# Injection molding thoughts...



## ParkRNDL (Mar 20, 2002)

I just posted this on the Yahoo HO World board, with a little extra discussion at the beginning relating to some recent threads there. Thought it might be interesting to kick around here too...

Yesterday at work, a colleague threw out a thought that I figured I'd share here. He knows I'm obsessed with these goofy little cars. He actually brought in the 2 Tjets he had in his box of old Lionel train stuff and let me tune them up so he could show his kids what slot cars were like in the days before their Lifelike NASCAR set (for the record, he had a brown flamethrower GT40 and a tan Maserati  ). He's heard me talk about the relative scarcity of some of the bodies and how it's apparently difficult to produce a good-running replica of the chassis, citing JL's and MM's QC problems. He said he once worked in a Vo-Tech school (in Erie County, PA) that had a full set of injection molding equipment, complete with CAD/CAM capabilities. He couldn't believe that none of us hobbyists had a friend or contact at a school that had this stuff. It should be easy, he figures, to hand the teacher a Tjet chassis or Camaro body and say "Hey, as next month's project, can you bang out a few (thousand) of these for me?" I kept telling him it's not that easy, there are setup costs that run into 5 figures. "For what?" "I don't know exactly... There are licensing issues, there are blah blah blah..." but I didn't know of any good solid facts or reasons that what he said couldn't happen. I decided instead of shooting down his idea and telling him it can't be done, I'd bring it here and ask: Can it be done? Could the manufacturing of Tjet chassis or bodies be done at a reasonable cost by a Vo-Tech school with programs in injection molding and electronics and manufacturing? And finally, does anybody here know anyone involved in such a school, maybe play poker on Friday nights with the Injection Molding 101 teacher?

Feel free to answer by giving me that list of reasons it can't be done... then at least I'll have an intelligent answer for my colleague... 

--rick


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## noddaz (Aug 6, 1999)

Injection molding at a Vo-Tech?
Do they have night classes?????? 
Scott


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## AfxToo (Aug 29, 2003)

This sounds a lot more like the kind of talk that takes place after quaffing a few cold ones at the local tavern on a Friday night. Unfortunately, the devil is in the details and coming up with answers to the nitty "blah blah blah" issues is what separates a pie in the sky idea from a viable commercial product. 

I do believe that building the precision molds requires an investment in the tens of thousands of dollars. How would Vo-Tech Mfg come up with the molds for less? 

Copying a "few thousand" of anything that has copyright or trademark protection associated with it would place Vo-Tech Mfg in a position of extreme legal liability. Why would they do this? 

Even if Vo-Tech Mfg were cheap, why would it be any better that China, Inc? Are MM and JL just poor evaluators of talent and capability? 

Hey, I'd like to see it as much as anyone. But unless there's a profitable market for investment then I doubt anyone's going to invest the capital into making it happen any better than it's already been done. I think it's far more likely that someone like Wizzard, Slottech, or BSRT would repop their own "precision" versions of the TJet chassis before someone with less interest in making money would redo the quaint little chassis of old.


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## JordanZ870 (Nov 25, 2004)

When i was a small boy (11 yrs old) I had the MM track Most of those center clips had been broken and the replacments were cheap black plastic. I asked my dad (Honeywell op MNGR & superintendant, tool design) If he could work up a mold to make me some new clips. He said it would cost thousands of dollars. Now that was 28 years ago. I did however end up using grounding wire wrapped around a screwdriver and clipped with a side-cutter. They worked great!
Sorry...anyhow...even a tiny U shaped clip cost thousands to develop back then, i would hate to know the cost today.


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## ParkRNDL (Mar 20, 2002)

I'm sure you're right about the mold costing tens of thousands (on the other board they're calling it a "tool")... I guess I was just wondering WHY it costs so much. If it's labor costs, well heck, classroom time is free... I know. Not really. And school tax dollars going to develop a toy car might not fly. But... aw, cmon, there's got to be a good "but" here...

As far as the copyright, this was kicked around on the other board too. A body such as a Camaro or Mustang or whatever would present a problem. But as far as the Tjet chassis, well, the copyright expired long ago. Aurora/AFX never renewed it. It's fair game now. According to the owner of the Yahoo board, Derek Brand himself said that, and Model Motoring never paid to use the design--they didn't have to as the patent was dead. Of course anyone going into business in this field ought to verify that and get some sort of documentation to that effect...

--rick


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## jack0fall (Sep 8, 2004)

joez870 said:


> When i was a small boy (11 yrs old)


JoeZ, That was last week right? 

Just funnin ya!!!

