|February 2013 Index||Tech Tips||National News||Biz Tips|
Gone are the days when you examined the color coded image of a car’s structure to locate the one or two high strength steel parts. On the brand new 2013 Cadillac ATS, you need to scan the image to find the few remaining old-fashioned mild steel parts.
The new ATS makes liberal use of aluminum, magnesium, high-strength steel, and ultra-high-strength steel. So much so that only 17 percent of the body structure is made from mild steel. The ATS body-in-white features an aluminum-intensive front end that includes cast magnesium engine mounts, front strut towers made of thin-wall aluminum casting and an aluminum tubular fabricated cross-beam.
Martensitic steel and other high-strength and ultra-high-strength steel alloys are used extensively in the structure with bake-hardenable types forming the A- and B-pillar outer stampings. Cadillac uses over 300 linear feet of weld bonding to assemble the complete structure which is also riddled with hundreds of holes designed to take weight out of the body and aid electro-coat access. The ATS will feature an aluminum inner and outer hood, and one of the car’s transmissions will be housed in a magnesium case. The finished design results in a car that is 500 pounds lighter than that of its closest predecessor, the Cadillac CTS.
Due to go on sale this fall, the brand new 2014 Corvette will contain a smorgasbord of high tech construction materials and processes. General Motors unveiled the new 2014 C7 Chevrolet Corvette on January 13 at the Detroit Auto Show. In the previous model Corvette, the really exotic materials were reserved for only the top trim package, the Z06. But that has changed this year. All of the 12,000 Corvettes GM expects to sell this year will contain advanced construction materials and techniques. The seventh generation Corvette contains so many advanced materials that the Society of Automotive Engineers called the car a “lightweight materials-fest” in its Automotive Engineering magazine. Car and Driver said the car “is constructed like an aircraft.”
The base model Corvette will be built with a carbon-fiber roof panel and hood (inner and outer). The fascias are made with Thermoplastic PolyOlefin (TPO) and the fenders, quarters, doors, and hatch are in a new, lighter-density sheet-molded composite (SMC) than the previous generation car. The outer door panel measures just 1.2 mm (0.047 in) thick and the inner panel is just 0.8 mm (0.031 in).
The C7 will have an all-new aluminum chassis that is nearly 100 pounds lighter than the previous generation’s steel-and-aluminum structure. Compared to the previous generation C6, which used continuous hydroformed main frame rails with a constant 2mm wall thickness, the new Corvette’s frame features main rails composed of five customized aluminum segments, including aluminum extrusions at each end, a center main rail section and hollow-cast nodes at the suspension interface points. Each segment is tuned, varying in thickness from 2mm to 11mm (0.08 to 0.433 in), – tailoring the gauge, shape and strength properties to optimize the requirements for each frame section with minimal weight.
The frame is assembled at an all-new welding shop at the Bowling Green Assembly Plant using a unique laser welding process in which a computer-controlled beam joins the components with exceptional precision and tolerances of about 0.001-inch. Helping to support the light weight frame are hollow, cast aluminum front and rear cradles that will replace the solid cradles used on the C6. The steering column is made from a new thin-wall magnesium casting. The balsa-wood-sandwich floor construction of the C6 Corvette has been replaced on the C7 with a new, lighter carbon nano-composite floor pan adhesively bonded in place.
C7 seat frames are made from magnesium as are the die-cast crossmembers that provide rigid attachment points for the powertrain, suspension, steering column, and instrument panel. Nearly all driveline and suspension pieces are aluminum castings or forgings, as in earlier models. The fiberglass-reinforced plastic leaf springs remain in the new C7. The 2014 Corvette Stingray will be built at GM’s Bowling Green, Ky., assembly plant, which underwent a $131-million upgrade, including approximately $52 million for a new body shop to manufacture the aluminum frame in-house for the first time.
In the midst of the winter driving season, particularly in the Northeast and Midwest, CAPA is highlighting the importance of galvanization on sheet metal parts such as hoods and fenders that are commonly used for collision repairs.
In a recent study of non-CAPA Certified parts, CAPA found that 6 of the 7 non-CAPA sheet metal parts tested were made of non-galvanized material. “While we were shocked at the rampant use of non-galvanized material in sheet metal, it simply reinforced the need to use CAPA Certified parts,” said Jack Gillis.
“A repair performed using a non-galvanized part may look great leaving the shop, but when the underlying metal begins to rust, the owner is going to be very dissatisfied with the quality of the shop’s work,” said Jack Gillis, CAPA’s Executive Director. “Because there is no easy way to tell if a sheet metal part is made of galvanized material, using a CAPA Certified sheet metal part means the part was actually tested for galvanization as part of the certification process.” CAPA requires that all of its sheet metal parts be galvanized, even if the car company brand part is not.
Galvanization is the process of applying a layer of zinc over the sheet steel. The zinc coating protects the metal beneath it from corrosion and rust. Even if the zinc coating is scratched, the steel will continue to be protected by the remaining zinc. For replacement parts, the presence (or absence) of galvanization is significant because galvanization dramatically improves corrosion resistance and there for, the life expectancy of parts.
Honda announced that it has developed a new factory paint process it is calling the “Honda Smart Ecological Paint (Honda S.E. Paint)” process, a painting technology that eliminates a middle coating process from a commonly used 4-coat/3-bake auto body painting process to realize a 3-coat/2-bake water-based painting process. Honda will introduce this new painting technology at its Yorii Plant at Saitama Factory in Japan that is scheduled to become operational in July 2013.
Conventionally, eliminating the middle coating process would have restricted the paint colors that can be used; however, Honda says it overcame this challenge by developing a highly-functional material for the color base coat used in the final coating process. This material used for the color base coat makes it possible to use any exterior paint color, which Honda also claims is a first for the automobile industry using a 3-coat/2-bake process.
Moreover, in addition to the Honda S.E. Paint, Honda also will introduce a wall-mounted paint robot system with a built-in quick load / quick wash paint tank. This will lead to a significant improvement in painting efficiency, reducing the amount of paint materials used and a 40 percent reduction in CO2 emissions.