The WelderDestiny Compass

The Special Process - Issue #012

Wednesday, March 22, 2017 / Perth Australia / By Niekie Jooste

In this edition of "The WelderDestiny Compass":

• From Uncertainty to Predictability
• An Uncertain World
• Special Process
• Welding in a Data Rich Future
  

From Uncertainty to Predictability

In past editions of The WelderDestiny Compass, we have spent a lot of time looking at how technology, economics and human nature will conspire to change the world of the Welder. The one central message is however that there will be a lot more information and data available regarding the actual welding parameters and welding outcomes.

In short, welding, like so many other fields, will benefit from all the real-time data generated and analysed, so that the uncertainty associated with welding inputs and outputs will greatly reduce. When uncertainty is reduced to a low enough level, the strategies for dealing with the uncertainty will also change.

Welders of the future will have a significantly different quality assurance and quality control process to contend with than present day Welders. 

If you would like to add your ideas to this week’s discussion, then please send me an e-mail with your ideas, (Send your e-mails to: compass@welderdestiny.com) or complete the comment form on the page below.

Now let's get stuck into this week’s topics...

An Uncertain World

I grew up in the age when the media told us that saturated fats like butter was really unhealthy. It was much better to use margarine. Every now and then there would be some "voices in the wilderness" claiming that butter was better, but those voices were dismissed as misinformed.

Then, slowly there was a swing away from this thinking, to claim that in fact margarine, that was based on hydrogenated fats, was much worse for our health than butter.

How could the "facts" around the health benefits of butter versus margarine change?

In the same manner, I was continuously told by the media that fats in general are really bad for me. Eating fats will result in cardio vascular disease and death! Rather, we should eat our grains. A healthy breakfast was a bowl of breakfast cereal.

Now we are told that grains in general, especially those containing gluten, are bad for us. In fact, refined carbohydrates in general can result in many chronic diseases. Best to eat proteins and "good fats". The good fats protect our hearts and minds!

How could the "facts" around the health benefits of carbohydrates, fats and proteins change?

Getting sun exposure has been vilified for decades. We are told to do our best to stay out of the sun, because the sun will result in us getting cancer. We were told that there is no such thing as a healthy tan. Now we are told that the lack of sun exposure is responsible for a myriad of cancers, chronic diseases and even psychological illness such as depression.

I can continue showing "facts" that have changed 180° in direction in my lifetime. Why is it that deeply held, and widely published "facts" can change? Surely if the people that "did the research" were not sure of their facts, they should have told us, right?

One of the obvious answers is that most research and reporting is biased. There is always somebody making a buck from getting a particular answer. That is why the organization sponsored the research in the first place! We have already discussed this shortcoming of human nature in a previous e-zine, so we will not pursue this line of thinking further today.

The ability to "find the answer we like" in data presented to us, is made possible by the fact that the data does not necessarily give obvious yes / no or right / wrong answers. The data collected during research has many different factors that influence the answers. Many of the influencing factors we are not even aware of.

The bottom line is that the less we know about something, the greater the uncertainty associated with the conclusions that we draw. The more we know, the smaller the uncertainty associated with the answers. But, how much do we really know?

The whole subject area of statistical analysis has been borne from this uncertainty in the world around us. Instead of seeing the world as a place where we have certainties, the world really is a place of probabilities. Not black and white, but many shades of grey. (Probably more than 50. - Sorry, I could not resist that!)

Given our current state of knowledge:

• Butter is probably healthier than margarine. 
• Eating certain fats is probably healthier than eating refined carbohydrates. 
• Getting some minimum level of sun exposure is probably better for our health than hiding in the dark.

As our state of knowledge increases, the probabilities associated with the conclusions above either increases or decreases.

Engineering obviously also lives in this uncertain world. In our world of welding, there are uncertainties associated with:

• The actual chemical compositions of the materials we are joining. 
• The actual state of heat treatment of the materials we are joining. 
• The level of defects in the materials we are joining. 
• The actual chemical compositions of the welding consumables we use. 
• The actual levels of contamination of the materials and welding consumables. 
• The actual compositions of shielding gasses or fluxes used during welding. 
• The level of discontinuities present in welds.
• The assumed stresses that the welded components will be exposed to. 
• The thermal conditions present when the welding is being performed. 
• The amount of dilution of the welding filler metals with the base metals. 
• The effect of random fluctuations in welding parameters during production welding due to human influence and power source characteristic influence. 
• The levels of residual stresses induced by the welding process.

To compensate for uncertainties, engineering uses a number of different strategies to enable us to make economical, useable and safe welded components and structures. One of those strategies is to treat some processes as "special". 

