Article Updated: May 2022
Background:
I entered the phenomenal world of thermal spray technology as a young engineer in my twenties. The very idea of being able to deposit exotic materials from metallic to cermets to ceramics on various substrates on a consistent basis appealed to me.
This was not a technology in development in the materials laboratories of the world, but a practical real world manufacturing process! There were several independent thermal spray coating houses by then, some large, some small, but all with the goal of surface modification.
I chose to work for a medium sized thermal spray company, because I wanted to learn the practical aspects of processing. My education in metallurgical engineering had given me the theoretical background, but needed a hands-on exposure as well.
As I continued to learn the ropes from my colleagues and superiors, I was assigned to various departments within the organization. All of the people were highly dedicated individuals, skilled in their own respective areas.
It was not just shadowing others that I was tasked with. Specific responsibilities were given in engineering, operations and so on. Deadlines were assigned and had to be met; no excuses allowed.
About two years into it, I was asked to computerize entire the inventory system. And that is where I was exposed to all the thermal spray consumables that had to be addressed. I never even dreamt of the magnitude of the work involved.
Over three decades later, here I am writing about thermal spray consumables! All that was learnt then is still true today in the world of thermal spray coatings processing companies.
With that brief introduction, let us jump into the topic.
Thermal Spray Consumables were broken down into three major categories:
Set One: those that touch the part and become part of the coating,
Set Two: those that touch the part but do NOT become part of the coating
Set Three: those that do not touch the part at all.
Set One Consumables:
To start off, let us look at the first set.
This will include thermal spray powders, wires, infused materials, etc.
One cannot simply buy these from any vendor, simply based upon price and delivery. Some need to meet stringent customer specifications. There are specific cases, especially in the aerospace industry, where the vendor company itself needs to be an approved entity.
This stringent quality and approvals requirement, which once existed only for the aerospace components world, has slowly expanded into other industries also, especially automotive.
A subset of thermal spray wires and powders consumables is in applications where no specific customer specifications exist. For example, if your company is primarily involved in aerospace coatings, but also rebuilds pumps and shafts for commercial industrial applications for the sewer and sludge industry, then the raw materials can be sourced from any vendor as long as they meet your own internal specifications.
Mind you there is a huge non-aerospace thermal spray applications world out there. Many tiny mom and pop operators thrive in this space, because they do not have the burden of meeting NADCAP and ISO systems. They have the liberty to purchase raw materials from any source.
The supplier himself may have purchased the powders from another source or manufacturer. Controls for “that” process are usually part of the sourcing quality specifications prescribed by the end customer.
We have thus far only addressed the purchase of raw materials that end up in the coating on the part. However, from an inventory standpoint on the Set One thermal spray consumables, there are more items to address. The most important of these is the inventory type. Let us address that now.
Companies may choose to have their powder or wire inventory system based on a First In First Out Basis. This means that if two lots of powder are received for the same chemistry and specification, the lot that was received first will be given to the operator to use and when that lot is finished, the second lot will be distributed.
There could also be a system wherein the higher priced lots are used first and lower priced lots are used later. This happens when the same powder chemistry is purchased from several qualified vendors. This system allows inventory carrying costs to be lower.
Another twist in the story happens with some thermal spray shops that deal with aerospace specifications. One cannot simply take the powder from the vendor and put it into production. Sprayability tests are to be performed on EVERY lot of powder received and only if it passes the metallurgical lab testing to meet specifications, such material can be stamped as Lot Released For Production.
This ensures that the powder or wire is in fact capable of meeting aerospace or other customer standards. If the powder fails to meet sprayability testing, that lot of powder or wire CANNOT be used in production.
Set Two Consumables:
As you may recall from above, this set comprises thermal spray consumables that touch the part but do NOT become part of the coating.
The first item that probably comes to your mind is abrasive grit blast media. And indeed you are correct. Abrasive grit blasting is used to roughen the surface of the part to be coated, to ensure proper bonding of the coating to the substrate. Mind you, many aerospace specifications deem abrasive grit blasting as a significant process and changes to it must be approved by the customer.
Abrasive grit chemistry, such as aluminum oxide or silicon carbide, as well as grit size such as Number 36, Number 24, etc are used in the specifications for purchase.
As before, the inventory system such as First In First Out, etc apply here also.
Abrasive grit should not end up in the part; one could say but what about grit entrapment; well, grit entrapment is a flaw and specifications usually limit the number of grit particle entrapment per field of view!
Next we need to consider industrial gases. Most air plasma coating parameters call for argon helium or nitrogen hydrogen parameters. You may also be involved in other oxy-fuel systems such as oxy-acetylene or oxy-propylene and the respective gases need to be considered as consumables.
