| Alloy and application | Zinc alloys such as Zamak 3 and Zamak 5 are commonly used for detailed, thin-wall components. Alloy choice affects strength, ductility, casting behavior, and finishing response. | State the required alloy designation, service loads, operating temperature, environment, and any applicable material specification. Do not rely on a generic “zinc alloy” description. | Review the material certificate and confirm that the specified alloy matches the drawing and purchase requirements. |
| As-cast surface | A well-controlled die can produce a smooth, detailed surface, but texture, flow marks, parting lines, ejector marks, and local porosity may vary with geometry and process conditions. | Identify cosmetic faces, acceptable witness marks, texture requirements, and areas that may be trimmed or machined. Add reference samples or clear visual acceptance criteria when appearance is critical. | Inspect cosmetic surfaces under defined lighting and viewing conditions. Check first articles and production samples against the agreed criteria. |
| Plating | Nickel- or chrome-based decorative plating may be suitable for appearance and wear requirements, but casting porosity and surface preparation can affect coating quality and consistency. | Specify the coating system, required thickness, appearance, corrosion-performance test, masked areas, and allowable surface defects. Confirm that the process is suitable for the selected zinc alloy. | Use coating-thickness measurement, visual inspection, and the agreed corrosion test. Define test method, duration, and acceptance criteria in the specification. |
| Paint or powder coating | Paint and powder coatings can provide color and environmental protection. Adhesion depends on cleaning, pretreatment, part geometry, and coating cure conditions. | Specify coating type, color reference, gloss or texture, coverage, thickness range, masking, and adhesion requirements. Identify edges, recesses, and threads that need special attention. | Check color and appearance against an approved standard. Verify coating thickness and adhesion using the agreed test method and sampling plan. |
| Dimensional tolerances | Achievable tolerances depend on part size, geometry, alloy, die design, tool condition, and measurement method. Tight tolerances can increase tooling and inspection costs. | Apply tolerances to functional features rather than tightening every dimension. Identify datum references, critical-to-function dimensions, and any dimensions requiring machining. | Measure critical features with suitable calibrated equipment. Review the drawing’s datum scheme and confirm measurement methods before production approval. |
| General casting tolerances | Use a recognized casting-tolerance framework, such as ISO 8062-3 or applicable NADCA product standards, as a starting point. The selected grade and scope must suit the part and process. | Call out the standard, edition, tolerance grade, and any exceptions on the drawing or purchase specification. Agree on requirements with the foundry before tooling release. | Compare inspection results with the agreed drawing and standard. Resolve any conflict between general notes and explicitly toleranced dimensions before production. |
| Parting line and flash | Parting lines and small amounts of flash are normal process considerations. Their location and allowable size should not interfere with assembly, sealing, safety, or appearance. | Show preferred parting-line locations, flash limits, trim requirements, and no-flash zones. Include sealing surfaces and mating interfaces as controlled features. | Inspect trim quality and critical interfaces. Use functional assembly checks where dimensional inspection alone does not confirm fit. |
| Porosity and pressure integrity | Porosity may occur in castings and can affect pressure retention, plating, appearance, or machining. The acceptable level depends on the part’s function and process. | State whether the part must be pressure-tight, plated, or machined through a wall. Define any porosity limits or repair restrictions rather than assuming zero porosity. | Use an agreed leak test, visual inspection, or other suitable inspection method. Set test pressure, duration, and acceptance limits for pressure-containing parts. |
| Quality system and inspection | A quality-management certification can indicate controlled processes, but it does not by itself guarantee that a particular part meets its drawing or performance requirements. | Define first-article approval, control-plan expectations, traceability, sampling frequency, nonconformance handling, and required records. Use a quality-system requirement appropriate to the project. | Review first-article results, material and coating records, process-control data, and calibration records. Confirm that inspection equipment is suitable for the tolerances being checked. |
| Design and cost trade-offs | Uniform wall sections, appropriate draft, generous transitions, and accessible trim features can support reliable filling and ejection. Design changes may improve quality and reduce secondary operations. | Review wall thickness, ribs, bosses, draft, machining allowance, and tooling access with the casting supplier before finalizing the design. | Evaluate design-for-manufacture feedback, prototype or first-article results, and assembly fit before releasing the part for volume production. |