Archive for August, 2015

Aug 17 2015


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A lot of my consulting covers three areas –
(1) Understanding the process. Injection Molding is really all about common sense. Before all the simulations, left handed statistics, and black boxes attached to the mold and machine, people did some very complex molding. Yes, not as well as we can do it now; but they did do it. Nobody told them they couldn’t do it, they just did it.

(2) While computer based systems are better and faster than paper ones. You need to be constantly vigilant that the accuracy of the output your system gives you is proportional to the accuracy/precision/validity of the inputs.

(3) A lot of consulting is giving information away for free. I use the “10 minute rule”: If I can’t help you in 10 minutes, we should be talking about a contract. Usually it involves a STUPID PILL.

Our current batch of new engineers/managers are in love with Technology. But computers, data bases and simulations are a cruel Mistress. Occasionally you need to not completely believe technology unless you fully understand the charts and numbers:

Example #1
Scenario: My client got a rush order. Two days before the mold had crashed. He wanted me to (“money is no object”) find a way to pull off a miracle repair in less than three days.

Client: “No need to panic we have ‘safety’ inventory.”

Me: (two hours later) “There’s good news and bad news: The good news is we found a spare cavity. It can be polished up and put into the mold. You’ll be running tomorrow morning. We’ll repair the smashed one and hold it as a back-up. The bad news is that you don’t have any safety stock. From what I can find, you shipped it a few months ago when your customer had a ‘pull-up’ order and nobody replaced it.

Client: “But (he sputters) the Computer says we do have the inventory!!!”

Me: “Don’t trust the computer.” Here’s your pill.

Example #2
Scenario – My client was molding soft urethane in a new larger multi-cavity tool to lower his costs, but couldn’t fill it.

Me: After two days of failures – “The flow path into the cavities is too long. It’s like molding rubber bands. By the time the material gets to the gate there’s no pressure left.”

Client: “But we used a simulation! I’ve got the charts and graphs! We spent $75K on a higher capacity mold and you’re telling me it won’t work?? I’ve just made a boat anchor???!”

Me: “Let’s re-visit the simulation. Something isn’t adding up.”
Sure enough in FEA slow motion the mold filled like a champ. They’d even spent the money on getting a proper characterization on the material. The material supplier told them everything was to specification.

Then I looked at the values on the side of graphs that showed the filling. Oops! When the mold didn’t initially fill with the oil pressure set at maximum (2,000 PSI) they kept re-running the simulation increasing pressures/speeds until the mold filled. The guy running the simulation totally ignored the machine’s ability to generate pressure and a few other little details. The model actually showed it filling perfectly if the machine could generate 300,000+ PSI oil pressure and the 300T machine could generate about three times its clamp capacity. Let’s forget about the potential explosion that would have happened.

Me: “If you don’t understand what the simulation’s assumptions are telling you, all you have is an executive coloring book.” Here’s your pill.
Example #3: I get a call telling me a portable hopper/dryer doesn’t work. They checked the dew point and it was singing along at -20 F but the material tested wet after six hours!

Me: “Look at the hookups – Was the inlet at the bottom of the material hopper and the outlet at the top? Take a look. Call me back if you still have the problem.”
— They never called back. Here’s your pill.

Example #4:
Client: “I’m a ‘Master Molder’. I eat, breathe, think and drink Scientific Molding, I’m a Black Belt Quality Ninja, we pre-qualified the mold in a simulation and qualified the mold at the machine, we did DOE’s and CpK’s. Everything was fine two weeks ago but now in production, the part isn’t to spec and we’re getting black specs we can’t purge out. HELP!!!!!”

Me: “You’ve got two problems
1. Look at the waterline hookups, are the exactly the same as the qualification set up?
1A. Check to make sure all the appropriate waterline valves are TURNED ON (both the inlet and outlet on each circuit). They were off when you hooked up the lines. Somebody has to turn them on to get water through them when you start the process to cool the mold properly. Different mold temps = different dimensions.

2. If you material isn’t contaminated, it’s coming from the outside. Did anybody suck a damp NERF ball through your loading system to clean out the fines before you loaded in the new material? What year did you last change the air filters on the dryers? A filter will build up a huge collection of dust (wannabe Black Specs). If you don’t change them the dust will get into the hopper. A contaminated system = contaminated material = black specs. Take a look. Call me back if you still have the problems.”

— They never called back. Here’s your pill. NO! Wait!  Here’s a handful of them.

* * * *

You can call it ‘TAKING A STUPID PILL’, a reality check, or just common sense. Never totally believe your data. Whenever you’re told it’s a fool-proof-totally-accurate system, there’s always some fool out there who can defeat it, go around it, or mess it up. There’s a beauty in physically checking the system the Olde-Way: You get to interact with the folks who work for you. You get to understand what they think of your ‘management by memo’ philosophy. But most importantly, the very people who have figured out a way to go around your system will also tell you how to use it more profitably.

Take a STUPID PILL occasionally. Trust your people but verify when something mysterious happens. It will invigorate your business.

It’s your choice.


Bill Tobin

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