Precision Measurement Services – Fax Film
Defects to Surface Integrity are called torn and folded metal, micro burrs, shingling, smeared metal, etc. In internal combustion engines, these defects are often blamed for things like high ring/cylinder wear, piston scuffing, high oil consumption, and premature cylinder failure. They are usually a result of poor cutting action due to dull abrasives or poor coolant quality. Compare the surfaces of two cylinder bores, each manufactured using similar processes.
Replicating materials such as fax film have been used to evaluate cylinder bore surface integrity for more than 50 years. Torn and Folded metal, graphite pullouts, and open graphite counts are attributes evaluated with fax film analysis. The evaluation is somewhat subjective, but we have many years of experience and have developed numerical grading system using an extensive portfolio of comparison photos.
Some automated evaluations can be performed using image analysis software but in most cases the images are visually compared to standard photos.
Modern bore scopes are slowly replacing this ancient technology but they do not provide a better picture than a good fax film photo. Speed is their advantage over fax film analysis. An SEM (scanning electron microscope) provides the best results available but requires destruction of the part and is relatively expensive. We often use an SEM in the initial phases of a development process to “calibrate” the bore scope and fax film evaluation process.
Customers use our measurement services to solve manufacturing problems, develop product specifications, perform failure analysis, and augment current inspection capability. We can set up temporary inspection facilities at your shop if necessary.
We also use metallurgical evaluation methods (listed below), but they are all destructive, requiring cross sectioning, mounting and polishing before evaluation.
- Percent open graphite/nodule quantification
- Graphite bending analysis
- Crush depth measurement
The percent open graphite/nodule analysis entails evaluating the percentage of graphite flakes or nodules that are open to the surface rather than “pinched” or closed off at the surface. The evaluation is similar for both honed cast iron and ground nodular iron.