Special Process

If the outcome of a manufacturing process cannot be measured without destroying the component manufactured, then the process is termed a "special process". Welding is a special process. Theoretically we cannot perform enough "non-destructive testing" on a completed weld to know with a high degree of certainty that the weld will be suitable for the application.

Machining is not a special process. We can measure all the necessary dimensional tolerances required on our final component, so we know if it meets the requirements or not.

Baking a cake is also a special process. There is no way to know for sure if a cake is 100%, without destroying the cake. Destruction through taste! So, how could we "know" that a cake will be good before we take a bite?

Well, after somebody develops the new recipe for the cake, we bake the cake the first time per a well-defined recipe, following a well-defined "method". Then we taste the cake. If the cake tastes good, then we are certain that future cakes will also be good, if we follow the recipe, use adequate equipment and make sure that the person baking the cake has the skill required to do the baking.

This is the same "qualification" methodology that is followed for all special processes. It is achieved by doing the following:

• A procedure is "qualified" by producing a representative component by following a standard procedure for our process, and then doing all the necessary destructive testing on this "prototype". 
• We qualify the equipment to be used when applying the standardised procedure. 
• We qualify the people that are going to follow the standardised procedure, to make sure that they understand how to follow the procedure, and that they have the necessary skill required to achieve a good outcome.

In the case of welding, we can clearly see how this works: 

• We qualify the procedure by welding a "coupon" and then performing all our required non-destructive and destructive testing. If the tests all comply, then the procedure is qualified. This is recorded in a document typically called a Procedure Qualification Record. (PQR) 
• The limits within which the production welding is to be performed is placed on a Welding Procedure Specification. (WPS) The WPS is provided to the Welder to do the production welding. 
• We ensure that the equipment to be used by the Welder in doing the final production welding is representative of that used during the procedure qualification process.
• We qualify the welder through "coding tests". 

What we need to appreciate at this point is that there are uncertainties associated with this qualification process. The mechanical tests are made on a limited number of test pieces, so statistically speaking, we do not know 100% that the mechanical properties are adequate. We only know within a certain probability that the mechanical properties are adequate.

The same goes for the corrosion properties, or the propensity of the procedure to induce welding defects.

If the necessary tests are passed, then we have a reasonably high probability that future welds following that procedure will be acceptable, but we never have complete certainty.

Welding in a Data Rich Future

I believe that we will get to a situation where almost all welds have a lot of data concerning their variables recorded during production, and this information will be made available for analysis. The more data there is for analysis, the better our understanding of what the effect of the welding variables are.

Under this scenario, it then becomes possible to develop a WPS with a much higher probability of success than from a single welding procedure qualification test coupon. When statistical analyses show that WPS’s based on a lot of real-time welding data is a lower risk methodology than the traditional qualification process, then traditional qualification processes will no longer be used.

So, what will the new process be? I suspect it will be something along the following lines: 

• A design artificial intelligence (AI) will forward the required design parameters for the necessary welded joints to a welding AI. This will include the needed statistical certainty for the weld properties. Some welds are higher risk, so they need higher certainty associated with their properties. This process will probably happen in conjunction with a human design engineer. 
• A welding artificial intelligence (AI) will develop a WPS based on a statistical analysis of the available data for welding the materials we need to join. This will probably happen in conjunction with a human welding engineer. This WPS is needed for planning of the work, including the needed equipment and consumables and manpower. 
• The Welder will be assigned to the job, based on the planning made by a planning AI and planning engineer. 
• The WPS will be forwarded to the Welder’s AI. Included will be all the necessary measures that need to be made during welding, to ensure that the necessary properties have been achieved. 
• The Welder’s AI will assess all the factors “on the job” and modify any of the WPS parameters to take account of factors that were not previously known. The modifications to the WPS will be based on meeting the risk profile associated with the weld. 
• The materials to be used will be checked on a blockchain register by the welding AI, to ensure that rouge materials have not been introduced into the production process. 
• During welding, the welding AI will assist the Welder to attain the required quality level in the weld. During the process, all the data necessary will be collected by the welding AI. This data will serve as the quality control checks and documentation for the weld. This will typically include: chemical analysis of the materials and weld; dimensional inspections; internal defect and microstructural inspections through ultrasonic testing; welding parameter recording; thermal history recording. 
• The collected data will serve as evidence of weld quality and as input for future WPS development.

For this process to work, there still needs to be a quality assurance and quality control process in place, but the emphasis will be a lot different than is currently the case. In a future edition of The WelderDestiny Compass we will think through how the new quality assurance process will look.

Looking at the process described above, we can see that the skill base of the Welder will need to be quite a bit different to that for current Welders. These changes will not happen overnight. They will take decades rather than years, but if you are a welder under the age of 40 years old, then you will feel the full force of these changes before you retire.

Are you looking forward to the coming changes?

Yours in welding

Niekie Jooste

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