April 2014

April 29, 2014

Problem Solved - The Mystery of The Plate Sealer That Wouldn't Seal

Okay, so several of you have gotten impatient and sent me emails asking for the solution to the plate sealer mystery in my last post.    As is often the case, the answer was simple but it was not obvious...a perfect storm of causes, if you will.

Let mtl_files/labsquad/blog_images/Mystery/carnak.jpge cut (no pun intended) to the chase.   The major factor was AC power...or lack thereof.   Although the measured power coming into the unit was within spec for the instrument (112 VAC), the user also had a JunAir compressor on the same circuit...as well as a large refridgerator and a centrifuge.   The combination of the sealer holding temp, the JunAir running almost continuously (due to a slight leak), the fridge compressor running and the centrifuge...centrifuging, resulted in a transient line voltage drop down below 100VAC.  This was only measurable using a chart recorder which monitored the true RMS voltage.   While the electronic display of the sealer operated and made it appear that the sealer was functioning, the timing of the pneumatics was not correct.   The cutting bar would advance but retract before cutting action could take place.   Because the JunAir runs quietly, it was difficult to see that it was pretty much always running due to the leak.  We believe the fridge compressor kicking on while the compressor piston was the bottom of it's stroke is where the power drain occurred.

Isolating the sealer and the JunAir (fixed the air leak)  from the circuit in question resolved the problem.

Chalk one up for the "doh!" list.


April 1, 2014

The Mystery of The Plate Sealer That Wouldn't Seal

tl_files/labsquad/blog_images/Mystery/mystery machine.jpg"Ruh-Roh Shaggy!" as Scooby Do might have said when faced with a recent tl_files/labsquad/blog_images/Mystery/Alps 300.jpgproblem we encountered with an ABgene ALPS 3000 sealer.

A customer had two units that operated pretty much 24/7.   One unit had tape seals while the other had foil seals, and  it was not uncommon to switch between the two.

Iniital failure reports centered around a error message "Not Down."   This was pretty simple and invovled the front access door switch.  Users like to look inside the instrument as it was operating, so they would tape the switch closed.  Occaisonally, the tape would expand and allow the switch to change states.   A simple closing of the door and press of the e-stop button would reset the error and allow operation to continue.   But, that was not the end...

Soon thereafter, additional calls for help were placed as the instrument would no longer cut seals.  The cutting bar which is pretty beefy would only slice through a small portion of the edge of the seal, but never fully perforate.   The unit in question was pulled for depot repair and of course upon power up, it ran fine.  In fact, it sealed over 50 plates without error.    The cutting blade was adjusted and another 50+ plates were run without fail.  The unit was returned, but just to be on the safe side, we brought along another identical unit to run side by side with the clients unit.

Onsite, the unit ran great for several hours...then same problem.   Our FSE's checked air (80PSI from a big honking JunAir compressor), and AC power...fine.   The customer's plate were polypropylene and the temp was set at 167C...a little high, considering polypro has a melting point of 130C.   Nevertheless, this is temp the customer had been using prior to failure with no issues.

The solution was simple...but not obvious.   Care to venture a guess?