Simple Solutions That Work! Issue 11

23 DO’S • Ensure the vacuum is the same from test to test • Implement a vacuum gage calibration procedure • Ensure vacuum cycle time is the same from test to test (install a timer for manual vacuum systems) • Create forms to record test parameters on manual vacuum systems (or) review the captured data from automated systems DONT’S • Don’t use wall clock to time test • Don’t walk away from vacuum test until vacuum gage setting is reached • Don’t run test without collecting the data. Either by form on a manual system, or electronically with an automated system 4. ANALYZE RPT SAMPLE Process variation can be caused during preparation of the sample for visual comparison to a chart and by inconsistent operator judgement of the sample. Frequently, successful efforts to control the RPT sample are completely wasted with poor analysis practices. For years, the industry standard has been to cut the sample in half, grind the surface, and compare it to a chart containing example photos which correspond to a material density or specific gravity (S.G.). This method takes time (10 to 15 minutes), uses consumables, and is fraught with process variation. The better, cheaper, and more accurate way to analyze the RPT sample is to measure the density directly. For example, a foundry wanting to produce a low porosity 356 casting would assign a target S.G. of 2.60. In less than 30 seconds the S.G. of the RPT sample can be measured. If the result is 2.60 or higher, cast. If the result is 2.59 or lower, continue to degas. No need to saw, polish, or make an arbitrary judgement. Eliminating the process variation in analysis of the RPT sample is that easy! To meet today’s quality system requirements, RPT results must be documented and repeatable. Using density measurements to analyze RPT results make this possible. In fact, RPT analysis systems like the Palmer PAS3000 and PAS5000, automatically record the results which can be exported directly to the foundry network or SCADA system. DO’S • Use density/specific gravity measurements to analyze your RPT sample • Create a target density for your alloy/process • Record the data with an automatic system or by control chart DONT’S • Don’t cut the RPT sample • Don’t analyze RPT sample by visual comparison to a chart • Don’t allow an arbitrary judgement call to guide your process Contact: BRAD HOHENSTEIN No need to cut samples (above) Density measurements (below) are safe, quick, and accurate MAKING YOUR INSTALLATION ASUCCESS