Automotive Weight Reduction Expo 2012 (1): lightweight materials
Carbon fiber reinforced plastics and lightweight metals
Below is a summary of exhibits of weight reducing technologies introduced at the 2nd Automotive Weight Reduction Expo held January 18-20, 2012 in Tokyo. They use carbon fiber reinforced plastics (CFRP), hot pressed and fineblanked parts, and lightweight metals such as aluminum and magnesium.
Toray Industries exhibited its two-seater EV concept, "TEEWAVE" AR1, characterized by a generous use of CFRP that reduced the gross vehicle weight to 846kg. Mitsubishi Rayon had panels showing its plans with CFRP semi-manufactured materials that are currently in progress.
YAC Denko proposed hot-pressing technology featuring high strength that contributes to weight reduction by reducing the required product thickness. Feintool Japan exhibited products made by fine-blanking.
Lightweight products on display included those made of aluminum, magnesium and titanium. Also exhibited at the show were bolts and screws that also contribute to weight reduction.
Toray: EV concept car "TEEWAVE" AR1
Toray exhibited "TEEWAVE" AR1, a road-worthy two-seater EV concept car developed under the cooperation of Mr. Gordon Murray, a famed British designer of supercars, and characterized by a generous use of CFRP (Carbon Fiber Reinforced Plastics).
"TEEWAVE" AR1, two-seater EV concept car by Toray
CFRP monocoque structure of Toray's EV concept car
Toray: "TEEWAVE" AR1, a next-generation EV concept car
|Structural Features of CFRP Monocoque||The EV's basic structure, comprising a monocoque body made of thermosetting CFRP and CFRP shock absorber, has reduced the vehicle weight while achieving superior stiffness as well as crash safety. The bonnet hatch and roof are made of thermoplastic CFRP that allows high-cycle molding in one minute or so.|
|Vehicle Design||The vehicle's body and structural design was performed by Gordon Murray Design Ltd. (GMD), a British design house of green town cars led by Mr. Gordon Murray, former F1 designer. The concept car is fully assembled as a road-worthy vehicle.|
|(Notes) 1.||"TEEWAVE" AR1 (Toray Eco Efficient Wave Advanced Roadster 1) is a two-seater convertible debuted in September 2011 and exhibited at the 2011 Tokyo Motor Show.|
|2.||Carbon fiber is a light and strong material with specific gravity (density) one fourth of that of iron, specific strength (strength to weight) 10 times that of iron, and specific modulus (tensile modulus to weight) 7 times that of iron. Carbon fiber has the same composition as diamond and a slightly different structure.|
|3.||Carbon fiber is made by baking polyacrylonitrile (PAN) and other raw materials repeatedly at 3,000 degrees Celsius during which unwanted ingredients are removed. This process is the main cause of high production cost.|
|4.||When heated, thermosetting resin forms a netted structure of polymers by irreversible cross-linking process. In contract, thermoplastic resin softens when heated and can be formed in any shape. It softens whenever it is heated after solidifying. Thermosetting CFRP is 50 to 60% carbon fiber while thermoplastic CFRP is 20 to 30% carbon fiber.|
Materials and technologies used in "TEEWAVE" AR1
|CFRP Monocoque||The lightweight, high rigidity CFRP monocoque of a hollow structure is formed in less than 10 minutes and weighs 45kg, 53% lighter than a steel-made body structure. Has a part count of only 3 (compared to 60 in a steel-made car). Its torsional stiffness is equal to or higher than that of a steel-made sedan.|
|Seat||Made of CFRP and ultrasuede. Ultra-light and posh appearance realized by using artificial suede.|
|Crush box||CFRP energy absorber has 2.5-times greater energy absorbing capacity than steel.|
|Roof, hatch||PP-based thermoplastic CFRP can be molded by stamping in a minute.|
Source: Exhibits and printed materials at the 2nd Automotive Weight Reduction Expo (throughout this report)
Toray compared performances of the four-seater model, as calculated from the two-seater EV concept car, with those of the steel-made EV being sold today. Assuming a common cruising range of 185km per charge, Toray's CFRP model four-seater would achieve vehicle weight reduction to two thirds, from 1,520kg to 975kg while lowering the motor's maximum output and maximum torque requirements at the same time.
