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Trial Number 0

Trial Purpose:

Request to determine method for evaluating cleaned parts. Want to compare two cleaning methods.

Date Run:

03/23/1999

Experiment Procedure:

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 it own photoemissive 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

Trial Results:

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

Table 3.  Part 3 OSSE Values

1 Branson     Crest  
Top Bottom Edge Top Bottom Edge
119 201 219 148 183 137
114 217 282 145 171 178
116 208 151 154 184 222
124 199 178 112 224 153
135 212 180 132 218 147
110 209 203 106 210 182
119.67 207.67 202.17 132.83 198.33 169.83
8.87 6.74 45.50 19.90 21.77 31.04
           
2 Branson     Crest  
Top Bottom Edge Top Bottom Edge
119 183 245 171 220 201
140 180 150 171 208 199
133 181 161 132 221 234
105 185 168 126 209 112
116 181 160 135 211 88
103 196 165 121 196 174
119.33 184.33 174.83 142.67 210.83 168.00
14.81 5.99 34.91 22.47 9.15 56.53
Table 4.  Part 4 OSEE Values      
SS Branson 1 SS Crest
Top Bottom   Top Bottom
232 240   205 263
222 235   243 255
233 281   218 261
233 287   218 238
223 251   214 256
207 213   221 230
210 229   208 219
221     193 217
289     222  
234     168  
230 248 Average 211 277
23 27 Std Dev 20 17
         
Alumina   Branson   1
Top Bottom Side Inside  
243 50 66 78  
43 41 43 96  
22 33 128 87  
63 24 39 68  
25 46 43 72  
60 44 30 78  
76 40 58 80 Average
84 10 36 10 Std Dev
         
Alumina   Crest    
Top Bottom Side Inside  
81 320 121 325  
101 60 34 523  
61 63 30 364  
45 70 34 152  
63 324 42 236  
98 25 52 366  
75 144 52 328  
22 139 35 127  
         
Branson   2 Crest  
SS     SS  
Top Bottom   Top Bottom
180 265   218 248
233 227   216 258
244 199   214 267
216 191   262 250
213 183   265 248
197 193   245 231
164 242   263 210
211 204   213  
234     244  
236     280  
213 214 Average 242 245
26 31 Std Dev 25 19
         
Alumina        
Top Bottom Side Inside 2
69 52 43 90  
78 28 76 63  
61 28 71 51  
59 25 81 66  
66 18 66 42  
47 18 41 55  
63 28 63 61 Average
10 13 17 17 Std Dev
         
Alumina        
Top Bottom Side Inside  
66 50 61 659  
94 15 74 853  
45 22 38 880  
62 21 67 916  
35 14 70 352  
38 11 29 610  
57 22 57 932  
22 14 19 216  

Table 5.  Part 5 OSEE Values

1-Branson Crest
Top Top
253 142
183 122
333 171
323 123
278 90
290 168
277 136
54 31
2  
Top Top
329 169
342 160
355 203
349 189
358 189
254 129
331 173
39 27

Table 6. Comparison of Cleaning Methods

Results: 5/6 substrates cleaner using Branson method

OSEE  Branson   Crest  
up Part 1 cleaner Part 1 dirtier
up Part 2 cleaner Part 2 dirtier
up Part 3 cleaner Part 3 dirtier
down Part 4s dirtier Part 4s cleaner
up Part 4a cleaner Part 4a dirtier
down Part 5 cleaner Part 5 dirtier

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

Success Rating:

A cleanliness study, addressing only various analytical techniques.

Conclusion:

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.