AUTOMOTIVE

Problem Solving

Automotive

The following examples illustrate some of our contributions to this business sector:

• Touchstone performed material characterizations for a company developing a high-pressure storage cylinder to be used for compressed methane for the automotive industry. The work included: evaluation of typical voids, the angle of the fiber layers relative to the long direction of the cylinder, fiber/resin volume determinations, fiber content, type, liner material, and typical resin/fiber interface photographs showing the degree of bonding achieved.
• A steel company reported a zinc-peeling problem on an automotive oil filter component produced from electroplated steel. The zinc coating was completely removed in the defect areas. SEM/EDS analysis did not detect any contaminants in the vicinity of the uncoated areas. The color and texture of the intact zinc coating was different between good and defective parts. The preliminary findings did not determine the cause for poor zinc adhesion. A more extensive examination using Auger Spectroscopy and Transmission Electron Spectroscopy was recommended.
• Touchstone has supported the development of new major engine components produced through new powder metallurgical processes by providing heat treatment studies and mechanical property measurements.
• A problem involving failure to form automotive bumper parts was resolved by examining the microstructure of several stamped parts and comparing the structure to both non-formed parts, and the SAE A620 specification. The steel stock was found to be of unacceptable quality for forming.
• Traditionally the galvanized coating on steel has contained approximately 1% lead by weight. When a major steel company changed its process to eliminate the lead, Touchstone performed qualification testing on the material to be utilized by a major automotive company. Tests were made of the ductility and the corrosion protection of the zinc layer.
• A major automotive manufacturer R&D group hired Touchstone to perform mechanical testing of brake assembly parts made from cast iron. Touchstone has many years of experience in cast iron research.
• Touchstone has performed pressure cycle testing on automotive air conditioner condensers. Using a test system built by Touchstone engineers, the test cycled units from 0 to 500 psi in thirty-second intervals for 10,000 cycles.
• A manufacturer employed Touchstone to perform corrosion testing of radiator caps to assure trouble free performance under various environmental conditions. Among the tests, caps were tested in SWAAT for 70 days.
• Touchstone has performed numerous investigations to determine the cause of occasional defects that appear either before or after brazing in radiators, evaporators, and condensers. The information obtained in these investigations allows aluminum braze sheet suppliers to eliminate sources of problems early in the manufacturing process and assure the production of higher quality heat exchangers without the need for excessive, costly inspection and rejection. Examples include small inclusions between clad and core alloys that are exposed during CAB braze operations, and rolled in contaminants such as hard water scale.
• Touchstone has performed many evaluations of defective automobile and truck radiators where poor tube manufacture led to defective radiators. One case involved poor tube welds and poor scarfing of weld joints which were revealed using metallography. Substandard tubes do not allow proper braze flow and therefore joints are poor or incomplete.
• Two specimens of a new radiator design were delivered to Touchstone for evaluation. After a visual and microscopic examination of the gasket area and a metallographic examination of the braze fillet area, Touchstone engineers found a buildup of braze clad material had accumulated in the tube side of the gasket area. This could have interfered with the fit of the gasket and tank. The other radiator specimen contained indications that it may have been overheated or held at braze temperature too long. Also, a small amount of dissolution was seen on the header stock one of the specimens. This could also indicate excess temperature or time at temperature.
• A manufacturer of trailer hitches hired Touchstone to mechanically test a new trailer hitch design. Touchstone built special fixture which allowed the hitch to be tested using a servo-hydraulic test stand. The testing data allowed the product to be marketed successfully.
• Touchstone is often requested to perform coating thickness measurements on electro-galvanized steel sheet used for automobile body parts. Methods included eddy current meter, magnetic thickness gage, and the traditional “weigh-strip-weigh” method.
• Touchstone has performed a wide variety of tests on chrome plated, carbon steel bumper stock.
• An investigation was performed to determine wheather a corroded door panel had been chemically treated in areas where oxidation had occurred. EDS evaluation was used to determine what surface treatment was used, and whether it was universally present.
• Touchstone often tests sheet steel material used to manufacture automotive body parts. Among the tests are tensile testing, hardness testing, chemical analysis and microstructural evaluations.
• An automotive company hired Touchstone to test a prototype HVAC assembly. The complete HVAC assemblies were tested in salt fog to determine corrosion resistance of the evaporator cores. It was found that assembled evaporator cores were less resistant to salt fog than evaporators tested outside the HVAC units. The cause was found to be fallout retention in a cavity within the assembly that led to the excessive corrosion. This problem was corrected before the prototype was put into production.
• Several different coatings were evaluated for use on heat exchangers as a substitute for chromate conversion coatings. Using standard B117 salt fog it was demonstrated that a new coating rendered the evaporator nearly impervious to salt fog, while standard chromate conversion coated units were significantly corroded during the same exposure.
• Touchstone has hydrostatically burst tested condenser header tubing to assure that the welding and brazing used in manufacture produce joints that are able to resist any anticipated operating conditions.
• Engine bearing specimens were evaluated in an attempt to identify any manufacturing characteristics, which may have led to engine failure. The following tests were performed: 1) elemental analysis of the lead babbitt overlay of the used, new, and diesel truck engines, 2) thickness measurements of 6 bearings, including 2 of the bearings from the damaged engine, one new bearing, and one bearing from a used diesel truck engine. Visual examination found that one bearing was significantly more damage than the other and demonstrated severe overheating. The cause was assigned to localized blockage of an oil port that deprived one bearing of oil. The debris form this bearing then caused secondary damage to the rest of the engine.

The above examples are only a sample of our work in this area. We would be pleased to provide any additional information you may require. We also invite you to review examples on our website of work that we have performed in support of other business sectors.