EPS Heat Treat Headlines

Our blog visitors have recently had the chance to learn more about how to go about choosing the proper oven for their application (“What to Look For When Choosing an Industrial Oven: Ken Klein Offers Tips for Buyers“) and now readers of Process Heating Magazine will get a chance as well.

EPS President Ken Klein’s article discussing tips and tools for choosing the right oven was featured this month in Process Heating Magazine, a well known resource for manufacturing engineers who use heat processing equipment and supplies, including product, design and plant engineers.

The article focuses on not only what to look for, but also what to avoid when choosing an industrial oven that will be designed specifically for the application. Customers with clear requirements, Ken points out, are the easiest to understand and to provide the proper oven for their needs:

“Oven building can be a challenging enterprise, especially where large industrial ovens are concerned.”

Included in Ken’s list of items to think about? Crucial items like airflow and rate of rise rank high on the list. These will influence things like efficiency and recovery time down the road.

EPS Ovens has been providing industrial and pharmaceutical oven solutions since 1978, and now offers its own line of batch and continuous ovens for industrial applications. Learn more about our custom industrial ovens, including EPS batch curing ovens, industrial heat treat ovens, industrial drying ovens, composite curing ovens and more.

President of EPS, Ken Klein, has been sharing tips about what to look for when considering a large industrial oven purchase. Last week he told us about the importance of air flow and rate of rise. This week, we’ll hear from him about temperature uniformity and the challenge of temperature control:

Uniformity – What temperature uniformity do you need? If there isn’t a spec we will assume it’s not so critical we need to do something special to our normal design. Many spec writers confuse uniformity with accuracy. Accuracy refers to the capability of a control instrument to achieve desired temperature that is stable and repeatable to within a certain tolerance. Uniformity, on the other hand, is largely a function of airflow. If airflow is managed properly, the air temperature uniformity throughout the chamber will be tight, assuming you don’t block the airflow completely with your load.

Most builders will state the oven zone in which uniformity can be expected, i.e. to within what distance of the walls, ceiling and floor. This defines the “uniform zone”. Your builder should advise you that if he has to test the uniformity before the unit leaves his shop he will state all uniformity statements and certifications apply to an empty oven at steady state conditions.

One more note on uniformity. If you specify, for example, + 10F at 300F, can you expect the readings you get during a survey to be 290F to 310F throughout the “uniform zone”? Only if you have done one of two things:

1) By experimentation you have been able to physically locate the sensor (the control thermocouple) at a point that represents the mean of all temperature readings in the chamber, or…

2) You have taken all readings, found the control thermocouple to be closer to one end of the range (say 305F when readings range from 290F to 310F) and put an “offset” into the controller, which “adjusts the reading of the sensor so that it appears to read the mean of the range.

Control – this often proves the biggest challenge for a spec writer, but it has pretty simple rules. The simpler your operation the simpler the controls should be. Let’s go from one extreme to another. Say you are leaving the temperature in the unit at one point all day, and taking your parts in and out several times a shift. A single set point controller will suffice, teamed up with a door switch that shuts down the heat and circulation when the door is opened for loading and unloading. At the other end of the spectrum is the application where perhaps you’re composite curing and you need to:

• ramp up and down at a controlled rate
• acquire data from vacuum transducers and part thermocouples
• Make data available to your computer system for archiving and print out. This most often requires a graphical human-machine interface (HMI) and a PLC (programmable logic controller).

In between these two extremes are the programmable controllers that will allow the cycle to run automatically, ramping up, holding, cooling down and shutting off.

Next up: Ken Klein concludes the Oven Selection and Specifications series.

Last week, EPS President Ken Klein shared with us three categories of customers who purchase large industrial ovens. In this week’s post Ken shares with us what to look for when making the purchase:

Airflow – In real estate, the three primary considerations are location, location and location. For a large forced convection oven the primary considerations, as I see it, are airflow, airflow and airflow. Sounds pretty basic, doesn’t it? But airflow is going to determine a number of things, like how efficiently you will heat your load, how fast you will recover after a door open if you will be taking parts in and out, and the temperature uniformity you can expect. And yes – I have chatted with prospective customers who are entertaining quotes from other builders for their standard horizontal-in-from-the-side-vertical-return-to-the-ceiling airflow patterns, when as it turns out their load would block vertical airflow. Likewise I’ve seen instances of a customer looking at horizontal side-to-side quotes when they will stand large panels on end that will block the flow. Give this some thought up front—it will save you a lot of nightmares downstream.

