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Fusing the Heat Treat Practices with Human Creativity

OC Creation requires endurance and continued hard work. Find out what creative applications and research services your colleagues are committed to bringing from across the heat treat industry.

These innovations could bring the next level of innovation to your industrial plants. Enjoy!


Novel Mechanical Testing Systems Powered By Finite-Element Analysis, Optimization Algorithms, and Machine Learning

- An excerpt from a Heat Treat Radio episode with James Dean -

Doug Glenn:  You may have already stated this a little bit, but briefly: indentation plastometry is basically taking an indentation to be able to test, not just hardness or not even necessarily hardness, but the deformation or the strain of material.  Do you have to know the microstructure of the material when you’re doing these tests?

James Dean:  That’s a good question.  In principle, no.  If we were to dig deep into the mechanics of what’s going on within our system and our software package, you’d come to recognize that it’s, from a mathematical point of view at least, insensitive to microstructural features.  There is a numerical method underlying this – a finite-element analysis – therefore, treating this as a continuum system doesn’t take account explicitly of the microstructure.

When you’re doing the test, it’s actually helpful to know something about the microstructure simply because our technology is all about extracting bulk mechanical behavior engineering properties.  Therefore, when we do our indentation test, it is important that we are indenting a representative volume of the material.

It is important that we are capturing all of the microstructural features that give rise to the behavior you would measure in a microscopic stress strain test.  Otherwise, you can’t pull out those bulk, core engineering properties, and therefore, the scale on which you do the indent is important.  Your indenter has to be large relative to the scale of the microstructure.  So, it’s only at that level that you need to understand or know anything about the microstructure.

DG:  This test is a nondestructive test, right?  You said you can actually test live materials, correct?

JD:  Yes.

DG:  You don’t have to destroy them, you don’t have to machine them, you don’t have to make them into something you can rip apart, right?

JD:  Right.

Read/Listen to the full interview here.


Bert demonstrates the benefits of working with a collaborative robot to induction harden steel parts. The robot gives the operator the ability to work directly next to it, as opposed to conventional robot arms where fencing and distance is required.

Robotic Revolution

- An excerpt from Metal Treating Institute Member Profiles with Penna Flame Industries -

The computerized robotic surface hardening systems have revolutionized the surface hardening industry. These advanced robots, coupled with programmable index tables, provide an automation system that helps decrease production time while maintaining the highest quality in precision surface hardening.

A few benefits of this service are:

  • Increased wear resistance
  • Higher hardness and longer life
  • Less processing time
  • Higher efficiency and productivity
  • Maintain tensile strength
  • Quick turnaround of the project
  • Consistent, repeatable process
  • Less distortion when compared to furnace treatment

Read the full article here.


High Pressure Break Through For Additive Manufacturing

- An excerpt from a Heat Treat Radio episode with Johan Hjärne -

DG:  Doing it all- stress relief, HIP, age, or whatever. Just for clarity sake, you’ve got a typical HIP process, you’re going to heat it up, put it under very high pressure, then, normally, if you didn’t have the high pressure heat treatment capabilities, you would have to cool that part down which is typically cooled quite slowly in a conventional HIP unit, taking more time and whatnot.  It then comes down to ambient, or close to ambient, where it can be held, you take it out, you put it back in another furnace (a normal furnace, not a HIP furnace), take the temperature back up, get it to the point where you want it, quick cool it, quench it, to a certain extent, to get the characteristics that you’re looking for, and you’re done.  What we’re talking about here is the combination of those two processes plus potential other things like stress relief, and all that, in a single unit, correct?

JH:  Yes.  This has very beneficial effects on time.  Many of the HIP vendors do not have HIP and heat treatment in the same facility.  Now we have sold a couple of units to some new HIP vendors that have this capacity, but, historically, the HIP vendors didn’t have both HIP and heat treatment.  First, the customer had to send it to a service provider for HIPing, they got the part back, they had to send it to somebody that could do the heat treat step, and then got the part back, and so on.  The time, and specifically for additive manufacturing, is important.  Keep in mind they can do a part pretty fast, anywhere between a day to two days, worst case a week, but then having to wait week after week after week to get the part back for the HIPing or for the heat treating.

DG:  So there’s a substantial, potential time savings, for sure; not just process savings in between furnaces, but the fact that you can buy one furnace and do both of those things.

Let’s talk for just a second about what types of products are most effectively HIPed and/or, if we can, high pressure heat treated.

JH:  As I said before, we really started to realize the potential with this technology with the additive manufacturing world.  That is were we started to realized that we can actually make a difference here.  Not only does it have a beneficial effect for the total time, but having the components under elevated temperature for a shorter period of time is actually beneficial for the microstructure; the grain doesn’t grow as much.

Read/Listen to the full interview here.


Modernizing Tech

- An excerpt from Metal Treating Institute Member Profiles with Franklin Brazing and Metal Treating -

Recent improvements include a new cooling tower, chiller system, enhanced duct work, LED lighting in the plant, a renovated breakroom for the associates, a quality room for the engineering staff, a new HVAC system for the front offices, and upgrades in technology systems.

The updated technology is not only used for improving efficiency and data analysis, but also for communication. It has been key to improving operations and has had a significant impact on relationships with clients. Franklin’s ability to effectively communicate enhances collaboration, which allows FBMT’s clients to more efficiently manage their supply chains, reduce the cost of rework and scrap, and better serve their clients.

