Fischer Technology Fischerscope H100 Benefits Provides material property data (e.g., hardness and modulus of elasticity) Programmable x-y stage with a travel of 2 in. x 2 in. and a positioning accuracy of 1 mm Metallurgical microscope with a maximum magnification of 1000X www.fischer-technology.com

Auto Parts Company Perfects Plastics with New Measuring Machine

When it comes to exterior trim components on automobiles, one of a manufacturer's primary concerns is that the plastics used are lightweight, resistant to surface damage and readily painted. However, such a plastic isn't created easily: The harder and more scratch-resistant a surface is, the more difficult it is to paint. The task facing any automotive component manufacturer is to develop plastics that come closest to achieving a balance of all three qualities. Visteon Automotive Systems' exterior systems group, which is responsible for developing new types of plastics, has found a useful new tool: the Fischerscope H100 ultra-low-load dynamic micro-indentation system.

 Visteon, located in Dearborn, Michigan, provides fully integrated systems to Ford Motor Co., other OEMs and aftermarket products manufacturers. Most of the plastics the exterior systems group creates are based on thermoplastics olefins. Because the injection molding process is a sensitive one involving many factors that can affect surface hardness, the ability to measure the surface hardness and plasticity of different thermoplastic olefin formulations is vital to developing the best molding process and achieving improved material properties.

 Rose Ryntz, a Visteon technical specialist in materials development, explains that the researchers correlate the data obtained with the Fischerscope H100 to the molding conditions (which include tool fill time, melt temperature, pack pressure, temperature differences between the mold and the melt, and injection speed) to determine the combinations that will result in optimal surface hardness for improved paintability and greater damage resistance. "There are other factors involved, too," Ryntz elaborates, "but knowing the hardness and elasticity helps us determine how the material will perform as an exterior trim component."

 Visteon runs one type of hardness test to determine the material's resistance to damage and another to determine its paintability. In a typical surface hardness test, an operator places a 4 in. x 12 in. molded plastic plaque on the Fischerscope H100's stage. A load of between 100 mN and 1000 mN is then placed on the plaque in 60 steps. Visteon uses the H-plast and WR/WT (plastic energy/total energy) values from the unloading. A similar evaluation is performed on painted plastic plaques to determine the effect of curing time on the material's ability to resist scratches and accept paint. Standard industry hardness test methods were too imprecise to generate the correlation data necessary for a true assessment of molding variables.

 The Fischerscope H100 measures ultra-low load hardness under test load. With a load range of 0.4 mN to 1,000 mN and test uncertainties below 1 percent, it provides maximum sensitivity over a wide range of materials and coatings. It also eliminates the need for overcoating of the test sample. Measurements can be taken with the coating or plating in place, and the results are unaffected by substrate material. The system can be used on virtually any thin coatings (from very soft elastomers to ultra-hard tool-coating materials) and on uncoated materials.

 "We're concerned with the top 100 micrometers of the plastic," explains Ryntz. "We tried the Fischerscope H100 and found it to be one of the only ways to get the kind of data that we wanted."

 With the Fischerscope H100, operators can control the load and indentor penetration such that the effects of the material substrate on measurement results can be virtually eliminated. The very light loads also provide a nearly nondestructive test, which allows the sample material to be used again in later tests.