Trial Number 0

Ten parts cleaned using the Branson method and ten parts cleaned using the Crest method were analyzed using OSEE. 

Optically Stimulated Electron Emission or PEE, Photo Electron Emission is based on the principle that metals and certain surfaces emit electrons upon illumination with ultraviolet (UV) light. These electrons can be collected, measured as current, converted to a voltage and digitally displayed. A surface contaminant will either enhance or attenuate this signal, depending on its own photo emissive nature. While OSEE will not identify a contaminant, it is a good comparative tool to determine the degree of contamination. This method is best suited for thin films (oils, etc.) and not particulate matter (dust, for example).

Readings were taken from multiple sites on each part to ensure characteristic measurements. Average values were determined and recorded. After each part was analyzed, five parts from each method were contaminated with the machining fluid and OSEE readings were taken again. This was to reveal the effect the fluid has on the electron emissions. Once the relationship was found, the two cleaning methods can be compared to each other. 

SUBSTRATE MATERIAL: Ion Gun Parts - Molybdenum, Alumina, 304 Stainless Steel with Alumina, Macor,Ti6AL 4V
CONTAMINANTS: Metal working fluid (Hangsterfer’s S-500CF_US) and Dirt

The following tables list the OSEE readings taken for two parts for each method.

Table 3.  Part 3 OSSE Values

Table 5.  Part 5 OSEE Values

Table 6. Comparison of Cleaning Methods

Results: 5/6 substrates cleaner using Branson method

The readings for both methods were relatively close and taking the standard deviations calculated, most readings were statistically the same.

Using OSEE analysis, two cleaning methods were compared. Five of six substrates were cleaned better using the Branson method. The stainless-steel surface was the only material to be cleaned better using the Crest system.
Even though the Branson method yielded cleaner parts, the two methods could be considered comparable when standard deviations are incorporated into the OSEE readings. Most of the readings for both methods could be considered equal and therefore parts would be at the same level of cleanliness.