Read the full article here.

Fusing the Heat Treat Practices with Human Creativity Read More »

“heatprocessing”: Innovative Partnerships and Research

Welcome to another Technical Tuesday! Today, we look to our European information partner, heatprocessing, to share several new partnerships and innovative research that are happening globally in the world of heat treat.


Salzgitter Flachstahl and Anglo American Reach an “Understanding”

“Salzgitter Flachstahl GmbH, subsidiary of Salzgitter AG, has signed a Memorandum of Understanding (MOU) with Anglo American. The two partners will join forces in investigating the optimisation of iron ore supplies for direct reduction.

“Anglo American is one of the world’s leading mining groups. The primary aim of the joint research activities is to minimise the CO2 footprint of steel production. The MOU also covers an examination of the lowest possible CO2 process and supply chains.”

Read More: “Joint research: Salzgitter Flachstahl and Anglo American sign Memorandum of Understanding


NOTICE: Farming for Wind, Need Furnace

“The Yeong Guan Group (YGG) based in Taiwan has chosen ABP Induction as its partner to develop a large-scale sustainable project on the west coast of Taiwan. There, Hai Long 2, a 300 MW offshore wind farm, is to be built in the harbour area of the megacity of Taichung, whose components will be manufactured entirely by local stakeholders in Taiwan.

Hai Long 2 is planned to be a regional industrial centre of excellence for offshore wind energy technology around Taichung. The idea is to concentrate the competence for development and planning as well as the production of corresponding components locally. This is intended to accelerate the transition to a sustainable energy supply through wind turbine technology for Taiwan and the entire Asia-Pacific region.”

Read More: “Energy transition in Taiwan: YGG opts for large furnaces and digital concept from ABP Induction

 

Aluminum is the New Steel

“Where steel was once used, aluminium is now driving the future: The ALUMINIUM Business Summit will celebrate its premiere at the Old Steelworks in Düsseldorf from 28 to 29 September 2021.

“With the new hybrid format of the Business Summit, ALUMINIUM, Aluminium Deutschland, the CRU Group and European Aluminium have joined forces to offer a new platform for technological, legislative and industrial exchange, enabling a constructive dialogue to tackle the biggest challenges of the future: low-carbon mobility, digitisation, sustainability and the future rules of the international market. The participants can either be present live at the networking event in Düsseldorf or follow the keynotes, discussion rounds and interviews online.”

Read More: “Premiere of ALUMINIUM Business Summit in the Old Steelworks in Düsseldorf

 

 

“heatprocessing”: Innovative Partnerships and Research Read More »

Enjoy the Long Weekend!

It’s an honor to serve the good people in the heat treat industry. This labor day weekend, we hope you take a rest from the meaningful work that you do to catch a late morning coffee with those rambunctious kids, the “independent” cat, or your bedside table book.

There won’t be a Heat Treat Daily on Monday, so don’t worry about missing out! 

See you tomorrow!

- The Team at Heat Treat Today 

9/6/2021

Enjoy the Long Weekend! Read More »

Redline Industries, Inc. Acquired by North American Refractory Solutions Provider

HTD Size-PR LogoA supplier of monolithic refractories and construction services announced that it has completed the acquisition of Redline Industries, Inc., solidifying its reputation for innovation and customer satisfaction.

Jim Host
Business Development Manager
Redline, Inc.

Based in Chicago, IL, Redline Industries, Inc. was founded in 1998 and today is recognized as a first-rate supplier of low-cement refractory castables and gun mixes, having earned industry recognition for the quality of its products and the integrity of its people and business practices. Redline™ refractories are engineered to safeguard furnaces in the high-temperature processing of non-ferrous metals, such as aluminum, as well as prevent furnace heat loss to promote greater energy efficiency.

 

Brad Taylor
President and CEO
Plibrico

The Plibrico Company, LLC will provide seamless consistency for Redline customers by continuing to manufacture Redline refractories to their current specifications, while promoting the Redline brand within Plibrico's broad portfolio. Dedicated Redline support experts will carry on serving customers with no interruptions.

"This acquisition enhances our ability to better serve our customers," said Jim Host, business development manager at Redline.

"We are thrilled to bring Redline into the Plibrico family," commented Brad Taylor, president and CEO at Plibrico. "We believe this acquisition will provide customers with more choices as we leverage our complementary technologies and our core competencies in customer care, product development and manufacturing."

Redline Industries, Inc. Acquired by North American Refractory Solutions Provider Read More »

Large Car Bottom Furnace for US Heat Treater

HTD Size-PR LogoFrom the southeastern U.S., a leading manufacturer of specialty alloys, pipes, tubes and fittings has placed an order for a large gas fired, car bottom furnace that is scheduled for delivery in Q4 2021.

The furnace from L&L Special Furnace Company will be used for normalizing various steels and specialty alloys at temperatures up to 2,200°F (1,200°C). It will also be used to preheat, stress relieve and temper various steels and large pipe fittings.

The L&L model FCG4410 has working dimensions of 48” wide by 48” tall by 120” deep. Uniformity of ±25°F ( 12.5°C) or better is expected throughout the work zone. Complete factory testing and on-site commissioning is included.

