Tooling question

[Cato]

I posted this in the 'muscle car' thread to Art Anderson without reply. Like to get knowledgeable answers from any 'industry' guys. In that thread it was in reference to re-issues. Now I'm asking about new tool production and re-issue. I know the business case is poor for new tools on re-issues. I'm really asking about new ways to create models. Here's the quoted post:

Art,

Just talking through my hat here but-could tooling be made with another material (other than steel) which would be cost effective, durable and easily repeatable?

OK-I know the simple answer is " they'd be using it if it existed". But have materials like a form of ceramic, or counter-top materials (soapstone?) been tried at least? I know that it must withstand heat and pressure and repeated use. It seems to me that between CAD and CNC this process could be done more easily these days-dunno about the relative cost be I'm sure the big mfgrs either have these systems or could afford them if the molds themselves were made more cheaply.

Sorry for the simplistic questions but it seems as though you could enlighten us on the process.

[Harry P.]

Just a guess here, but I'd say the material the molds are made of isn't the major cost factor.

The major cost is the actual work involved in getting to the point that you can cut the steel (or whatever material the molds would be made of). Plus the cost of the injection-molding machines themselves, plus the cost of the factory to put them in, the salaries and benefits for people to run them, etc.

I think that the actual cost of the steel is a pretty insignificant part of the equation. And yeah... if there was a better, cheaper alternative, like you said... they'd already be using it.

Ok, halftime is over, Madonna's done. Back to the Superbowl!

[Darin Bastedo]

another thing to take into account is that the actual production of model kits is farmed out to facilties that make other injection molded items. The volume on a model car kit is much lower than an order for about 4 billion sporks for the fast food industry, thus less profitable. Therefore the factory has to make up for it with set-up fees and a higher per-unit cost.

[Dave Van]

Mold material is not the highest cost component. But just FYI Plastic injection molds can be made from high nickel steel, aluminum, or even epoxy resins. And some cottage guys are injecting resin into RTV molds so that counts as injection. Design, licensing and fine tuning it takes, tooling mods, to make a kit fit and build it where your cost is.

[scalenut]

it's hard to replace hardened tool steel , not without going to exotic metals and that would be out of the question.

soapstone,corian,ceramic would crumble to dust .

no matter how well you cnc machine molds they have to finished by hand.

than several days of testing-tweaking-testing-tweaking.polishing

than you deal with the quality of the bulk plastic,, and tweaking operating temperatures...

than you go thru QC and changes are requested and made ,, than more tweaking-testing,polishing,ect...

than the customer wants more changes,,, more tweaking , followed by more polishing and retesting.

eventually you get to production

btw ... aluminum can be about 7X more expensive than steel when buying it in large chunks like that

Edited February 6, 2012 by scalenut

[Cato]

But just FYI Plastic injection molds can be made from high nickel steel, aluminum, or even epoxy resins. And some cottage guys are injecting resin into RTV molds so that counts as injection.

All good points made so far. But this gets closest to my question.

It just seems to me that pouring a mold from a master would be easier and cheaper than carving (CNC) a solid metal material. Will epoxy resin molds not hold up well to injecting hot styrene over time?

[Dave Van]

btw ... aluminum can be about 7X more expensive than steel when buying it in large chunks like that

True....but it is often used in hobby tools that are as small as 1 inch square and are needed for a limited life. Just trying to inform.

[Harry P.]

All good points made so far. But this gets closest to my question.

It just seems to me that pouring a mold from a master would be easier and cheaper than carving (CNC) a solid metal material. Will epoxy resin molds not hold up well to injecting hot styrene over time?

You can either cut steel molds via computer and create the cavity that the plastic has to fill... or, according to your hypothetical case, create master parts trees (made out of...what? Created how?) to use as masters to create the poured molds (assuming that way of doing things is even feasible).

Why would you assume that cutting steel molds is more expensive than creating some sort of parts tree master and pouring the molds out of another material?

