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Two-platen IMMs ruleTwo-platen IMMs rule

March 4, 2005

13 Min Read
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Krauss-Maffei?s IMC Series reduces costs by combining compounding with injection molding (below). Toshiba?s ISFD Series is built for repeatability (above).

Ube exhibited at NPE?03 in Chicago the largest-tonnage all-electric press ever seen there. Also the largest all-electric ever sold, at 2000 tons, it was built jointly by Niigata and Ube.

Demag?s new Titan series of two-platen hydraulics are made in the U.S., but combine the best features of Demag?s Caliber Series machines with the best features its European-built Maxx Series has to offer, including smooth-running linear-bearing guidance for the moving platen.

Battenfeld?s HM20000 two-platen unit was shown at K 2004 in Düsseldorf molding large PC car windows, using a proprietary injection compression technology from the company. HM 2?s are available up to 4400 tons.

Expanding your machine tonnage range may mean expanding your plant. I2-Tech had to perform major renovations to fit its new 3000-ton Husky Quadloc (and its big Husky robot) into its facility.

CK Technologies recently bought two customized Cincinnati Milacron Maxima 3900?s, both with electric screw drive.

Engel?s Duo two-platens are so compact that one molder fit in six more than they thought were possible in a given space.

Despite the current popularity of large-tonnage, space-saving, two-platen injection molding presses in North America, the three-platen, five-point, double-toggle machines are still available. One example is this 3520-ton machine from Italy?s NPM Plastic Metal SpA.

?Its distinctive clamping unit design eliminates the massive clamp cylinder castings found on three-platen large-tonnage machines? This machine requires neither a large oil reservoir, nor a prefill valve? Its retractable tierods provide complete access to the mold area? A short-stroke load cell applies equal clamping force at all four corners of the mold...?

The description above sounds kind of like what you?d read in an ad for any of today?s big, hydraulic, two-platen molding machines, doesn?t it? Guess what? You would have read words like these describing a series of big two-platen presses in ads in the 1960s. They pertain to Impco 200 ?Breechlok? machines, which featured retractable tiebars and were available with either reciprocating or fixed screws.

The Impco 200 Breechlok was built by Improved Machinery Co. (Impco; Nashua, NH). Ingersoll-Rand?s Plastic Machinery Div. once owned Impco?and Negri-Bossi, as well?before discontinuing production and dissolving its Plastics Machinery Div. in 1986.

Impco 200 Breechloks were the first U.S.-built two-platen machines, according to Steven R. Schroeder, the president of a prominent machinery remanufacturer, Epco LLC (Fremont, OH).?We rebuilt two 1200-ton Breechloks 1991. They were 1969 models. I?m pretty sure they were available from 1000 to 2500 tons before Impco stopped producing them in ?72 or ?73,? Schroeder says.

?They had so many moving parts. The clamping unit had a mechanism like a gear rack mounted underneath the platen. When the clamp closed these ?Breechlok? mechanisms, as they called it, clamped up on the rods and applied the clamping force.?

So, why are we talking about the origins of large-tonnage, two-platen molding machines? Well, when we started asking you how you compare the technological plusses and minuses of new big machines (1200 tons and up) with those of yesteryear one fact very quickly became clear?today, two-platens rule!

All but one of those we contacted who have recently purchased big machines has purchased big two-platen machines. Two-platens clearly are the new standard in big machines. So, in honor of a built-in-the-USA original, the Impco 200 Breechlok, let?s find out why.

Heavy Metal

Speaking of built-in-the-USA originals, one of the molders we interviewed for this story, I2-Tech?s Bob Janeczko, tells us that his company is the proud owner of a 1968, 350-ton Cincinnati Milacron press, which was the first injection molding machine Cincinnati ever sold. It was remanufactured 11 years ago and is still running.

One of the biggest problems molders have had with big three-platen presses is tiebar breakage. Big machines means hanging big, heavy molds, some weighing over three tons.

?A problem like tiebars breaking is almost unheard of on machines less than 700 tons, but I think you can always predict that you?re going to have some broken bars on big machines,? says Royal Alliance?s Dave Hamilton. He ought to know. His company runs only three-platen presses.

?I think that two-platen technology is O.K. on small-tonnage machines. Obviously you wouldn?t be dealing with 60,000-lb molds on smaller machines. But I don?t know that I?d trust a two-platen to handle molds like that.?

?What?s that ? 60,000-lb molds?? asks Collins & Aikman?s Ed Rutowske. ?Yes, we?ve got a couple around here in Rantoul that small. We have 489 active tools right now. Some weigh just, oh, 78,000 lb, but only a couple.?

C&A?s automotive interior trim production facility in Rantoul, IL, where Rutowske is based, is its largest plant, running 87 presses from 1500 to 4000 tons. When we spoke to him he had recently returned from overseeing the start-up of C&A?s new 422,000-sq-ft Mexican plant, which is now equipped with about 50 molding machines up to 3000 tons.

