This section was written by Associate Editor Gale Morrison		 Materials and Assembly

Technology Focus part 1
High-Temperature Graphite Process Mitsubishi Heavy Industries of Tokyo reports development of a microwave process for producing graphite from carbon powder. According to Mitsubishi, researchers achieved a milestone 3,200°C heating temperature with the microwaves. In some quarters, this was thought impossible.

MHI, whose Kobe Shipyard and Machinery Works worked with the Takasago and Hiroshima Research and Development Centers to develop the process, makes graphite for use in pencils, crucibles, and electrolytic anodes of batteries. The substance also is an ingredient in lubricants, paints, and glitters. The greatest increase in demand may come from graphite's application in the anodes of lithium-ion batteries, which are a part of the rising tide of mobile computing and communications devices. The milestone high temperature improves graphite quality for greater battery capacity and charge/ discharge efficiency, according to the MHI researchers.

Carbon powder is notoriously difficult to heat, because it is highly conductive and also because it reflects microwaves. Above 3,000°C, the layers that form in the graphite under heating become just 0.336-nanometer apart, an indication of a better-quality substance, Mitsubishi said.

Still, MHI has a long road ahead in moving the process into production. For instance, the graphitizing furnace is a batch production system and the process from the start of carbon powder heating to the end of extraction after cooling is measured in days.

Bonding Polyurethane and UHMW
Poly Roll Inc., a component manufacturer in Loudon, N.H., is in the business of supplying cast and foam polyurethane parts bound with substances like ultrahigh molecular weight polyethylene and nylon.

A cutaway graphic of a Poly Roll part shows the bonded polyurethane and UHMW polyethylene.

Poly Roll president Dave Stewart said the company now has the capability to make items like bearings and washers with polyurethane sides for durability and, in the same part, a UHMW side, with its low coefficient of friction.

Poly Roll engineers ran parts through a sand and water slurry abrasion trial for one hour at 3,600 rpm. Unfilled polyurethane disintegrated in this environment, and machined UHMW polyethylene showed a 3 percent loss by weight. A part of bonded polyurethane and UHMW showed just 0.2 percent loss by weight, the company said.

When building covered bearings, for instance, Poly Roll provides the option of adhering a cast urethane tire directly to the bearing race. The direct-to-bearing option eliminates the need for an intervening shell or stamping, thereby decreasing the cost of the part without sacrificing the quality, Stewart said.

Poly Roll said it is supplying one of its customers to the tune of 20,000 parts per month. More information is available at www.polyroll.com.

Bearings for Xerox From Sarnatech BNL
Novel thermoplastic bearing assemblies for certain Xerox Corp. Document Centre products are being produced by Sarnatech BNL, the Foxboro, Mass., arm of the Sarna Kunststoff Holding polymer group of Switzerland. These are the copy giant's latest digital copier/printers.

Sarnatech BNL manufactures drive rollers, used to move paper in Xerox Document Centre digital copier/printers, by acetal injection molding. They require no machining.

Sarnatech injection-molded the acetal drive roller, which is one component that moves paper through the printer. No machining operations are required in Sarnatech's process for manufacturing the assembly.

An eight-sided feature on one side of the bearing is the outer race of the single row bearing. The shape secures the bearing in the machine frame molding. An inner bearing has two elastomeric tires that provide friction and drive the paper forward. A tongue and clip hold the bearing onto a steel driveshaft.

Sarnatech says this type of multifeatured assembly is possible only by injection molding. Using miniature steel bearings would require more complex and more expensive manufacturing.

According to Terry R. Holmes, VP for sales and marketing, Sarnatech engineers were involved from the very start of Xerox's design program for the line. Now that an extensive validation schedule is complete, the bearings are being shipped in large quantities to Xerox factories in the United States and the Netherlands.
University of Delaware Revs 'Green' Process The Center for Composite Materials at the University of Dela-ware is investigating "green," or environmentally sound, composites manufacturing and repair. Many of the scientists and engineers involved in the field of composites are looking into ways to reduce the amount of resin that becomes part of the waste stream during conventional composite making.

Specifically, the Department of Defense's Strategic Environmental Research and Development Program granted $3.7 million for a four-year program. Replacement technologies under consideration include electron beam curing, induction curing and bonding, and co-injection resin transfer molding.

Bruce K. Fink of the Army Research Laboratory is leading a research team that is based at the CCM, where he is a scientist in residence. He is collaborating with Giuseppe R. Palmese, a CCM scientist, and John W. Gillespie, Jr., the CCM technical director, among others. One of the program's primary corporate participants is Northrup Grumann Corp., which is based in Bethesda, Md.
Gerwah Couplings for Controlling Torque Germany's Gerwah Gruppe is offering a line of long-life hysteresis magnetic safety couplings to U.S. customers through Rimtec Corp. of Palatine, Ill. The couplings are said to transmit torque smoothly and cost- effectively, while providing servo-class overload protection across the spectrum of industrial manufacturing. They do this via the production of a magnetic field across the air gap between the two sections of the coupling. If overload occurs, hysteresis magnetic couplings disengage without the abrasion and jerks that increase wear on conventional mechanical couplings.

Rimtec Corp. is marketing these Gerwah magnetic hysteresis couplings for controlling torque.

The hysteresis clutch also gives smooth, constant torque over the motor's entire speed range. All Gerwah products transmit torque from 0.1 Newton meter to 9.0 Newton meter on shafts from 3 mm to 40 mm. Following an overload, the torque transmitted remains at the rated torque level.

The Gerwah magnetic safety couplings can be maintenance-free, because they are designed as two parts that do not make physical contact. Engineers can specify shaft-to-shaft, disk, or shaft-flange designs.

According to the maker and the distributor, this particular coupling is especially useful for tension control and bottle-filling applications. For high-cleanliness applications, like pharmaceutical and food processing, special models are available.


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