Science of Plastics
- Thread starter urumomo
- Start date
RocketRanger
Member
- Joined
- Jul 17, 2024
- Messages
- 23
Thanks for posting this video. I worked at a disposable medical device company back in the 1980s and we had a plastic molding shop for producing corrugated ventilator hose & connectors, air filter housings, etc. From this experience, I found that molding high-quality plastic parts consistently at mass scale is a lot harder than most people think.
In particular, we had a small cone-shaped filter housing mold with 48 cavities and not all produced usable parts. We had a worker who would look at each batch of parts produced by the molding machine and pick out the individual housings that came from the "bad" mold cavities (btw: if you look at some plastic components, you may notice tiny numbers or cavity IDs molded into the part). This particular mold only produced about 75% usable parts and the rest were ground up (regrind) and fed back into the raw plastic hopper. I could not believe how hard it was for us to produce a consistently high quality molded part of a simple shape. I mentioned this to a couple of our engineers and their answer was "plastic molding is hard". The next day I brought in the (then) new Monogram 1/72 F-4J Phantom II model to show them what other companies were doing with plastic molding and they were astounded! They couldn't believe the complexity and detail that the Monogram mold must have had. Didn't really help with fixing our plastic molding quality problems, but I felt better. As a side note, the guy who was the head of the molding shop actually worked at Revell for a short time and he was always complaining about how the medical device company's management would not spend the money to correct all of the molding problems we kept having.
So when I hear modelers complain about the quality, fit, detail, etc. of plastic model components, I just wish they could appreciate how much work was put into the design and production of a kit. Working with plastics is as much an art as it is a science and this video does a good job of conveying this.
In particular, we had a small cone-shaped filter housing mold with 48 cavities and not all produced usable parts. We had a worker who would look at each batch of parts produced by the molding machine and pick out the individual housings that came from the "bad" mold cavities (btw: if you look at some plastic components, you may notice tiny numbers or cavity IDs molded into the part). This particular mold only produced about 75% usable parts and the rest were ground up (regrind) and fed back into the raw plastic hopper. I could not believe how hard it was for us to produce a consistently high quality molded part of a simple shape. I mentioned this to a couple of our engineers and their answer was "plastic molding is hard". The next day I brought in the (then) new Monogram 1/72 F-4J Phantom II model to show them what other companies were doing with plastic molding and they were astounded! They couldn't believe the complexity and detail that the Monogram mold must have had. Didn't really help with fixing our plastic molding quality problems, but I felt better. As a side note, the guy who was the head of the molding shop actually worked at Revell for a short time and he was always complaining about how the medical device company's management would not spend the money to correct all of the molding problems we kept having.
So when I hear modelers complain about the quality, fit, detail, etc. of plastic model components, I just wish they could appreciate how much work was put into the design and production of a kit. Working with plastics is as much an art as it is a science and this video does a good job of conveying this.
Peppylepugh
Active Member
- Joined
- Mar 27, 2012
- Messages
- 366
Was this for entertainment purposes, or do you have an idea?
the Baron
Ich bin ja, Herr, in Deiner Macht
- Joined
- May 12, 2009
- Messages
- 2,253
I remember a couple of years ago, in a thread about the chemistry behind different types of paint, someone got frustrated and just growled, "I don't care about the science!!!"
And it made me think of Magnus Pyke.
Apparently, after Thomas Dolby's video was released, people would walk up to Pyke on the street and yell, "SCIENCE!". He got irritated, like that poster did.
It's amusing!
Peppylepugh
Active Member
- Joined
- Mar 27, 2012
- Messages
- 366
I thought maybe you had an idea for a venture.
Hobby related.
I worked with a guy, who tried to manufacture a microwaveable poached egg cooker.
Seems the problem, is the membrane around the outside of the egg, or the inner layer of the shell, explodes before it is cooked.
His idea was the pierce the shell and a tick of the membrane and poach the egg in place.