Rate of Rise – How fast do you want to get to temperature? It’s one thing to say you want to get there in 45 minutes if you are heating a load that doesn’t weigh much. Heating up a 40,000 lb. weldment is another story. Be realistic, and depending on the weight and nature of your load the air temperature may get there long before the core of your product.

Next up: Ken talks about the difference between accuracy and uniformity and the challenges of control.

This four-part series from EPS President Ken Klein, “Oven Selection and Specifications,” shares tips and tools for customers looking for large industrial oven applications.

In this first post, Ken talks about three customer categories for large industrial oven purchases:

One of my college professors started each day’s lecture with the words “today we’re going to talk about…” So, everyone, today we are going to talk about selecting and specifying an oven, a subject near and dear to every oven builder’s heart.

This is a challenging industry, especially where large industrial ovens are concerned. If we’re talking small lab units or other small standard catalog ovens, the process is easy–unless the customer’s requirements are misinterpreted. For larger units that must be designed for the application I tend to group customers in three general categories. That’s not to say some don’t slop over from one category to another, but in general they fit into distinct categories:

Category #1: The primary contact is inquiring on the behalf of others and has very little information on the application. He or she can try to get more information for you, but they may or may not repeat the requirements accurately and additional questions may or may not yield helpful answers.

Category #2: Primary contact is inquiring on behalf of others and is passing on a spec that makes it sound like they are constructing the next great missile system. Every detail is spelled out in exact terms. There are paragraphs and sub-paragraphs, ranging from those that are straightforward to those that ask for features either extremely complex or plain impractical.

Category #3: Primary contact is the end user and can tell you anything you want to know.

Of these three the second is received with mixed reactions by most builders. Certainly you have an apparently unyielding spec which should make it easy for the customer to evaluate all bids on an apples-to-apples basis, but most often the requirements are seen to be over the top or unrealistic, meaning many builders will need to take exception to a number of the requirements. That’s where things get murky. The builder wonders if he has a chance at getting the order. He may feel that if he quotes exactly to the spec the unit is going to be so expensive that the customer is likely to buy from another bidder who had the sense to take exception to the requirements he feels pile on the costs unnecessarily. In addition, the customer has a lot of technical exceptions to wade through. He may or may not have the expertise to evaluate the exceptions properly and may end up tossing the quotes that are too difficult to wade through.

So – let’s guess at which one is my favorite. The third of course. Easiest to understand and respond to. This article is addressed to those of you who need an oven and want to get a good comprehensive bid on your requirements. We are going to concentrate on forced convection ovens. Here’s what you should be thinking about when you talk to prospective bidders.

Next up: Ken Klein talks about the characteristics that matter when choosing an oven.

A Detroit entrepreneur surprised university engineers here recently, when he invented a heat-treatment that makes steel 7 percent stronger than any steel on record – in less than 10 seconds.

In fact, the steel, now trademarked as Flash Bainite, has tested stronger and more shock-absorbing than the most common titanium alloys used by industry. Now the entrepreneur is working with researchers at Ohio State University to better understand the science behind the new treatment, called flash processing.

What they’ve discovered may hold the key to making cars and military vehicles lighter, stronger, and more fuel-efficient.

In the current issue of the journal Materials Science and Technology, the inventor and his Ohio State partners describe how rapidly heating and cooling steel sheets changes the microstructure inside the alloy to make it stronger and less brittle.

The basic process of heat-treating steel has changed little in the modern age, and engineer Suresh Babu is one of few researchers worldwide who still study how to tune the properties of steel in detail. He’s an associate professor of materials science and engineering at Ohio State, and Director of the National Science Foundation (NSF) Center for Integrative Materials Joining for Energy Applications, headquartered at the university.

“Steel is what we would call a ‘mature technology.’ We’d like to think we know most everything about it,” he said. “If someone invented a way to strengthen the strongest steels even a few percent, that would be a big deal. But 7 percent? That’s huge.”

Yet, when inventor Gary Cola initially approached him, Babu didn’t know what to think. “The process that Gary described – it shouldn’t have worked,” he said. “I didn’t believe him. So he took my students and me to Detroit.”

