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November 4, 2002

22 Min Read
Are full hydraulic injection molding machines yesterday?s news? Part 2


Nth degree modularity is built into Arburg?s new Allrounder Alldrive (Allrounder A). The main functions of a press?opening and closing the mold, injection, and metering?are servodriven. But all other auxiliary axes movements, like nozzle touch or mold actions, can be either electrically or hydraulically driven, depending on the application.

In the September/October issue of PM&A we presented the opinions of injection molders and machine manufacturers who believe that it’s too early to write off full hydraulic presses. In this, the second part of the discussion, we’ll hear from those who say time is running out for full hydraulic machines, and also from those who believe there’s room in the market for machines with all types of drive systems.

Those who say full hydraulics are here to stay have strong arguments. Take Gordon Darling of the Northeast machinery rep firm Superior Industrial, for instance. “There will always be hydraulic ram-type machines, and hydraulic toggle-type machines. Metalworking machines (machine tools) went 100 percent all servoelectric in the ‘70s and ‘80s. But machining steel is a far more precise process than injection molding.”

Electric machines are expensive, says Darling, especially in larger sizes. “And, just like God made little green apples, there will always be customers who want to pay a low price for their equipment.

“There will always be about 50 percent of the molding market that really has nothing to gain by buying all-electric, such as a hanger maker in Alabama, or somewhere, who is paying $.03/kWh for his power and the tolerance on his product is ±.250 inch,” says Darling.

Yes, But
Still, we received almost twice as many responses sounding the death knell for full hydraulics as we did for those saying full hydraulics still have a life. Twinshot consultant Joseph J. McRoskey of JMJ Management LLC (Carlsbad, CA) says full hydraulics are history, although Joel Thomson, a colleague of his at Twinshot Technologies & Community Products (Rifton, NY), has a different opinion (see September/October 2002 PM&A). Still, McRoskey doesn’t expect them to become obsolete in his lifetime.

“They represent a lower capital cost, they’re less complex and easier to maintain, easier to repair, and most of us processors have much more experience with them. Some of us enjoy the flexibility of simple accumulator systems that permit fast injection when we need it.

“I have run a lot of machines,” McRoskey says, “and I prefer the electrics. But forget about wholesale replacement. It won’t happen.”

Even though his company has recently installed all-electrics in a new molding cleanroom, Michael McGown of Hy-Ten Plastics (Milford, NH) thinks hydraulic injection molding machines will remain on the scene for some time to come. Why? One word: price.

“Machine cost will be the primary driver of many of the smaller injection molders’ decision making,” McGown says. “I’ve toured no less than two dozen injection molding facilities in China and have yet to view an all-electric machine.”

Nevertheless, Hy-Ten’s new presses are electrics. Why? One word: costs. “As for myself, every machine purchase requires a complete evaluation. Power cost here in southern New Hampshire is quite expensive compared to some of our neighboring states. There is no doubt that the electric machines have the edge here at Hy-Ten Plastics.”


Although it has introduced a small-tonnage all-electric optical disk molding machine, the e-Jet, Netstal expects to add all-electrics in the same tonnage range as its SynErgy series of hydraulic toggles (60 to 240 tons) for Q1 2004.

Time’s Up
The coming obsolescence of full hydraulics is obvious to at least one man—Yoshiharu Inaba, member of the board of directors and executive VP of the world’s largest supplier of all-electrics, Fanuc Ltd. (Oshino-mura, Yamanashi Prefecture, Japan). Inaba says that from subcompacts to midsize presses, all-electrics are multiplying and already have become the predominant machine less than 300 tons in Japan. He also says that larger-tonnage hydraulic rams are on their way out because of developments in larger servomotors and multiservomotor drive systems.

Reasons why include the narrowing price gap, energy savings, and repeatability. Full hydraulics fail to pass muster in the modern plastics technology world for four reasons, according to Inaba:

  • Machine control is susceptible to hydraulic fluid temperature, which varies over long-run operation, making it difficult to maintain process stability.

  • Servovalves and proportional control valves deteriorate over time, making it difficult to maintain the initial performance of full hydraulic machines over the long haul.

  • Hydraulic drives normally require continuous operation with minimum startups and shut downs, making it difficult to improve energy savings. Inaba also reminds us that high-performance hydraulics with high injection-speed acceleration cannot use energy-saving variable-volume pumps.

  • Full hydraulics can be messy and noisy, making it difficult to improve the workplace environment.