The gas fired furnace uses six medium velocity burners that fire over and under the load. The furnace car moves in and out of the unit on supplied railroad type rails. The door is mounted to the car and is motorized with all required stops and clearances. The side seals are pneumatic and seal to the car bottom once the car is inside the furnace. Castable piers provide good support for up to a 10,000 pound load. The furnace is completely insulated with ceramic fiber modules.

The control is a floor-standing NEMA12 panel with fused disconnect at the source. All fusing and interconnections are included. The furnace is controlled by a Eurotherm Nanodac program control with two slave units. Three-zone control is provided to promote uniformity. Overtemperature protection is provided along with a six-input paperless chart recorder and jack panel.

Large Car Bottom Furnace for US Heat Treater Read More »

Mercury Marine Launches Heat Treat Upgrades

HTD Size-PR LogoMercury Marine of Fond du Lac, Wisconsin, recently launched a plan to upgrade its heat-treating capabilities with a move to the low-pressure carburization and high-pressure gas quench system. The new plan incorporates completely automated vacuum heat treating systems.

In the partnership with ECM Technologies, the Nano vacuum heat treating system (pictured above) incorporates 20 bar nitrogen gas quenching along with low pressure carburizing (aka vacuum carburizing). The Nano will operate several different carburizing, hardening, and spheroidizing processes simultaneously.

This change marks a departure from Mercury’s traditional atmospheric carburization and oil quench system while benefiting from advantages that come with vacuum processing:

  • Applies vacuum heat treating in lieu of traditional atmosphere (elimination of intergranular oxidation & highly repeatable process with consistent results)
  • Employs preventive maintenance planning, remote system status access, and facility information systems integration
  • Relocates heat treat from a secondary location to the clean, controlled environment of the machining centers
  • Converts to small batch processing principles to maximize process efficiency
  • State-of-the-art growth with ECM’s advanced system automation and robot capability with load building and breakdown
  • Controls downstream operations by matching incoming dunnage with exiting workpieces
  • Takes advantage of vapor and vacuum-based pre-cleaning technology to remove multiple machining lubricants
  • Incorporates cryogenic and tempering processes within the automated system

The system uses all CFC workload fixtures and ECM’s advanced automation fixture tracking to maintain a precise cycle count to know fixture life. For Mercury, this significantly reduces energy consumption and process cost per piece. Additionally, the vacuum process takes their heat treatment to a near-zero emissions for drivetrain components processed within the system.

Mercury Marine Launches Heat Treat Upgrades Read More »

Moving Beyond Combustion Safety — Designing a Crystal Ball

In June, we spent a good deal of time discussing a simple pressure switch to emphasize the many considerations that are necessary for proper installation. Now we will expand the discussion to how the switch works and what steps we can take to detect a failure that is likely to occur sometime in the future.

This column appeared in Heat Treat Today’s 2021 Automotive August print edition. John Clarke is the technical director at  Helios Electric Corporation and is writing about combustion related topics throughout 2021 for Heat Treat Today.


John B. Clarke
Technical Director
Helios Electric Corporation
Source: Helios Electric Corporation

A pressure switch is a Boolean device — it is either on or off — so how can we evaluate its performance in a manner where a potential failure can be detected before it occurs? The simple answer is time — how long does it take for the switch to respond to the condition it is intended to sense? What is the period between starting an air blower and the pressure switch closing? Has this time changed? Is a change in this time period to be expected, or does it portend a future failure?

A simple approach to evaluating this pressure switch’s time is to create predetermined limits — if the switch responds either too rapidly or too slowly — an alarm is set and the operator is alerted. Graph 1 illustrates this approach.

In Graph 1, the black band represents the time between the action (the start of the air blower) and the pressure switch closing. There is a warning band (yellow) — both high and low — that provides the early warning of a system performance problem. There is also a critical band (red) — both high and low — that provides the point at which the feedback for the pressure switch is determined to be unreliable. If the switch is part of a safety critical interlock, the system should be forced to a safe condition (in the case of a combustion system, with the burner off and a post purge being executed) if required.

Graph 1

Graph 2 depicts when a switch closing time exceeds the warning level. It could be the result of a problem with the blower and/or the pressure switch, but the deviation is not sufficiently large as to undermine confidence in the switch’s ultimate function.

Programmatically, if the time exceeds the warning band, and an alarm is registered, the responsible maintenance person is notified. If that is in the warning band, it can be addressed as time allows.

Graph 2

The warning bands give us the crystal ball to potentially see a problem before it causes a shutdown. As it is continuously monitored by the programmable logic controller (PLC), it may provide an increased level of safety, but that is dependent on a number of factors that are beyond the scope of this article.

The switch can be not only too slow to respond: an unusually fast response is a reason to be concerned as well. It could be that the pressure switch setpoint has been set too low — so low that it no longer provides useful feedback. Graph 3 is an example with an unusually fast response.

If the time is less than the “Critical Low” preset value, the switch’s feedback is determined to be unreliable. In this case, the setpoint may have been changed during a maintenance interval or even worse — the switch may be jumpered (this assumes we have an interlock string wired in series). The critical values are NOT intended to provide forward looking estimates of required maintenance — they are simply an enhanced safety measure.

