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Technology development and application of high glass fiber reinforced plastic chassis
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Thursday 5 July 2012

High-strength mechanical parts are necessary to manufacture light and thin chassis for ultrabooks. In addition to expensive aluminum magnesium alloy, mechanical part makers can also achieve metal-like characteristics of ultra-thinness, high strength and sleekness by using plastic plus 25-50% glass fiber when making high-strength chassis. The method will also significantly reduce the cost of ultrabook's mechanical parts.

Speaking at the recent DTF 2012 Ultra Mobile & Ecosystem Forum, MiTAC Precision Technology (Kunshan) president John Lin started with an introduction to the background of Getac Technology Corporation and MPT. Founded in 1989, Getac is an entity that is listed on Taiwan's Gre Tai Securities Market (TAIPEX: 3005) with a NT$5.8 billion capital. The company reported NT$15.8 billion of revenue in 2011.

Getac's main business encompasses ruggedized computer, composite mechanical component, plastic and metal component module, auto mechanical component and aerospace mechanical component. Getac is now the world's second largest ruggedized computer manufacturer and supplier. The company now owns 11 manufacturing bases: one in Shunde (located in Guangdong Province, China), three in Kunshan and one in Changshu (both cities are located in Jiangsu Province, China), two in Nanchang (in Jiangxi Province, China), two in Vietnam's Bac Ninh Industrial Zones, one in Shanghai, China and one in Taoyuan, Taiwan.

MPT is a composite mechanical component subsidiary of Getac founded in Kunshan in 2003, with 4,500 employees and a R&D/engineering staff of 800 people. Major injection equipments at MPT factories include 330 injection molding machines and 297 RHCM controllers, delivering a monthly capacity of 8 million pieces. The company's tooling center can produce as many as 320 sets per month with a short lead time of 15 to 35 days. MPT also owns key technologies for HCM injection, high-temperature mold, gas-assisted injection molding, IMR, IML, double injection, sputtering lines and coating lines.

Light and thin chassis: An inevitable trend amid the ultrabook boom

Lin said Apple's decision to cut the price of MacBook Air to around NT$30,000 shook up the market. People no longer find appealing the bulky notebook computers that are at least three to four centimeters thick. That's why Intel requires a thickness below 18 mm and less than 1.5 kilograms of weight for 13.3-inch ultrabooks. Intel hopes to achieve a 43% penetration for ultrabooks by 2014, and reduce the average selling price (ASP) to below US$600 in an effort to cater to enthusiasm for thinner and lighter devices with affordable prices.

In addition to specs, cost is another key problem for higher penetration of ultrabooks. And among all cost-related problems, chassis and frames are the most crucial subject. Currently more than 90% of ultrabook chassis are metal, and one single chassis item in the CNC process would cost over US$100. As one CNC machine can produce eight pieces per day and three of the items will be used in CNC machines, existing CNC machines are not enough to achieve an annual mass production of 24 million ultrabooks, and the prices of ultrabooks will remain high. Under such circumstances, high glass fiber reinforced plastic chassis, which is also light, thin, stiff and affordable, has become an alternative for ultrabook chassis.

Technology development of light, reinforced glass fiber Chassis

Lin mentioned that mid-end notebook computer makers used to adopt PC ABS because it is quite cheap, but the material fails to achieve ultra-thinness due to poor stiffness. Glass fiber is therefore added in order to improve plastic chassis' stiffness as more plastic fiber offers higher stiffness. However, mass production would become more difficult at the same time.

Due to limitations in fluidity, PC ABS can only consist up to 30% of glass fiber. Manufacturers turned to nylon later, adding up to 50% glass fiber to meet the fire-proof and heat-proof requirements. Up to 75% glass fiber can be added if not considering the fire-proof requirement, so that the chassis can be thinner with strength and stiffness greater than existing metals.

Other crucial technology barriers to mass production of glass fiber chassis include the problems of warp and floating fibers, simultaneous delivery of lightness, thinness and toughness, and stronger chassis structure in order to pass drop tests.