[62rebel]

it stands to reason that the molder (of whatever they produce, sporks, kits, no matter) does whatever they can to extend the life of their molds; to make as many different products as possible with those molds, and to avoid comebacks for ANY reason. the machinery itself has set parameters for mold sizes and complexity; the kit designers work within those limitations. i understand the frustration many of you feel when you keep seeing "ancient" versions of kits on the shelf and you'd like to see those cars redone with more accuracy, but the kit makers can only budget so many completely new kits every season. we had to plug along for how many years with the AMT "Old Pro" Nova kit before Revell released several different versions of that same type car? patience pays in the end.

[Cato]

You can either cut steel molds via computer and create the cavity that the plastic has to fill... or, according to your hypothetical case, create master parts trees (made out of...what? Created how?) to use as masters to create the poured molds (assuming that way of doing things is even feasible).

Why would you assume that cutting steel molds is more expensive than creating some sort of parts tree master and pouring the molds out of another material?

Let's back up and educate me on how masters are created. My understanding is that a master modeler creates the original form of a vehicle (our example) from drawings and photo reference, in a scale larger than the desired finished product. The material can be carved wood, clay or some other durable material. I am leaving RP out of this discussion.

Then the master is then digitized into the correct scale and that data fed to a CNC which cuts the steel molds. Now as far as the component break-down and the creation of a tree 'master' for the components-I don't know how that's done now. That's why I asked Art, who is / was an industry insider. This is my child-like understanding. Please enlighten if this is wrong.

To answer your second question Harr, I just am under the impression that resins are cheaper than an ingot of steel cut in half and the computer and cutting and machining tools needed to machine them.

Would like a better understanding.

[Harry P.]

Back to the original question (whether the molds could be made for less $$$ by using a different material)...

you already answered your own question. If there was a "cheaper, better, faster" way, they'd be doing it already! There's no way they would stick to steel molds if another material was ultimately cheaper (or better) to use.

[Casey]

Just talking through my hat here but-could tooling be made with another material (other than steel) which would be cost effective, durable and easily repeatable?

OK-I know the simple answer is " they'd be using it if it existed". But have materials like a form of ceramic, or counter-top materials (soapstone?) been tried at least? I know that it must withstand heat and pressure and repeated use. It seems to me that between CAD and CNC this process could be done more easily these days-dunno about the relative cost be I'm sure the big mfgrs either have these systems or could afford them if the molds themselves were made more cheaply.

As Harry stated, you answered your own question, and considering they have been using tool steel for the better part of 50 years, it stands to reason it was a very good choice.

Also consider the heating and cooling cycle a tool goes through- hot molten plastic is injected at high pressure, then coolant is run through passages to cool the molten plastic and harden it, all within a matter of a minute or so. Which other materials would stand up to this requirement alone? I also recall Art mentioning styrene is highly abrasive, so whatever the tooling is made from would need to have high wear resistance, too.

Maybe as we see more specialized and lower volume production runs we will see a shift in mold making materials, but for now, I think what is being used is probably the best choice.

[Cato]

Also consider the heating and cooling cycle a tool goes through- hot molten plastic is injected at high pressure, then coolant is run through passages to cool the molten plastic and harden it, all within a matter of a minute or so. Which other materials would stand up to this requirement alone? I also recall Art mentioning styrene is highly abrasive, so whatever the tooling is made from would need to have high wear resistance, too.

This is among the things I'm asking from model manufacturing professionals. Has nothing else been tried? But it seems everyone is away today.

[Art Anderson]

To a great extent, this thread seems to be more about "reinventing the wheel" than anything else. Hard steel injection molding dies are used simply because they work and can work for a long, long time. And steel is probably the least expensive of all materials from which to cut injection molding dies when all factors are considered. Yes, aluminum can and has been used, but aluminum doesn't hold up nearly as long.