This scenario assumes that the response of a component is consistent. In our example of a pressure switch monitoring an air blower, we can assume the time the blower required to reach full speed, the time for a pressure rise time in the air piping, and the responsiveness of the switch is consistent. These time intervals may not be consistent. The air supplied to the blower could be sourced from outside the building (temperate climate), which could cause air density changes between a cool, dry day and a hot, moist day. In this instance, what can be done to detect a failure?

An approach where we see fluctuations in the timing even in instances where all the components are operating properly would be to run a moving average of the time based on the last n operations. Then we compare the moving average to the last time and confirm that any change falls within a specific range.

Step 1 would be to average the last n values for the time required for the switch to trip. Then compare this value (ta) to the last time and see if the deviation exceeds the preset values. Let us assume if the time varies by more than 20% a warning should be issued to the maintenance staff.

Now this method will accommodate rapid fluctuations – but if the performance of the component degrades in a near linear fashion, this formula will not detect a premature failure.

An alternate approach would be to execute this routine on the first n cycles, as opposed to continuously updating the average. Using this method, the performance of the specific component is captured. Or this averaging can be executed on demand or based on the calendar or Hobbs timer.

These concepts are far from new, and it has only been because of the recent expansion in PLC memory storage capacity and processing power that it has been reasonable to perform this analysis on dozens of components on a furnace or oven. Remember, it is a shame to waste PLC processing time and memory!

One or more of these approaches, or similar approaches analyzing time, can indeed be a crystal ball that gives us warning of any of a number of potential failures — warning before a system shutdown is required.

About the Author:

John Clarke, with over 30 years in the heat processing area, is currently the technical director of Helios Electric Corporation. John’s work includes system efficiency analysis, burner design as well as burner management systems. John was a former president of the Industrial Heating Equipment Association and vice president at Maxon Corporation.

technical Tuesday

Moving Beyond Combustion Safety — Designing a Crystal Ball Read More »

IHEA Monthly Economic Report: The Good. The Bad. The Ugly.

"That sense of euphoria over the rapid growth sustained since the start of the year has started to fade and not for the reason that was expected," states July's Industrial Heating Equipment Association’s (IHEA) Executive Economic Summary. Remember at the beginning of the year, there was an expectation that there would be growth, but it would hopefully be a bit slow. That was preferred because then "producers would be able to keep pace with demand and that would minimize the inflation threat."

As indicated, when looking at the data for capacity utilization, there has been a great deal more investment in equipment, machinery, and technology in the last few months. The swift recovery of the economy convinced many companies they needed to move quickly to meet that surge in demand.

The report explains that "What we actually got was an economy on fire with a 6.5% growth rate in Q2. Suddenly the inflation threat was real as producers were quickly overwhelmed." But, as everyone was preparing for growth, Covid reared its ugly head again. "Now we see potential decline in the last half of the year as those protocols and restrictions reappear. "Will there be another lockdown? Will consumers retreat again and send the service sector back into recession?" Those are vital questions that are begging for answers.

Businesses had two possible responses to the early surge, both based on consumer action: add capacity to meet the demand and trust the surge will continue or hold tight and possibly lose business to competitors. The summary reports, "Until roughly a month ago, it would have been a good bet to assume that demand would continue to grow – all the signs and indicators were pointing that way. Today the story is far less clear. The resumption of pandemic protocols has been an immense disappointment and has created significant tension."

The data from the PMI has been getting progressively better and these are very high numbers in general. (The PMI index indicates expansion when the numbers are above 50 and contraction when they are below 50. The last time the index was even close to that decline was a year ago when the reading was 50.9 and it has been climbing ever since.) The unique aspect of the PMI is that it is current and honest – it is literally a monthly assessment of what industries are buying.

So, where does that leave the U.S. economy for the remainder of the year? There are three scenarios: the good, the bad, and the ugly. The good is one in which "people basically adjust to the protocols with some patience. . . . If that is the case, the expectation is that growth rates will be relatively unaffected." The bad suggests that "consumers do not adapt well and begin to shift their behaviors back to what they were last year – shunning events, restaurants, travel, and other public activity." And the ugly scenario could result if "the outbreak gets bad enough that lockdowns are reimposed."

The report concludes that "consumer growth and tension are not good companions." Time will reveal the consumer's chosen scenario.

Anne Goyer, Executive Director of IHEA
Anne Goyer, Executive Director of IHEA

Check out the full report to see specific index growth and analysis, which is available to IHEA member companies. For membership information, and a full copy of  the 12-page report, contact Anne Goyer, executive director of the Industrial Heating Equipment Association (IHEA). Email Anne by clicking here.

 

IHEA Monthly Economic Report: The Good. The Bad. The Ugly. Read More »

The Clean and Pure: 8 Heat Treat Tips

OCWant a free tip? Check out this read of some of the top 101 Heat Treat Tips that heat treating professionals submitted over the last three years. These handy technical words of wisdom will keep your furnaces in optimum operation and keep you in compliance. If you want more, search for “101 heat treat tips” on the website! This selection features 8 tips to make sure your operations are clean and pure.

Also, in this year’s show issue, Heat Treat Today will be sharing Heat Treat Resources you can use when you’re at the plant or on the road. Look for the digital edition of the magazine on September 13, 2021 to check it out yourself!