Next, come thermal spray masking materials. These are used to expose only the areas to be coated and “hide” or “mask” the “not-to-be-coated” areas. While seemingly harmless and a “no-brainer”, let me tell you switching masking materials suppliers just based on price is not a good idea.
Of course you want the lowest priced supplier, but quality is of paramount importance. If the masking material frays either during the subsequent grit blasting of spray operations, then the “No-Coat/Coat” demarcation will not be accurate, leading to possible rejection. Masking materials must be strong enough to withhold grit blasting and coating, but also allow for easy de-masking operations subsequent to coating.
Now masking materials are not limited to tapes. There are liquid masking materials also to be considered as well as Poly Urethane Boots. The same properties apply to these as those that apply to thermal spray tapes.
A key element to be considered in the case of liquid masking materials is their shelf life. Many of these have limited shelf life and this has to be taken into consideration both while purchasing as well as in inventory management.
Hard tooling components such as shadow masking plates, fixtures, buttons, plugs, etc form a set of items that may need to be purchased, put in inventory and maintained.
De-Masking and De-burring processes involve the use of stones, blades, files and other de-burring items such as burring tools, etc. Engineers often look away from the deburring department. But let me tell you, by the time the coated part has reached the deburring department, so much of work has already been put in and a lot of money has already been spent on the part(s).
A mistake at this juncture is very costly. You need to make sure that the best tools are made available to deburring personnel and ensure they are trained properly.
Next, we need to consider part cleaning and associated chemicals involved. We have included these in this section, since they vaporize after cleaning.
In the olden days, 1-1-1 Trichloroethane was widely used in part cleaning tanks. With the world becoming increasingly environmentally conscious, companies are required to stir away from volatile organic compounds as much as possible and stay with green technology.
And if your firm is also in the business of chemical stripping of thermal spray coatings, you will be dealing with stripping chemicals that need to be considered also. As you can imagine, stripping chemicals such as sodium hydroxide to strip aluminum based coatings, nitric acid to strip nickel-aluminum bond coats, sodium cyanide to strip tungsten-carbide-cobalt coatings need to be purchased and kept in inventory.
Purchasing and inventory control of the same also falls on the desks of the purchasing function personnel.
Set Three Consumables:
As you may recall from above, this set comprises thermal spray consumables that DO NOT touch the part at all.
The first subset within this set is all the thermal spray gun components that need periodic replacement. Electrodes and nozzles are the first things that come to mind when considering plasma spray guns. HVOF heads, cooling tubes, etc also fall into this category. You may want to throw in cables also into this bucket. Wire guides for wire-spray equipment and feeder nozzles may be included.
Metallurgical lab consumables such as polishing papers, polishing compounds, tensile bond strength testing adhesives and glues should not be forgotten as being part of this set.
Not included in any of the above are shipping supplies, office supplies, etc, since they form part of any business entity.
Putting Together:
Having considered all of the above, I developed a massive database that included validations for Sprayability, Approved Vendor List, Shelf Life Controls, etc. It took me almost a year to complete, but at the end, it proved to be worth it’s weight in gold. And for me, it was one superb learning experience.
Getting Ahead:
You may be thinking, this is great, but how can I benefit from this write up? What is in it for me? How can I benefit my employer or my thermal spray coatings company from the consumables standpoint?
Regardless of whether your company sells thermal spray consumables such as those addressed above and would like to reach potential buyers of the same OR you are looking to source these items from sellers at the best possible price and delivery points subject to constraints of specifications, OEM approvals, etc, you can benefit by signing up with FirstPageit.com for free!
Here is the brief step by step instructions.
Step 1: Click Sign-In, Create a New Account, Enter Your Details, Email, etc.
Step 2: If you SELL thermal spray consumables, enter the Company Product and Services Screen, Choose Industrial Products and Materials, Coatings and Surface Treatments, Thermal Spray, Consumables and choose a geographical radius in which you want to sell and choose a secondary email address. That’s it. You’re done !
Step 3: If you SELL thermal spray coating services, enter the Company Product and Services Screen, Choose Industrial Products and Materials, Coatings and Surface Treatments, Thermal Spray, Services, Plasma-HVOF-LPPS and choose a geographical radius in which you want to sell and choose a secondary email address. That’s it. You’re done !
FP in Action: Anytime anyone searches for thermal spray consumables in the main search box and enters the details of the search, YOU – the consumables supplier will get an email instantly. Anytime anyone searches for thermal spray services such as Plasma Coating Services in the main search box, YOU – the Coatings Services Supplier will get an email instantly.
Thus you can offer your services as well as buy products and services without spending money on ads, helping your sales team AND your purchasing team at once with one registration.
Your competitors may already be on FirstPageit.com garnering business quietly under the radar !
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