30-40-50 years ago, model kit tooling mockups (patterns) were made by hand, from wood. Every part of a kit was carved largely by hand by skilled patternmakers in a time-honored fashion born of the metal casting trade. Generally, those wooden model kit patterns were created in a scale larger than what was to be produced--1/12 scale for a 1/24 scale model, 1/10 scale for a 1/25 scale model, as these scale relationships could easily be dialed in to the analog (mechanical) milling pantograph machines then the common standard for injection molding tooling. As the parts were developed, they would have been test fitted together, and once approved, were then used to create impressions that could be turned into large scale wood and resin mold cavities exactly like the final steel cavities would be cut. These molds could then be filled with a liquid resin to create "model kit" parts not unlike the final products, again tested for fit, mold alignment etc.

One deviation from what I am pointing out here were the patterns for body shells. Those were done as SOLID wood masters, just the exterior shapes and contours carved--the creation of the inner surfaces being done from the large scale wooden tooling mockups with various clays etc., to allow the creation of the internal "core" die(s) that would make possible the molding of hollow, one piece body shells. This is why those older kits have thicker, more uneven inside surfaces, quite unlike the "state of the art" model car kit bodies we see today.

The cutting of steel dies was done by a 3-dimensional "pantograph" milling machine, (old time draftsman will remember 2D pantographs which were used to either enlarge or reduce a drawing on the drafting table--3D pantographs worked in very much the same way, but on three axes, length, width and depth). This was one of the major costs in tooling back decades ago--a toolmaker had to guide the cutting tools using a stylus which followed the shapes of the final wooden mastering for the various molding cavities to create the final tooling. Long, drawn out process, very laborious, very tedious as well. Along the way too, the various moving sections of the tooling had to made to close precisely, particularly that for the one-piece body shells we came to demand in model cars by 1957 or so. In a day when so much depended on the human hand and the human eye, it's little wonder that there were mold misalignments that happened--to a great extent, they were practically inevitable.

Once that tooling was cut, it was on to "test shots", the new dies loaded into an injection molder, and molten plastic shot through the runners, and what often came out left lots to be desired. Material thickness errors would crop up, either that roof was too thick, or perhaps so thin in a spot or two as to actually be a hole. Adjustment time! Same with every part of the kit. Once all the fitments and tolerances were corrected to at least an acceptable level, then the adding of small details. And this is where the toolmakers really earned their pay--artistry had precedence over science. If one but thinks about say, a recessed door line in a model kit body, realize that is created by machining a "raised ridge" in the tooling, tooling being exactly the mirror image of the plastic production part. Scripts, badges, chrome spear details--all that required intense hand work, jeweler's work if you think about it, all done as recessed details in the tooling.

End part one

[Art Anderson]

Part two:

And here is the rub: A couple of generations ago, a newly tooled model car kit could reasonably be expected to see hundreds of thousands, if not millions of units produced, and in a relatively short period of time. In the 1960's, there really weren't that many model car kit tools in existence--AMT Corporation, for example, might have had a couple of dozen "Annual Series" subjects, along with not more than that in Trophy Series, or other kits projected to be run for multiple years. The same would have been true over at JoHan, MPC, Monogram, and Revell (the latter two were still far better known for non-automotive subjects in the industry back then, believe me!). With a $2.00 MSRP model car kit laying less than 80-cents in the till at AMT, they ran on sheer volume. In the fall of 1966, my Dad brought home the Wall Street Journal, with a FASCINATING article about the World's Largest :"Automaker": It wasn't any of the Detroit Big Three, not even close. AMT Corporation was making more model car kits (the number 100,000,000 sticks in my mind here!) than all the world's automakers put together in the world of real cars. To a lesser extent, the story was the same with other model car kit manufacturers. That alone dictated the use of steel tooling. AMT Corporation's largest selling plastic kit perhaps of all time wasn't a model car kit, but rather their first kit of the TOS USS Enterprise from Star Trek! I was told in the late 70's that the original tooling for that kit was cut in aluminum, they figuring it would be a "flash in the pan", quick popularity then die--within a year or so they had multiple steel dies squeezing out millions of the Enterprise, and its popularity far outlasted The Original Series of Star Trek by at least a couple of decades. One model car kit in particular, the original Trophy Series 1957 Chevy Bel Air Hardtop remained in continuous production from early 1962 all the way to 1997, when it was supplanted by the newer tooling introduced that year--millions were produced over those 35 years, probably the most produced model car kit of all time.

