NPE News in Compounding
Compounding news at the show includes several new ways to feed low-bulk-density materials faster for higher outputs with corotating twin screws. There are also a lot of interesting new laboratory twin-screw extruders and pelletizing developments. And check out Sulzer Chemtech's unusual compounding process to make EPS pellets for bead foam molding (details on p. 14).
Steer Engineering Pvt. in India will show its new Omega 40 H Class corotating twin-screw extruder in the U.S. for the first time. It reportedly delivers 17 Nm/cc of torque at 720 rpm, thanks to a new gearbox that Steer developed and builds itself. The screws have a 40-mm center distance, 52:1 L/D, and high free volume (OD/ID ratio of 1.71).
Because of its high torque, the H Class reportedly can produce 25% higher throughput for its size. This requires a higher feeding rate, so it uses two side feeders and a top feeder at the main throat. The H Class also has another downstream side feeder and side vacuum-vent stuffer.
Coperion will unveil another new feeding enhancement for low-bulk-density materials, displayed on a 32-mm twin-screw ZSK MEGAcompounder. According to U.S. Pat. Applic. 20080248152, it uses a screw bore in the inlet zone made of a gas-permeable material, so air can be removed from powdery material as it's being fed.
Meanwhile, NFM Welding Engineers will highlight a newly designed crammer feeder for low-bulk-density materials.
To make pulling screws easier, Coperion will also show a new quick shaft coupling and a side-vent stuffer, both first introduced at the K 2007 show. Coperion's STS 95 corotating twin-screw compounder will also be displayed with a new gearbox capable of up to 800 rpm, vs. 600 rpm before.
Leistritz is now building the biggest model yet in its ZSE Maxx corotating twin-screw series, which offers high torque and high free volume (OD/ID ratio of 1.66). The new model will have 180-mm screw diam. and output of 22,000 to 44,000 lb/hr. (Leistritz's biggest Maxx before now was 140 mm.)
Also, NPE will be the first North American show appearance of a Leistritz ZSE-40 Maxx with a beefed-up gearbox that can provide torque up to 1128 Nm and up to 30% higher throughput.
On the small end, Leistritz's 16-mm Nano 16 will be demonstrated publicly for the first time, running 20- to 100-g micro batches. It's reportedly the lowest-volume twin-screw that can be scaled up to production size. By exchanging the Nano-16 barrel and screw for a Micro-18, the lab line can run up to 15 lb/hr.
Reimelt Henschel Mixing Systems in Germany (represented in the U.S. by its Henschel-Mixers division) will introduce its corotating twin-screw extruders to the U.S. Reimelt Henschel acquired twin-screw technology when it bought Rockstedt Compoundiertechnik in 2005, and has offered it in Europe for four years. The RHC extruder comes in five sizes (40, 55, 75, 95 and 120 mm) for throughputs from 880 to 11,000 lb/hr, plus a 25-mm lab model. The RHC line offers high free volume with OD/ID ratios of 1.62 to 1.66.
Century Extrusion will show an RLX lab extruder for the first time. Built by Nanjing Ruiya Polymer Processing in China (acquired by Century in 2007), it costs only $99,000. At the other size extreme, Century is building its largest Apex twin-screw ever in Traverse City with 133-mm screws. Century is also introducing new process controls at three price levels: Lean Package, Agile Package, and Engineered Series.
Entek Extruders will display a 27-mm corotating twin lab extruder with 44:1 L/D, fitted out for biopolymer processing with dry and liquid feeding and venting. One of the more interesting lab trials Entek has run recently for customers combined HDPE or PP with dried cow manure full of straw fiber for making agricultural building products.
MORE NEW MIXERS
As we reported in our “NPE News Flash” last month, Xaloy Inc. will show the first commercial version of a new low-shear conical-rotor mixer, called nXmix, which is licensed from Stratek Ltd. It is mounted on its own stand and attaches to the end of an extruder. Also reported last month, Buss AG will show its higher-output MX kneader for polyolefin wire and cable coatings for the first time in North America.
SAVE WEAR & TEAR & COST
High-isostatic pressing (HIP) of powder-metal hard coatings onto barrels and screws is a growing trend. Century Extrusion offers a new HIP metallurgy, which it calls CX465, containing over 65% tungsten carbide and a high nickel level. It's applied from 4 mm to as much as 6 mm thick.
Mixer barrels and shafts are also getting more hard surfacing. Farrel Corp. will display its recently upgraded CP550 continuous mixer, which feeds a single-stage extruder. It now offers hard surfacing over the entire surface of the rotors and liners of the 6:1 L/D barrel. This model processes 770 to 1500 lb/hr.
Entex Rust & Mitschke in Germany (represented here by Triad Sales) has introduced a segmented central spindle for its planetary-gear extruders to reduce wear. This allows a worn segment to be replaced, rather than having to replace the entire spindle.
Gala Industries Inc. will show a new and less expensive underwater pelletizer, called The Edge, for the first time in the U.S. It's a no-frills model that comes in one size for up to 2200 lb/hr.
You'll see two updated lab-size underwater pelletizers with driers: Gala's LPU for up to 150 lb/hr, skid-mounted with its water system and dryer; and Kreyenborg Industries' Lab Line 100, with a centrifugal drier.
New pellet dryers include an innovative three-stage system for fragile, hard-to-dry polymers and micro-pellets, introduced by Crown Machine. Pellets are first dewatered in a rectangular box, then they pass to a stainless-steel belt for vacuum water stripping, and finally enter a fluidized bed with either ambient or heated air. Cleanout reportedly takes 10 min vs. hours for a centrifugal drier.
For very large pellet throughputs in resin production, Gala is announcing a continuous centrifugal dryer capable of 220,000 lb/hr.
Brominated flame retardants restrict its use. Most now goes to China, but new recycling processes promise to ‘clean up’ e-waste.
With capacity scale-ups driving prices down, the pace has picked up for commerical applications that boost electrical and thermal conductivity, structural strength, and thermal stability.
You may be thinking of buying one of the new ‘high-torque/high-speed’ twin-screw compounders in order to raise your output without going to a larger machine. But how much torque or speed do you really need? Underusing a high-powered extruder wastes investment dollars. So look carefully at what is required for the materials you run.