Jeff


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## JordanZ870 (Nov 25, 2004)

lol...yeah..i wish i was 11 for a day or 2...or 17 when I sold all of those sweet slots for 90.00
*sigh*


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## AfxToo (Aug 29, 2003)

I have no doubt that the chassis design is wide open for copying at will. I still wonder why an opportunist who is already involved in chassis production, like Wizzard, Slottech, or BSRT doesn't produce one already. Maybe it's the chassis electricals that present the biggest challenge? After all, a skilled caster can resin cast a copy of the chassis plastic but you still need a donor electrical system. 

I contend that the TJet chassis design is needlessly complex for what it does. TJets have a lot of individual parts that need to be precision fitted to a small number of subassemblies. I assume that the level of manual labor involved is quite high since it reflects 1950s/60s (or earlier) era assembly techniques and Aurora was even outsourcing their assembly to Asia even back in the 60s. You could probably produce a functional replacement chassis that would have a form factor needed to fit the TJet bodies but with a fraction of the parts count of the TJet. But hey, it wouldn't be a TJet and there's something about the throwback style, overly complicated design, flapjack powered, and massive gear train that endears them to us 40+ years after their creation. They are a one of a kind snapshot in history.


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## sethndaddy (Dec 4, 2004)

I wonder? can the "tools" being used to make all johnny lightnings diecast cars be used to make plastic cars too, or is it a different technique. Imagine that, wow.


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## ParkRNDL (Mar 20, 2002)

I don't know any of the details, but this has been asked before, and folks from JL (back when they were on the board) said that the casting process for diecast cars is entirely different from the molding process for injection-molded bodies and none of the same stuff can be used. It's a shame, but...

--rick


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## 69Ed (Jan 23, 2005)

Wow, lots of questions being asked here. I'll do my best to answer them. If I miss anything, or confuse you, ask again. 

So, the process of creating an injection molded part goes something like this...

1. Create an electronic database with CAD software. This is generally an electronic 3D representation of the surfaces of the car itself. Modeling it would be tough because of the sculpted shape. Therefore the best option would probably be to laser or white light scanning (there are many options) of the exterior of the car (maybe $1k). Then shell it (give it thickness), and add the mounting posts. (Maybe free if you know an engineer with access to CAD software.

2. The next step is to build an injection mold, called the tool. There all different levels of complexity here, stemming from whether the part is straight drawn, or has lifters or side actions. A straight drawn part would be like a T-jet body with a post on the underside. An x-traction body, with the inside clips requires a collapsible core of steel also called a lifter. A chassis with its axle holes and side wall openings requires side actions, or moving pieces of steel to allow the part to be released from the mold. 

If you were doing a simple T-jet body with mounting posts, a small, simple tool called a MUD (multi-unit die) tool could be built for probably $4k to $7k dollars. Why so much? A tool builder needs to take the engineering cad data and machine carbon electrodes for EDM machining of the tool steel. Once the tool halves are rough machined, they are carefully fit together by hand so that no "flash" occurs around the parting line (edges of the part). The mold is then polished with special diamond grit tools to eliminate machine marks, or smooth up the EDM marks. This is generally done by some extremely skilled folks. And this would be considered a low end, prototype or low volume mold. 

I would imagine back in the day, Aurora made big, multi-cavity tools for high volume production. A complex part like a chassis might be molded 4, 8, or even 16 at a time, and require water cooling lines, complex ejection systems, etc. Those tools at that time probably cost $80k - $150k, depending on size and cavitation.

So, while it can be done, its generally not for the garage inventor. Thats where the vacuum form lexan bodies come in, because you don't need a metal tool since there is no pressure to speak of. There is also no detail to speak of either. 

Not sure if I answered all the questions or not. Been typing so long I can't remember. 

Ed


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## 69Ed (Jan 23, 2005)

Yes, I did miss a few things. 

1. Tools in China usually are much, much less expensive than stateside simply because labor rates are a fraction of what they are here. 
2. A chassis mold, even in china, would be fairly expensive in a multi-cavity tool. If I had to guess, a 4-cavity mold over there with lifters and side actions would probably run at least $15k - 20k. There are so many variables, its hard to nail it very close. However, a comparable tool stateside might run 3 - 4 times as much. 
3. Those little stampings on the bottom of the cars will run $10k per progressive stamping die. The pickup shoes would be quite a bit less, maybe $5k. Again, 25% of that in China. 
4. Plus, you still have to assemble it, and thats where it really gets expensive. Our T-jets would probably cost $80 each or more if there were assembled here. Not enough volume for full automated assembly. Not sure if you realize it, but every level of distribution generally doubles the price. I don't know if that rule necessarily applies here, but if you buy a product at Wally-world for 4 bucks, Wally-world probably paid about 2, if there was a distributor, they paid 1, and that means the manufacturer had to make it for 50 cents. Thats why Wally-world now buys most everything directly from Chinese manufacturers. I guess that means our t-jets are probably fully manufactured, assembled, and packaged for somewhere in the neighborhood of $2, maybe less. WOW!
5. Miniature die-cast zinc tools, while similar in concept to injection-molded plastic parts, are entirely different animals, made to run on a different machine, with different injection systems, etc. 

