Milacron brings back two-stage approach
Milacron Inc. is going back to the future, with a two-stage injection unit for its all-electric presses with large shot sizes.
An extruder screw charges the shot, then a plunger pushes the resin into the mold. This two-stage approach was used on standard hydraulic injection presses until the 1960s, when the reciprocating screw took over. Reciprocating screw machines lower machine cost because a single screw does both functions. That requires big screws.
``These larger-diameter screws are no problem to push with a hydraulic system, but it becomes cost prohibitive to do so with today's electromechanical drive technology,'' said Barr Klaus, technical director of Milacron's Elektron Technologies unit.
Milacron could have simply used a bigger ballscrew, roller screw or rack-and-pinion mechanism. But, according to Klaus, suppliers are not yet mass-producing those large components, so the price remains high.
Milacron offers the two-stage electric design in shot capacities of 80, 110 and 150 ounces. On Milacron's largest all-electric press, with 725 tons of clamping force, the two-stage unit doubles its existing 76-ounce capacity, to 150 ounces.
But Klaus said larger capacity is not the only advantage. Electric machines already use two separate motors to drive plasticizing and injection.
Also, the new injection unit can shoot its full volume. A reciprocating screw unit usually is sized two times larger than its maximum shot requirements.
``The two-stage unit is a complete departure from old thinking,'' Klaus said. ``If frees the design of the injection function from dependence on the plasticizing function, with an independent shooting chamber. This allows use of a smaller diameter injection barrel and longer injection stroke for a given volume, making it easier to generate high injection rates, pressures and volumes with smaller, precise and proven electromechanical drives.''
Tel. (513) 536-2000, fax (513) 536-2552.
LNP says compound conducts thermally
LNP Engineering Plastics has introduced what it claims is the first product line of thermally conductive compounds.
Its Konduit compounds are 10-50 times more thermally conductive than conventional resins and compounds, according to Exton, Pa.-based LNP. They are aimed at applications such as integrated circuit heat management, heater systems, fiber optics and uses in automotive and appliance systems.
LNP said Konduit is easier to process than metals used as heat sinks. Product manager Mark Kaptur said Konduit can be processed into intricate shapes to improve its performance for heat management.
Metals outperform Konduit's heat transfer rates but in most applications limited air convection actually determines how fast heat can be removed from an electrical device, Kaptur explained. In a sense, a metal heat conveyor can be overbuilt if it absorbs heat faster than it can get rid of it by convection.
Konduit is commercially available as compounds of polypropylene, nylon 6 and polyphenylene sulfide, Kaptur said in an interview. Heat conducting additives are ceramics or high-performance carbon fibers. The highly filled materials have potential to wear injection press parts but LNP adds lubricant to Konduit to minimize it. LNP is focusing on crystalline rather than amorphous resins because they provide better flow.
Laptop computers have built-in aluminum heat sinks with a fan with the sole purpose of absorbing and dissipating heat generated from working electronic circuits. Konduit can provide heat dissipation at the same time as it acts as a mechanical and structural component. Replacing other plastics in electronic appliances with Konduit could allow computer makers to get rid of bulky metal heat sink systems, LNP predicts.
Ceramic-loaded conduit provides thermal conductivity of up to 2 watts per meter per degree Kelvin. Higher cost carbon fiber-filled types conduct heat up to 10 w/m/K.
Tel. (610) 363-4500, fax (610) 363-4749, e-mail [email protected]
Ferro Corp. unveils granite-like colors
Ferro Corp. introduced liquid, granite-effect colors for injection molding.
Granite-Effect Type 91 colors can make transparent, translucent, pastel and fluorescent substrates, the Edison, N.J., firm said. It offers particles in shades of brown, green, blue-purple, red, black and white.
The colors are compatible with most thermoplastics and are injected into the feed throat of molding presses at levels of about 50 to 100 parts per hundred parts resin.
Tel. (732) 287-1930, fax (732) 287-8966.
Easman develops LLDPE coating grades
Eastman Chemical Co. has developed extrusion coating grades of linear low density polyethylene.
The Kingsport, Tenn., firm claims the resins offer performance advantages over low density PE, such as better stress-crack resistance, tensile strength and tear resistance.
New products include Eastacoat M30036-P with melt index of 5.5 decigrams per minute and density of 0.922 grams per cubic centimeter, and M30026-P with melt index of 2.4 decigrams per minute and density of 0.918 grams per cubic centimeter. Eastman said the new materials have low gel, good tear strength and puncture resistance.
The resins round out Eastman's line of extrusion resins made of high density PE, LDPE and LLDPE.
Tel. (423) 229-2215, fax (423) 224-7244, e-mail [email protected] man.com.
Rumber Materials touts impact modifier
Rumber Materials Inc. developed a rubber/plastic composite that acts as an impact modifier in compounds.
The Austin, Texas, company mixes ground rubber tires with polyethylene or polypropylene to create Rumber Composite. The material boosts elasticity and crack and tear resistance.
Rumber Composite is suited to a range of processing for applications such as buckets, highway signs and livestock feeders.
Tel. (877) 786-2371 or (512) 794-8473, fax (940) 759-4011.
Maac Machinery Corp., a sheet-fed thermoforming machine builder in Itasca, Ill., now has models exclusively manufactured to meet European CE safety standards. ... Cincinnati-based Hunkar Laboratories Inc. says that, under its new Smart System Performance Guarantee, if performance objectives are not realized then customers can return the entire system.