The cheapest granule is rarely the cheapest choice. The real difference never appears on the invoice.
Say your line runs 300 kg an hour. If material variability forces one correction a day and each costs 20 minutes, you have lost close to ten production hours in a month.
The second hidden cost: start-up scrap
Every stop and restart produces a run of off-spec material that goes to scrap. That figure is routinely left out of unit-cost calculations.
How to compare properly
Instead of comparing price per kilo, work out the cost per kilo of good product. A supplier five percent more expensive that takes your scrap rate from eight percent to three is, in practice, the cheaper one.
A simple test
Ask your current supplier to state the exact grade and mesh, then compare two consecutive shipments against it. If the numbers do not line up, your problem is not price.