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Want to Get More Out of Your Hydraulic Machines?

By: Matthew H. Naitove 3. January 2017

Get up to 10% more energy efficiency out of a hydraulic press without spending a penny on drive hardware upgrades.

 

Injection molders today have a daunting range of choices when shopping for the most efficient machine—all-electric, partially electric (hybrid), hydraulic with electric servo or variable-frequency (VFD) pump drive, or plain old-fashioned fully hydraulic. But what if you heard that you could get up to 10% more energy efficiency out of a hydraulic press without spending a penny on drive hardware upgrades?

 

At last October’s K 2016 show in Dusseldorf, the German chemical company Evonik (U.S. office in Parsippany, N.J.) revealed the results of tests in 2015 on its Dynavis oil-additive technology in a Boy 35-ton and an Engel 120-ton press. Comparisons with standard hydraulic oild showed energy savings of 6% to 10%. Details of the tests are available at dynavis.com.

 

Normally, hydraulic equipment works at optimal efficiency when the oil is within a particular temperature range. Oils formulated with Dynavis technology (which utilizes Evonik’s Viscoplex family of polymer-based viscosity improvers) extend that high-efficiency temperature range.

 

The modified oils both flow better at low temperatures and remain more viscous at higher temperatures. When such oils are used in injection molding machines, the press reportedly uses less drive energy, and the oil does not get as hot and withstands shearing forces better. Until recently, Dynavis technology has been used mainly in construction equipment. Dynavis technology has been licensed to a number of hydraulic-oil suppliers around the world.

 

3D-Printed Plastic Molds: K Exhibit Would Make You a Believer

By: Matthew H. Naitove 23. December 2016

Perhaps you have heard that additive manufacturing—a.k.a. 3D printing—can be used to make injection tooling inserts out of plastics—relatively quickly, at relatively low cost, and with little human labor involved.

 

Perhaps you have been skeptical about the capabilities of those molds. Perhaps you have been told—as I was, by one proponent of 3D-printed plastic tooling, that it could be used for “simple” plastics like PE or PP, and for low-volume prototyping of up to around 50 parts.

 

If so, you probably would have come away from the recent K 2016 show—as I did—with a very different idea of what can be done with 3D-printed plastic cores and cavities. Stratasys, Eden Prairie, Minn., the leading supplier of 3D printing equipment and materials for this application, devoted its exhibit almost entirely to displays of plastic tooling and parts made from it. The exhibit also featured Stratasys’ new Polyjet J750 printer, which can print up to six different colors or materials at the same time. It does that by dispensing droplets of different colors or materials on top of each other, inkjet style, so they mix before being hardened (crosslinked) by UV light.

 

What I didn’t realize before this was that the “digital ABS” formulation that is most commonly used for printed plastic tooling is not really ABS, but a blend of acrylate photopolymers whose combined properties mimic those of ABS. Stratasys senior application engineer Gil Robinson, from the firm’s Israeli office, explained something else I hadn’t previously imagined: The “digital ABS” material is formulated during the deposition process by overlaying droplets of two different polymers chosen for heat resistance in one case, and toughness in the other.

 

The capabilities of this tooling material are best illustrated by what customers are doing with it. According to Robinson, they are running nylon, polycarbonate, acetal, PPE alloys, and PPS—even some glass-filled grades—as long as injection temperatures remain below 300 C (572 F). How many shots you can get depends on the material and the part. Robinson said the printed tooling inserts can last for five to 20 parts in nylon or PC, 50 to 100 parts in polyolefins, and up to 700 to 800 shots in acetal. The more complex the geometry, and the thinner the walls, the shorter the tool life.

 

Because the plastic molds are poor heat conductors and have no internal cooling, the molding cycle for acetal was 100 sec, and the molds were cooled with air between cycles. Robinson said a university has printed mold inserts with conformal cooling channels and that the results were encouraging.

 

He said “a few hundred” molders and OEMs worldwide are experimenting with printed plastic tooling. One of them, discussed on the company’s website, is Danish pump manufacturer Grundfos, which used digital ABS molds to mold simple parts of 40% glass-filled PPS and more complex parts of 30% glass filled Noryl PPE alloy. The Noryl parts were made in plastic molds with side actions to mold internal and external threads, as well as many ribs.

 

Another customer using printed plastic molds for prototyping is Berker, a German electrical switch maker. As reported in the November Starting Up section of Plastics Technology, Berker molded 25 to 50 parts of ASA, PC, and TPE in these molds.