The solutions provided by all-electrics begin and end with their servomotor drives. Injection, extrusion, clamping, and ejection are all driven by a-c servomotors on Fanuc presses. Inaba says this results in a system that is highly immune to ambient temperature changes or other external disturbances, thereby enabling long-term molding precision and stability. The Fanuc Roboshot’s pressure control is ±.1 MPa, he says, on par with a machine tool.

A-c servomotors operate only when needed, resulting in two-thirds more energy savings when compared with full hydraulics. "In the case of Fanuc Roboshot, using a regenerative function, the energy in deceleration converts to electrical energy. Therefore the efficiency of energy consumption is higher than other all-electric injection molding machines," says Inaba.

Mold protection also is improved. Upon detecting an abnormal load during clamping, Fanuc presses bring clamping to an abrupt halt, thereby protecting the mold from breakage. They cycle faster, too. The Roboshot’s four motors can be operated simultaneously, and they’re getting faster. Inaba says the Roboshot has a blistering injection speed acceleration time of 0 to 300 mm/second in only 27 ms.


Sumitomo has no plans to discontinue its smaller-tonnage (18- to 80-ton) hydraulic clamp machines. These models may eventually be replaced by all electric models, but only if dictated by industry demand. The company?s hydromechanical SHC and SHA machines (100 to 650 tons) will continue to be produced and aggressively marketed.

Big Electrics
Jerry Johnson of JSW Plastics Machinery Inc. says he believes hydraulic machine makers are shaking in their boots. He says JSW plans to obsolete its own line of small hydraulics (55 to 110 tons) in the very near future, replacing them with all-electrics. Like Inaba, he takes issue with those who believe that the larger-tonnage market will continue to be the stomping ground of full hydraulics.

“During the 1950s through to the 1990s, hydraulic transmission power was the best possible method for driving heavy steel platens and injection screws under a lot of pressure. And, even when the all-electrics were introduced, the first models were small. For example, in 1994, JSW introduced the U.S. market to our all-electric machines, but we only had three sizes: 40, 60, and 120 tons,” says Johnson.

Even though JSW could document the accuracy and energy savings of its electrics, Johnson says they were not taken as a serious threat against hydraulics simply because they were small. However, he says this perception is rapidly changing. The company now offers all-electrics from 500 to 1450 tons, and is looking to increase that range. JSW recently added the 1450-ton all-electric to its line, and is testing a 1660-ton machine.

Speaking of size, UBE Machinery (Ann Arbor, MI) manufactures both hydraulic toggles and all-electric machines—big ones. As a matter of fact, UBE has built and sold the largest all-electrics in the world. A 1500-tonner was on show at NPE 2000. More recently UBE announced the sale of an all-electric with 7 by 4.5 ft between the bars and a clamping force of 2000 tons.

Understandably, UBE’s Jason Forgash believes that full-hydraulic machines are not the latest or best technology available in the market today.

“The advantages of all-electric—including accuracy, repeatability, energy consumption, and environmental issues—outweigh even the newest and best hydraulic machines on the market,” he says.

"I strongly feel that if the electric machine price was similar to hydraulic machines, the sales of hydraulic machines would be a very small percentage of the market. I think that if you asked almost any molder in the country their choice hydraulic or electric (assuming the price was the same), the response would be 99 percent electric."

Forgash says full hydraulics will only hold out as long as this price differential persists. And for those who say that there are applications that only a full-hydraulic machine can cover, he has this to say: "Modifications can be made to the electric machines to meet the requirements of most applications."

Opinions are Changing
The pro-all-electric party is winning in the public opinion polls. Some of our respondents say full hydraulics are goners, even though they’ve yet to buy an electric press. Brad Hilton of automotive lens molder Emrick Plastics (Windsor, ON) is up front and honest in saying that his perceptions of the superiority of all-electrics are just that—perceptions—based solely on what he has heard and read about them.

“We currently run 18 hydraulic machines, and have internally decided to seriously look at an all-electric when we purchase our next machine. Since I have never run an all-electric machine, I must rely on my perceptions,” he says.

Hilton has seven reasons why electric technology is tomorrow’s news. Electrics, he says, are quieter and cleaner (better for ISO 14000 and waste stream management), they consume less energy, have better process consistency and control, have smaller footprints, they’re easier to service, and they’re much faster.

“The only advantage of hydraulic presses that I can see is in mold setup,” says Leo I. Montagna (Sterling, MA) of custom molder Lee Plastics, one of the oldest custom molders in the U.S. “If utility costs are important to you, then electrics are the only way to go. If precise control is your concern, the hydraulic press can’t compete. If you want me to believe the hydraulic press is as good as an electric or hybrid, then prove it!”

