Components which can be characterised include cylinder heads, camshafts (Figure 1), pistons and rings, fuel injectors, connecting rods, ABS systems and fascias. Micro and Nanoscale measurement and characterisation are crucial to development of next generation automotive technology including MEMS actuators, satellite navigation systems, adaptive cruise control and novel paints/coatings.
Figure 1. Camshaft under test to measure roundness of bearings and lobes.
Testing for Roundness using a Taylor Hobson Talyrond 365
A roundness measurement on an automotive fuel injector (Figure 2) made using the Taylor Hobson Talyrond 365. The circumference measurement showing deviation from form (bottom image) reveals surface roughness and the presence of 2 scratches which can cause leakage. A scratch is more likely to cause component failure if it is aligned with the component axis. Pass/fail criteria can be programmed and data exported to SPC software.
Figure 2. A roundness measurement on a fuel injector (top image). The circumference measurement reveals surface roughness and the presence of 2 scratches which can cause leakage (Copyright Taylor Hobson).
Testing for Constant Thickness, Flatness and Parallelism
Brake disk faces must be parallel to each other and the wheel face mount. A constant thickness is required and the brake surfaces must be flat. Talyrond roundness measuring systems track the flatness, parallelism and thickness deviation using circumferential polar traces. Powerful Disk Thickness Variation software automatically identifies unwanted defects on brake disks and other components. The plots in Figure 3 show the measurement points and roundness deviation plots highlighting flatness and thickness variations (copyright Taylor Hobson).
Figure 3. Stylus Profiler Analysis of Brake Disk Assembly (Copyright Taylor Hobson)
Checking Critical Dimensions Using Optical Profilometry and Confocal Laser Scanning
Variations in critical dimensions and wear reduce clutch efficiency. 3-dimensional non contact optical techniques such as optical profilometry and confocal laser scanning track step and channel depths with nanometre resolution. Roughness, volume and depth of the channels are automatically logged in software. In figure 4, optical profilometry characterises the roughness and machining lay together with the depth and volume of a cross cut scratch on a defective sub-assembly component (copyright Taylor Hobson).
Figure 4. Clutch component (top image) and optical profilometry data characterising channel critical dimensions (Copyright Taylor Hobson).