Re: Scrap rate in the foundry industry
I spent 3 and half months last year in a green sand foundry casting grey, ductile and compacted graphite cast irons. WRT the scrap rate, a lot depends - how complex are the castings? Well designed and proofed, or start-up of a new part or at a new foundry? We were doing complex castings for the automotive industry - lots of complicated coring. For us the goal was 5% or less, and with some start-up jobs it was a lot higher. For some long term jobs that were pushing the capabilities of green sand casting we were happy with 10%, but that scrap rate had been built-in to the customer cost. We had good capability as far as prototyping and running software to predict solidification in the castings, and still occasionally missed on how the part actually solidified versus how it was predicted to solidify.
We had an in-plant group that regulary looked at scrap rate per part and selected high scrap items to investigate, so we could improve our processes and reduce scrap rates.
We also had customers who wanted and tried to hold us to investment cast tolerances while specifying green sand castings, and only paying for green sand casting.
" We have met the enemy and he is us." Pogo