says. “Now, if we have a container that’s uniquely different or softer than the overall population, we know it’s leaking and we’re going to reject it offline.”

Using inspection equipment can potentially save a company from recalling thousands of containers, Kearbey says, thus improving a container manufacturer’s operating efficiencies. Achieving those efficiencies is as important as ever as beverage companies are turning to lightweighting and other initiatives to work smarter.

“The beverage market is really taking the lead on lightweighting,” Kearbey says.

In addition to lightweighting, clear bottles with colorless liquids prove challenging for inspection equipment, particularly photoelectric devices that trigger another action, such as etching or painting, says Tim Kelley, vice president of business development and marketing at Tri-Tronics Co. Inc., Tampa, Fla.

“When you fill a plastic or a glass bottle full of water or vodka or gin or anything that’s clear, you just turn that into a lens,” Kelley says.

Tri-Tronics developed its SmartEye RetroSmart retroflective sensor to detect translucent and transparent containers and shiny objects from the leading and trailing edges, the company says. The device points a narrow red light beam at a reflector, which bounces the light back to the sensor and creates a “thru-beam.” When the beam is broken by a passing object – even clear bottles that create a lens – the system can trigger an action.

The optimal distance between the sensor and reflector is between 6 inches and 8 feet, the company says. The RetroSmart sensor can be autoset or remotely autoset and features light state tracking, which continually will adjust to the perfect setting on the contrast indicator when the setting is enabled, the company says.

To accurately trigger actions in the inspection system, companies use the RetroSmart sensor to automatically detect the leading edge of a transparent or translucent container, Kelley says.

“Anything less clear than perfectly clear, it’s going to see that,” he says.

Speed of throughput is essential as many inspection machines analyze thousands of containers a minute, Kelley says. RetroSmart operates at 100 microseconds and can be used in several operations, including filling, packaging and labeling, the company says.

More than they seam
Lightweighting also has affected the accuracy and repeatability of inspection equipment in the canning industry, says Alex Grossjohann, vice president of CMC-Kuhnke, Albany, N.Y.

Grossjohann says that some beverage companies have made changes to material thickness and alterations to the size and shape of containers, such as slim cans or aluminum bottles, to generate interest in their products during the recession.

“As unique designs have peaked customer interest, they pose inspection issues for us because another way to drive customer demands and compete in that type of economy is to change your container,” he says. “…As we see the innovations in the product or the container, we have to innovate our inspection of it. It can be very difficult because new containers offer all sorts of different angles and thickness and production challenges.”

To measure beverage, food and aerosol cans, CMC-Kuhnke offers several manual and fully automated options, including the entry-level Video SEAM Monitor 5 (VSM 5) and the fully automatic MARS-SEAM system, Grossjohann says. Some of the company’s systems have a return on investment period of one year, he says.

The VSM 5 uses auto SEAMview 5 software installed on an integrated micro-PC connected to a machine from the company’s VSI-5000 series of imagers to automatically measure the double seam on a can.

A high-resolution camera and pre-configured auto SEAMview software work together for automatic double seam measurement displayed on a large TFT screen. The VSM 5 also features an optional touch screen and color camera, the company says. The user can make notes directly on the image, which can be saved as a .BMP, .GIF or .JPG file and used in an e-mail or document.

The 5.0 version of the SEAMview software features an AutoLearn capability that will recognize patterns over time to reduce measurement time and improve accuracy, the company says.

“In general, we’ve been asked for fully automatic measurement systems that provide more accurate results in less time and at lower costs than the manual methods. This is a major shift from a few years ago,” Grossjohann says. “I believe it’s probably related to a need for more accurate equipment, but also driven by the rising labor costs.”

CMC-Kuhnke’s flagship fully automated system is the MARS-SEAM double-seam inspection system, which Grossjohan says “will automatically tear down a beverage can in about a minute.”

The MARS-SEAM system follows a five-step process for can inspection: in-feed, contact double seam measurement, product purge and cleaning, cross-section and seam image measurement, and out-feed.

A high-speed can ejection system delivers cans automatically to the system’s in-feed conveyor when connected to the production line. At station No. 1, the system measures seam thickness, countersink depth and seam height in 297 places, or about every sixteenth of an inch, the company says.

The machine opens the bottom of the can with a specially designed punch to avoid leaving sharp edges before draining, cleaning with a jet of water and drying the can with a blast of compressed air, CMC-Kuhnke says.

In an enclosed chamber, the double seam is cut using two carbide blades. The residual tab is indented and the cross-section is cleaned for high-resolution digital imaging with the company’s VSM imager and auto SEAMview software.

When finished, the cans are placed in order onto a conveyor or into a carrying basket, and the company is provided with an inspection report, the company says.

“The can industry seems to be catching up with other industries,” Grossjohann says. “Manual inspection systems are becoming more of a commodity. Automatic systems are becoming more important.” BI