REAL-WORLD CASE STUDIES
In 2011, faced with significant vacuum pump failures attributed mainly to contaminated oil, ATI Wah Chang’s maintenance department embarked on a proactive lubrication program to enhance fluid cleanliness through improved filtration. This program was spearheaded by Dale Jones, who has extensive lubrication experience and currently holds six lubrication certifications. Jones worked with his lubricant marketer Moreland Oil and, through Moreland, with Hy-Pro Filtration, in an effort to develop a filtration improvement program. The result was a dramatic improvement in fluid cleanliness that significantly enhanced bottom-line savings for the company. This case history focuses mainly on improvements made to vacuum-pump reliability and the operation’s Z-Mill rolling oil. They have led to enhanced product quality, dramatic equipment life-cycle extensions and increased productivity. A quick review of basic filtration principles It’s been shown that approximately 70% of premature equipment failures are caused by particulate contamination, and over two-thirds of equipment wear is from abrasive particles. Since 70% of premature failures are caused by contamination, it stands to reason that controlling particulate contamination through better exclusion and filtration would provide a high return on investment. Although the basic principles of fluid cleanliness have been discussed in previous articles in this and other series in LMT, let’s review some of them here: Fluid cleanliness is measured primarily with the use of laser particle counters. Particles are measured in many size ranges but are expressed in a simplified system ISO 4406. This system expresses cleanliness in three size ranges: > 4µm(c), > 6µm(c) and > 14µm(c). Table I is used to arrive at the ISO 4406 Cleanliness Code. Notice that for each increase in range number, the number of particles doubles. This method is a convenient shorthand way of assessing fluid cleanliness without worrying about the actual number of particles. As an example, assume you measure 1042 particles/ml > 4µ. 412 particles/ml > 6µ and 152 particles/ml > 14µ. Referring to Table 1, the range number for particles > 4µ is expressed as 17. The number of particles > 6µ is 462/ml,
Table I. ISO 4406 Chart
Number of particles per ml
Range Number
More Than
Up To & Including
24
80000
160000
23
40000
80000
22
20000
40000
21
10000
20000
20
5000
10000
19
2500
5000
18
1300
2500
17
640
1300
16
320
640
15
160
320
14
80
160
13
40
80
12
20
40
11
10
20
10
5
10
9
2.5
5
8
1.3
2.5
7
0.64
1.3
6
0.32
0.64
which translates to a range number of 16. Finally, the number of particles > 14 µ is 152/ml, which is expressed as a range number of 14. Putting this three-number code together results in expressing the above fluid cleanliness as 17/16/14. Remember, the first number is always greater than the second, which is greater than the third.
Some companies still don’t believe that fluid cleanliness affects equipment reliability. The company featured in this article has discovered otherwise. SEPTEMBER/OCTOBER 2013
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