Lin said plastic chassis makers using conventional injection molding technology would melt plastic material and then inject it into molds of 40-50óJ temperature before unmolding after cooling down. It would warp the item if the material fails to cool down before reaching its crystallization temperature.

MPT developed a Rapid Heat Cycle Molding (RHCM) technology for plastic since 2003, employing a rapid temperature-changing molding process. Temperature of the molds will first be raised to a certain high level, and then the plastic material with high percentage of glass fiber is injected into the molds. The item is finished when the mold is set to room temperature, and the chances for warp will be significantly reduced.

Flatness and stiffness close to aluminum magnesium alloy

Conventional plastic manufacturing process is prone to floating fibers that often cause unevenness and obvious welding lines. Getac's glass fiber reinforced plastic chassis adopts the RHCM process technology to achieve a glossy surface. The surface, plated with a 50nm layer of resin without any floating fibers and welding lines, is sleek and meets the requirement for glossiness and seamlessness. In terms of the characteristics of stiffness, lightness and thinness for a 13.3-inch notebook chassis cover, the Al alloy-6063 process (unibody, CNC) adopted by MacBook Air has a 67 GPa bending modulus, with an actual weight of 227 grams and 0.7-1.2 mm minimum wall thickness, while the PC/ABS plastic chassis has a 2.5 GPa bending modulus with a 218 gram weight and wall thickness of 1.8 mm. MPT's PA+50% glass fiber chassis has a 17.5 GPa bending modulus, with a minimum wall thickness of 1.0-1.1 mm when the actual weight is 157 grams, which is pretty close to aluminum magnesium alloy in terms of stiffness and wall thickness.

Lin added that surface treatment for chassis with 50% glass fiber, with an IMR or coating, can result in great product texture and pattern transfers, satisfying the need for stylishness and environmental protection at the same time. Requirements for cost efficiency, mass production and sufficient capacity will also be met. As a leader in RHCM technology process, MPT offers clients the shortest cycle time in the industry and reasonable prices with an economic and eco-friendly (heating by steam) process.

Glass fiber material is cost-competitive as its price is only one third of that for metal. With experiences in plastic molding technology and excellent control of mold temperature precision, the company offers molds with lifespan close to those of regular molding molds, and chassis with 50% glass fiber can achieve a yield of over 90% due to great command of glass fiber's characteristics. With 330 injection molding machines and 297 RHCM controllers, monthly capacity can reach 8 million pieces.

Lin concluded that a chassis with 50% glass fiber is ultra-sleek, seamless and free from floating fibers and welding lines, offering great stiffness for device protection. It is also 40% thinner than plastic chassis, not to mention other features such as metal-like lightness, diversified styles with post processing, eco-friendliness (paint-free, with great product texture and pattern transfers), low costs (one third the prices of metal), potential for mass production (with over 90% yield) and sufficient capacity. All the aforementioned characteristics demonstrate that molding with high percentage of glass fiber is the best chassis solution for ultrabooks.

Technology skill to collaborate with notebook industry and facilitate mass production

With strong engineering analysis capability and powerful databanks, MPT has accumulated 307 tooling patents and 59 patents related to HCM R&D (material, manufacturing process and equipment). The company has also accumulated over 625 development projects, developing more than 1,709 sets of molds and offering solutions to covers, LCD frames, computer keyboards and bases.

Taking billiard balls and combs as examples, Lin said finally, earliest products made with ivory, ox horns, rhino horns and goat horns were only affordable for aristocrats. When the plastic industry emerged, billiard balls and combs made with petrochemical material began to deliver excellent quality and durability, with prices low enough to affordable levels. Chassis with a high percentage of fiber glass consumes lesser energy but its capacity is limitless, making the mass production of ultrabooks and higher penetration rates possible.

MPT Precision Technology (Kunshan) Corp. President, John Lin, Ph. D

MPT Precision Technology (Kunshan) Corp. President, John Lin, Ph. D

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