When I review a die casting RFQ, the first thing I check is wall thickness distribution. Uniform walls are the single biggest lever on casting quality — abrupt section changes create shrinkage porosity, cold shuts and hot spots that no amount of die tuning will fully fix. In practice we hold thin walls around 0.8–1.5 mm for small zinc parts and 2.0–3.0 mm for typical aluminum housings, and we keep thickness transitions gradual, ideally within a 1:3 ratio over a generous length rather than a step. Where a boss or rib must stand proud, I spec a fillet radius of at least half the wall thickness at the root; sharp internal corners concentrate stress and erode the die steel prematurely. These are not cosmetic preferences — they directly drive die life, cycle time and scrap rate, which is exactly what shows up in your piece price.
Draft angle is the next item on my checklist, and it is where a lot of otherwise good designs fail at tooling. For aluminum and zinc die casting, I typically call out 1–2° draft on vertical walls, with 1.5° as a safe default, and push to 2–3° on deep cores or textured surfaces. Zero-draft features force the toolmaker to add slide actions or lifters, and every slide adds cost, maintenance and flash risk. I also look at ejector pin placement and gate location early — a part that cannot be ejected cleanly or fed without turbulence will run high porosity no matter how good the wall section is. Overflows and venting deserve space in the design review too; trapping air is the most common cause of rejects I see on first shots.
The lesson I keep relearning is that die casting design is a conversation between part geometry and tooling reality. Get the wall sections, radii, draft and gate layout right on paper, and the mold build goes smoothly; get them wrong, and you pay for it in tool rework and launch delays. If you are sourcing castings and want to compare quotes or check design guidelines before committing to a tool, visit MoldSo at www.moldso.com for mold sourcing information and supplier options.