 

As shown in the accompanying photos, Stratasys showed at K that printed plastic molds can also be used to prototype blow molded bottles and thermoformed shapes. In the case of thermoforming, a different type of Stratasys printer, using the FDM process of extruding and fusing thin plastic filaments, produces a porous mold that needs no drilling of vacuum holes. Other exhibits displayed printed plastic layup tools for vacuum bagging continuous-glass composites. In one case, soluble material was used to print a core for laying up a composite tube with curves and bends. The printed core could be washed out after curing the carbon-fiber/epoxy part.

 

After that booth visit, I have to say, I’m a believer.

 

Injection mold insert of Stratasys Digital ABS

 

3D-printed injection core and cavity for electronic components, made by Robert Seuffer GmbH in Germany.

 

Printed plastic blow mold for a PET bottle.

 

FDM-printed tool (left) for thermoformed part (right). The tool is inherently porous, so no vacuum holes are needed.

 

Back side of FDM-printed thermoforming tool.

 

Printed plastic layup mold for epoxy/glass-fabric composite.

 

Printed soluble core for layup for epoxy/carbon-fiber tube. After curing the part, the core is washed out.

One Place to Hang Out at K

By: Matthew H. Naitove 25. November 2016

If You Thirst for More Than Technology

 

I gather it’s something of a K Show tradition: Near the end of a hard day at the world’s biggest plastics trade fair, those in the know (and maybe a journalist with an interview appointment) repair to a quiet upstairs lounge at the booth of Gammaflux, the venerable hot-runner controls source (since 1966), based in Sterling, Va.

 

One of the worst-kept secrets of the show—that upstairs retreat is stocked with 50 (yes, 50) different single-malt Scotch whiskeys. The atmosphere is casual and welcoming. Of course, hospitality is not just its own reward. Amid the relaxed camaraderie, and a bit of liquid lubrication, the talk may turn to the events of the day: “I just got an order for 10 machines—maybe they need hot-runner controls, too?”

 

The Universal Setup and the Six Key Process Variables

By: Matthew H. Naitove 21. November 2016

One setup sheet for one mold on any machine.

 

Scientific molding expert and Plastics Technology columnist John Bozzelli is offering a three-day seminar, Dec. 6-8, in Troy, Mich. to help molders create a “true 24/7 process.” The seminar concentrates on a scientific process optimization with at-the-press instruction. Hydraulic and cavity pressures will be measured to prove out the strategy, according to Bozzelli.

 

Attendees will learn the key "Plastic" variables and define them to establish a Universal Setup Sheet. This setup sheet is intended to work for a given mold on any press, across different barrel sizes, and on electric or hydraulic machinery.

 

“One setup sheet per mold saves time and assures consistency by keeping the plastic variables constant, not the machine conditions,” Bozzelli says. Attendees will also learn the six key process variables that must be monitored to assure consistent production.    

 

Attendees will see how to make their process accommodate most viscosity changes, including those that come with changes to the material lot, resin color, and process temperature. In this way, molders can detect process changes as they occur, not after hours of production. They can also document the process so that it can be duplicated on other machines. Using glass mold videos of plastic filling various cavities, attendees will see the effects of drag, flow, in-mold decorating, splay, sinks and more.

 

The seminar will take place at the INCOE Hot Runner Research Center in Troy, MI. Register here.

 

Old Faithful Robot Gets Its Due at K Show

By: Matthew H. Naitove 15. November 2016

The purpose of a trade show like K 2016 in Dusseldorf last month is to show off new products to entice buyers. But Star Automation Inc. took the contrary approach, highlighting a 34-year-old model at the center of its booth, which was still running just fine.

 

This MHY-L900 II unit was purchased from the Italian customer, Rigamenti Srl, which had been running the robot since 1982. The paint was scratched a bit, and the overall design was a lot less clean than sleeker current models, but “old faithful” kept on cycling without complaint.

 

Technology marches on: Equipment gets faster, more energy efficient, and easier to maintain. But sometimes hardware that’s well made and well maintained will just keep on doing its job, long past the horizon of nominal obsolescence.

 

It’s no wonder that machine suppliers sometimes have a hard time convincing processors to let go of “old faithful” and scrap it or trade it in for a new model. At a respectful distance from the battle-scarred veteran, Star Automation showed off a new model (not aimed at the U.S. market). The unspoken message seemed to be, “Take good care of it, and you’ll have plenty of time to grow attached to it.”

 




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