Oil and Water Don’t Mix

Keep water out of your oil quench. A few pounds of water at the bottom of an IQ quench tank can cause a major fire. Be hyper-vigilant that no one attempts to recycle fluids that collect on the charge car.

(Combustion Innovations)


Dirt In, Dirt Out!

Parts going into the furnace should be as clean as possible. Avoid placing parts in the furnace that contain foreign object debris (FOD). FOD on work surfaces going into the furnace will contaminate the furnace and the parts themselves. Dirty work in, dirty work out. FOD comes in many forms. Most common: oil, grease, sand in castings or grit blasting operations, and metal chips that generally originate from the manufacturing process before the parts are heat treated. It could also be FOD from the shipping process such as wood or plastic containers used to ship the parts.

(Solar Manufacturing)


Remove Particulates

Adding a strong magnetic filter in line after the main filtration system is an effective way to remove fine, metallic particulates in an aqueous quench system.

(Contour Hardening, Inc.)


Seal Away Dirt or Dusty Environments

Use a sealed enclosure or alternative cooled power controllers for dirty and dusty environments. For heavy dirt or dusty environments, a sealed cabinet with air conditioning or filters is recommended. Alternatively, select a SCR manufacturer that offers external mount or liquid cooled heatsinks to allow you to maintain a sealed environment in order to obtain maximum product life.

(Control Concepts)


Copper as a Leak Check

If maintaining dew point is a problem, and it’s suspected that either an air or water leak is causing the problem, run a piece of copper through the furnace. Air will discolor the copper; water will not.

(Super Systems, Inc.)


Oxygen Contamination Sources

A common source of oxygen contamination to vacuum furnace systems is in the inert gas delivery system. After installation of the delivery lines, as a minimum, the lines should be pressurized and then soap-bubble tested for leaks. But even better for critical applications is to attach a vacuum pump and helium leak detector to these lines with all valves securely closed, pull a good vacuum, and helium leak check the delivery line system. Helium is a much smaller molecule than oxygen and a helium-tight line is an air-tight line. Also, NEVER use quick disconnect fittings on your inert gas delivery system to pull off inert gas for other applications unless you first install tight shut-off valves before the quick disconnect. When the quick disconnect is not in use, these valves should be kept closed at all times. (Though the line is under pressure, when you open a back-fill valve to a large chamber, the line can briefly go negative pressure and pull in air through a one-way sealing quick disconnect valve.)

(Grammer Vacuum Technologies)


Container Clarity Counts!

Assure that container label wording (specifically for identifying chemical contents) matches the corresponding safety data sheets (SDS). Obvious? I have seen situations where the label wording was legible and accurate and there was a matching safety data sheet for the contents, but there was still a problem. The SDS could not be readily located, as it was filed under a chemical synonym, or it was filed under a chemical name, whereas the container displayed a brand name. A few companies label each container with (for instance) a bold number that is set within a large, colored dot. The number refers to the exact corresponding SDS.

(Rick Kaletsky, Safety Consultant)


Discolored Part—Who’s to Blame?

If your parts are coming out of the quench oil with discoloration and you are unsure if it is from the prewash, furnace, or oil quench, you can rule out the quench if the discoloration cannot be rubbed off. Check this before the part is post-washed and tempered.

Other possible causes:

  • Can be burnt oils as parts go through the quench door flame screen
  • Poor prewash
  • Furnace atmosphere inlet (particularly if it is drip methanol)

(AFC-Holcroft)


Check out these magazines to see where these tips were first featured:

 

 

 

 

 

 

 

 

The Clean and Pure: 8 Heat Treat Tips Read More »

Heat Treat Radio #61: Thermocouples 101 with Ed Valykeo, Pelican Wire (Part 1 of 3)

Heat Treat Today publisher Doug Glenn sits down with Ed Valykeo from Pelican Wire in the first of a three-part series on all-things thermocouples. This first episode covers the history, types, vocabulary, and other basics of understanding how thermocouples work.

Below, you can either listen to the podcast by clicking on the audio play button, or you can read an edited transcript.

 



The following transcript has been edited for your reading enjoyment.

Doug Glenn (DG):  Ed, why don't you take a minute, as we typically do on these interviews, to talk briefly about you and your background especially your qualifications for talking about thermocouples.

CLICK the image to access the article!

Ed Valykeo (EV):  I've actually been in the wire and cable industry for a little over 40 years now.  I actually first started in the industry as, well maybe not a grunt, but certainly I was called a “melter's helper.”  I worked at a company called Hoskins Manufacturing in Ann Arbor, Michigan where we actually melted the raw materials to make thermocouple wire, resistance wire, and a whole host of other things.  I was actually the guy that, after we got done pouring that molten metal into the molds to make the ingots, was cleaning up all the mess that happens after you pour and you're pulling those ingots.

That's really where my career started, with Hoskins.  As a matter of fact, it kind of ran in the family.  My dad retired at Hoskins with 42 years of service with Hoskins, so it was kind of a natural progression that, eventually after I got out of the service, I ended up joining Hoskins.  I was there about 18 years at Hoskins Manufacturing, again, starting out right at the bottom.  I worked my way up to becoming an associate engineer working in the R&D department.  That's where my career really started focusing a little more on thermocouples.  I enjoyed working with thermocouples.  We were developing some new products using thermocouple wire and things like that.

