TECHNOLOGY FOCUS

CENTRAL SYSTEMS -  PART 3

TROUBLE SHOOTING THE SYSTEM or
WHY HAS MY TOOL LIFE DROPPED?

by Dom Ruggeri

MAY 2002:

I was sitting in a group meeting on another rather bland Wednesday. These meetings normally consisted of alerting us to new formulations, modifications, and policy changes.  We were also advised of field trials with new and existing products.  All things included, the meeting killed about two hours.

Today’s meeting was a bit different in that a plant trial was being conducted within driving distance of the laboratory.  In such circumstances the laboratory manager would normally ask for a volunteer to attend the trial; but not today.  It seems the powers that be wanted me to supervise this particular trial.  I agreed, and requested that a new hire, chemist accompany me.  I felt that this type of trial would give the young chemist some valuable field experience; also if things went to pot, as they sometimes do, the extra help could be the difference between success and failure.

We drove to the plant on a Sunday night.  As we drove, we discussed the potential problems, possible solutions, and plant safety.  The system had already been charged and the maintenance personnel said it was as close to 20:1 as they could get it.  Of course, we would test it ourselves and calculate the necessary neat product adjustment, or water addition as needed.  However, that would come later, we had 7 hours until the operators arrived to work.  As usual, and as I had come to expect, the salesman and regional manager were late.  When they arrived they asked why I had not made the necessary adjustments to the system.  My response was clear; policy required that sales be present before any adjustments to a system could be made.  This policy is a safeguard.  The salesman knows the account and he knows the politics.  He is best equipped to contact the right people and get things done.

We toured the Plant Laboratory.  I was pleased that they had everything we would need to keep the coolant monitored.  So it was time to check the coolant.  We sampled the coolant and I used the refractometer while my young colleague did the titration.  The concentration by refractometer was 5.01%; we were shooting for 5.0%.  Not bad I thought, but before celebrating I waited for the titration results.

My young colleague came running over to me.  She was in an abject panic.  “Dom the concentration is 6.1% we’ll never get it down in time,” she stammered.  I mentioned the concentration by refractometer was 5.01.  She was confused, and so was I, but I could not let her know that. We re-sampled the coolant and I retested the concentration using the refractometer.  Again, 5.01%.  We wandered over to the titration area and I watched her technique and the answer was obvious.  They had a self-zeroing burette set on 1ml instead of zero.  Of course if one reads the burette directly, the mls of acid used will be off by 1 ml.  By now the regional manager and the salesman were in the lab with the plant superintendent.  I had a real dilemma.  I immediately knew the answer, but how do I communicate the problem to her and not embarrass her.  I asked her to do the titration again hopping she would see her mistake no such luck.  I checked the expiration date on the acid, and I ran the titration, my result was 5.015%. She ran the titration again once again she gets 6.1%. They accepted my results and left the lab leaving her and I alone, “you told them what they wanted to hear”, she jabbed. “No I did not, re-zero the burette and look closely”, I instructed, perhaps stronger then I should have. She saw her error and laughed loudly, she apologized, I told her I was trying every way to help her save face she understood.

As we all know a plant trial can go sour real fast; when that happens tempers and finger pointing are at an all time high.  A lot is on the line and the faster you resolve the problem the better it is for all concerned. Let’s look at a typical problem:

Tool life is going to pot.  They were getting 1000 parts before resharpining now they are down to 500, 250 of these are scrap.

This same product that was running with about 0.5 inches of surface foam is now foaming out of the system and onto the floor.

Operator XYZ who has been there forever says the coolant lost its slip.

In short you’re in deep. It is common knowledge among formulators that 90% of shop problems blamed on the coolant are caused by something else.  The loyal METALWORKING FLUID MAGAZINE readers will remember the Small Shop Series where I stressed many shop problems can be avoided with proper fluid maintenance.  This is even more important as the systems get larger.  I would proceed this way:

Check the coolant concentration by more then one method:

    Concentration by alkalinity

    Concentration by refractometer

    Concentration by acid split

The concentration will tell you if the fluid is being properly maintained and if there is tramp oil contamination.  The alkalinity measures the water-soluble portion of the coolant, this parameter can be fine and yet the lubrication package may not.  The refractometer will measure the amount of oil in the coolant; if you have a high concentration of tramp oil this measurement will show this by reading high.  However, to get the amount of tramp oil you must run another test.  The acid split will confirm the refractometer reading.  Whether you have high tramp oil or low lubrication, something must be done, but these conditions are easy to fix with an adjustment of water or neat coolant.  High tramp oil can be skimmed off or centrifuged out, either way, not a real big problem.  This is a beginning to central system problem solving.  We will go deeper in future articles.  Until then thanks for reading and if you have any questions please feel free to e-mail me at the magazine.

Good Luck

Dom