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PROCESS AUTOMATION IS REDEFINING HOW

ARE HEAT TREATED

Peter Hushek is president of PhoenixHeat Treating, a fourth-generation heattreater, and owner of one of the largest andleading heat treating companies in thesouthwest. “A bad atmosphere that’s evenslightly out of calibration can cause manydelayed onset problems for fastener manu-facturers,” Hushek said. “Why take chanceswhen there have been significant advancesin heat treating that guarantee that theprocess has been performed exactly as youhave specified?”

Precise measurement and control can bechallenging when operated manually, butthe new technology has led to tighterprocess control and higher quality stan-dards, while keeping costs down. Tempera-ture and atmosphere control affect thecomposition of the part as it is heated andtransformed. Typically, atmosphere is con-trolled by using endothermic gas to eithercarburize or prevent decarburizing on theparts processed. If the temperature oratmosphere deviates, the desired resultscannot be achieved.

Hushek is a pioneer in the use of heattreating automation. In 2001, his collabora-tion with Steve Thompson of Super SystemsInc., based in Cincinnati, Ohio, led to thedevelopment of logic control systems thatallow temperatures and atmospheres to beguaranteed based on customer variables.Because of pioneers like Hushek and

Thompson, huge advances in control-sensortechnology and automation have driven pro-cessing requirements to acquire moredetailed information and achieve greateraccuracy, maintain safeties and reduceopportunities for error. Today’s process con-trol is really about providing fastener manu-facturers with a greater ability to achieverepeatable performance, remain cost com-petitive and have access to all the data thatbacks up the required results in real-time.

“I think about quality processing all thetime,” said Paul Tiffany, manager for CopperState Bolt and Nut Company’s Phoenix man-ufacturing division. “We sell fasteners allover the world and have to maintain cus-tomer-defined specifications on every ship-ment. Having verifiable data assures us thatour quality is consistent.”

A common practice is controlling theendothermic gas up-stream on theendothermic generator. The endothermicgenerator creates an atmosphere to providea positive pressure in a heat-treating fur-nace and a platform on which a carburizingor decarburizing environment can be formu-lated. The most common source ofendothermic gas is the reaction product ofair and natural gas. Gas providers today areobligated to provide customers with a gasmeeting a BTU rating, but that does notmean the gas being provided is made up ofjust methane. In this situation, the

Reprinted from American Fastener Journal November/December 2008

by Tom Kirby, Advanced Marketing Approaches, Phoenix, ArizonaJim Oakes, Super Systems, Inc., Cincinnati, Ohio

fastener partsfastener parts

Today, fastener manufacturers want controlled uniformity in the mechanical properties of

their heat-treated parts. The major challenge has always been in maintaining the process

requirements as the parts move through continuous furnace applications. The manual

methods of controlling multiple zones of temperature, atmosphere, agitation, belt speed(s),

loading, unloading, quench media, etc., add up to many opportunities for error in maintaining

exact specifications. Fastener manufacturers who must meet higher quality certifications,

quicker turnaround and documented proof of performance don’t have the time or the profit in

their jobs to waste on trial and error.

endothermic gas produced may not providethe necessary atmosphere the processrequires. This is where automated controlsworking with sensor technology are used tomaintain a quality atmosphere that theparts are exposed to. Microprocessor-basedcontrollers calculate and display dew point,control output for maintaining the dewpoint set point and generator temperature.With these inputs, the controller regulatesthe addition of enriching gas or dilution airto achieve that critical atmosphere neces-sary in the furnace.

“It’s paramount to keep threaded compo-nents free of surface contamination, whichcan be managed with real-time visibility inthe automated furnace,” Hushek said. “Theprogrammable controller can be set to hityour target values from start to finish.”

The precision control of the variables ofheat ramp-up, carbon-boost and carbon dif-fuse, cool down and quench delivers a guar-anteed process that can be duplicated bylogic systems to be the same every time.Simulation software such as Super SystemsCarbCALCII carburizing simulation and con-trol software can be used to identify how anout-of-control situation related to tempera-ture or atmosphere can produce undesirableresults before the parts are run. The natureof a continuous furnace is such that furnaceopenings and impurities from parts andquench oil are always playing a factor incontrol. However, atmosphere control inmulti-zones provides precision control thatfastener manufacturers desire. Phoenix HeatTreating has multiple oxygen-probes thatare used to ensure proper atmosphere, onelocated at the beginning of the heat cycleand one just before quench. The oxygensensor is connected to a microprocessor-based controller that uses that informationto determine if the atmosphere is at thedesired set point. The automated PID (pro-portional integral derivative) controller usesthe information, along with numerous con-

Process Automation is Redefining How Fastener Parts are Heat Treated

trol parameter settings, to add enriching gasor air to meet the desired set point. Mostconventional heat treaters will use eitherfixed gas flows or a single oxygen probe.

