NPE2018 Show Daily - Tuesday

NPE is truly ‘Breaking the Mold’ as a multifaceted experience, with activities, discoveries and opportunities to satisfy the needs of anyone who works in the plastics industry or has a need to know about plastics

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Page 35 of 103

TUESDAY NPE 2018 : THE PLASTICS SHOW SHOW DAILY On the fly Color Changes. PDQ. There are a lot of features that distinguish a Plastrac blender, but none greater than the ability to change colors as often and as quickly as customer orders demand it. The secret is our level-sensing vane switch (standard on every single blend- er). Harried processors can hurry up color changes by swapping top castings without any need for cable removal. Easy does it blending. Now. And down the road. Plastrac designs and builds blenders to uncompli- cate life for our customers. They are simple to set up. Simple to operate. Simple to adapt in the field. Simple to expand in the future. Let's say you buy a two-component (color + additive) system now, but a few years later, you need to make it a multi-component system. Plastrac blenders are all entirely modular, so you won't be locked into the original configuration if your needs change or grow. What's more, all our parts, mechanical and electronic, are always well stocked, because we don't think your present or future operations should include downtime. Plastrac puts you in total (touchscreen) control. The perfect blend. Every time. 610-356-3000 • Visit us in WEST HALL 2 BOOTH #W129 Our new touchscreen controller, optional on all our blenders, puts complete, intuitive process manage- ment at your fingertips. Set-up parameters are viewable during operation and stored auto- matically. There is a non-volatile shot counter. A thumb drive enables easy software updates and transfer of the recipe files. A full keyboard enables easy entry of all recipe and component names. All events and alarms are captured with both a real time and a day stamp. In other words, everything you always wanted to know about blending in a single panel. Just for R-PVC: New Gear Pump, Screen Changer PSI is showing its first-ever gear pump and screen changer built specifically for rigid PVC. By Jim Callari Plascs Technology To hear Don Macnamara tell it, rarely does a trade show go by without at least a handful of aendees stopping by the booth of PSI-Polymer Systems Inc. asking, "What do you have for PVC?" At NPE2018 (Booth W5791), the PSI general manager can now play show-and-tell, as the firm is introducing its first-ever screen changer and gear pump specifically for rigid vinyl (RPVC). Target areas for the two new products include sheet and profile extrusions. Generally, the systems can be used on PVC formulaঞons that can tolerate melt temperature varia- ঞons of 10-15°F. Says Macnamara, "PVC with lile to no stabilizer has a very narrow process window. This material will generally tolerate heat as long as it keeps flowing. If the flow slows relaঞve to heat input, the carbonizaঞon process starts and triggers the release of chlorides." As he explains it, screen changers are generally not ap- plied to RPVC processes because of flow transiঞons in the sealing areas exposed to the melt stream. As RPVC travels over these transiঞons and steps, shear heat is introduced, in turn triggering localized burning of the material. But PSI has developed a work-around in the patent-ap- plied-for Expansion Plate Screen Changer (ESC), solving "the chemistry issues relaঞve to heat, flow and thermal conduc- ঞvity" to enable it to be used in PVC processes capable of toleraঞng those 10-15 F swings in melt temperature. The screen changer requires a momentary shut down for screen change. This eliminates the need for disassembling the die, which on short runs in parঞcular results in high scrap rates. To change screens on the ESC, the PLC rapidly heats the expansion spacer bars, which separate the body halves above and below the slide plate between the body halves. In the design, the spacers are far from the bore to avoid mo- mentary raising of the melt temperature. The expansion of the spacers pushes the bodies apart, freeing the slide plate to move unimpeded. Once the new screen pocket is in posiঞon and the spent screen is outside the body, shop air or a cooling medium is directed through the spacer plates, cooling and contracঞng the steel. This effecঞvely shrinks the body halves back against the slide plate, recreaঞng a seal through inঞmate steel-on-steel contact. The ESC features chrome-plated flow bores that are straight-through the screen changer to eliminate hang-up ar- eas. The unit has no mechanical seals, so galling is eliminated. Moreover, the upstream and downstream bodies are idenঞcal. These interchangeable halves are field repairable—if a body surface in contact with the slide plate gets scratched, the body can be surface ground by a local machine shop and placed back in service. Components are made from corro- sion-resistant stainless steel, says Macnamara. Concerning temperature control, the ESC offers electric heat and air or liquid cooling for the expansion spacers. The bodies are ar- ranged standard with electric heat and can be jacketed for more consistent heat transfer. Processors of RPVC generally eschew melt pumps as well, according to Macnamara, due to heat generated in the axial clearances of the gears and lubricaঞon zones in the bearings. He states, "While many of today's pumps are capable of dis- charging material used for gear and bearing lubricaঞon, main- taining suitably low temperatures over the bearings and gear journals has remained elusive." But PSI's Chlorinated Gear Pump (CGP) is ideal for thermal- ly sensiঞve polymers and brings all of the die-pressure stabili- zaঞon, increased output and extruder-pressure reducঞon benefits of gear pumps to RPVC sheet and profile applica- ঞons. The new design uঞlizes modified components and im- proved heat transfer to reduce temperature excursions that can trigger carbonizaঞon/degradaঞon of sensiঞve materials. The gear pump body and side plates are jacketed for steam or oil heat-transfer media. This media travel through the enঞre pump in a single pass. Dual-extended gear sha[s aid in con- ducঞve transference of heat out of the high load areas of the gears. Heat transfers outward from the bearing journals into the cooler seal journals and then through the seals into the jacketed side plates. Seals are contained within and are inte- gral to the side plates for best conducঞvity. Cooling channels in the body wick heat away from the bearing ODs to control heat buildup. Large, jacketed side plates provide addiঞonal heat transfer from the bearings. Bleed material used for lubricaঞon of the bearings and gears is evacuated from the process flow via internal ports to outside the pump (approximately 0.01% of flow) in a con- stant bleed. "While many of today's pumps are capable of discharging material used for gear and bearing lubricaon, maintaining suitably low tempera- tures over the bearings and gear journals has remained elusive." 32

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