Opinions Have Changed
Others, with hands-on experience in all-electrics, have already begun to write the full hydraulics obituary. Molder Nypro Inc. (Clinton, MA) is among them. For Nypro, full hydraulics are history. “The answer, for us, is yes, at least for the smaller machines (200 to 400 tons) with which we are most familiar,” says Nypro’s Al Cotton, summarizing the answers he got from his colleagues at Nypro’s headquarters. Cost savings, especially power savings in the 50 to 60 percent range, is the main reason.

Cotton says there are a number of qualitative—as opposed to quantitative—reasons as well, which are important to the Nypro technicians who oversee these machines. “For instance,” says Cotton, “oil leaks are the bane of every injection molding technician, particularly in cleanrooms, and they are virtually eliminated with electrics.”

Cotton says Nypro has at least one electric in every one of its many plants around the world, “and we see them mushrooming as a percent of our equipment in the near future.”

Netstal Machinery has earned its reputation over the years fielding high-performance, high-speed, hydraulically driven toggle presses for thin-wall packaging and demanding technical parts. Reto Morger of its Swiss parent company, Netstal Machinen AG (Naefels, Switzerland), says such applications will keep hydraulic and hybrid machines in fashion.

Nevertheless, Morger says Netstal knows that the market is going for both concepts—hydraulic and all-electric. “Therefore,” he says, “we will provide at least from the next K show, a fully electric injection molding machine for standard applications.” At K 2001 Netstal displayed an all-electric machine for molding optical disks.

“Yes, hydraulic machines are yesterday’s news,” says Gordon Sanford of insert molding specialist PMT Inc. (Seymour, CT). “Their only redeeming factor is the lower initial price.”

Sanford, like many others, says that once the prices drop on the servodrives, it will be possible for OEMs to build electric machines for less than a hydraulic. “We have seen steady price reductions in the servo components used in our in-house automation over the last 10 years, and expect the same will happen to the molding machines.”

Sanford says all-electric presses get the job done a whole lot easier than full hydraulics. “The all-electric conversions of energy to motion have a simpler, shorter path to control the pressure and speeds that are the heart of the injection molding process.”


Van Dorn Demag?s Cadence series of full hydraulic presses (25 to 125 tons) reportedly are repeatable, energy-efficient, high-performance machines with generous tiebar spacing, but without an all-electric?s price tag.

Are All-electrics Yesterday’s News?
As they did in the first installment of this series, many of our respondents were hesitant about saying the day of the full hydraulic machine has passed, while at the same time strongly voicing their belief that electrics were the presses of tomorrow. One such respondent, a spokesperson for a major, lean-thinking automotive molder, who requests anonymity, says his company got burned when first trying to flip the all-electric switch.

"We have nearly 500 molding machines globally and 95 percent of them are hydraulic," this source says. "Initial capital costs are an important factor. Generally, during the introduction of the electric machines there was a 50 percent premium for electric technology. Also during the introduction, the infrastructure to support machines in the field was not so good."

His field engineers back then were much better at diagnosing hydraulic presses. "We introduced electrics to the molding floor on two occasions. Within two years we returned the machines for not being capable in the simplest form. Three years later we again attempted an electric introduction. This time the results were very good until there was a breakdown. It's a great machine until it breaks."

The repair diagnosis process and parts re-supply caused frustration and discontent while the company waited for the repair. He says his company did see one major benefit.

"The electric nature of the electrical machine was excellent for the integration of robots and pickers," he says. "We could start the descent of the picker arm directly and before full mold open for simple cycle improvements without modifying to the actual cycle parameters."

Introductory training for the electrics was found to be very important. He says all-electrics are far less forgiving of processing errors and mistakes. These errors cause downtime. However, even after the relatively bad experiences, this source says electric machines will become the machine of the future at his company.

Here’s why. "The noise level of the electrics is much less. We have a very high density of machines to floor space and the decibel level is very important. No oil and no oil cooling is another inherent advantage. Moving, cooling, filtering, and testing oil are all non-value add activities, and the electrics will have the decisive advantage when their reliability is better and their initial purchase cost becomes more in line with the hydraulics."

All-electrics still need work in other areas, this source says. Some very serious improvements to the back end of the machine have to be made, for one thing. All-electric proponents celebrate their fast injection speed. That much, he says, is true. "However, the electric knockout speed is the biggest deterrent to the electric machine here. We need high velocity KO speed to eject our parts. The electrics just aren't capable of the kind of KO speed we need at this point in time."

Core-pull sequencing in all-electrics also is found to be lacking. "The electrics do a good job at straightforward A-B plate molding, if you can live with a relatively slow eject stroke. But they must rely on a hydraulic add-on for more sophisticated core-pull molds. To use an electric machine to turn a hydraulic pump to power the core-pull sequence seems inadequate."