Ever since then, I've kind of stayed in thermocouple arena at some of the other places I've worked.  After I left Hoskins, I started working for companies that insulated wire.  So, we were taking the wire, like we made at Hoskins, and we were putting a whole host of insulations on it from ceramic braid to extruded products and things like that.  And, again, both the companies, and even the one I'm currently employed with at Pelican, but before that I was working for a company out in New Hampshire called PMC, are real similar, it's just we insulated wire.  So, we purchased the raw materials (raw wire from Hoskins or whoever) and then insulated it.

DG:  For the unbaptized in this topic, what are thermocouples, how do they work, how do they come about, and then are the modern-day thermocouples any different than the thermocouples of old?

EV:  I always start out with a little bit of history about thermocouples, whenever I'm talking about them, just to give people background.  Thermocouples were introduced in the early 1800's with the most significant developments taking place in Europe.

One of the very first gentleman that worked on it was Alessandro Volta.  You can probably recognize the name because Volta actually is the volt, today, which everybody recognizes, not just with thermocouples but, obviously, in the electrical industry too.  He basically built a couple thermopiles using metals, silver and zinc and some cloth in between them, soaking them in salt water, and discovered that it would produce a voltage.  That's kind of how it got started.  The significance of that discovery was that there is a source of steady and reliable current flow from using dissimilar metals and saltwater and things like that.

Thomas Johann Seebeck, Baltic German physicist, who, in 1822, found the relationship between heat and magnetism.

Over the years, many others have experimented with the phenomenon.  Probably the most famous, anybody that's in the thermocouple industry will hear it a lot, in 1821, Thomas [Johann] Seebeck announced that he had discovered that when two dissimilar metals were placed in a closed loop and one of those junctions was exposed to a change in temperature, electrical current was produced.  This production of the electromotive force and electromatic force is the electric current is known as "the Seebeck effect" or "Seebeck coefficient."  It was, obviously, much later, before everything was understood and correct mathematics, but Seebeck's name will always and forever be associated with the discovery of thermoelectricity and thermocouples.  Again, even to this day, even ASTM books reference Seebeck coefficient.

Some other gentlemen that we involved, again you'll recognize some of these, were Michael Faraday, Georg Ohm, Claude Pouillet, and Antoine [César] Becquerel.  It was Becquerel, actually, that suggested using Seebeck's discovery for measuring high temperatures.  He proposed the strength of the current generated was proportional to the change in temperature in exactly the principle behind the thermocouple.  We're measuring temperature, whether it's 200 degrees or 2300 degrees.  That's how the modern day thermocouple got started way back in the early 1800's.

DG:  And the modern-day thermocouples are, essentially, the same as that?  Have there been any major changes?

EV:  In reality, Type J was the first thermocouple to really be experimented with.  After Type J, then some additional thermocouple types came on board.  People experimented with other metallurgical compositions to develop different millable outputs.

DG:  Let me understand:  Type J, what that basically the first type of thermocouple that was developed?

EV:  Let me back up a little bit.  Actually, the early metal thermocouples were based on what we can call noble metals.  Noble metals are rare earth elements such as platinum, rhodium, tungsten and uranium.  The problem with the noble metals is that noble metals are much more expensive than our base metal thermocouples, or what we call base metal thermocouples, today.  Base metal thermocouples, today, typically the compositions are just a handful of elements.  You have iron, nickel, chromium, copper and things like that, which is considerably cheaper than the noble metals, the platinum and rhodium and things like that.

DG:  I want to learn this history a little bit, because it's just kind of fascinating to me.  So, the very first ones were made of noble metals, primarily. So, they would put those together and then, basically, we said, "This is great but it's way too expensive.  Can we get the same effect, if you will, (the difference in voltage, or whatever, between dissimilar metals), if we use a little less expensive metals?"

EV:  Right.

DG:  You’ve said there is a difference voltage when there's a difference in temperature.

EV:  The EMF (electromotive force) generated by the thermocouple is linear.  So, at 200 degrees, it produces this amount of voltage, at 300 degrees, it produces this much.  All the thermocouples are, basically, the same principle.  It's very linear.  That's one thing that is good about a thermocouple- the EMF output is linear.  You aren't producing a millivoltage at 200 degrees and then at 300 it goes down and then at 500 it goes back up; it's linear proportional to the temperature.

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DG:  I have heard in the past, and you mentioned it here, maybe we can discuss it a little bit:  noble metal versus base metal.  Obviously, we know noble metals, you mentioned what those are.  Those are expensive; they work to do the same thing.  Base metals, though, tend to be what?  Which metals?

EV:  As I already mentioned, the nickel, chromium, copper, and others.

DG:  And those are, in fact, just less expensive, right?  Essentially, they do the same thing but they're less expensive.

EV:  Exactly.  But, there are some other differences, too, between the noble metals and the base metal thermocouples.  When you're talking noble metals, the platinum and the rhodium, and things like that, they can handle much higher temperatures than even the base metal thermocouples.

DG:  I'm going to make an assumption, but probably the vast majority of the thermocouples used in the heat treat industry are probably base metal, although, I'm sure they've got some specialized ones for high temperature, which probably jump into noble metals.

EV:  Absolutely.  A lot of the base metal thermocouples are used in the load sensors where they're putting multiple sensors in and then the oven may be controlled by a noble metal.