This company may have been in the planning stages, when Sam tried his idea, 20+ years ago.
urumomo
Well-Known Member
- Joined
- Mar 18, 2013
- Messages
- 7,425
haha , no , no business plans .
I'm really interested now in how you arrived at this speculation from that video , though .
BTW
I poach eggs out of the shell , like the gods intended .
I think I've seen devices for sale that hold an egg and pierce the shell as you describe .
Maybe Sam was successful after all .
I'm really interested now in how you arrived at this speculation from that video , though .
BTW
I poach eggs out of the shell , like the gods intended .
I think I've seen devices for sale that hold an egg and pierce the shell as you describe .
Maybe Sam was successful after all .
Peppylepugh
Active Member
- Joined
- Mar 27, 2012
- Messages
- 366
A stream of consciousness, through an idle
mind. I'm always looking for the next step.
Interesting video.
Polystyrene, is similar to human skin. It's point of change in higher temperatures is around
120-130°F.
I built a paint drying oven several years ago and was looking for a threshold on the high end.
At 120°F it's characteristics are starting to change, at 130, it's pretty much toast to us.
Of course, I'm not telling you anything new.
I found that 90°-110° kept me below the margin and at maximum heat allowed and not have to monitor it the whole bake.
I can get oven to 110 in less than ten minutes with a 40 watt incandescent bulb and a PC cooler fan.
Card carrying member of the
Cheap 3astards club.
mind. I'm always looking for the next step.
Interesting video.
Polystyrene, is similar to human skin. It's point of change in higher temperatures is around
120-130°F.
I built a paint drying oven several years ago and was looking for a threshold on the high end.
At 120°F it's characteristics are starting to change, at 130, it's pretty much toast to us.
Of course, I'm not telling you anything new.
I found that 90°-110° kept me below the margin and at maximum heat allowed and not have to monitor it the whole bake.
I can get oven to 110 in less than ten minutes with a 40 watt incandescent bulb and a PC cooler fan.
Card carrying member of the
Cheap 3astards club.
Peppylepugh
Active Member
- Joined
- Mar 27, 2012
- Messages
- 366
I agree. Depending on where I have it set up.
Damp basement, calls for a higher temp.
Upstairs, closer the the coffee maker a little
bit lower.
Damp basement, calls for a higher temp.
Upstairs, closer the the coffee maker a little
bit lower.
Peppylepugh
Active Member
- Joined
- Mar 27, 2012
- Messages
- 366
A stream of consciousness, through an idle
mind. I'm always looking for the next step.
Interesting video.
Polystyrene, is similar to human skin. It's point of change in higher temperatures is around
120-130°F.
I built a paint drying oven several years ago and was looking for a threshold on the high end.
At 120°F it's characteristics are starting to change, at 130, it's pretty much toast to us.
Of course, I'm not telling you anything new.
I found that 90°-110° kept me below the margin and at maximum heat allowed and not have to monitor it the whole bake.
I can get oven to 110 in less than ten minutes with a 40 watt incedecent
So I took it as gospel and never bothered.
I'm not cooking at production levels and poly or manufacturers have changed the chemistry of what they use over the years, so why temp the fates.
I also sand bagged to lower limits and not destroyed anything yet.
mind. I'm always looking for the next step.
Interesting video.
Polystyrene, is similar to human skin. It's point of change in higher temperatures is around
120-130°F.
I built a paint drying oven several years ago and was looking for a threshold on the high end.
At 120°F it's characteristics are starting to change, at 130, it's pretty much toast to us.
Of course, I'm not telling you anything new.
I found that 90°-110° kept me below the margin and at maximum heat allowed and not have to monitor it the whole bake.
I can get oven to 110 in less than ten minutes with a 40 watt incedecent
I've never cranked it up that high. The article I read when I started to research on optimum heat had used the analogy of human skin and it starts to rubberized or blob, for lack of a better term at that temperature.
So I took it as gospel and never bothered.
I'm not cooking at production levels and poly or manufacturers have changed the chemistry of what they use over the years, so why temp the fates.
I also sand bagged to lower limits and not destroyed anything yet.
