Quality Control: Taking Control
December 01, 2009
by Kimberlie Clyma
Very few food processors today are willing to take the risk of operating without quality control systems in place, and with the costs of a product recall — both in the expense of lost production and wasted product, as well as the cost of public relations — it’s no wonder. As a protective measure, companies can select from a number of end-of-line quality systems that check finished product before it is sent to distributors or retailers. Metal detection systems and checkweighers are the oldest and most common automated quality control systems found in food manufacturing plants.
Checkweighing systems are employed as a quality control technique to ensure the product on the line is the accurate weight after production. The systems also are used to provide accurate product count with packaged items.
Heat and Control, Hayward, CA, offers the DACS-G series checkweigher by Ishida to baked food and snack product manufacturers. The system features proprietary double-beam load cell and noise reduction technology designed to deliver precise verification of weight or product count. Dual-range weighing capacity can be changed from 600 to 1,500 g or 3,000 to 6,000 g depending on the model. Operating presets stored in the system’s memory allow fast product changeovers. The no-tools removal of the conveyor belts and the open design of the stainless-steel framework reduce sanitation costs. The system also comes complete with an operating system ideal for off-line reporting and management of production data.
The VersaWeigh system from Thermo Fisher Scientific, Waltham, MA, is “accurate, easy to use, easy to clean, easy to maintain and can handle a broad range of applications.” To help guarantee its accurate performance, the system features Thermo Fisher Scientific’s exclusive Dynamic Broad Spectrum Vibration Analysis and Compensation to eliminate ambient environmental influences while products are being weighed.
In addition, the VersaWeigh offers a method of fixing uneven weights that may occur during the production process. “Aside from their typical use at the end of the line to assist with the final check of the individual products or packaged boxes, checkweighers can also be used in the production process to control added components,” said Volkert-Jan Hage, product manager, checkweighers for Thermo Fisher Scientific. “Our systems offer this benefit through our Filler Feed Back option, which can save the manufacturer a lot of money by considerably reducing product waste.”
The Filler Feed Back servo control allows the system to adjust the weight of the products by sending an automatic signal to the filler or dosing device to make adjustments. A slight adjustment at this point — for instance adding some additional cheese to a pizza or more chocolate enrobing to a bar — might prevent a product rejection because of inaccurate weight toward the end of the production process. This can mean considerable savings to the manufacturer, Mr. Hage said.
Checkweighing systems are an important quality control tool to help protect the bottom line and reduce unnecessary waste, but metal detection systems help assure processors the baked foods and snacks they are shipping from their factories are free of contaminants that could be potentially dangerous to the consumer. They are a crucial step in the production process.
Metal detectors can be installed at any point in the production line. In fact, there are benefits to having multiple systems installed at different points of production. First, they can be used at the front end of the production line to ensure raw materials are mixed in without any additional contaminants. They can also be installed prior to particular pieces of equipment such as slicers to avoid any possible damage to that equipment. And of course, metal detectors are essential after packaging to ensure the product is as safe as it can be before being shipped out the door.
Fortress Technology, Toronto, ON, offers its Phantom series metal detector, ideal for bakery operations, featuring its Digital Signal Processing technology designed to detect and reject ferrous and non-ferrous materials including stainless steel. The company’s Vector conveying systems integrate with the Phantom detectors to provide a convenient and “all-in-one” detection system, according to Steve Mason, national sales manager for Fortress. Conveyors are built to customer specifications including a selection of reject mechanisms. The systems are built using a stainless-steel frame and can withstand the rigors of washdown and other sanitation and maintenance operations.
The Phantom metal detection system is also designed to help bakers with their internal Hazard Analysis Critical Control Point (HACCP) programs. The system’s Contact software provides operators with an effective solution for event logging and data collection, both of which are essential if the metal detector is to be considered a critical control point in the bakery’s HACCP program. The software captures detailed system activity information and maintains records of system status changes. It can also output QA reports on demand.
Heat and Control’s CEIA metal detectors are available as horizontal metal detectors for bulk or packaged products, a free-fall system with automatic reject valve for powdered or granular products, systems for pumped products and gravity metal detectors for mounting above form/fill/seal baggers for snack foods and other products.
CEIA introduced a new generation of metal detectors, the THS/MS21 series, which is continuously self-calibrating to maintain maximum stability and performance. Its “autolearn” system selects, displays and stores the optimal sensitivity settings for up to 500 products to prevent changeover guesswork and inspection errors. The system also provides Bluetooth connectivity as a standard feature, which allows connection to a laptop for programming and monitoring. SWITCHING SIGNALS. Thermo Fisher Scientific recently introduced a new signal processing technology to its line of APEX metal detection systems. This new software changes the way its metal detectors process information and, in turn, makes them more accurate in certain situations, according to Bob Ries, product manager, metal detectors and x-ray systems, Thermo Fisher Scientific. The Intellitrack XR (IXR) helps with metal detection challenges for wet products such as freshly baked breads.
All metal detectors use highfrequency radio signals to detect the presence of metal in the product. Typically, detectors have one transmitter and two receivers. The transmitter sends identical signals to each receiver, and when one receiver’s signal is subtracted from the other, the result is zero or a balanced condition.
Metal objects that pass through the detector cause magnetic (X) and resistive (R) signals which affect the receiver. Typically, if the receivers are in balance, no metal is present, and if the signals are unbalanced, then there is metal present. But with certain products, this isn’t always the case.
Wet or salty products — such as freshly baked bread and many snack products — have X and R effects, which can appear to be similar to metal. “The moisture and salt content of certain baked products make it seem as if the product itself is conductive, which can lead to false positives from the metal detector,” Mr. Ries said. “This will lead to unnecessary product waste, which can be costly.”
To compensate for these existing X and R effects in the products, traditional systems learn the products peak X and R signals. The ratio of the two effects is known as the phase angle. To prevent false positive readings, the detector will ignore any readings that fall in the product’s phase angle. The problem with this method is if the metal type of size generates a signal that falls into the phase out region, and then the system would ignore the metal.
Thermo Fisher Scientific’s new IXR software overcomes this challenge by replacing traditional phasing. “It’s a totally new technique of processing the signals in the metal detector so that you don’t run the risk of missing metal by ignoring the signals when they look like the bread’s signals.
Basically, IXR takes the product’s signals and cancels them out — not unlike noise cancellation headphones,” Mr. Ries said. “It looks at the product’s signal and takes the opposite signals and subtracts them, so what’s leftover is the metal.” With this system, up to 50% smaller diameter metals can be detected, and as a result, there are less costly false negatives, he added.
The IXR software is available on all APEX metal detectors. After the software is added, the system simply needs to run its Autolearn program to detect the product’s threshold, and then it can be used with a push of a button. The company is offering this software upgrade to all its existing customers free of charge.
Quality control at bakeries will continue to be an important part of operations. Whether using a checkweigher to verify product weights and counts in packaging or relying on metal detectors to protect consumers from unnecessary and potentially dangerous contaminants from remaining in outgoing products, bakeries need to devote time and money to these systems upfront, to avoid paying for it in the end.