New and innovative techniques to help processors reduce energy consumption, eliminate secondary operations, and raise productivity were center stage at the recent SPE Blow Molding Conference in Bartlesville, Okla. A novel extruder for industrial blow molding is claimed to offer the highest productivity in the industry and a new flexible die ring for optimizing wall thickness
gained its first commercial application. Other news at the conference included a next-generation online leak detector with higher throughput and new in-mold cutting and punching techniques that eliminate secondary operations and reduce labor.
The new Q Extruder from Kautex Machines Inc. is said to offer the highest productivity for extrusion-blow molding of technical parts and packaging. Kautex has tested it in 60-, 120-, and 150-mm sizes. The 150-mm model can process HDPE at 1870 lb/hr, reportedly a 30% improvement over current models.
What’s more, it reportedly cuts energy consumption by 29% with a new barrier screw, spiral-grooved feed section, and water-cooled motor and drive. “With the soaring cost of energy, we decided to focus on the extruder, which is the largest energy consumer in the blow molding process,” says Chuck Flammer, v.p. of sales.
The barrier screw and spiral-grooved feed section reportedly impart less shear, resulting in a melt that is 15° C cooler at maximum plasticating rate. A higher plastication rate is achieved at the lower melt temperature with less energy use and a shorter cycle time. The water-cooled motor and drive are also big energy savers vs. air-cooled versions, according to Kautex. The new extruder design also means longer wear life for the screw and barrel.
The company also offers the new screw, feed section, and drive/motor as retrofits for existing machines. They sell at a premium but there is a long-term net savings due to reduced energy use, according to Flammer.
Kautex is also examining different barrier screws with additional shear lands and new drive concepts such a direct drive without a gearbox and special torque motors.
FLEX DIE RING SAVES RESIN
A new flexible die ring for optimizing wall-thickness distribution has been commercialized for the first time in an extrusion blow molded part. The die ring was introduced at the K 2007 show in Dusseldorf. The Big Bobby Car, a toy produced by BIG-Spielwarenfabrik GmbH in Germany, uses this device to shave 50 g off the 1.8-kg part, trim cycle time by 6 sec, and improve part quality.
As we reported in January, the mechanism is a layered, flexible metal die-ring with several hydraulic or electric “pushers” or cylinders that apply external pressure on the ring. The number of pushers depends on the part’s complexity. The one-piece flex-ring sleeve has an upper conical region consisting of 15 separate wall segments. The overall wall thickness can withstand the internal pressure generated by the melt while the individual wall segments are thin enough to be flexible and deformable, according to the inventor, Dr. Heinz Gross, president of Kunstsoff-Verfahrenstechnik Messtechnik of Darmstadt, Germany. The die ring can be retrofitted on any head and is particularly suited to asymmetric parts.
Compared with other deformable die rings, this technology allows for much more locally limited deformation or adjustment of the flow geometry, claims Gross, and it is suited to die diameters down to 6 mm. It is claimed to be more versatile than the more complex and costly Parison Wall Distribution System (PWDS), which is limited by fixed movements and can only be used with dies of 80 mm or larger diam.
Germany’s Rikutec, a supplier of accumulator-head machines for large drums and containers, is licensed to make and sell the flexible die ring for 150-mm and larger dies. In development in Europe are intermediate bulk containers (IBCs) and water tanks using this device. Dr. Gross also is looking to license the technology for molding smaller parts.
HIGH-OUTPUT LEAK TESTER
The SPE conference also saw the launch of the NexGen rotary leak tester from Air Logic Power Systems (ALPS). This new system boosts throughput by 25% from 1600 bottles/hr to 2000 bph per station. It offers faster electronic controls, test algorithms, and pneumatics, according to Scott Heins, sales manager. Among the electronic advances is encoder-based timing, which eliminates mechanical cams, trip points and adjustments, allowing speed compensation of the test probe movement and air-reject functions.
Another feature is a more sensitive leak test that can now detect 25% smaller holes at the higher test speeds, from 0.004 to 0.01 in. diam. for single-serve containers. Changeover time has also been reduced from approximately 45 min to 15 min with a quick-lock mounting technique requiring no tools.
An interesting option is integrated laser coding for traceability of PET bottles, claimed to be an industry first. The latest laser scribing technology is offered through a partnership with Domino Amjet Inc., Gurnee, Ill., a manufacturer of laser coding instruments. NexGen is priced competitively vs. prior rotary models and is available with 4 to 30 heads.
Spain’s ABM Moldes is said to be the first to incorporate in-mold multi-shape punching for extrusion blown technical parts. In-mold punching of round holes has been done before but multi-shape punching is new for large tubes and automotive ducts, according to Andre Lanhoso, commercial director.
Automatic punching is done early in the cooling cycle and has no impact on cycle time. Specially designed knives and punches are hydraulically actuated in the mold. The technology has been used in the U.S. in non-automotive parts, says Gerry Hobson, president of Hobson Consulting Ltd., a North American representative for ABM Moldes.