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OEM Report: Automotive

Strong results

By Russ Olexa

March 2010- Although limited to the automotive sector as a niche segment, press hardening--often called hot stamping--has allowed high production of stampings using high-strength and ultrahigh-strength steels.

Without the use of press hardening, forming these steel parts would be difficult using more conventional methods, such as mechanical presses, because of the extreme amount of press tonnage required and the high wear that the tooling experiences.

But what is press hardening? Instead of using a mechanical press with extremely high tonnage rates to form HS and UHS steels, parts are heated up to 1,700 F in a furnace adjacent to the stamping press and then hydraulically stamped and quenched while still in the die under pressure from the ram. This is done all in one stroke. Trimming these parts is usually done with a secondary trim die or a laser. This process allows a stamping company to produce parts up to three times stronger than if they were cold formed and all in the same press operation.

The heat is on
"The driving force behind this process are the national highway transportation committees throughout the world," says Rick Nicholson, inside sales and projects, AP&T North America, Monroe, N.C. "They're trying to get the automakers to reduce the weight of the vehicles, which increases their gas mileage. This also means that they can't just reduce the vehicles' weight by using lighter materials. The construction and the materials still have to maintain a specific safety rating. Therefore, there are collision-sensitive components on a vehicle, such as the front-end-crash box, side-impact A and B pillars and the transmission tunnel, that press hardening is used for with HS and UHS steels."

Nicholson says the B-pillar component weight has been reduced by up to 12 percent using HS or UHS steels and the press hardening process over a cold-formed component.

"The part has also gone from 650 megapascals tensile strength up to about 1,500 megapascals tensile strength," he says. "This process has more than doubled the strength of this component."

Nicholson adds that in the press-hardening application, because the part is heated up, the press tonnage is far less than what would be needed using a conventional stamping. Also, because of the HS or UHS steel being used, forming this steel conventionally would be difficult. For instance, about a 400-ton to 800-ton press would be needed for hardening, versus a 2,500-ton to 3,500-ton one for cold forming.

"With press hardening, you don't have the stresses that you would normally experience with the cold-forming application," says Nicholson. ÒCold forming can cause a lot of cracking in the corners of the stamped component, which doesn't happen using press hardening.

"Any mechanical press can't be used for this application either," he continues. "We need a hydraulic one that can press the part, hold the tonnage for a certain period of time at the bottom of the stroke and maintain it while the part cools. The cooling process can be anywhere from eight to 11 seconds or even more. We have customers that are producing these parts in their press that might dwell for 15 to 20 seconds to get the proper form."

High-performance presses
As an OEM, AP&T provides a turnkey system for press hardening.

"We don't make the parts--we just make the equipment that enables the stamping companies to make these components," says Nicholson. "We have the technology and, specifically for our system, the modularity. We build all of our components as modules. When a customer wants to build a bigger system, he can because our system allows them to expand. The performance and quality of this equipment also has to be extremely high. For instance, for the press to dwell for eight to 12 seconds at full tonnage, we need extremely high-quality hydraulic pumps for the stamping press. When we first did this, we had to change our pumps because they didn't have the performance needed for these long dwells. There are only a few companies right now that can provide this type of high-performance hydraulic stamping press."

Nicholson adds that it's really the Tier One stamping suppliers to the automotive OEMs that are getting involved with this type of stamping. Smaller companies can't afford these systems, he says.

"You're looking at a basic line that would produce about 500,000 components a year that would cost about $2.5 million," says Nicholson. "Whereas if you get into the UHS steels, a 3,500-ton mechanical press for this work will probably cost about the same amount of money, depending on the size of the press bed and other components."

But Nicholson believes press hardening can be used by other industries, such as aerospace and medical.

"Press hardening isn't only helping the gas mileage situation, but it's also helping with the safety side for the automotive industry," says Nicholson. FFJ

Sources

  • AP&T North America Inc.
    Monroe, N.C.
    phone: 704/292-2900
    fax: 704/292-2906
    www.apt-usa.com

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Company Profiles

AIR FILTRATION

IRONWORKERS

NESTING SOFTWARE

SERVICE CENTERS

Camfil APC - Equipment Trilogy Machinery Inc. Metamation Inc. Admiral Steel
Camfil APC - Replacement Filters

LASER TECHNOLOGY

PLASMA TECHNOLOGY

Alliance Steel
Donaldson Company Inc. AMADA AMERICA, INC. Messer Cutting Systems Inc.

SOFTWARE

BENDING/FOLDING

Mazak Optonics Corp.

PLATE

Enmark Systems Inc.
MetalForming Inc. MC Machinery Systems Inc. Peddinghaus Lantek Systems Inc.
RAS Systems LLC Murata Machinery, USA, Inc.

PLATE & ANGLE ROLLS

SigmaTEK Systems LLC

BEVELING

TRUMPF Inc. Davi Inc. Striker Systems
Steelmax Tools LLC

LINEAR POSITION SENSORS

Trilogy Machinery Inc.

STAMPING/PRESSES

COIL PROCESSING

MTS Sensors

PRESS BRAKE TOOLING

AIDA-America Corp.
Bradbury Group

MATERIAL HANDLING

Mate Precision Tooling

STEEL

Burghardt + Schmidt Group Fehr Warehouse Solutions Inc. Rolleri USA Alliance Steel
Butech Bliss UFP Industrial

PRESS BRAKES

TUBE & PIPE

Red Bud Industries

MEASUREMENT & QUALITY CONTROL

AMADA AMERICA, INC. BLM Group
Tishken Advanced Gauging Technologies Automec Inc. Prudential Stainless & Alloys

CONVEYOR SYSTEMS

METAL FABRICATION MACHINERY

MC Machinery Systems Inc.

WATERJET

Mayfran International Cincinnati Inc. SafanDarley Barton International

DEBURRING/FINISHING

LVD Strippit

PUNCHING

Flow International Corporation
ATI Industrial Automation Scotchman Industries Inc. Hougen Manufacturing Jet Edge Waterjet Systems
Lissmac Corp. Trilogy Machinery Inc.

SAWING

WELDING

Osborn

METAL FORMING

Behringer Saws Inc. American Weldquip
SuperMax Tools FAGOR Arrasate USA Inc. Cosen Saws Strong Hand Tools
Timesavers MetalForming Inc. DoALL Sawing T. J. Snow Company

HYDRAULIC PRESSES

MICROFINISHING TOOLS

HE&M Saw

 

Beckwood Press Co. Titan Tool Supply Inc. Savage Saws

 

Triform

 

 

 


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