Put a Lid on It
CAPPING MACHINES ARE A FRONT-LINE DEFENSE AGAINST PRODUCT LEAKAGE, CONTAMINATION, AND TAMPERING.
By Bridget McCrea
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The COMPUTORQUE capper from Inline Filling Systems |
It’s a fairly simple proposition: When you package liquids, powders, pills or anything else that can easily spill, you need caps, closures, ends, lids or some other means of effectively sealing the containers. And when you need caps and these other types of closures, capping machines are indispensable.
Capping machines are highly versatile; they tighten or secure a cap or closure on containers and bottles with an almost infinite range of shapes and sizes. The caps and closures come in various forms, including screw caps, snap caps, sports caps, lug caps, child safety caps, spouts, spray caps and trigger spray caps—each of which may require a different type of capping machinery.
On the packaging line, caps serve a number of purposes: They prevent product leakage, contamination and tampering. They also help extend the product’s shelf life. “Capping machines play a significant role on the line, second only to the filler itself,” says Greg Raines, president at SUREKAP, Inc., in Winder, Ga. “Once you get the product where it needs to be, the capping machine’s job is to keep it there.”
Most capping machines fall into either the in-line or rotary varieties. In-line machines typically are used with medium-speed lines of 20–200 products per minute. They offer high flexibility (the machines include easy-to-adjust parts that can accommodate different cap types) at a lower cost.
One example of an in-line capper is the Computorque Capping Machine from Inline Filling Systems of Venice, Fla. Using a parallel set of rotating cap-tightening belts rather than separately adjusted quill pairs, the machine allows for toolless adjustments on virtually all bottle and cap sizes. The company says the system can reduce setup/changeover time by 60 percent.
Rotary-style capping machines can handle higher speeds of 60–2,000 products per minute, but offer less flexibility because as products are pulled off the line for capping, they must go through a turret-type apparatus. In this apparatus, parts are specific to each bottle diameter and must be changed to accommodate each new cap type. As a result, rotary machines cost more than their in-line counterparts, often fetching $5,000– $20,000 for a set of change parts alone, according to Raines.
In-line capping machines do their job as the products move down the conveyor, where both the placement of the cap and the torque (which ensures that the cap is seated tightly) are handled. Rotary machines, which can have between three and 50 heads, move the containers from the conveyor and into the turret-type apparatus.
AUTO OR SEMI-AUTO?
Capping machines can be broken down further into automatic and semi-automatic styles. With an automatic machine, the operator would simply “dump” a case of caps into the machine, which caps the containers without any further human intervention. In some cases, these capping machines are integrated with filling, plugging and labeling systems as a single unit.
“These machines are referred to as Monoblock equipment,” says Douglas Powanda, director of solutions and alliances at CAPMATIC Ltd., in Montreal North, Quebec. “Some of the possible advantages of an integrated system over an in-line system are quicker payback, reduced head count and increased throughput efficiency.”
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"CAPPING MACHINES PLAY A |
Semi-automatic machines are small, hand-held or tabletop cappers. These can be designed to function in three different modes: pneumatic, electric or mechanical. Semi-automatic machines require manual placement of the cap, with the machine handling the final tightening process.
Raines says semi-automatic capping machines range in price from $15,000 to $50,000, while automatic machines range from $25,000 to more than $1 million. Drake Chocolek, vice president and CIO at Vista, Calif.–based Accutek Packaging Equipment Company, Inc., says capping systems from his firm range in price from $695 for a semi-automatic hand-held capper to $250,000 for an automated, high-speed rotary capping system.
Much of the choice in cappers is “cap-size dependent," according to Raines. A machine that’s capping small (28mm or 38mm) caps will run faster than a large-cap (89mm) operation. Most in-line capping machines run anywhere from 20 to 200 units per minute, while rotaries run anywhere from 60 to 2,000 per minute, depending on the number of heads that the rotary machine contains.
SECURE SYSTEMS
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Accutek Packaging Equipment Company’s ASC-6. |
On a typical packaging line, the capping machine is positioned directly after the filler and before any labeling machines, induction sealers or bottle unscramblers, says Raines. He adds that the events of September 11 brought capping machines into new prominence, based on new oversight for foods and drugs, and the need to keep contents securely sealed in tamper-resistant containers.
“Safety has been the key concern in many industries, particularly with pharmaceuticals,” says Powanda, who adds that while capping machines have historically been found in the last phase of packaging, more are being used during the product research and development stages, particularly in the biotechnology and pharmaceutical sectors.
When selecting a capping machine, Powanda says companies should consider the project from several perspectives: objectives and specifications, financial and human resources, quality and craftsmanship of the equipment and future needs.
