The Bottom Line
Phygen PVD coatings provide a hard, slick barrier that protects die surfaces from wear.  They also enhance the flow of steel as it deforms against the die. The slick coating reduces friction that can cause bits of material to become welded to the tool, resulting in workpiece galling, scoring, and scratching.

The Numbers
With TD coating:
20,000 to 25,000
With CVD TiC coating:
139,000 hits
With FortiPhy coating:
199,000 hits


See Other Metal Forming Success Stories with FortiPhy High Performance Surface Coating


Die Casting Success Stories about FortiPhy Corrosion Resistant Coating

Injection Molding Success Stories with FortiPhy PVD-based Tool and Die Coating

See Other Emerging Application Success Stories where FortiPhy Chromium-Nitride (CrN) Surface Coatings Have Helped.

 

 

 

Metal Forming Success Story

PVD Surface Coating Outperformed TD Coating and CVD Coatings for Metal Forming Company Along with Fighting Downtime

Progressive stampers invest a lot of time, money, and energy in finding ways to fight downtime and make their presses as productive as possible.  Omni Mfg. Inc., St. Marys, OH, is one such stamper. A mentality of continuous improvement permeates the entire business, including the tool room that manages hundreds of dies used in 68 stamping presses.  About 5 percent of the dies are coated to prevent galling and heating during severe draws. Omni also relies on coatings to improve the performance of certain punches used in piercing operations.

Phygen’s PVD surface coating outperformed TD surface coating and chemical vapor deposition coatings (CVD coatings).
As one of Omni’s presses forms the heavy-duty door hinges, a transfer mechanism advances the workpiece to the next station in the die. Because Phygen’s FortiPhy Ultra Endurance coating on the four forming inserts inhibits galling and metal pickup, the four inserts last for nearly 200,000 hits, which is approximately 43 percent longer than a CVD TiC coating would last on the same tool steel.

“Typically, we look to coat anything that has a deep draw, does a lot of forming, or forms stainless steel,” says Bob Prater, tool room manager. In some cases, such as when working with stainless steel, coatings are mandatory for forming the part properly and achieving an appealing cosmetic appearance.

Coatings provide a hard, slick barrier that protects die surfaces from wear.  They also enhance the flow of steel as it deforms against the die. The slick coating reduces friction that can cause bits of material to become welded to the tool, resulting in workpiece galling, scoring, and scratching.

Omni had a particularly stubborn application in cutting and drawing heavy-duty door hinges from 5-mm-thick, high-strength, low-alloy steel—a project that originally had been contracted to another stamper. The die for this application required frequent reconditioning.

With a carbide-based thermal diffusion (TD) coating the previous stamper had been using, form inserts in the die lasted 20,000 to 25,000 hits before they needed to be recoated.  “In my mind, that wasn’t an acceptable number,” says Prater. He thought the coating should last for at least 100,000 hits.  To achieve this goal, he began experimenting with different substrates and coatings.

The first round of experiments involved two conventional titanium carbide-based (TiC), chemical vapor deposition coatings (CVD coatings) on three tool steels: D2, conventional M4, and powder metal M4. The coatings performed approximately the same on all three tool steels, boosting insert life to between 40,000 and 45,000 hits. Although performance doubled, it still fell short of the goal Prater had in mind. He continued his search for a better combination of substrate and coating.

During the search, he heard about a new coating/substrate combination that one of his tool suppliers used for severe draws. The dies were made of DC53 tool steel and coated with FortiPhySM UltraEnduranceSM Coating from Phygen Inc.

Phygen’s PVD surface coating outperformed TD surface coating and chemical vapor deposition coatings (CVD coatings).
Producing these heavy-duty door hinges is 10 times more economical since Omni switched both the substrate and coating on the inserts that form them inside the stamping die.