Cola showed them his proprietary lab setup at SFP Works, LLC., where rollers carried steel sheets through flames as hot as 1100 degrees Celsius and then into a cooling liquid bath. Though the typical temperature and length of time for hardening varies by industry, most steels are heat-treated at around 900 degrees Celsius for a few hours. Others are heated at similar temperatures for days.

Cola’s entire process took less than 10 seconds.

He claimed that the resulting steel was 7 percent stronger than martensitic advanced high-strength steel. [Martensitic steel is so named because the internal microstructure is entirely composed of a crystal form called martensite.] Cola further claimed that his steel could be drawn – that is, thinned and lengthened – 30 percent more than martensitic steels without losing its enhanced strength.

If that were true, then Cola’s steel could enable car makers to build frames that are up to 30 percent thinner and lighter without compromising safety. Or, it could reinforce an armored vehicle without weighing it down.

“We asked for a few samples to test, and it turned out that everything he said was true,” said Ohio State graduate student Tapasvi Lolla. “Then it was up to us to understand what was happening.”

Cola is a self-taught metallurgist, and he wanted help from Babu and his team to reveal the physics behind the process – to understand it in detail so that he could find ways to adapt it and even improve it.

Original Source: A New Way to Make Lighter, Stronger Steel – In A Flash

For a limited time we are now offering free freight on all SHEL LAB ovens as well as Cress Single Chamber and Cress Dual Chamber Heat Treat Furnaces.

The SHEL LAB oven series offers a diverse choice of forced air ovens (floor models and bench-top units), gravity convection, clean room ovens, nitrogen purge ovens, and vacuum ovens. You will often hear the terms drying oven, curing oven, or bake out oven being used in industrial applications. These are generic terms that can be represented across multiple heat processing applications.  Click here for help finding the SHEL LAB Oven that will best fit your application.

Cress Heat treat (Hardening) furnaces have higher heat output power than draw furnaces due to the elevated temperatures at which they operate. Heat transfer to the tool steel is accomplished by a very efficient process called direct radiation. Temperature uniformity in these furnaces is best in the red heat range. Normal maximum temperature is 1232°C (2250°F). Optional 1316°C (2400°F.

For a free quote or questions about EPS Ovens Contact Us Here

Our company is using a commercial heat treater and we’re getting good results. Why should we buy a Cress furnace and do the heat treating in house?

This is one question that we hear over and over again and there are arguments to steer the answer in both directions.  We’re going to look at several scenarios so that you can select the correct solution for your company.  Not all heat treaters operate this way, but with the high cost of energy, some are forced to take steps to keep costs low to stay competitive.

Background

You’ve created a tool, a part or series of parts in your machine shop that you need for your operations, or your customer’s requirements.   The designer has chosen A2 tool steel and specifies a hardness of 60 to 62 Rc is needed.  The part or parts could weigh 2 pounds, or 50 pounds and may have taken five hours, five days, or five weeks to make.  Regardless of the time, your company has invested time and money into producing the parts to satisfy a need.  You package the parts up, ship them off to the heat treater and ask them to be heat treated to 60 to 62 Rc.

Scenario Number Two

This is one of my biggest complaints about commercial heat treaters.  The parts arrive, a job ticket is written up.  The job is assigned to a person on the floor who often has no formal training in handling parts or heat treating for that matter.  The company metallurgist sat in their lab and only is called to verify the process to be applied if the leadman, or shop foreman can’t find the process in his private notebook.  The only time the metallurgist gets involved is if the hardness level is incorrect, and you know that the owner of the company will always be in his office concerned with bill paying or sales.

Bottom line of this scenario….. Even if the hardness reads correctly, you have no absolute assurance the times, temperatures, pre-heat, quench or tempering cycles were followed to the prescribed recipe.  Your part quality is at risk.  The life of the part is at risk along with your reputation. Your only hope is to request and pay extra for strip chart recordings of every step of the parts in process.  Even then there are things that can effect the quality of the finished product.

DISCLAIMER OF LIABILITY
The material presented in this article is intended for general educational information only.  It should not be used for a specific application without careful analysis and study of the in¬tended use.  Anyone using this information or relying on it assumes all risk and any liability arising from their applications and use.