Materials Update 19826Materials Update 19826

Human transporter gets aesthetic, structural boost from thermoplastics 
What had been known until recently only as "It" or "Ginger" was finally revealed in December as a souped-up scooter that boasts six different engineering thermoplastics and five high-tech gyroscopes to keep it in balance and upright. Dean Kamen, the inventor and president of Segway Co., predicts that the Segway Human Transporter (HT) "will be to the car what the car was to the horse and buggy. Cars are great for going long distances but it makes no sense at all for people in cities to use a 4000-lb piece of metal." 

The vehicle is a two-wheeled self-balancing, electric-powered human transporter. It's designed to allow people to go farther, move quicker, and carry more anywhere they can walk. The top speed of the HT is 12.5 mph--about three times faster than the average walker--and it has a range of 17 miles per battery charge under optimal conditions, but more realistically about 11 miles over average terrain. The HT can carry a passenger load of 250 lb and a cargo load of 75 lb. The platform height measures 8 inches with a footprint of 19 by 25 inches and a total weight of 80 lb. 

The chassis is made of diecast aluminum and serves as the user platform as well as a protective housing for the motors, batteries, transmissions, and all electronic components. Each of the two wheels is independently driven by high-speed electric motors that have been tested to power levels of 2 hp and produce no emissions. 

Perhaps the most innovative feature of the transport is its inertial sensor assembly--two tilt sensors and five gyroscopes that work together to determine the orientation of the machine relative to the direction of gravity. The gyroscopes are oriented in such a way that any angular motion of the machine will always be sensed by at least two gyroscopes. Variable terrain is compensated for by three-axis measurements that are communicated to the controller boards to keep the user balanced and moving safely. It's these attributes that users say make the scooter difficult to fall from or knock over. The gyroscopes keep the transporter upright and discern what speed and direction the rider wants to go. 

GE Lends a Hand 
From the outset of the design process for its Human Transporter, Segway knew that in order for its product to be successful, people would need to interact with the visual side of the design. "When we weighed the aesthetic needs with the required mechanical performance characteristics, we found that engineering thermoplastics were the best materials that met our criteria," says J. Douglas Field, Segway's vp. Segway turned to GE Plastics for six lightweight engineering thermoplastics that would provide the design freedom to create durable and environmentally friendly aesthetics for its transporter. Five different molders, one in Europe, were needed to complete the project. 

Sollx film, a precommercial polymeric film, is used on the fender and is applied using an inmold decoration process over an injection molded Xenoy PC/PBT resin substrate. This process yields a high-gloss, Class A, paint-free exterior trim component in a champagne color. This film was chosen for its superior performance vs. paint in weatherability, scratch, and chemical resistance tests. The Xenoy X5300WX PC/PBT resin used gives the injection molded fenders a molded-in color capability, either light or dark gray, as well as good chemical resistance, impact strength, and weatherability. 

For the wheels, a molded-in black Noryl GTX 820 PPE/PA resin met all quality criteria for strength, dimensional stability, and resistance to environmental conditions. This resin is a blend of a nylon-based product reinforced with modified polyphenylene ether (PPE) and is 20 percent glass-reinforced. This resin was chosen to ensure a proper seal for the low-pressure tubeless pneumatic tires. From the same resin family the Noryl GTX 830, a 30 percent glass-reinforced material, was selected for its critical strength requirements for use in the HT's handlebars. 

The user interface is made of molded-in gray Cycoloy C6600 ABS/PC, a halogen-free, flame-resistant resin that offers a property balance of heat, flow, and impact strength while meeting stringent ECO standards. 

The control shaft attachments are created using two-shot molding. They're first molded of Cycoloy C1110HF PC/ABS and then overmolded with an elastomer to produce the desired feel and function. A clamp made of a 25 percent carbon-fiber-reinforced Ultem 7801 PEI joins the user interface to the control shaft and provides the steering mechanism with stiffness, strength, and dimensional stability. 

The battery housing is a box made of Valox 3706 PBT, an impact- and flame-resistant resin. The housing is molded in two halves, which are then welded together. 

The U.S. Postal Service, National Parks Service, and GE will be the first customers to purchase the transporter for $8000 apiece. A $3000, 65-lb consumer model will be available to the public by late 2002. 

GE Plastics, Pittsfield, MA
(800) 845-0600
www.geplastics.com 

Segway LLC, Manchester, NH
(866) 473-4929
www.segway.com 

TPE brings shock, splash resistance to CD case 
A few months ago, IMM used this CD storage case as an example of how to design a tool for overmolded parts. The challenges in manufacturing the product extended beyond the mold, however. Attempting to solve these problems and set its product apart from competitors, Allsop Inc. (Bellingham, WA) turned to TPE compounder GLS Corp. 

Known as the CD Sport 10, the case holds up to 10 CDs, DVDs, or CD-ROMs. Its protective hard shell is made of polypropylene to protect the disks from exterior impact. Disks are held in place inside the case by soft, nonabrasive CD mitts for no-touch handling. As is sometimes the case with a rigid substrate and a thermoplastic elastomer, the polypropylene shell did not adhere properly to the overmold materials. Allsop's requirements included a soft, tactile, comfortable feel on the areas of the case that were frequently handled, but it was also searching for a material that would be grippy, abrasion resistant, and not attract excess dirt to the product. 

Versaflex CL-40, a clear TPE from GLS, was chosen for the product. The TPE reportedly adhered well to the substrate and provided shock and splash resistance. It allowed Allsop to offer the case in a wide range of colors and gave the product a distinctive look and added performance value with the desired grip. 

Allsop Inc., Bellingham, WA
(360) 734-9090
www.allsop.com 

GLS Corp., McHenry, IL
(815) 385-8500
www.glscorp.com 

User-driven enhancements speed online procurement 
Online resin marketplace Omnexus has reportedly accelerated the speed of its procurement processes through an enhanced ordering system. The revised template speeds the flow of order input through a new set of order screens. Transactions using the system reportedly have been processed in 30 seconds, with immediate order confirmation sent to the user's desktop for acknowledgement. Actual times vary by user, depending on user-specific conditions. 

Omnexus, Atlanta, GA
(678) 302-3438
www.omnexus.com