Magnetic testing: A "Product modified by the manufacturer, for sure"

Many years ago again - we quite often give "veteran memories" as examples! - a user of a water-based fluorescent magnetic ink phoned us:

-"For the last three years, we have used your xyz product. We inspected ca 2,500 parts per bottle of concentrate. For the last month we have faced a recurrent problem: after ca 250 parts, there are no fluorescent particles left in the ink; further, when we take out the product from the reservoir, we get sticky slurry. You have modified the formula!"

-"Did you change anything in your process?"

-"No, Sir, nothing."

So, 250 km (156 miles) by car to the customer's plant.

Knowing that no modification had occurred to the formula, and seeing this slurry, we imagined that there was a kind of lubricating grease leaking from the jacks on the magnetic bench. A visual inspection quickly led to a "No" answer.

"Let us go to the process line backwards."

We went along the machining line, and arrived along an automatic machine-tool comprising several tools. And there, our "chemist-eyes" saw immediately the culprit: there was a brownish sticky "grease".

-"Do you use water-based machining fluid?"

-"Yes."

-"So take a look at this brownish chemical. It is a fatty amine, used as -rust preventive additive in the formula. By the way, we have not seen any degreasing machine between the machining units and the magnetic bench."

-"Oh, that's right: we thought it useless, and have removed it from the line, to speed up the process."

-"When did you remove the degreaser?"

-"One month ago".

-"When did you begin to meet this problem?"

"One month ago. Do you think there is some correlation?"

-"Oh yes! The fatty amine stays glued to the parts. When you used a degreaser, it was then dissolved and taken from the parts. The magnetic ink was not polluted. But now, say there is about 0.1 mg of amine per part going to the ink. 25 mg are enough to make the product stick to the reservoir wall: that comes to 250 parts!"

-"So please, put the degreaser back in service!"

Another "philosophy" from this example and from the one issued next month: in at least 50% of problems, the problem is not due to a supplier's failure, but to some change on the process line.

On phone, the user always says that "nothing has been modified on the line."

Better to have the user "understand by himself" that HE is at the origin of the problem!!

In the '60s a UK Company had a motto: "For every surface treatment problem, there is a product xxxxxx" (trademark we do not display).

Engineers and Commercial people in this Company had made a "translation": "With every surface treatment product xxxxxx (trademark we do not display), there is a problem".

This anecdote is there only to remind everyone that problems met in workshops may be due to the suppliers/manufacturers as well as to the users.

Our idea in these documents is NOT to target anyone, but on the contrary to bring to your knowledge some interesting cases which may prevent you to duplicate the same mistakes while performing Penetrant Testing (PT) or Magnetic Testing (MT).

All the ministories you will read are TRUE. We think they will be helpful:
• First as examples of specific technical --or non-technical-- requirements or peculiar problems.
• Second to let you see that the problems do not always come where you think they should come from.
• Third so that users feel free to ask for help from people (the experts) who may know more than they do.