Comparative specifications of "TEEWAVE"-based EV and a steel-made EV
|Range: 185km (constant)|
|"TEEWAVE"AR1 (Exhibited)||"TEEWAVE" based 4-seater calculated||Steel EV (Estimate value)|
|Weight (of which the weight of battery) (kg)||846 (220)||975 (243)||1520 (300)|
|Maximum Power (kW/rpm)||47/3,000-6,000||47/3,000-6,000||80/2700-10,000|
|Maximum Torque (Nm/rpm)||180/0-2,000||180/0-2,000||280/0-2700|
|Total battery capacity (kWh)||16||-||-|
Toray also exhibited Torayca Pellet, carbon fiber reinforced thermoplastic resin. The thermosetting resin is used in nearly all CFRP production processes, but the company has been making research and development efforts to use thermoplastic resin as well since it requires a shorter process time. Torayca Pellet may be used in injection moldings. The Torayca Pellet is available in two types, chopped fiber and continuous fiber. The chopped fiber type can be formed in nearly the same conditions as glass-fiber reinforced nylon.
Toray's carbon fiber reinforced thermoplastic resin (Torayca Pellet)
|Torayca Pellet||Pellet-type injection molding material consisting of thermoplastic resins (PP, PC, ABS etc.) reinforced with carbon fiber (20 to 30%). Has high mechanical properties (strength, elasticity, abrasion resistance, etc.) and low specific gravity that contribute to weight reduction. The superior radio shielding property (reducing the flow of electromagnetic fields) promises use in making electromagnetic shielding cages.|
|Two types are available based on the length of the carbon fibers. Chopped fiber type has carbon fibers that are placed randomly and can be molded in nearly the same conditions as glass-fiber reinforced nylon. Continuous fiber type has carbon fibers that are placed in an identical orientation and is characterized by high strength, high impact resistance and low warp.|
Mitsubishi Rayon's CFRP plan
Mitsubishi Rayon had panels illustrating plans for its thermosetting CFRP materials that have been developed and commercialized as products. It has been an issue to shorten the processing time before CFRP can be applied to the volume production of automotive components. Mitsubishi Rayon is saying the thermosetting time can be reduced to a minute.
Mitsubishi Rayon's plan for producing CFRP semi-manufactured materials
|CFRP semi-manufactured material and molding technology||Mitsubishi Rayon has developed thermosetting CFRP high-cycle resin (cured in 2 to 5 minutes) for medium-volume production (up to 3,000 units per month) of outer panels of automobile bodies (40% weight reduction compared to aluminum), interior trims, seats and structural components. The company also provides various molding technologies based on high-pressure press molding technology (press pressure 2 to 10MPa) referred to as a new technology that may "change the course of automotive industry."|
|The immediate challenge is a faster speed of processing before the material can be used for volume production of automobiles. The cycle time of curing has already been reduced to 2 to 5 minutes, and the company's new challenge is to reduce it to 1 minute.|
(Note) Mitsubishi Rayon, allied with BMW, will supply polyacrylonitrile carbon fiber precursor (an intermediary substance), a raw material used to make CFRP that will be used in BMW's "i3 Series" EV being released for sale in 2013 at the earliest. Volume production of the substance began in April 2011 at the company's Otake Production Center in Hiroshima Prefecture (the substance displayed at the expo is from another project).
Hot-pressing that increases steel strengths, precision-stamped parts
Automakers are increasing the use of high-tensile steel material and increasing their strength further by means of hot-pressing (also known as hot-stamping or die-quenching) to reduce the required thickness, thereby reducing the overall vehicle weight.
YAC Denko, a manufacturer of infrared radiation heaters, proposed a new technique to increase the material's strength by hot-pressing. The company has also developed a partial hardening method to manufacture steel plates having two portions of different strengths (1,800MPa and 635MPa). The company is using a new method called second-generation hot-pressing to explore new customers in the automotive industry and has already had some promising results.
Feintool Japan exhibited and introduced parts manufactured by a precision-stamping method (one of the press working processes) called fine-blanking and forming.
A rectangular infrared preheater by YAC Denko
A circular infrared preheater by YAC Denko (ceramic insulators with slits are woven by heater elements)
Precision-stamped parts by Feintool Japan
Feintool's seat reclining parts (an example of weight reduction)
Hot-pressing that increases steel strength, fine-blanking process
|Manufacturer||Product / Technology||Description|
|YAC Denko||Automotive parts heater||The far-infrared radiation heater is used to preheat high-tensile steel to up to 1,000 degrees Celsius. It may be combined with the die-quenching process (see Note) to preheat and quench the high-tensile steel to further increase its hardness and tensile strength.|
|2nd-generation hot-pressing||Steel is partially hardened (heated to 850 degrees Celsius or higher and cooled quickly) to produce areas having extremely high strength (1,700 to 1,800MPa) and ordinary strength (635MPa). This allows the required thickness to be reduced and thus contributes to weight reduction (in conventional methods, portions requiring high strength and those requiring low strength are prepared separately and welded together).|
|Die pre-heater||Preheating and natural cooling allows accurate, homogeneous heating of irregular sections of the die. Since the die surface is heated evenly to a temperature suitable for stamping, non-defective parts can be produced from the initial forging operation (conventionally, dies are heated with a gas burner). The company has several types of die pre-heaters including panel type rectangular infrared heaters (maximum temperature 1,000 degrees Celsius) and the pad type circular radiant infrared heaters (the foldable heater wraps around and heats the die to 900 degrees Celsius maximum).|
(Note) "Die-quenching" is a coined word for a process in which the heated steel plate is pressed under a cooled die to perform forging and hardening simultaneously and manufacture high-strength stamped parts. The process is also referred to as hot-pressing and hot-stamping.