Speed of the product line itself, and operator involvement in the capping process, should also be factored into the buying decision, says Powanda, who advises companies to base their final choice on a comparison of machine price and quality. “Visit the capping machine company and evaluate the company’s operations,” he adds. “Compare the quality of the machine in an ‘apples to apples’ manner.”
FLEXIBILITY, PLEASE
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"SOME OF THE POSSIBLE |
As technology continues to evolve, Chocolek says capping machines will likely become smaller, particularly as electronic motors and related components shrink in size. It’s a trend that some manufacturers may not appreciate, he adds. “But the machinery doesn’t always have to be the size of a car to work well,” Chocolek says, “and some of the smaller equipment is just as capable as their larger counterparts.”
Chocolek also expects to see more use of servo drives in cappers, a greater reliance on the Human Machine Interface (HMI) for data (such as touch screens that feature enhanced controls and readings on speeds, accuracies and torque values) and more adjustable parts.
“Many capping machine manufacturers make custom parts that will only work with the machine as it is sold,” says Chocolek. “So if you want to change to a different cap size, you have to buy a set of custom change parts from the vendor, and hope that they match up with your current machine. [But] we see that changing as more manufacturers create more flexible options for their customers.”
Bridget McCrea is a Florida-based writer who has been covering manufacturing and technology topics for 10 years.
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TAKING THE MEASURE OF PACKAGING TERMS BY BEN MIYARES When it comes to package/container functionality, capping is the most critical of packaging operations. An efficient capping system will accept bulk-loaded closures, orient them and seat them. Specialized units are engineered to gas-flush, draw a vacuum or seal products under pressure. Some specific vocabulary related to closures and the closure-application process includes: Capper: Webster’s won’t help you. It defines the word simplistically as “one who makes or sells caps.” In the packaging field, it means a machine that puts plastic, metal or composite (metal/plastic) caps or closures onto plastic, glass and metal containers. Most capping units fall into the screw-capping category, though capping application operations are as varied as the closures they are engineered to handle. Major categories include continuous thread (CT), lug roll-on and snap or friction-fit cappers. Dispensing closures (sports caps, toggle-action spout caps, dispensing pumps, trigger caps, etc.) are run on equipment specifically engineered to handle, orient, place and seat those cap styles. Torque: Wonkish packaging engineers may give an understanding nod when they see the physics textbook definition of torque as a “physical vector quantity characteristic for an object in rotational motion around a certain given axis.” But, if you’re trying to convey the concept to a line mechanic, or even your fellow packaging engineers, you’re better off saying “twisting force.” Torque is a key factor in properly seating and easily removing most closures. Application Torque: The force, measured in inch-pounds, necessary for a capping machine to screw a closure onto a container. Also referred to as “on torque.” Removal Torque: The twisting force necessary to loosen, open or remove a closure from the container on which it is seated. “Off torque” is the yin to on torque’s yang. The secret to effective screw-capping operations is to apply a precise amount of application torque to seat the container effectively without binding or back-off (see below). The ABCs: Describing closure types, acronyms in the capping field are used to identify the equipment applying the various types. Among the most common are CT (continuous thread); CR (child-resistant); CR/EF (child-resistant/elder friendly); TE (tamper-evident); TR (tamper-resistant), and PT (press-on/ twist-off). Lug Cap: A metal closure with raised internal impressions that mesh with mating threads on the throat of the container. Lug closures are commonly applied to wide-mouth jars containing vacuum-packed foods. Backoff: Don’t use this term to greet C-level execs who want to know how things are going on the bottling line. Instead, use it to describe a loosening of the cap or closure. Closure back-off can occur immediately after closure application, but is more often affected by physical and environmental conditions (i.e., vibration, changes in atmospheric pressure, top loading, temperature variations, etc.) once the container is in the distribution pipeline. Liner: A disk of compressible material, usually some polymer/pulp/aluminum foil combination, placed in the head of the closure to assure seal integrity by compensating for any irregularities on the sealing surface of the container. Induction Seal Liner: A liner containing foil and a plastic heat-sealing polymer that hermetically seals a container with an induction cap sealing machine. Linerless Closure: A thermoplastic closure incorporating a molded baffle that rings the interior head of the cap for seal effectiveness. Skirt: The vertical, often knurled (see below) or striated, wall of a closure, the inside of which is formed to mate with the container’s threads. Band: A ring of material extending below the skirt. The band is secured tightly to the neck of the container during the capping process. To provide tamper evidence, the band either remains anchored to the container neck or is broken when the closure is removed. Knurl: A debossed or crimped bulge around the top of the skirt of a metal cap that provides additional leverage for removing the closure. The liner fits into the interior chamber formed by the knurl. Cocked: A condition describing the misaligned seating of a closure so that the container is not sealed effectively. |
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Ben Miyares , vice president for industry relations at the Packaging Machinery Manufacturers Institute, has been providing packaging market analyses and commentary since 1963. |