Using a proprietary physical vapor deposition (PVD) process that exploits plasma acceleration, the coater is able to deposit a thin, hard, dense protective layer at about half the temperature of conventional hot TD and CVD coatings process. Because the resulting coating has a single-phase, nanocrystalline structure, it has the critical load strength to withstand the constant pounding and extremely high forces inherent in metal stamping. Moreover, the hard coating has a low coefficient of friction (less than 0.1).

To test the coating, Prater bought a bar of DC53 from International Mold Steel Inc. and made two sets of inserts from it to conduct a controlled study that compared the performance of the new coating with the conventional TiC coating on this unfamiliar grade of tool steel. “All of the DC53 came from the same bar,” explains Prater. “They [test inserts] were heat-treated at the same time and processed in the same way.”

Although both substrate-coating combinations improved tool life substantially, and more than met Prater’s performance goal, FortiPhy from Phygen outperformed the CVD coatings (chemical vapor deposition coatings) by 43 percent. It lasted approximately 199,000 hits, whereas the CVD TiC coating lasted only 139,000 hits.

Phygen’s PVD surface coating has the adhesion and wear resistance of CVD coatings, but does not distort tooling.
Omni had this set of four forming inserts stripped, polished, and recoated with Phygen’s high performance tool coating. The coating has the adhesion and wear resistance of CVD processes, but because it is applied at a relatively low temperature, it does not distort the tooling. This characteristic lends itself to recoating the tooling over and over again.

Not only did the longer-lasting FortiPhy coating reduce downtime by allowing the die to run longer between reconditionings, but the Phygen PVD process did not distort Omni’s die inserts. “Anytime there are blocks that fit together, we have only a thousandth [of an inch] or so to play with,” Prater said. Despite the limitation, the inserts fit into the die after the FortiPhy coating process and conformed to the print.

This had been a persistent problem for Omni. “If we’d send out rings, for example, for coating, they’d come back too big, egg-shaped, or too small,” reports Prater. “So we would have to regrind them back into shape.”  Phygen’s cooler PVD process eliminates the tendency for tooling to distort. “We temper our tool steel at roughly the same temperature that Phygen applies its coating,” Prater said. “So, theoretically, the stresses are relieved.”

Despite the benefits that his controlled study documented, Prater enlisted Phygen’s help in running another battery of tests. The first of these tests will help Omni determine the optimal number of strokes that the door hinge die can run the coated inserts before pulling them for reconditioning.  “I think that press operators ran [both sets of dies] maybe 10,000 pieces more than they should have” in the first study,” Prater observes.

Although results showed the new coating/substrate combination exceeded his goal by nearly 100 percent, Prater wanted to determine the right number of hits for production to use as a guideline for sustained use.  In addition, two other experiments are pending. One is testing the coating on a tool for producing an exhaust resonator.  The other is testing it on some deep-drawing rings for manufacturing stainless steel bushings for front-end suspension units.

Management at Omni puts great stock in such dividends and invests heavily in finding more productive ways of stamping better parts. In fact, it credits these gains and others from continuous improvement programs as crucial to the company’s growth throughout the past few years when many of its competitors closed their doors.  “We like new technology,” Prater summarized. “We’re fairly aggressive about trying new things.”

The key to FortiPhy's exceptional toughness, low coefficient of friction, and corrosion resistance is its uniform, nanocrystalline structure. Phygen’s patented plasma acceleration process improves upon traditional PVD methods to produce the most uniform coating deposition layer possible, with exceptionally high adhesion.

Having solved the uniformity problems inherent in the PVD processes of the past, Phygen can apply thinner coatings that outperform thicker, less-uniform coatings. In addition, Phygen FortiPhy metal form tool coatings are applied at much lower temperatures. Low-temperature processing and thinner coatings help keep critical tool dimensions within tolerance, without the costly rework of other processes.


Phygen Coatings, Inc.
1400 Marshall Street, NE / Minneapolis, MN 55413-1040
Toll Free 888.749.4361 / Fax 612.331.4230 / tech@phygen.com