He says that complex molding—side-action with core pull sequencing—requires that kind of technology to be on-board. All-electrics will not become the machines of choice for complex molding without an integral core-pull sequence capability at his company. "For us, the electric/hydraulic hybrid may actually be the machine of the future."


A spokesperson for Boy Machines asks, ?Does the full hydraulic machine make a good part, a consistently good part? Isn?t that all that it?s about?? He feels his company?s 60-ton Boy 55A does just that for less money.

More on Hybrids
Laurie Weeks of Cascade Engineering (Grand Rapids, MI) says full hydraulics are definitely becoming yesterday’s news. However, she feels that all-electrics may eventually share the same fate.

“With the introduction of the all-electric machine we saw some very repeatable results on the injection units of these machines,” Weeks says. “These results have allowed for some greater complexities in tooling to take place over the years.”

But Cascade has also learned that the all-electric clamp lacks the power necessary to hold the mold closed during filling and packing. This, says Weeks, is leading the industry toward hybrid machines.

“It is my belief that the best injection molding machine built will have a full hydraulic clamping system and an all-electric injection unit. We will really be able to mold some complex products then,” she says. “Another example of the hybrid machines is the combination of the molding processes that is happening now—injection molding combined with compounding, for example.”

Weeks then offers an even more compelling vision: “If an OEM is going to play in the future markets of injection molding machines, it is going to have to package its equipment as modules, meaning that you, as the buyer, will choose the style of clamp unit that you want with the injection unit. So all the machines of today will still be used, just in a different fashion.”

Room for Everyone
Some of our respondents believe there’s room for full hydraulics, hybrids, and all-electrics. One is the noted author and industry expert Jack Avery, manager of operational assets at GE Plastics. “My thoughts on this are that electrics will have the best fit in the small machine market where the added costs of all-electrics are not as significant as in the larger machines. Plus, the more environmental operational aspects of electrics are important in many markets, including medical and electronic.”

Avery believes that the midsize machine market will be the segment penetrated by hybrids. “Utilizing electric components for the material delivery system is the most economical means. Hydraulics for the clamp system reduce cost vs. all-electrics, as well as the commercial availability issues with large electric motors.”

Finally, he sees hydraulics maintaining their toe-hold in the market for big iron, primarily due to the high costs of the large servomotors required for the clamping system of large all-electrics.

Van Dorn Demag (Strongsville, OH) covers all the bases—from full hydraulic ram-type presses, to toggles, to hydromechanicals, to all-electrics. And, if you care to put the Demag Ergotech USA El-Exis machine under the VDD umbrella, it even has machines with hybrid hydrostatic transmission systems. So VDD’s marketing manager, Larry Doyle, has a well-balanced view. Overall, he says, there is room for full hydraulics, all-electrics, and any other type of molding machine.

For starters, he says that full hydraulics at 300 tons and less are losing market share and that most machines in this tonnage range will be electrified in the next five to seven years.

“Prices on a-c servomotors and drives, as well as ballscrews, are stabilizing,” Doyle says. “As a result, all-electric machines in this size do not carry as high of a premium in price as they once did. This all-electric technology has become more affordable and ultimately a better buy.”

With all of this said, VDD’s Cadence series of hydraulic machines (28 to 125 tons) reportedly remains a good buy. The machines have a dual-pump hydraulic system and servovalved injection. “In addition, the generous distance between tiebar specifications allows molders to run larger molds in smaller-tonnage machines,“ says Doyle.

Doyle feels that all-electrics above 300 tons are cost prohibitive at this time. The larger servomotors and drives are non-standard products and tend to increase machine costs. And as ball-screw diameters increase, he says, this leads towards yet another expensive, non-standard product, or to new, unproven technologies.

Larger all-electrics using multiple motors on one axis require multiple drives, another cost driver. "In addition," says Doyle, "synchronization of these motors on one axis involves special sequencing in the program and could involve additional hardware requirements. Ultimately, the costs associated with these machines put them at a price most molders will not pay."

From his vantage point with a company with an all-encompassing line, Doyle makes one observation others often fail to make when debating the merits of the different drives—namely, the impact on floorspace. VDD’s two platen hydromechanical machines use 25 percent less space than a three platen machine. Most all-electric machines are toggles, so, as their tonnage increases so does the footprint of the machine.

"Only rarely do we see hydraulic toggle machines above 700 tons. These machines take up entirely too much space in a manufacturing environment. This will be something for molders to ponder when they evaluate all-electric machines in the larger sizes," Doyle says.

