Designing a plastic housing for electronics in CAD is fun, until the mold quote lands.

Abal Mechanical Design LLC can help you avoid paying for unnecessarily complex tooling or a few “quick” welds, we pay attention to some quick design rules:

1. Wall thickness

• PC-ABS: 2.0–2.5 mm.

• PBT-GF: 1.2–2.0 mm.

• PA-GF: 1.5–2.0 mm.

Anything thicker begs for sink, warp, and longer cooling. If you need stiffness, core the bulk and create ribs (rib base ≤ 60 % wall, height ≥ 2.5 × wall, spaced ≥ 3 × wall).

2. Draft angles

Minimum 1 ° per side on textured walls, 0.5 ° on polished, 0.25 ° on mirror-polished surfaces for gasket sealing. Deep ribs still get 0.5 ° minimum. More draft means less ejector load, a shorter cycle, and no scratches. Rule of thumb: 1 ° per inch of draw depth; light grains live with 3 °, heavy grains need 5 °. Add draft angles early, even if your prototype is machined; steel does not forgive.

3. Parting-line strategy

Pick the line that lets both halves pull straight without touching functional surfaces. If a bearing shaft or gasket land crosses the line, add small flats or relocate the seal to avoid flash.

4. Flow length

Keep flow length below 100 × nominal wall, or clamp tonnage increases and knit lines explode. A quick flow analysis shows where the front freezes; if it stalls, split the cavity, add a hot tip, change the gate strategy, or switch to a higher-flow grade.

5. Gate location & size

• Gate into the thickest section and let flow move toward cosmetic faces. Filling thick-to-thin keeps pressure up and short-shots down.

• Gate diameter or thickness ≈ 0.8–1.2 × wall.

• One gate for flow lengths ≤ 100 × wall. If the longest path exceeds that limit, add a second gate or shift the first until every flow path fits inside the rule. Place the weld line where it won’t hurt cosmetics or sealing.

• For glass-filled parts, orient the gate so fibers align with the primary load path or hinge axis to curb warpage and boost stiffness.

6. Ribs, bosses & stiffening

Rib thickness ≤ 0.6 T, fillet 0.4 R, draft 0.5 °/side. Space multiple ribs ≥ 2 T to avoid hot spots and keep sink invisible on Class-A skins. Gusset every boss back to a wall; free-standing towers love to crack. Use the ribs to facilitate the flow of material.

7. Side holes without sliders

Side vents or key-ring holes can be molded with kissoff shut-offs: core and cavity meet at a 5 ° angle, creating a through-slot that releases in line-of-draw, with zero sliders and zero extra maintenance. Keep the through-hole smaller than 3 × wall and add draft so the steel doesn’t wear.

Let us help in your current or next project by providing expertise and production ready designs.