When using process automation, cus-tomers can be assured that parts are deliv-ered to pre-defined specification with proofof process using data acquisition. Anotheradvantage is the ability to run differentprocesses for different fasteners on thesame furnace. Because of the variation ofspeed, temperature and atmosphere, themore in-situ sensors tied in with controls,the greater the utilization of the furnacewithout compromising the results.

Process automation has led to simplifi-cation. Phoenix Heat Treating’s continuousfurnace runs itself from customer programsthat are stored in the data system. Time,temperature and atmosphere are controlledfrom start to finish by the programmablecontrols, and the electronically documentedprocess is stored in the logic center andprinted out for verification of processing.Hushek said the furnace can be remotelycontrolled from a laptop anywhere in theworld to make adjustments in any of thevariables.

The fastener manufacturers who areusing the new “intelligent heat treating,” asHushek calls it, are reaping the rewards oftraceability and verifiable data that showload characteristics and proof that the pro-cessing meets industry certifications.SCADA systems (Supervisory Control andData Acquisition) are known for providingquick access to this information and a foun-dation for plant automation.

“There’s not enough manufacturingcapacity to produce fasteners for the aero-space industry today,” said Bob Herber, Ari-zona operations manager for Pilgrim Screw.“Most companies are quoting one to two

years for delivery. We’re quoting 26 weeks,and when our shipment arrives, it has tomeet AMS-H-6875 (Department of Defense)certifications. With Phoenix Heat Treating’sautomated processing, we receive electronicdocumentation with time-dated traceabilitythat guarantees the consistency and qual-ity.”

The goal of these systems is to provide auser-friendly environment to enter dataassociated to the load and make the processof gathering this information quick and easy.Scanning technology, computers and load-ing systems provide a method of automat-ing this process.

The other benefit to SCADA systems isthe reduction of paper. With control andsensor technology available today, data islogged using direct communications to con-trollers and accomplishes the same thing asa paper recorder with a significant amountof additional functionality. The data that is

logged can be viewed by many peoplethroughout the plant and is very easy toretrieve. When valuable information isaccessible to multiple parties, others cantake advantage of it. Maintenance, qualityand production planning all have quick andeasy access to information. The direct bene-fit comes with reliability and integrity of thedata as well as a reduction in maintenancelabor to support the equipment. Informa-tion, both real-time and historical, is acces-sible at your fingertips, and there is no morechanging paper stock on the recorders.

With automated processing, heat treat-ing of fasteners can be simulated on a com-puter, with your variables programmed inmemory, before the job is actually run. Thecomputer simulation will determine if therecipes need to be adjusted in advance ofrunning the job. Once the variables arelogged in, the programmable controls drivethe automated process, and each processingstep is tracked and time-stamped with anelectronic record that retains all the processdata. With one operator and computerizedautomation, your next processing job will bea duplicate of the previous job.

For fastener manufacturers, automatedcontrol of your heat treating processes willguarantee higher quality, quicker turnaroundand more competitive costs. !

Phoenix Heat Treating, a leading heat treating company inthe southwest U.S., is located in Phoenix, Arizona. PeterHushek, president of the company and a metallurgicalengineer, is a fourth-generation family heat treater. Thecompany has been a leader in the development and implementation of state-of-the-art automation, computer-ized modeling and programmable control systems. For moreinformation on automated heat treating, contact PhoenixHeat Treating at 602.258.7751, or visit www.phoenix-heat-treating.com.

Reprinted from American Fastener Journal November/December 2008

Peter Hushek and the automated, continuous cast link belt furnace that is usedto process fasteners, stampings and screw machine parts. The furnace can handle 2,500 pounds an hour for either neutral or light case work.

Peter Hushek verifies automated processing control set points before heat treating a fastenerjob. The programmable logic controllers auto -matically run every system in the continuous castlink furnace.