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					                                                                  QUALITY CONTROL

                                                                                            net material from wear associated with
                                                                                            product flow, damage or from contami-
                                                                                            nating the feed material.
                                                                                                Different types of magnet material
                                                                                            such as Alnico, Ceramic and Rare Earth
                                                                                            have their own unique advantages and
                                                                                            disadvantages. Depending on various fac-
                                                                                            tors related to a specific application, any
                                                                                            of these materials could be appropriate
                                                                                            for pharmaceutical applications. It is
                                                                                            essential to work with a qualified mag-
                                                                                            netic supplier to determine the ideal mag-
                                                                                            net material needed.

                                                                                            Application Considerations
                                                                      E-Z Tec               Temperature: Permanent magnetic
                                                                      Pharmaceutical MD:
                                                                                            materials lose strength when exposed to

                                                                      Detecting minute
                                                                      metal contamination   elevated temperatures. Some losses are
                                                                                            reversible—when the temperature is
                                                                                            returned to normal, the magnetic strength

 Separation                                                                                 returns. Permanent magnets heated
                                                                                            beyond certain temperatures (which
                                                                                            depend on the specific material) may
 How can you select the                                                                     also suffer irreversible loss that cannot
 best equipment for the job?                                                                be recovered by cooling. When specify-
 BY BILL DUDENHOEFER                                                                        ing a magnet application, it is important
                                                                                            to keep in mind the ambient as well as any
                  hile foreign object detection holds a certain degree

                                                                                            clean-in-place (CIP) temperatures to
                  of importance in virtually every industry imagina-                        ensure a proper magnet design suitable
                  ble, end products for the pharmaceutical market                           for long-term separation performance.
                  must meet the most rigid purity standards. Because                             Flow Rate: Magnetic separators per-
                  tablets and capsules are manufactured for human                           form best when the contamination is pre-
 consumption, even the minutest particles must be completely                                sented to the surface of the separator. It is
 extracted. Before anything can be removed, it must first be                                best to select a magnetic separator that
                             detected. And, because hygiene and qual-                       provides for a thin burden depth over or
                             ity criterion for the pharmaceutical is reg-                   under the magnet to ensure the magnet
 ularly upgraded, pharmaceutical manufacturers must proactively                             will have the best opportunity to capture
 search for newer, better solutions to detect foreign objects.                              the ferrous contamination.
                                                                                                 Flow Characteristics: Many products
     When used properly, magnetic separation equipment can virtually eliminate              exhibit different flow characteristics when
 ferrous metal contamination from dry and liquid products. Magnetic separators              damp or moist. Large chunks may plug
 are available in a wide variety of designs to meet manufacturers’ specific needs.          an opening or gap in the separator. So the
 For maximum extraction and results, the right equipment should be chosen for               product must be able to flow freely
 the particular job. Selecting the proper magnetic separator requires an under-             through the selected magnetic separator.
 standing of magnetic properties, the process application and environmental ele-                 Process Issues: How the material will
 ments that exist in each specific installation. Equipment should be selected based         be presented to the separator is crucial.
 on the materials being processed and the many application considerations.                  If the material is not metered, then the
                                                                                            equipment must be capable of handling
 Magnet Materials and Styles                                                                a surge flow. If the system can’t be
 Magnet material generally refers to the magnetic pressings or castings used to             stopped for cleaning, a self-cleaning
 develop the magnetic field within the separator. This material may be cut and              magnet is required. Also be aware of any
 arranged in a linear fashion using other materials to create a magnetic circuit.           ferrous material in the area that may cre-
 Depending on the desired outcome, circuits may be designed to cast a shallow-              ate a hazard for magnet handling. Two
 wide magnetic field, a deep-narrow field or anywhere in between. This is why it is         last considerations are the amount of con-
 often difficult to compare competing products made of similar material. Once the           tamination to be removed and the level
 circuit is assembled, it is usually encased within stainless steel to protect the mag-     of product purity that is required.

