Letter 19056

DECENT PROPOSAL?

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What are your thoughts on the following proposal:

Spray System

Current Process:

Substrates = HRP&O, grit blasted HRS, shot peened HRS
Pretreat - Alkaline Clean, Rinse, Iron Phos, Rinse, Rinse (non-chrome sealer is used on the grit blasted substrate to reduce flash rusting)

Proposed Process:

Substrates = HRP&O, grit blasted HRS, shot peened HRS
Pretreat - Ambient Water Rinse, Iron Phos, Rinse, Rinse (no sealer)

We aim for 720 NSS hours at a failure of 7 (ASTM 1654) single scribe. We meet this with the current Process but want to reduce costs. This new process was proposed by a competing pretreat supplier not the current pretreat supplier.

Can we expect to have the same performance? What about cleaning?

Looking forward to your comments.

Chris Ellen
- Oakville

Hi Chris,

The competing supplier is probably pulling your leg if he's trying to convince you that a cleaner/phosphate with no sealing rinse will perform on an equal basis with your current process, which is an ideal set-up for a five-stage line. A cleaner/phosphate can be adequate for substrates which are not heavily soiled. HRPO does not normally fall into this category.

The only way to know for sure, however, is to do a side-by-side comparison between your current process and the new process. The new process may be cheaper in $/gallon, but can you put a price tag on the decrease in quality of your finished parts?

George Gorecki
- Naperville, Illinois

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