Thermal spray rework costs

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No manufacturing operation is one hundred percent error free and thermal spray operations are no different. As a matter of fact, because of the multiple steps involved in part preparation and the myriads of variables involved in the actual thermal spray coating operation, thermal spray processing is more prone to errors than many other industrial processes. This is not stated with the intention of justifying all the mistakes made by thermal spray operators, but rather to stress that mistakes can happen during processing. In fact, some of the reasons why parts get rejected in the thermal spray operation may be completely out of operator control, such as when a robot decides to malfunction and lock up with the gun lit and the powder feeding on the part, what is the operator to do besides react as quickly as possible and shut off the gun and feeder and hope he was not too late. The hope in all cases is that a rework procedure be available so the part can be redeemed rather than scrap the hardware which may be the case in some instances.

Nevertheless, thermal spray rework costs money and this cost needs to be worked into the pricing sheets for future thermal spray quotations. Obviously, the less the rework rate in your thermal spray shop, the lower these added costs will be and the more competitive your bids can be. But I observe time and again that for one, many companies do not even attempt to quantify their rework costs and second, even if they do quantify these costs, they do nothing with the data. Rework costs data is very valuable in adjusting pricing on future thermal spray jobs and must be included in the pricing calculations.

A simple way to accomplish this is to find out all of the parts that were reworked in a specific time frame of say a year. Then find out the costs for reworking these parts. Let us assume that is ten thousand dollars. Then find out the total sales in the same time frame. Let us say that is one million dollars. With these two pieces of information, you can compute the rework costs as a percentage of sales volume. In this instance we can deduce that for every dollar of sales generated, one penny goes towards rework; in other words there is a one percent rework expense. Hence when quoting a job for ten dollars, you really need to quote it at ten dollars and ten cents in order to accommodate the rework rate in your thermal spray facility.

This rework costs data is thus an extremely important piece of information for thermal spray estimating personnel, but should also be used to improve the operations of your company by having a measurable goal to reduce rework. But please let it not be used to start battles between the quality department and production personnel; let us grow up and be real thermal spray men!

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Sire said...

Is thermal spray coatings the same as 'powder coating'? I have a steel door which was powder coated and after a few years it had developed some rust spots, so I took it down to a place where they specialized in powder coating. They told me they would take the door down to bare metal and then do what was necessary to apply the powder coating. The thing is that I don't think they did a good job as it has rusted worse than before an all under the coating.

Raj K said...

Thermal spray coatings are NOT the same as what are commonly referred to as powder coatings. The latter are generally deposited by an electrostatic process. Detailed descriptions of thermal sprayed coatings can be found in a blog that I write called and I would refer you to that especially the posts dealing with the basics of the technology. Thank you for your comment.