More and more processors need more precision in their feed equipment. This is what some people do. #Hint process
       The Plastrac gravity disc feeder has been modified to run on the vertical injection molding machines used by Weiss-Aug Surgical Products’ injection molding division.
       Preform Solutions primarily specializes in injection molding custom preforms in a variety of colors, but here it uses Plastrac feeders to ensure dosing accuracy and fast changeovers on its stretch blow molding line.
        Movacolor’s MCNexus is currently undergoing customer trials after a soft launch at K 2016; The low speed feeder will make its commercial debut at Fakuma in October.
        To avoid the use of pre-blended resins, processors in some markets are increasingly asking their material handling equipment suppliers to provide more precise feeding – down to grams of individual granules and additives – for example, applying one dye particle that falls off is the difference between a good part and an unnecessary Part. Roger Hultquist talks about recent medical work to illustrate his point. The customer in question wanted to accurately feed three cylindrical dye pellets into the injection molding machine’s feed port within a screw recovery time of approximately 3 seconds.
        “It’s not like feeding at 100 pounds an hour,” says Hultquist, co-founder and president of sales and marketing at Orbetron, a supplier of feeding, mixing and material handling equipment in Hudson, Wisconsin. One shot, one particle can make a huge difference in accuracy, which is becoming a much bigger problem, especially in medical applications and especially in the manufacture of translucent products. “
        In short, as feedrate requirements decrease, so do accuracy requirements. Orbetron, which specializes in low speed pipettes, has adapted a powder feeding technology originally used in the pharmaceutical industry to plastics. (See July 2017 Hultquist article: Understanding Low Feed Rates for Continuous and Batch Processes.)
       Several equipment vendors target the niche market of processors who use the precision and flexibility of low speed feeds to mix materials in machines and other applications where maximum precision is required.
        For processors adding additives at a rate of 0.5 lb to 1 lb per hour, high accuracy is not critical, but as this amount decreases, accuracy becomes critical. “In a wire and cable project where you are feeding material at 15 g/h, it is very important to get these particles exactly where they need to go,” Hultquist said. “At low interest rates, this becomes critical, especially when it comes to color – the color consistency of this product is one of the things we focus on.” extruder throat, helping to solve what Hultqvist says is a two-way problem for pellets.
       ”You can serve it, but once it’s served, you now have to make sure it’s properly distributed in your process,” Hultquist explained.
        Hultqvist noted that in addition to accuracy, players in this area also require a high degree of flexibility. “For a custom mold shop that changes colors quickly, maybe 10, 12, 15 times a day, it becomes very important that they can stop and change colors in a few minutes.” is pulled out of the device, allowing processors to switch from one feeder to another as the color changes.
        Orbetron currently offers feeders in four sizes – the 50, 100, 150 and 200 series – with capacities ranging from 1 gram/hr to 800 lb/hr. In addition to painting in markets such as wire/cable and medical products, Hultqvist noted, the company has recently expanded into the building materials industry, where disc feeders are used to feed blowing agents, siding dyes, profiles and panels, agents and other additives. .
        Quick changeover is “our deal,” explains Jason Christopherson, manager of Preform Solutions Inc., based in Sioux Falls, South Dakota. Solutions for short and medium runs of molds with 16 and 32 cavities. This avoids the huge volume chase associated with water or soft drink bottle preforms, which can be as high as 144 or more.
        “A lot of our projects use dyes,” says Kristofferson. “Every day of the week we can have two, three, four lines with different colors and different additives for our preforms.”
        All of these shades require accurate dye delivery, and the company’s targets are getting more complex, up to 0.055% at 672g and 0.20% at 54g (the latter being 98.8% resin and 0.2%). % color). Preform Solutions has been in business since 2002 and for most of that time, their preferred quick change precision feeding solution has been the Gravity Auto-Disc Feeder from Plastrac, Inc. from Edgemont, Pennsylvania. The company currently has 11 Plastrac units with four more on order.
        The advantage of Preform Solutions based on Plasrac technology is the unique design and its impact on accuracy. The feeder uses a blade, essentially dosing the granules by cutting. The feeder drops the pellets into pockets on the disc and the blade scrapes off any part of the pellets that extends beyond the pockets. “When the Plastrac device cuts through the grains and smooths out the pockets where the material gets under the blade, it’s very accurate,” Christofferson said.
        Plastrac feeders have also found use in the related industry with Weiss-Aug Surgical Products in Fairfield, NJ. According to Elisabeth Weissenrieder-Bennis, director of strategic planning, the parts are usually small, often 1 to 2 or less.
        According to Leo Czekalsky, molding manager, 12 Weiss-Aug Plastrac units have been specially adapted by Plastrac to work on Arburg’s vertical injection molding machines. Plasrac units provide machines with portion sizes from 2 to 6 ounces and auger diameters from 16 to 18 mm. “The injection sizes and the tolerances we have to keep for these parts are within thousandths of an inch,” Chekalsky said. “And since repeatability and injection volume are absolutely essential, there is no room for variation.”
        According to Chekalsky, this repeatability extends to the colors offered by Plastrac. “I have never seen anything more accurate and reliable than this device,” said Chekalsky. “Many other systems require someone to calibrate and adjust when changing shape or color, but here the system does not require anything.”
        Weiss-Aug appreciated this accuracy and hassle-free operation, especially given the market that serves its Fairfield operations. “These components have a high visual standard because they are used in surgery,” said Weissenrieder-Bennis. “There are very specific color standards and you really can’t have any variation.”
        At K 2016, Dutch company Movacolor BV (distributed in the US by ROMAX, INC. of Hudson, Massachusetts) introduced its own low feed technology, MCNexus, which it says can feed 1 to 5 particles (see K show report for February 2017). ).
        A Movacolor spokesperson said that MCNexus is currently being tested by several customers in Europe who use it to accurately dispense small amounts of dyes in toys and household products. Movacolor will present MCNexus at Fakuma 2017 in Friedrichshafen, Germany in October, also marking its official commercial launch.
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