Foundry proofs synonymize with the following phrases:
1. Casting samples: Samples of finished products produced by the foundry before mass production begins.
2. Foundry samples: Samples of raw materials tested in the foundry before mass production begins.
3. Prototype proofs: Test samples of products created to determine if they meet design specifications or rework needed to meet requirements.
4. Test castings: Samples created to determine if the molds and castings are able to sustain wear and tear.
5. Proof casts: A sample of finished products produced by the foundry to check the products' quality before giving the green light for mass production.
Overall, all of these terms serve as a type of quality control before mass production begins.