Hope this helps....even though it takes some of the fun out of dreaming about making your own t-jet bodies!

Ed


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## ParkRNDL (Mar 20, 2002)

Hey Ed, WOW. Thanks for the detailed explanation. It goes a long way toward explaining why this isn't a semester-long project for a Vo-Tech class--it's just too complicated. Kinda gives you an appreciation for the companies who actually do it, too, and an understanding of why it's so important to them to sell this stuff and sell it in volume when it does get produced...



69Ed said:


> I would imagine back in the day, Aurora made big, multi-cavity tools for high volume production. A complex part like a chassis might be molded 4, 8, or even 16 at a time, and require water cooling lines, complex ejection systems, etc. Those tools at that time probably cost $80k - $150k, depending on size and cavitation.
> Ed


 I have a book on the history of Aurora that has some interesting information in it regarding this. I'd have to wait till tomorrow to dig the book out and quote it directly, but it says something about how at one point, when Tjets were increasing in popularity and sales by incredible margins, they changed their molding machines and process for molding bodies... I may be wrong, but I think it said they went from a multi-cavity mold (4 bodies per tool) to a single-cavity which was actually faster because it was fully automated and ran by itself. Maybe it was called an Arburg machine... I'll check the details in the book tomorrow... I know an Aurora guy was quoted as saying the new machines "went like jackrabbits"...

--rick


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## roadrner (Jul 21, 1999)

Some great insight into the process of IM, thanks Ed! :thumbsup: rr


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## AfxToo (Aug 29, 2003)

Ed, it's so cool that you would lend this kind of insight into the whole process. I also agree with your estimation that the per-unit production cost on these cars, as sitting on the shipping doc in China, is probably in the $1.50 - $2.00 range.


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## 69Ed (Jan 23, 2005)

No problem. Product development is a very interesting process!


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## jeauxcwails (Jun 13, 2000)

Whether he was spoofing me, or not, an Aurora Exec. once told me the mold cost per TJet body was about $18,000.
Of course that was in 60s-70s $$$$$$$$$$$$$$$$$.
Ron Esterline


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## jeauxcwails (Jun 13, 2000)

Makes you wonder how JL can produce their Tjet bodies on a limited run, and make a profit.
There should be someone on this Forum with the cost figures at hand.


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## JordanZ870 (Nov 25, 2004)

Is the limited run that JL does consist of the body style or color and tampos?
If they are using the same molds and changing colors and decoration, kind of takes the wonder out of it, eh?


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## 69Ed (Jan 23, 2005)

Cost numbers would vary wildly based on a ton of factors that include the company's overhead, and more directly, the type of equipment the molds are being run on. Time on a modern press with full robotics will be much more expensive than a 40 year old press that has been paid for about 100 times over. 

Its hard to say without knowing their production numbers, but a simple open and close mold with 10 second cycle time (just a swag) would net you 6 cars a minute, 360 an hour, 8640 a day. A mold like that might be as little as 2 or 3k if they are proficient at making them (all these are just guesses).


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## sethndaddy (Dec 4, 2004)

I wonder what ever happened to all those old tjet injection molds. Imagine someone finding them laying in the attic of a warehouse somewhere. I would crank up the elcamino, 32 ford pickup truck, hotrod and towtruck......weeeeeeeeeeee


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## JordanZ870 (Nov 25, 2004)

I was under the impression that MM was using them right now. No?


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## GOOSE CHICKEN (Apr 9, 2000)

Sethndaddy, My freinds aunt worked for Atlas. She told us that the old molds are in the basement and are in poor shape. I told Tom Lowe about them years ago and he said that molds wear out and there was most likely no hope in bringing them back to life.

I'd still love to go and see if they really exist. I'n no one to judge if there any good but wouldn't it be cool to run some rare colors that Atlas never made and find someone on E bay to have a bidding war on a 

"SUPER RARE Atlas Buick Station Wagon in Pink"


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