When it comes to applications, Doyle believes some are better suited to all-electrics, particularly those requiring what he says are their superior positioning accuracy, environmental friendliness, and energy efficiency. Still, he says machine control technology is an important issue to consider.

"Servomotor encoders do an excellent job in counting pulses of light to provide very accurate positioning. But it is the machine control technology that will make the all-electric machine respond better to variables in the molding process." Doyle tells us VDD’s next generation Pathfinder control on its IntElect Series all-electrics allows the machine to automatically compensate for temperature and material viscosity process variables.

For some applications, though, all-electrics need not apply. Thin-wall applications with high length to thickness ratios require high-performance injection specs that are out of the reach of all-electric technologies, according to Doyle. Accumulator-assisted injection on hydraulic machines meets these requirements at an affordable price and with proven technology.


Many molders and machinery suppliers believe the global marketplace is big enough for all-electrics, hybrids, and full hydraulics, like this Goldstar 610H. It still may be too early to write the latter off.

Apples to Apples?
David Geiger, industrial systems engineering manager at Moog Inc., heads a group that develops solutions for electric machines, hydraulics, and sealed electric/hydraulic actuators.

Geiger believes that there is a big misunderstanding in the marketplace regarding electric machines. Most of the misunderstanding is coming from sales organizations using data that he says compare old hydraulic technology to modern electric servo technology. Others compare the costs of sequential hydraulic machines to the parallel movement possible with electric machines. “The end user must look for the best technology for his application,” says Geiger.

“All technologies can reach the precision required in the most demanding application, if you use the best products available. It is difficult to summarize which technology is the best without going into the specific application. I recommend that the customers investigate in detail their application before choosing a drive technology.”

Keeping your application in mind, Geiger believes there are five main areas of concern:

  • Do you require the most cost-effective sequential movement machine? If so, hydraulic is preferred.

  • Do you require a parallel movement machine? If so, go for an electric or hybrid.

  • Do you require a large amount of force and speed? If so, go hydraulic.

  • Do you have environmental impact concerns? If so, go electric.

  • Do you have environmental impact concerns with parts that require large amounts of force or speed? If so, sealed electric/hydraulic actuators are preferred.

Hydraulics Today
“Milacron responds to customer requirements based on their application needs and regional preferences,” says Dale Werle of Ferromatik Milacron North America (Batavia, OH). “Today, these requirements are filled by all types of machinery designs, including all-electric, hybrid, two-platen, and traditional hydraulic.”

With such diversity, Werle admits that it’s hard to make generalizations about the life-span of full hydraulics, but he feels that all-electrics are taking over at 200 tons and less. "There is strong preference for our advanced all-electric IMMs in this range, and our mid-sized Powerline Plus series electrics have excelled in the high-speed packaging markets," he says.

Produced in North America and Germany, Werle says Milacron’s Powerline machines are making inroads into the medical and packaging fields where high-speed full hydraulics have dominated. They are now available up to 1125 tons.

"A key to the growth of larger electrics will be the electrification of mold motions, which is well under way at D-M-E. That said, we are still successfully selling the all-hydraulic Babyplast micromolding machine and a very small 'true hydraulic' machine, the Edge, to satisfy a segment of the market that clings to this technology."

Regarding its other hydraulics, Werle says Milacron’s Magna series presses have been successfully transplanted to India, where they are now the market leader. And he adds, "The pure hydraulic machines we build in Germany are still very much in demand due to the mature, large customer base that continues to be delighted with this type of technology."

Electrics Tomorrow

The company’s U.S.-built hydraulic two-platen Maxima Series machines, from 300 to 6600 tons, have enhanced Milacron’s hydraulic line-up’s speed, footprint, and oil conservation. Maxima machines are available in conventional or hybrid configurations, in Europe and the U.S.

But Werle has this to say about hybrids: "We have made such hybrid machines for 25 years. While the market has been stirred up about hybrids with 'lipstick on the pig' salesmanship, we are certain it is not a technology of the future, but a competitive reaction to our strong all-electric patents and considerable investments in technology and supply chain development."

All told, Werle definitely believes all-electrics will be tomorrow’s news. “Without revealing specific numbers, I can say that all-electric IMMs make up a higher percentage of Milacron’s overall sales each year—much higher than the SPI numbers reported for the broad market, “ he says.

With each new year, Werle says, all-electric technology will become more accepted and inexpensive, and bite off another machine-size range or application that had been the exclusive domain of hydraulics. “The pace of this transition will vary from year to year, but it is as inevitable for molding as it was for robots, where many persisted in thi

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