Here at Consolidated Conglomerates we make circuit-breakers ranging from home-panel models up to fairly large "shunts", I think 1000 amps is our biggest.
Well we have a 250-500 amp one we mold in two sections. The base is fairly robust and has few processing issues.
The face has always had a bit of a knit-line where the two flow-fronts merge behind a cutout feature. From a molding standpoint it's a piss-poor layout, but it works if you know how to process.
Every time I set it up and run it for a shift I process out the knit line. It's fairly easy when you know how. Next shift would come in, get a different lot of material and end up with a knit line.
This line is a weak-point in the product, and it will fail in service. When one of these puppies trips it snaps with CONSIDERABLE force and the face will crack there every time.
An alarming number of rejects later they decide to change materials to a more easy-flowing grade. Oddly enough some batches have a knit line others don't. It's better in service but still too many rejected batches.
This lead to another material change -- now with more fiber reinforcement. Again, some batches have a knit line and fail, others do not.
So now they change the base resin and add an impact modifier. Gentle readers, guess what happened. If you guessed "same thing" you are now smarter than our engineering staff.
Two more material changes later, they are overhauling the press because clearly there is a mechanical or hydraulic issue at play here. That wasn't it.
They took apart the water control unit that heats the material. That wasn't it either.
Now they are seriously looking at the mold, that's the only thing left that it could be right?
Well they sent a memo down to our shift, please run baseline samples out of each of the materials before we modify the tool. This is considered a "****ty" job so I ended up stuck with it because I am the new-guy still.
Shift Tech comes over, I start 'er up.... look at the parts there is the knit-line. I reach over dial it out using "scientific molding" -- basically I read a chart in a classroom one time that said "fix knit-lines with these settings."
Shift Tech raises an eyebrow, I run parts. We change materials. We start up again... knit-lines. I make them go away. Repeat this tiresome nonsense several more times.
He looks at me and goes "well that explains why only one batch out of 20 passes the crack-testing those are the ones you run aren't they. If I cross-reference them with your clock number that's what I'm going to find, am I right?"
He was right.
He presented this to his boss On High, I got called into the office and yelled at.
Let me take that back. They didn't just yell at me, they cussed me out up one side and down the other.
Then they told me there was no way in hell that someone with as little seniority as I currently have... could possibly know something that THE MOST SENIOR BMC MOLDING ENGINEER IN THE HISTORY OF OH JUST SHUT UP YOU ARROGANT BASTARD.
That's when I had enough. Explained to him in as simple terms as I could how scientific molding works, what causes knit-lines, how to process them out in most conditions and how the viscosity variations between buckhorns of resin were the REAL problem, compounded (no pun intended) by the fact that my 19 counterparts have no idea what they are actually doing they do their job by rote and don't actually THINK about how the process works.
Furthermore there was no way in hell that he could possibly be considered an engineer, let alone a SENIOR engineer in a plastic factory because holy poop-tarts he didn't even recognize one of the most BASIC injection-molding errors and had NO CONCEPT that it took two button presses and a valve adjustment to correct -- that he was convinced that it was EVERYTHING ELSE except a simple rooten-toot'n adjustment to the process. An adjustment, that I teach people the FIRST DAY ON THE JOB when I wear the trainer hat in days gone by.
Then I dropped the bomb: You have to be smarter than the material you are working with. If you manage to get your a$$ beat by a lump of polymer goo and glass fibers you are not smart enough to drive a car let alone claim the title of engineer. Now, if you want to learn basic injection molding theory better stand the farfignewton by and ask your questions now because this is my two weeks notice please and thank you now if you excuse me I need a can of Red Bull to calm down before I drive home.
...
This is why my toolbox has wheels.
I start my new job on the 28th.
Well we have a 250-500 amp one we mold in two sections. The base is fairly robust and has few processing issues.
The face has always had a bit of a knit-line where the two flow-fronts merge behind a cutout feature. From a molding standpoint it's a piss-poor layout, but it works if you know how to process.
Every time I set it up and run it for a shift I process out the knit line. It's fairly easy when you know how. Next shift would come in, get a different lot of material and end up with a knit line.
This line is a weak-point in the product, and it will fail in service. When one of these puppies trips it snaps with CONSIDERABLE force and the face will crack there every time.
An alarming number of rejects later they decide to change materials to a more easy-flowing grade. Oddly enough some batches have a knit line others don't. It's better in service but still too many rejected batches.
This lead to another material change -- now with more fiber reinforcement. Again, some batches have a knit line and fail, others do not.
So now they change the base resin and add an impact modifier. Gentle readers, guess what happened. If you guessed "same thing" you are now smarter than our engineering staff.
Two more material changes later, they are overhauling the press because clearly there is a mechanical or hydraulic issue at play here. That wasn't it.
They took apart the water control unit that heats the material. That wasn't it either.
Now they are seriously looking at the mold, that's the only thing left that it could be right?
Well they sent a memo down to our shift, please run baseline samples out of each of the materials before we modify the tool. This is considered a "****ty" job so I ended up stuck with it because I am the new-guy still.
Shift Tech comes over, I start 'er up.... look at the parts there is the knit-line. I reach over dial it out using "scientific molding" -- basically I read a chart in a classroom one time that said "fix knit-lines with these settings."
Shift Tech raises an eyebrow, I run parts. We change materials. We start up again... knit-lines. I make them go away. Repeat this tiresome nonsense several more times.
He looks at me and goes "well that explains why only one batch out of 20 passes the crack-testing those are the ones you run aren't they. If I cross-reference them with your clock number that's what I'm going to find, am I right?"
He was right.
He presented this to his boss On High, I got called into the office and yelled at.
Let me take that back. They didn't just yell at me, they cussed me out up one side and down the other.
Then they told me there was no way in hell that someone with as little seniority as I currently have... could possibly know something that THE MOST SENIOR BMC MOLDING ENGINEER IN THE HISTORY OF OH JUST SHUT UP YOU ARROGANT BASTARD.
That's when I had enough. Explained to him in as simple terms as I could how scientific molding works, what causes knit-lines, how to process them out in most conditions and how the viscosity variations between buckhorns of resin were the REAL problem, compounded (no pun intended) by the fact that my 19 counterparts have no idea what they are actually doing they do their job by rote and don't actually THINK about how the process works.
Furthermore there was no way in hell that he could possibly be considered an engineer, let alone a SENIOR engineer in a plastic factory because holy poop-tarts he didn't even recognize one of the most BASIC injection-molding errors and had NO CONCEPT that it took two button presses and a valve adjustment to correct -- that he was convinced that it was EVERYTHING ELSE except a simple rooten-toot'n adjustment to the process. An adjustment, that I teach people the FIRST DAY ON THE JOB when I wear the trainer hat in days gone by.
Then I dropped the bomb: You have to be smarter than the material you are working with. If you manage to get your a$$ beat by a lump of polymer goo and glass fibers you are not smart enough to drive a car let alone claim the title of engineer. Now, if you want to learn basic injection molding theory better stand the farfignewton by and ask your questions now because this is my two weeks notice please and thank you now if you excuse me I need a can of Red Bull to calm down before I drive home.
...
This is why my toolbox has wheels.
I start my new job on the 28th.

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