?Tiebar breakage had been a problem. But with our new two-platen Demag Calibers, we don?t have to worry about that. There?s a huge mold opening dimension, a huge daylight on the Calibers for us to put our big tools in.?

A Lot Of Hooey?

?I had one big 3000 tonner that broke a tiebar once,? one molder says. ?Everybody in a two-block radius knew it when that happened.?

CK Technologies? Bob Houston is looking into purchasing 80-ton cranes right now for handling bigger molds. Luckily, its 165,000-sq-ft, totally climate-controlled plant has ceilings that are 50-ft high.

Others, such as Rehrig Pacific?s Barnabee believe older machines were more robust:?Though I?m not classifying it as a drawback, the newer machines are a lot more sensitive. You can?t beat them up like you could the older machines. We have a 1968MY press that we?ve only leveled once in the last 30 years.

Some molders say talk about the fragility of older three-platen machines is just a bunch of hooey, molders such as Plydex?s Gilmer:

?Klöckner-Windsor built the finest injection molding machines in the bloody world. They beefed-up their tiebar and platen dimensions. We?ve never broken a tiebar on our K-Ws and have never seen any platen deflection.?

He?s been keeping the K-Ws running at Plydex since they came in 1984.

?I am not exaggerating when I say we have the finest Windsors in the world here. They look like new and run like new. We have an outstanding level of maintenance expertise around here and zero turnover. Most plants don?t want to give their presses up to maintenance.?Gilmer is, however, quite pleased with his newer 4000-ton, two-platen, MX-Series Krauss-Maffeis.?They?re absolutely sweet,? he says. ?Somebody finally got it right.?

Easier Mold Changes

Wisconsin Tool & Mold?s Hans Lang is proud to say he?s never broken a tiebar. Then again, his company has only been in business for five years.

?It?s been my experience that tiebars always interfered with mold changes and robotics, so we decided to buy two-platen machines. Tiebars are not in the way with two-platens, so it?s easier to hang molds.

?A tool change? There?s almost nothing to it,? Lang continues. ?And our robots move much faster, since they no longer have to retract and move up and over tiebars. On our HM Series two-platens from Battenfeld the tiebars retract into the moving half when the mold opens. Everything is so much simpler and faster.?

?I have to say that the lubricators weren?t all that great on some of the older, three-platen, hydraulic-toggle stuff we?ve got in the back, but I?ve never been a big fan of big-tonnage toggles,? says Blackhawk Automotive?s Greg Sexton. ?The toggles started to wear, so we started fighting flash on our tools. This was a big problem.?

He adds that mold protection on older presses is nowhere near as sensitive as it in on newer machines.

?We?ve had some tiebar breaks, but seal technology has come a long way. We replaced three ram seals on some of our 1500-ton HPMs,? says Rob Lee of Metamora Products.

?We once were the largest HPM house in Pennsylvania. We?ve got 40 of them now, up to 1650 tons. But I?ve since become a real fan of Engel. They?ve really overcome the platen weight problem. It?s not at all like we used to see on our older stuff.?

?Hydraulic circuitry and the amount of control we have over it is the biggest improvement I?ve seen in two-platen technology.?

Shorter Circuits

The amount of oil three-platen machines use and the amount of oil they leak is another problem frequently cited by some molders.

?Our newer big hydraulics use way less energy to move things back and forth,? says C&A?s Rutkowske. ?Our big Calibers only use a couple of hundred gallons, they certainly don?t leak as much, and there?s much less of a clean-up involved when we do an oil change.?

Rutkowske adds that newer, two-platen presses are much more cost-effective purchases in general, since they use smaller pumps, are more economical to run, and, since they weigh considerably less than their three-platen predecessors, they?re also much easier to move around.One of the performance features CK Technologies? Houston likes most about his newer two-platen machines is their speed:

?I never thought we?d be able to go from point ?A? to point ?B? so fast with this kind of control. I attribute that mostly to their hydraulic circuitry and the overall design.?

Although Blackhawk?s Sexton says that in general the hydraulic circuitry on the company?s older, three-platen presses is not too bad, he adds, ?We?re getting to the point where it?s harder for the company?s maintenance team to troubleshoot the hydraulic circuits on the old timers. It?s mostly trial and error.?

Rehrig Pacific?s Joe Barnabee agrees. He says acquiring spares and drawing for his company?s older machines is, ?The most difficult problem we have with our older machines, which date back to 1968. Essentially, we?ve rebuilt them all ourselves.?

Barnabee says his older presses continue to be reliable, but adds that in terms of speed and energy efficiency, ?Our newer machines are two-thirds faster and use one-third less energy.?But CK Technologies? Houston cautions that two-platen technology is anything but perfect:?You?ve got more speed and capability, but you must support your customers by doing the required maintenance. There are more checks and balances, due to newer smart valves and hydraulics. A poor maintenance program is unacceptable. Machines must be in tip-top shape today, 24/7.?

All-Electrics Anyone?