|Feintool Japan||Precision stamped parts||Feintool is a Swiss manufacturer specialized in precision blanking called "fineblanking and forming." In contrast to the conventional blanking in which the workpiece is stamped solely with a downward force, the fineblanking and forming method uses the (1) downward force, (2) force to keep the workpiece in place and (3) counter pressure (upward force) to hold the stamped out sections in such a way the three forces coordinate with each other to complete the operation. This method is ideal for volume production of complex and multifunctional parts in a single operation (ready for assembling). Blanking accuracy is higher than forging and does not require reworking.|
|Product design, production material, tool design, tool material, fineblanking press, and lubricant are the six elements that are interrelated to increase mechanical accuracy.|
|For example, more than 40 parts that are manufactured by fineblanking and forming are used in the latest automatic transmissions and dual-clutch transmissions. The method is also used to make synchronizer parts for manual transmissions, seat adjuster parts, etc.|
Weight reduction with aluminum, magnesium and titanium
Use of aluminum, magnesium, titanium and other lightweight metals was proposed as a way to reduce the vehicle weight. Among the practical metals that are used as structural material, magnesium has the lowest specific gravity (1.7), compared to iron (7.8), titanium (4.5) and aluminum (2.7).
Keishin exhibited aluminum-made heat sinks for automotive lighting equipment. ST Group (Sanki Blast) exhibited magnesium-made key locks. Morimura exhibited magnesium-made products supplied by Magontec and titanium-made exhaust system parts by Akrapovic of Slovenia.
Magnesium-made steering wheel key lock (exhibited by ST Group)
Magnesium-made engine bracket used on the Chevrolet Corvette (exhibited by Morimura)
Magnesium-made instrument panel used by Volvo (exhibited by Morimura)
Titanium-made exhaust system parts made by Akrapovic and used by BMW (exhibited by Morimura)
Weight reduction with aluminum parts
|Manufacturer||Product / Technology||Description|
|KEISHIN||Aluminum parts||Keishin, a manufacturer of diecast aluminum parts, exhibited heat sinks (radiators) for lighting equipment, ECU case, sensor case, etc., which are made of diecast aluminum containing highly conductive material.|
|TECHNO ASSOCIE||High-strength extrusion aluminum material TAL400||A new aluminum alloy for extrusion molding with high strength and high corrosion resistance developed by Sumitomo Light Metal Industries and Sumikei Techno. Has the same tensile strength as steel and is ideal for reducing weight of structural members that require high strength. Freely formable into hollow and other complex shapes. Used in hot forging to manufacture products that may replace existing ones made of iron or A6061 (highly corrosion resistant aluminum alloy).|
|Manufacturer||Product / Technology||Description|
|Morimura Bros., Inc.||Magnesium products||Morimura is affiliated with Magontec Group (an Australian company with production sites in Germany and China) and involved in integrated magnesium business from development to joint production. The company exhibited engine brackets made by Magontec and used on the Chevrolet Corvette, instrument panels adopted for Volvo cars etc.|
|ST Group Sanki Blast||Magnesium products||Sanki Blast, a manufacturer of magnesium molded parts, supplies business-use video camera parts, notebook PC parts, exterior parts and covering for motorcycles, etc. Its molded parts for automotive use include interior parts, key locks, immobilizer covers, and oil covers. The company feels the future application of magnesium molding for automotive use depends on the carmakers' long-range policy.|
|Maruemu Works||Magnesium/ aluminum alloy screws||Maruemu, a screw manufacturer, has developed lightweight, high-strength screws made of magnesium alloys. The company proposed that the magnesium alloy screws were the best fasteners for magnesium structures. Conventional stainless steel screws are often used at the risk of electrolytic corrosion, thermal stress, loosening etc. The company also proposed the use of aluminum alloy screws for the same reason.|
(Note) Morimura is allied with Magontec Group in Australia and Magnesium Elektron in the United Kingdom.
|Manufacturer||Product / Technology||Description|
|Morimura Bros., Inc.||Exhaust system parts||The company exhibited titanium-made exhaust system parts (cast parts) by Akrapovic, a Slovenia-based leading manufacturer of mufflers. Its products are used primarily on motorcycles and built on know-how with exhaust system parts learned on racing circuits. Its customers include BMW, Porsche and other European automakers.|
(Note) Titanium has a specific gravity nearly half that of iron and is stronger than iron. Titanium is heavier than aluminum by 60% but twice as strong as aluminum.
