What is Brake Die Steel?

Let’s begin this post with two of my favorite words; Ubiquitous; (everywhere, like raindrops during a storm), and, Esoteric; (known by a select small group of people).

What do these mean? Brake Die, Gun Barrel or Rifle Stock, Pump Shaft Straightness, Boat Shaft, Food Service Grade Stainless, Cold Roll, “Ultrasonic Inspect to 388, (and even FDA approved). While they may have a specific meaning to someone (esoteric), they do not have a defined meaning to everyone (ubiquitous in certain industries). In reality these are generic descriptions without reference to defined requirements and properties, at best they are like answering someone’s question regarding the location of your pending vacation by responding; “Up North.”

From my experience, and from a supplier’s point of view, the only real commonality they have is the suggestion of liability. You cannot hope to avoid potential mishap if you really do not have more information on the chemical and physical requirements of the steel the person is discussing.

Brake Die Steel – Generally, a high quality carbon or alloy, appropriate for dies, that may be, or is, hardened. Often an alloy from the 4000 series. Is it pre-machined? Not necessarily. Is it pre-hardened? Not necessarily. Is it oversized square and shiny? Not necessarily.

Food Service Grade Stainless – Generally means it does not contaminate food with residue from the steel and it maintains a clean finish. Most often some grade of stainless. More information is needed.

Gun Barrel and Rifle Stock – Generally a 4000 series high integrity hardened alloy. But, not a specific grade.

Boat Shaft – You really have no information from that term. Could be anything, carbon, alloy, stainless, monel, bronze, etc. Most customers will require specific properties that conform to some sort of Marine Agency such as ABS, etc.

Cold Roll – Not a steel grade but a production method. Need more information.

FDA Approved – A misnomer. FDA does not grant approvals for metals.

Pump Shaft Straightness – The specifics are different for everyone. There are ASTM specifications but many large companies have their own “esoteric” specifications. You need to know more.

Ultrasonic Test 388 – An ASTM test method to determine the internal integrity of steel. Requires more detail such as acceptability and reject-ability levels.

-Howard Thomas, April 22nd 2019

Defective Material

So, for almost 50 years I have had the opportunity to investigate various material/component failures, and with all the variables, two things have been fairly consistent. The first statement that is most often heard, aside from; “Don’t look at me!” is, “It looks like defective material.” Eventually, and more often than not, the actual reason for failure involves something other than material defect; incorrect material, design and engineering misunderstandings relative to material availability and the creativeness of people when it comes to overcoming those obstacles, changes in the application or environment, or a mishap in the installation, assembly, disassembly or earlier repair, etc.

The instances of material defect are very often the least contributory to failure. Perhaps the cleanliness or toughness of the steel was not up to the task. But that is not really a defect. It is a specification problem.

There are of course defects in material. That is true with any product. The point here is, don’t make that the first assumption. Besides, you are more apt to be able to quickly fix the problems that are most often contributory, right there on location, if you can identify them early.

Not to be MOTO (Master of the Obvious) here, if you are in maintenance you already have developed a mental checklist to identify the most frequent culprits; steel grade, toughness, change in temperature, alignment, moisture, chemical environment, load, vibration, lubrication, wear, surrounding forces, surface scratches, gouges, or cuts, new employees (Don’t look at me!!), sabotage, Keyser Söze, Russian interference, inc.

When the usual suspects have been ruled out, begin planning for some failure analysis testing. You will eventually need to provide a specimen of the failed piece (preferably at least 4″ to either side of the break). Contact your supplier and request their assistance. They may contact their local independent testing facilities, may have their own lab, and/or, they may contact the producing mill. I have been reminded; “In maintenance, as in life, most of our wounds are self-inflicted”.

Routine industrial applications can destroy some of the toughest materials known. And that is just during the daily conduct of business. Be mindful of the effects of those forces and respect the potential for catastrophic failure (whether it results from material defect or not). Make use of appropriate safety gear, stay alert, and if you don’t know, ask!

-Howard Thomas, April 9th 2019

Conclusion – Ten Things to Know About “Finish Size”

REMAINING FIVE POINTS – elaborated

  1. If the finish shaft involves substantial step downs, or, if only a small portion of the bar needs to finish… share that information.
  2. Remember, your supplier cannot be responsible for a third parties work, and/or mistakes.
  3. If liability on the shaft is considerable, consider parking it in another parties driveway.
  4. Try to “Talk the Talk” Phrases like, “a stick of steel”, or, “cold roll”, or, “a length of steel”, will get you in trouble.
  5. Share important ancillary facts with your suppliers; have you received steel in the past that has not been straight enough, hasn’t cleaned up, or was inappropriate in another way?

Why share info on details of a finished part with the supplier?

Well, you don’t need to go over everything, but statements like; “It’s going to be a long small diameter shaft with a big lollipop head on one end” will tip off an astute vendor to the potential of post machining stress related problems. On the other hand, a statement such as: “There is only a very small high spot near the middle of a short shaft that needs to finish to 8″ Dia. The rest of the shaft is 7” Dia. That might make a difference on how much stock is needed for allowance on the raw material.

The caution stated in number 2, above, is just a gentle nudge to limit how much responsibility you find yourself mentally assigning to the supplier. In the final phase, except for mill defect, unless the vendor is handling the job from cradle to grave, the responsibility for success or failure is really out of their hands.

Jobbing the actual machining to an outside source is not just about saving money, mostly because it will generally cost more. But, there are times when “potential problems are probable”. Who knows the product better than the supplier? You may want to see if they felt confident making a difficult piece. If so, why not let them. That eliminates lots of “finger pointing” if the job goes south. If the job goes wobbly, who’s wallet comes out? Their product, their method, their machining, their liability. If they screw it up the burden is on them to do it over at their expense.

TALK THE TALK

Like it or not, many terms are esoteric to specific industries. With hydraulic components, a bar of steel is a rod. When dealing with freight haulers and steel coils, they use terms like; “Eye to the sky”, or, “Suicide”. If you find yourself working within the maintenance steel industry, try to use the same terms you hear the suppliers using. It will go a long way to eliminating surprises. Surprises in maintenance are generally not good.

In closing, if you know some relevant history about a specific shaft or application, by all means share it. If the bar diameter did not clean up the last time, share that. If the shaft broke or bent, share that. If you encountered hard spots or glazing, share that.

Now, if your supplier is decidedly not interested in your ancillary comments, or, if they cut you short and enjoin you to just tell them the dimensions of the steel you want, perhaps you should try a second source. No harm no foul. You can always go with the first source. It is always nice to test the waters.

-Howard Thomas, April 1st 2019