Estimating Pretreatment Costs

Q. I'm looking for a formula to calculate/estimate the cost to pretreat steel per foot (or square foot) based on a typical five-stage process (cleaner/rinse/conversion/rinse/seal). Any suggestions? –D.V.

A. I am fairly certain there is no simple formula to calculate pretreatment costs due to the number of potential factors that need to be accounted for. Here's a list of some of them.

Energy usage. This can be significant depending on how many stages are heated and to what temperature. This would largely be a fixed cost regardless of how many square feet you are processing. You may be able to turn off recirculation pumps and lower tanks’ temperatures, but you will generally not be shutting down the entire system unless it is for a longer plant shutdown. Additionally, you should have a dry-off oven, which will be a significant source of energy usage.

Chemical usage. This will largely be dependent on the area of material processed. I have seen pretreatment chemical costs vary significant (a factor of two for functionally the same chemicals). The usage cost is usually a function of actual concentration required in the process and the dump frequency needed.

Capital costs. Installing a five-stage pretreatment system along with the associated support equipment (oven, conveyor and waste treatment or holding) will cost a sizable amount—typically several hundred thousand dollars on the low end and more than a million dollars on the high end. This cost of capital needs to be captured in your cost model and would typically involve the depreciation value along with a markup to cover the cost of the investment.

Labor. Loading/unloading the conveyor, system maintenance and troubleshooting, quality checks of each stage, oven profiles, final part inspection, packaging, shipping and receiving will all need to be done by trained personnel. Payroll and benefits to these employees will need to be factored into your cost model.

I am not aware of a simple formula that will take into account all of these variables at once. There are some proprietary and specific software programs to assist finishing shop owners in estimating operational costs of their systems. This will also typically involve a paint system, though, so may be more than you are looking for. I would suggest checking the Products Finishing site for additional details.