Weight reduction with bolts and screws
Bolts, screws, hose clamps and self-tapping screws were exhibited at the show. They are all light and tiny but are used in large quantities and thus contribute to reducing overall vehicle weights.
Self-tapping screws, create their own thread and advance to fasten materials together. A trial calculation indicates they contribute to cutting costs by JPY2,034 per vehicle.
Fasteners, a generic term for bolts, nuts, clamps etc., often owe to technologies of non-Japanese origin. For instance, Oetiker is a Swiss manufacturer and tapping screws are made under licensing by EJOT, a German company.
Low-head bolts exhibited by Techno Associe (bolts to the right in each pair are the smaller, more lightweight bolts).
Fasteners by Oetiker (pointed) as used on drive-shafts
Weight reduction with hose clamps, bolts and screws
|Manufacturer||Product / Technology||Description|
|TECHNO ASSOCIE||Low-head bolts and sockets (LH-SS low-head)||The head of the bolt is 30 to 40% shorter than the height of the common hexagonal flange (protruding part used for fastening) and 20% smaller in diameter to contribute to weight reduction. The company has also developed sockets (wrenches, spanners) to go with the low-head bolts. These also result in higher tightening strength compared to conventional products.|
|Since special sockets and other tools are needed to use the low-head bolts, potential users of the low-head bolts need to change product designs and overall production processes. The company admits that this presents a problem in promoting sales.|
|Daido Kogyo||Flowdrill||Flowdrill, a unique technology developed by a Netherlands-based company of the same name, Flowdrill, uses a hot drill to form a hole in iron and other materials at temperatures ranging between 1,200 and 1,400 degrees Fahrenheit and, at the same time, heats the displaced material to form a bushing (a cylindrical wall formed in the lower side of the hole).|
|The bushing is up to three times the original material thickness. The unique part of the technology is the ability to create formed threads in the bushing and give enough strength. This eliminates the need for welding the bushing as in conventional methods. Flowdrill can be used with mild steel, stainless steel, aluminum, copper, brass etc.|
|OETIKER||Clamp and Ring (Connecting technology)||Oetiker, a Swiss company, supplies connecting technologies for hoses and tubes. Its hose fasteners (solid rings, clamps) are used in large numbers in automobiles because of the uniform sealing performance around the periphery and ease of use. Most products are made of stainless steel material.|
|Products are used in large numbers on drive-shafts, oil lines, airbag systems etc., in automobiles manufactured by European and US automakers. Among Japanese automakers, Toyota is using Oetiker products in its vehicles for Chinese markets.|
|Tool-less pipe connection||The pipe is connected in a single insertion action by hand. Developed for pipe connection in hard-to-reach spaces in the engine assembly line. Used by European automakers for pipe connections in tight engine compartments where tools cannot be used.|
|NATEC||Self-tapping screw (see Note)||Self-tapping screws, create their own thread and advance to fasten materials together. This eliminates the tapping work and cost while providing stable connections over an extended period.|
|NATEC supplies Altracs Plus (self-tapping fasteners for light alloys (used in oil pumps and manufactured under licensing by a German company, EJOT), Delta PT for resin material (EJOT product), G.T.O. tapping screws for high-tensile steel (by G.T. Onoe), etc.|
|Aluminum alloy screw||Self-tapping screws made of aluminum alloy. Aluminum screws are the most preferred screws for aluminum structures as they put an end to electrolytic corrosion (rust) and other problems arising from using screws made of different materials. The recent progress in processing technology has led to strength and resistance of aluminum alloys that are on par with iron. The screws can be recycled directly and they also eliminate the tapping process in the aluminum material.|
|YAMASHINA||Tapping screw (see Note)||YAMASHINA, a manufacturer of screws for metals, screws for plastics, and multifunctional parts, also supplies tapping screws including PT and Delta PT tapping screws for plastics under licensing by EJOT with which the company is allied.|
|TAPTITE 2000||Currently the company is promoting TAPTITE 2000, a new tapping product invented by CONTI (a Swiss corporation) and REMINC (a US corporation), characterized by an innovative new thread design that allows use in large-diameter parts of deep thread meshing. The company says TAPTITE 2000 is used by many US and European automakers including Mercedes-Benz, BMW, Volkswagen, Ford and GM.|
|According to YAMASHINA, European carmakers use 1,800 fasteners per car on average and estimates that replacing one third of them with TAPTITE 2000 will reduce costs by approximately 18 Euro (JPY2,034) per car.|
(Note) Conventional fastening methods require five stages including forming of parts, drilling, tapping, reworking, and fastening. Self-tapping screws require only two stages, forming of parts and fastening.
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