End part 2

[Evil Appetite]

I love this guy! Fascinating!

[Cato]

Honest-I'm NOT trying to re-invent anything. Just find out about the process.

Art, thanks for the detailed history to this point. I'm now hoping to learn if anything else has been tried and rejected because steel molds have been found to be the most successful.

Moebius' Chrysler and Hornet seem like superior tooling techniques compared to many manufacturers for fidelity, accuracy and thicknesses. Am I right?

[Art Anderson]

part 3:

Fast forward out to the 1990's and into this Century: The old methods of creating model kit tooling began to change by the middle 1980's--Tamiya started using EDM (Electro-Discharge Machining) whereby tiny electric arcs are used, in a bath of cooling oil, to remove bits of metal from the blocks of tooling steel--and CAD/CAM slowly entered the model kit industry. Now, a toolmaker need not stand there, making every move with a pantograph, EDM literally allowed the operator, once setups were done, to push the start button, and the rest became almost automatic. This certainly found a lot of use in the creation of diecast model tooling. In addition, wood began being replaced as a pattern making material by, get this: Styrene! Yup, to look at a tooling mockup for either a diecast, or a plastic model kit today, is to look at a body shell and related parts, representing the finest scratchbuilding you will ever see, bar none. Also, with laser scanning technology, the laborious drafting of drawings has gone digital, CAD has taken over, done before the first tooling mockup parts are created. But it's not all a simple matter of loading files, then clicking "START". Laser scanning and both CAD and CAM have a limitation, and that is simply do to how we actually see a miniaturized version of a real automobile. So, along the way, particularly with body shells, a lot of plain old visual study by human eyes, comparing to pictures (and to properly reference a real car for shrinking down into an acceptable scale model can require often a couple hundred photographs of the actual subject, pics shot for shapes, contours, small dimensions, definitely not "Beauty Shots" for the likes of Hemmings, or Collectible Automobile Magazine). Still the human equation becomes the final arbiter here. I know Dave Metzner has sweat bullets over the Hudsons and the upcoming Chrysler C300, along with the designers, engineers and pattern makers in China--that is still a big part of the game, has always been, and not likely to ever go completely away. In the bottom line, it can still take upwards of 12-18 months to get that kit right, particularly of older cars for which only limited factory drawings may have been preserved (most were consigned to dumpsters decades ago), and certainly no modern CAD files either. In fact, it can take as long as 2 years to get to a final product that you, me and the other guy too can and will accept as being a model car we'd build--and that probably isn't all that much different no matter what continent, no matter the model kit mfr.

I hope I have added something to the equation here: it's not so much the materials from which model kit tooling is cut that is the cost factor--it's the WHOLE process, all the skills of all the skilled people involved, and added to that mix, a passion to make any kit produced, as good as it can be. So some things will probably remain the same where tooling materials are concerned. For every "magic bullet" of technology, there still remains the human factor, and that's not gonna change anytime soon, I suggest.

End!

Art

[Harry P.]

So the bottom line after all that is what I said in the first place: steel is the best and cheapest material to make molds from (regardless of the ever-evolvong technology that comprises the process of getting the tool cut, which was not the original question). If there was a better, cheaper alternative to steel, they would be using it.

[Cato]

Thanks Art, for sharing your knowledge here. It clears up a lot of details about the process for me.