DG:  The different types of thermocouples.  You mentioned, and I've forgotten the letter already, that there are different types.  Was it Type J you mentioned?

EV:  Yes, Type J.

DG:  OK.  We've done a study recently asking about what's the most popular one in the heat treat industry, but I know we listed down there J, E, K, N, and T.  Can you run us through those and tell us what are the differences, and whatnot?

EV:  J, E, K, N and T are the most common noble metal thermocouples.  Obviously, you've got two dissimilar metals or, what we refer to in thermocouples, two legs of the thermocouple – the positive leg and the negative leg.  So, for instance, on a Type J thermocouple, you're using iron as a positive leg, which is basically pure iron, (there are some coatings on the iron to help against oxidation and things like that), and the other leg is a copper nickel alloy.  That makes up the two legs of the Type J thermocouple.

If we look at Type K thermocouple, the negative leg is the KN which is, basically, just high nickel with a little bit of chromium; the KP leg, or the positive, of Type K is higher content nickel chromium.  There are also some other minor elements.

With Type T, the positive leg is pure copper.  The TN leg is, again, a copper nickel alloy.  So, when we talk about Type E, what is interesting is that with the Type E thermocouple, you're actually taking the Type KP leg and matching it with the TN leg.  So, again, it's just a mismatch or some hodgepodge of some legs.

DG:  So, you're using some lingo that I'm just picking up on and I want to make sure our listener's are, as well.  You talk about a P and an N leg.  Obviously, you didn't say it, but you're talking about a positive leg and a negative leg.

EV:  Yes, I'm sorry.  KP and KN.  So it's K positive and K negative leg.

DG:  Great.  So, with the Type E, you're taking a few and switching them around and matching them up and seeing what you can come up with.

EV:  Yes, that's the E, and I already mentioned the T.  N is a relatively newcomer to the thermocouple industry.  I say new, but it's still probably 40 or 50 years, I'm not sure when it was developed.  But, again, the Type N is similar to the Type K where the KP leg is a nickel and the KN leg is nickel and some silicon.  So, it's just a little bit different composition from the Type K thermocouple.  But, there are some differences.

Some of the differences, when you're looking at the different types of thermocouples, for example, Type E has the highest EMF output of any of the thermocouples.  Your question might be, "Well, why wouldn't we just use Type E because it has the highest output?"  What the higher EMF output means is that the sensitivity is a little bit greater in the Type E thermocouple.  Then why wouldn't we use that throughout all the industries?  Well, the short answer is, a couple things:  Type E has a limited temperature range, because, again, you're using that TN leg which is copper nickel alloy and the melting point of a copper nickel alloy is much lower than a nickel chromium alloy.  So, that's some of the differences, and with all the thermocouple types, also.

Each one has their own EMF output at certain temperatures but one of the biggest considerations is, really, the environment that you're using the thermocouples in.  Type K has good oxidation resistance; Type J, not so much, because you've got a pure iron leg which is going to oxidize much faster.  That's some of the differences between the individual thermocouple types.

DG:  I assume that if there's oxidation, or any type of corrosion or anything of that sort, it's going to change the EMF, it's going to change the reading and therefore that thermocouple, out the door she goes.

EV:  Absolutely.  And there have been even some recent changes in some of the specifications that some of the heat treaters are using nowadays where they finally realize that these thermocouples do deteriorate over time and so they start limiting the amount of uses that each thermocouple can be used in, in a bunch of different applications, but heat treating mainly.

DG:  Let's pause for just a second and do a little vocabulary.  You've mentioned EMF a couple of different times.  Could we have just a brief review of that just to make sure?  Also, I've heard about millivolts.  Are those two things related?  If so, how?

EV:  EMF stands for electromotive force.  It is, basically, when two dissimilar metals are put in contact with each other, a small voltage is generated.  When we're talking about millivolts, that's exactly what we're looking at: a millivolt is 1/1000 of a volt.  It's a very small amount.  If you look at some of the millivolt outputs for some of these thermocouples, at 200 degrees, for example, you're putting out .560 of a millivolt.  So, these are small.

DG:  And you're saying that it was the Type E that has the highest millivolt of all, so the current that is produced between those dissimilar metals is the highest, but you can't always use that one because in certain temperature ranges you're going to melt one of the legs.

EV:  Exactly.

DG:  The millivolts are measured by what?  I mean, it goes into an instrument that is able to read that?  What is that instrument?

EV:  Actually, some DVMs (digital volt meters) have the capacity to measure in the millivolt range.  So, it could be as simple as a digital voltmeter.  But, in the industry, we have temperature controllers, things like that, that you hook a thermocouple up to and it measures the EMF and then it converts it into a temperature.

DG:  It will measure that millivolt and then tell us what the temperature is?

EV:  Right.  With the instrumentation nowadays, it has the formulas in its memory, or whatever, and can convert that millivolt into an actual temperature that you actually read on a meter.

DG:  We've got an EMF which is measured in a millivolt.  It's going to travel across a long wire, I assume, to some place where it's going to be read.  Let's talk about that wire a little bit.  The impact of this, whatever EMF is being created, millivolt, what about that wire?  Tell me about it and what do we need to be careful of, etc?