Blackhawk?s Sexton, who as you might recall is no fan of large-tonnage toggles, says he?s yet to hear of folks rushing out to buy large-tonnage all-electrics:

?I heard about one of GM?s suppliers buying one. The tool sampling was done on a twin-platen press. When they brought the tool in-house I heard they had flash problems, so they had to go back out and beef-up their tools. That must?ve been pretty expensive.?

We weren?t able to get in touch with anyone running large-tonnage all-electrics for this report, but we did talk to molders who opted for electrifying their screw drives, such as CK Technologies? Houston:

?We?ve upgraded to ?e-drive? technology on our new Cincinnati Maximas, using servos for screw recovery, but these new machines of ours are very competitive even without them.?

Wisconsin Tool & Mold?s Lang is another fan of electrified shooters:

?We?re buying hybrids. Every new machine we?ve bought is equipped with an electric screw drive. We mold medical devices, so better precision and fewer defects are really important.?When asked whether he?d ever consider buying a large all-electric, Lang sighed and said, ?I am not a friend of toggle-clamp machines. I believe in hybrids. Smaller machines, say 30 to 80 tons ? in certain applications, all-electrics definitely may be a better choice.?

Royal Alliance?s Dave Hamilton says, ?On smaller machines, you can get the screws to fly. Newer injection units need different types of motors, and maybe different types of screws. They need to get better recovery and still mix properly at the same time.?

Rather than going hybrid his company has tried to solve this problem on its own. It has customized a 2000-ton NPM press with an NPM injection unit usually used on a 3000 tonner.

Plydex?s Gilmer says his company is entertaining the idea of retrofitting all-electric injection units on its older Klöckner-Windsors. But he says he?s much more interested in Krauss-Maffei?s Injection Molding Compounding (IMC) technology.

?I?d like to see us buy an MX 4000-ton machine with a compounding extruder on it. I think that?s the best homerun I?ve seen hit in years.?

New Controls vs. Old

Are the new controls on newer big machines any better than the old?

?Old controllers? I think they do just what they?re designed to do?nothing more, nothing less,? says Blackhawk?s Sexton. ?None of our older machines are closed loop. Sure, they can control the machine alright, but they can?t do any sort of automatic compensation for things like oil temperatures going up and down, or lot-to-lot material variations.?

?There?s nothing there saying, ?I?m going out of whack, or I?m drifting.? You really need a good screw and barrel on those older machines.?

?The CC100 controllers on our new Engels are excellent all the way around,? says Metamora Product?s Rob Lee. ?Hydraulic ramping really smoothes the press out, we?ve got good control over the ejector, everything is right there at our fingertips.

?Our Unilog B4 controllers on our Battenfeld?s are very fast and are very accurate,? says Wisconsin Tool & Mold?s Lang. ?They were a breeze for our employees to learn and it wasn?t even a week before they were up and running with them.?

I2-Tech?s Janeczko says his newest controls are even better than his fairly new ones: ?We had computer controls on our 2200-ton machines. We brought in two 1760-ton machines and the 2200 between 1997 and 2000. But those controls are of another generation altogether. ?On our new 3000-ton Husky machine we?ve noticed the more precise control we have over developing the process in just the first few trial shots. Once you?ve got it down, it repeats what you ask for.?

Downsizing is Good

If there?s one thing all agree on, it?s that two-platen presses are space savers. Rehrig Pacific?s Barnabee estimated that, ton-for-ton, two-platen machines provide a 20% space savings.?The real estate of our two-platen Battenfelds is so much smaller,? says Wisconsin Tool & Mold?s Lang. ?That means we can fit more machines and more automation beside the machines onto our floor to help us compete. We?ve ordered two more.?

?We have 24 two-platen Engels in our new building and they?re just 52 inches apart,? says Metamora Products? Lee. ?Their smaller footprint enabled us to fit six more machines in the building than what we originally planned. We just ordered some more Engels this week.?

Still, Houston says, CK Technologies planned for the future and requested a huge guided length to support future molds, while assuring parallelism. The Cincinnati team met the challenge.

?Big parts are our business. We know big molds and big machines. It?s a core competency here at CK Technologies,? says Houston. ?When customer demand went up we had to look at capacity planning. With the two Cincinnati Milacron Maxima 4400-ton machines sitting side by side in a cell we produce so much more.?

Even though they may be more compact than three-platen machines, really big two-platen presses can sometimes literally raise the roof. Just ask I2-Tech?s Janeczko:?Our new 3000-ton Husky Quadloc was delivered in 13 tractor trailers. Though we already had two 1760 tonners and a 2200-ton machine, we had to raise our 22-foot roof to fit the new press in our building.?

It wasn?t just the size of the machine either. The 3000 tonner is equipped with a three-axis Husky servorobot?one with 78 inches in the X axis, 141 inches in the Y, and 198 inches in the Z. It?s capable of handling a 99-lb payload.

Luckily, I2-Tech availed itself of a factory planning audit offered by its supplier to ensure a harmonious integration of the big press into its facility.

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