The Perfect Combination

Applications vary as widely as the mathematical combinations behind those buckets. Anything weighed and packaged in pieces seems to be fair game: fruits and vegetables; snack seeds, nuts and chips; candy and candy bars; cereals from bagged rice and grains; and wet, sticky meats and poultry.

“And you’d be surprised how much beef jerky sold every day that comes of our weighers,” says Anthony Delviscio, president of CombiScale Inc., Elk Grove Village, Ill. He notes those machines typically run 120 packages a minute using 14-head machines.

While he says the price on the first generation of machines may have been too high for “mom and pop” shops, the market for combination units has exploded with competition. Combi, for example, offers larger units as well as an inexpensive eight-head machine for small to medium food processing lines. “In the past, there was a tremendous jump in price from a volumetric system to a combination weigher,” says Delviscio. “It could be the difference between a $20,000 system or one over $100,000. Now we can offer the same system for $40,000.”

While more buckets translates to more speed, the low-end system still offers value, he says. “We can save processors money by packaging more accurately, minimizing their giveaway and lessening their investment into this technology."

As with throughput, the ideal size, number and shape of buckets vary with the size of pieces being packed, the final package’s net weight and other factors. A machine with the same number of buckets and discharge hoppers below might bag 170 small bags of hard candy, 100 1-lb. bags of rice or 30 8-oz bags of frozen chicken nuggets per minute.

Production needs also dictate the best solution. For example, radial designs are the nearly universal choice for all products. They are adaptable for larger products because it’s easier to fit them with bigger buckets.

But in some cases, users may also consider a linear design. A free-flowing product like cereal may lend itself to an in-line weigher’s smaller floor-space footprint and ease of retrofitting a cover to collect the dust that kicks up in such applications. And while vibratory infeed conveyors may be most common, a sticky product such as raw meat may require a conveyor that may be more easily installed below an inline unit. Below are some additional application considerations:

• Sticky, meat and poultry: Raw, marinated or otherwise wet and sticky products such as chicken tenders and other meats, as well as some fruits and vegetables, can present some of the greatest challenges. They can cling to vibratory conveyors, necessitating dimpled or embossed metal surfaces to minimize the surface area of product contact. Belt instead of vibratory conveyors may be used, and water sprays can keep sticky product moving.
• Fragile products: You must “handle with care” products that can break, such as bakery products — think mini-muffins and mini-doughnuts that are bagged. “For applications like these, we have gentle handling solutions,” says Heat and Control’s Barr. “We generally try to make sure each transition from hopper to hopper is very gentle and gradual. We can reduce the slopes or angles, and minimize drop distances to avoid any degradation of the product while you're feeding it through the system.”
• Temperature extremes: High heats can cause oils and greases to build up, particularly for deep-fried foods. The solution comes with more frequent washdowns and cleanings. Air conditioning units may be used to cool control cabinets. In freezing environments, washdown presents its own problem: freezing. Some processors may cycle their machines “dry” until they’re ready to run product in order to prevent machines from freezing and seizing.
• Fine grains: Tight-closing “sift-proof hoppers,” as Ishida calls them, ensure that fines don’t get through the hopper openings when in the closed position.
  There’s a learning curve to adopting new technology, even for what might appear to be a simple machine. Simply put, replacing a slow, old machine with a new one that runs twice as fast “doesn't mean you can use your old packaging materials. You can't just buy a faster machine and have it magically make everything faster,” Triangle’s Bergholt says, noting that an old set of packaging jaws may need more dwell time.

Both the supplier and the food processor share the responsibility to ensure such issues are addressed long before a purchase is made and that the solution meets application requirements.

This is often alleviated by the nature of the supplier or OEM; many offer services and equipment for both mechanical and electronic integration to upstream and downstream product handling, processing and packaging components.

And while the heart of the high-speed logic that controls weight combinations is proprietary, vendors are increasingly offering connectivity features and services to help processors transfer and access data through Windows interfaces and Ethernet connections, which are but two of the standards food processors expect.