                                                                                                                 August/September 2005
         Type of Material Being Processed:            Pharmaceutical                                                       cannot be stopped to
                                                      metal detector
     Assessing the material being processed is        incline tablet                                                       deal with detected
     a vital step in selecting the proper mag-        transfer conveyor                                                    metal contamination,
     netic separator. Product generally falls into                                                                         state-of-the-art metal
     three different categories: dry, moist or liq-                                                                        detectors can be con-
     uid. Within each of these groups, a wide                                                                              figured to reject a con-
     range of product variation exists.                                                                                    taminated product
                                                                                                                           automatically, even if
     Separation Equipment                                                                                                  the possible rejection
     Plate Magnets: These are used in the bot-                                                                             point is some distance
     tom of an inclined chute or suspended                                                                                 from the detector. The
     above a thin burden of material on a belt                                                                             detector can also keep
     conveyor or stainless steel vibratory feeder     units are also available, enabling a com-      detailed records of detected metal—includ-
     to remove occasional pieces of ferrous con-      pletely automated cleaning process.            ing the date, time and estimated size—so
     tamination. Rare Earth models do a supe-             Pulley and Drum Magnet Designs:            that the suspicious product can be isolated.
     rior job on very fine or weakly magnetic         Magnetic Pulleys replace standard con-              One new, high-tech, innovative metal
     contamination.                                   veyor head pulleys and effectively convert     detector for the pharmaceutical industry
          In a typical chute installation, the mag-   the conveyer into a self-cleaning magnetic     is specifically designed to improve process
     netic material adheres to the magnet face        separator. As the conveyed material passes     purity through detection of minute metal
     while the product slides across the face of      the head pulley and discharges in its nat-     contaminants during the production of
     the magnet. The magnetic field attracts          ural trajectory, the magnets “scalp” large     any capsule or tablet-based product. This
     and holds ferrous material until the plate       tramp metal from the burden, then dis-         unit’s advanced electronic design simpli-
     is removed for cleaning. The magnet is usu-      charge it as the belt pulls away from the      fies setup, ensures reliable operation, pro-
     ally hinged and swung away from the chute        backside of the pulley.                        vides instantaneous recovery from phase
     and cleaned manually. Plate Magnets are              Drum Magnets are self-cleaning mag-        adjustments and requires minimal opera-
     simple and economical to install and there       net assemblies that continuously remove        tor training. The five-minute QuickStart
     is an extensive range of designs available.      tramp metal from a product flow. The mag-      feature allows users to pass sample prod-
     Plate magnet designs include Round Pipe          net assembly is enclosed within a stainless    uct, test and begin production in less than
     Separators (RPS), Hump Magnets and               steel drum and fixed in position. The drum     five minutes. By fixing the downslope of
     Deep Reach Separators.                           rotates around the magnet, conveying           the unit’s polished stainless steel head at
           Grate Magnets: These consist of one-       material through the magnetic field.           30 degrees, lengthy timing adjustments of
     inch diameter (25mm) magnetic tubes in               Liquid Line Trap Magnets: Magnetic         downstream reject equipment are elimi-
     a grid formation designed to allow feed          Traps employ powerful tube magnets that        nated. For added product purity, an easy-
     material to cascade through the grate,           are specifically designed for liquid prod-     clean chute reduces cross-contamination
     spreading magnetic protection through the        uct flows. The traps are available in many     during product changes.
     cross-sectioned area of a pipe, chute or         designs, but basically include an inlet port        Recent advances in magnetic separa-
     hopper. Ceramic Magnet models are effec-         to match the existing pipeline, a magnetic     tion technology have resulted in a variety
     tive in removing relatively large ferrous        element to collect the tramp metal con-        of separators specifically developed for the
     contamination, while Rare Earth models           tamination, then a transition back to the      treatment of fine, high-purity materials.
     do a much better job on fine or weakly           existing pipe. Ceramic Magnet models are       The technology to produce the highest
     magnetic material.                               effective in removing chunky metals, but       quality, purest and safest products for the
          The simplest of grate magnet designs        Rare Earth models do a much better job         pharmaceutical industry is improving
     incorporate a single layer for use in a hop-     on fine or weakly magnet contamination         every day. With so many choices, it is imper-
     per, forcing raw materials to pass through       such as rust or scale.                         ative that pharmaceutical manufacturers
     the grates as material feeds from the hop-                                                      thoroughly understand their options and
     per. Multiple row units improve separa-          Metal Detectors                                needs. The first step in properly selecting
     tion effectiveness. Some applications will       Modern metal detectors reliably operate        magnetic separation equipment is finding
     utilize a single row of magnets and incor-       for long periods of time, often in adverse     a reliable, progressive magnet manufac-
     porate them into a grate housing assem-          environments, with little attention or main-   turer that not only offers the most up-to-
     bly of the user’s design. Some magnet            tenance. They can be configured for mini-      date products and services, but also
     manufacturers will also fabricate hous-          mal interference with established process      provides close customer support during
     ings that include one or multiple rows of        flow. The power required to operate both       selection as well as ongoing maintenance
     magnetic grates, depending on the level          the detector and the reject device (if any)    assistance. I
     of protection required for the application.      is minimal, even if a special conveyor is
     These units are common for vertical chutes       needed to pass the product through the         Bill Dudenhoefer is a technical representative at Eriez
                                                                                                     Magnetics (Erie, Pa.). Reach him at 814-835-6000, ext. 385
     of free flowing materials. Self-cleaning         metal detector. In cases where a process       or

58   PFQ                                                                                                              

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