EV:  We're actually saving that for another podcast, but I will touch on it a little bit.  So, there are limitations on the length of the thermocouple.  There are a lot of different mindsets, but probably the one I've heard the most is no longer than 100 feet.  So, you have your thermocouple sensor and that arrangement, the configuration, can be a number of ways.  At PMC Corp. we insulate the wire.  You could just take that insulation off at the end, weld the junction there, stick it and [. . .] then run it to a meter.

But in other industries, you may have it in a ceramic tube because of the temperature it's being used at.  You have a ceramic tube with a connector at the end, you may run what we consider an extension wire from that point all the way back to your instrumentation.  Again, the general rule of thumb, is 100 feet.

DG:  Let's talk about that wire with the different types of thermocouples.  What do we need to be sensitive to?  What do we need to be careful about?

EV:  Again, temperature range is probably the first consideration, but then also the environment that it's in.  Again, each thermocouple has its limitations on the environment.  Some are good in a vacuum, other thermocouples are not good in a vacuum.  Some thermocouples are good just in air, (like Type K), but Type J is not so good.  It still can be used in air but it will oxidize faster.

Like I said, in an environment of a vacuum, some thermocouple elements will actually leech out or evaporate out and that definitely would cause a problem with the EMF output and would have an erroneous reading.  Certain acids you can use some thermocouples in, others you can't.

DG:  With all of this pyrometry stuff going around, especially the AMS2750 revision, there are a lot of places where the tightness of the tolerance on the temperature really needs to be paid attention to.  Are some thermocouples inherently tighter tolerance, where they can go down to + or –2, or less than that?

[blockquote author="Ed Valykeo, Pelican Wire" style="2"]Special limits of error is the tightest tolerance, and that's according to ASTM.  But, there are some customers and some companies that want tighter tolerance material.  So, when we talk about that, that's really a special order.  Now you have to back all the way back up to the melters that melt these elements and make the thermocouple wire.  It's on them to produce something that is a tighter tolerance. [/blockquote]

EV:  Again, that was something we were going to touch on a little bit later, maybe on another podcast, because it can be a whole category on its own.

But, yes.  If you think about in general, overall, when we're thinking about the different thermocouple types, they basically all have the same tolerances according to ASTM.  The rule of thumb, that we kind of use, is from say 200 degrees to 500 degrees, the tolerance on all thermocouples are + or - 2 degrees if you want special limits of air material.

Now, there are other tolerances.  In the thermocouple industry, you’ll here – at least calibration-wise – you'll hear special limits of error, standard limits of error and extension grade.  Special limits of error is the tightest tolerance, and that's according to ASTM.  But, there are some customers and some companies that want tighter tolerance material.  So, when we talk about that, that's really a special order.  Now you have to back all the way back up to the melters that melt these elements and make the thermocouple wire.  It's on them to produce something that is a tighter tolerance.  Once that metal is poured in that mold and it's processed down the wire, it is what it is.  When they calibrate that wire, you can't really do a lot with it to change the EMF output, per se, other than there are some heat treat operations that can, what they call, stabilize, and there are processes to oxidize thermocouple wire, and things like that, but you're pretty much stuck with EMF right from the melt.

DG:  And it's dependent on the material composition or quality of the material.

EV:  Absolutely.  In some cases, they may melt 10 melts to get 2 special limit of air thermocouple types.  I don't think it's quite that bad, bur from my early melting days, we've had to downgrade many a melt because it didn't quite meet the tolerances.

DG:  Just reviewing, we talked about the basic history, how they got started.  We talked about the difference between noble versus base metal thermocouples.  We talked about the different types.  We defined EMF, electromotive force.  We talked about millivolt a little bit.  We talked about the wire, the differences in what we need to pay attention to as far as wire, and some other considerations like temperature range, calibration tolerance and environment.

EV:  Just so you know, the only base metal thermocouples there are, at least what ASTM recognizes, are the Type J, E, K, T and N.  We covered all the base metal thermocouples.

DG:  Just out of curiosity, a noble metal thermocouple, what are those?

EV:  There is a fairly large list of those.  You've probably heard of thermocouple Type R or Type S thermocouple.  Those are all made with noble metal thermocouples.  It's not really considered a base metal, but tungsten uranium thermocouples.  Those are in more the noble metal category Type C.  There is even development of some other additional noble metals:  gold is used.  Thermocouples are made out of gold.

DG:  Those could be expensive.  Of course, some of those other metals are more expensive than gold, so, who knows?

Well, that's very interesting.  So, J, E, K, N and T are all base metal thermocouples.

I want to make sure that we give appropriate credit to your company.  We talked about the fact that you're from Pelican Wire, part of the wire expert group.  I want to make sure that our listeners know that they can go check out your website which is pelicanwire.com.  You're not obligated to do so, but would you like to give out any other information where they can get a hold of you?

EV:  Yes.  Through the Pelican website, you can certainly get a hold of me.  Our number is on the website.  It's 239-597-8555 and it goes through a central board.  If anyone wants me, they can just ask for me through the operator.

Doug Glenn <br> Publisher <br> Heat Treat Today

Doug Glenn
Publisher
Heat Treat Today

 

 

 

 

 

 

 

 

 

 

 

 

 


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Heat Treat Radio #61: Thermocouples 101 with Ed Valykeo, Pelican Wire (Part 1 of 3) Read More »