FALL 2015

34 THE DISTRIBUTOR’S

34 THE DISTRIBUTOR’S LINK Laurence Claus Laurence Claus is the President of NNi Training and Consulting, Inc. He has 25 years of experience with a medium sized automotive fastener manufacturer, holding positions including Vice President of Engineering, General Manager, Director of Quality, Director of New Business Development and Applications Engineer. In 2012 he formed NNi offering technical and business training courses as well as technical consulting, expert witness and consultation work. He can be reached at 847-867-7363 or Lclaus@NNiTraining.com. You can learn more about NNi at www.NNiTraining.com. WHAT FASTENER DISTRIBUTORS NEED TO KNOW ABOUT SALT SPRAY About a month ago I was teaching a two day class in California and had the good fortune of being included the first night in a gathering of the West Coast Fastener Distributor Association. At this gathering the main event was a panel discussion regarding plating. After short presentations by the experts the floor was opened up for questions. Immediately a hand shot up in the middle of the room and its owner shared a story with the panel about conflicting salt spray test results and a customer that was threatening to reject thousands of parts because of this conflict. His question was one that many others have asked, “What should I do?” This is a fair question and one that many distributors have had to address at some time in their existence. Unfortunately, when the question comes, many are not well prepared to answer it because they don’t know enough about the test and take for granted that because it is defined in standards or customer requirements it must be accepted without any challenge. To do so, however, can result in stiff and potentially unnecessary consequences including sacrificing potentially good parts to rejection and losing your reputation or hard earned goodwill with your customer. What Is A Salt Spray Test? To understand the significance of the dilemma described above, one must grasp a basic understanding of what salt spray testing is and a little about its history. Salt spray testing is intended to be an accelerated test for part corrosion. It exposes parts to a controlled environment of heated, salt laden mist in which the parts must survive without showing signs of corrosion for a specified length of time. Most requirements gage acceptance on the number of hours a part can survive CONTRIBUTOR ARTICLE these conditions without showing evidence of red rust or white corrosion on significant surfaces. This test has endured many years of usage. In fact, it is over one hundred years old with the first instances of its use dating to 1910. About 30 years later, in 1939, ASTM would publish the first version of ASTM B117. This earliest version was significantly different from today’s modern B117-2011 version. Most notably, this early cousin called for a whopping 20% (by weight) of salt, almost ten times greater than the 1.8% to 3% salt concentrations naturally existing in the Earth’s marine environments and four times greater than today’s standard. In addition to not even remotely reflecting real world conditions, this ultra-high percentage of salt caused erratic test results and commonly plugged up the jets in the salt spray cabinets. For these reasons, the standard was amended in 1954 to 5% (by weight) salt concentration. This is still higher than any naturally occurring conditions but solved the process issues with test cabinets and remains in-force today. In the United States, the test itself is most often governed by ASTM B117 or a standard based off of the ASTM standard. There are other standards such as NASM 1312- 1 and ISO 9277, but, by and large, the ASTM version is universally considered to be the “gold standard.” The ASTM standard dictates that the test be conducted in 5% by weight salt and water mist with a pH between 6.5 and 7.2 (considered to be pH neutral which is why the test often is called a “neutral salt spray” test). The temperature inside the test chamber is 35 °C +/-2 °C. Although these factors are perhaps the primary ones, there are other factors controlled by the standard as well including control points like part positioning, allowable fixturing materials, purity of the salt, type of water, and the air supply. CONTINUED ON PAGE 152

THE DISTRIBUTOR’S LINK 35