Design references for
better, cheaper parts.
DFM guides, tolerance & surface-finish charts, material selection and cost-optimization tips — the references our engineers use, free for yours.
Design-for-Manufacturing guides
Design with the process in mind and you cut cost, lead time and rework. Quick rules by process:
CNC Machining
- Keep wall thickness ≥ 0.8 mm (metal), 1.5 mm (plastic)
- Limit pocket depth to 4× tool diameter
- Add radii to internal corners (≥ ⅓ pocket depth)
- Avoid deep, thin features and tiny text
- Call out only the tolerances you truly need
Sheet Metal
- Bend radius ≥ material thickness
- Hole/slot ≥ 1× thickness from a bend
- Keep uniform thickness across the part
- Allow for K-factor / bend deduction
- Design tabs & slots for self-fixturing welds
Injection Molding
- Uniform wall thickness (avoid thick/thin transitions)
- Add 1–2° draft on all vertical faces
- Use ribs (≤ 60% of wall) instead of thick sections
- Round corners to ease flow & reduce stress
- Plan gate & ejector locations early
Casting
- Uniform sections; avoid heavy isolated masses
- Add fillets & generous radii to all corners
- Design draft for pattern/die release
- Specify machining stock on critical faces
- Consider NDT zones for safety-critical parts
Tolerance reference
Unless specified, parts are made to ISO 2768 general tolerances. Tighten only critical features — every extra-tight callout adds cost.
ISO 2768 linear (general)
| Nominal size | Fine (f) | Medium (m) | Coarse (c) |
|---|---|---|---|
| 0.5–3 mm | ±0.05 | ±0.1 | ±0.2 |
| 3–6 mm | ±0.05 | ±0.1 | ±0.3 |
| 6–30 mm | ±0.1 | ±0.2 | ±0.5 |
| 30–120 mm | ±0.15 | ±0.3 | ±0.8 |
| 120–400 mm | ±0.2 | ±0.5 | ±1.2 |
| 400–1000 mm | ±0.3 | ±0.8 | ±2.0 |
What's achievable by process
| Process | Typical | Best |
|---|---|---|
| 5-axis CNC milling | ±0.05 mm | ±0.005 mm |
| CNC turning | ±0.025 mm | ±0.005 mm |
| Sheet metal | ±0.13 mm | ±0.05 mm |
| Injection molding | ±0.1 mm | ±0.025 mm |
| Investment casting | ±0.25 mm | ±0.1 mm |
| Die casting | ±0.1 mm | ±0.04 mm |
Surface-finish comparison
Choose a finish for function (corrosion, wear, conductivity) and appearance. Common options:
| Finish | Materials | Key benefit | Typical Ra / spec |
|---|---|---|---|
| As-machined | All metals | Lowest cost, default | Ra 1.6–3.2 µm |
| Bead blasting | Metals | Uniform matte texture | Ra 1.6–3.2 µm |
| Anodizing Type II | Aluminum | Corrosion + color | 5–25 µm coat |
| Hard-coat (Type III) | Aluminum | Wear resistance | 25–50+ µm coat |
| Electroless nickel | Steel, Al | Even wear/corrosion coat | 10–25 µm |
| Zinc plating | Steel | Cost-effective corrosion | 5–25 µm |
| Powder coating | Metals | Durable color finish | Any RAL/Pantone |
| Passivation | Stainless | Restores corrosion resistance | ASTM A967 |
| Polishing | Metals | Mirror / cosmetic | Ra < 0.1 µm |
Material selection guide
A starting point for common engineering materials. Send us the application and we'll recommend a grade.
Metals
| Material | Grades | Strengths | Typical use |
|---|---|---|---|
| Aluminum | 6061, 7075, 2024, 5052 | Light, corrosion-resistant, machinable | Aerospace, automotive, housings |
| Stainless steel | 303, 304, 316L, 17-4PH | Corrosion & heat resistant | Medical, food, marine |
| Carbon / alloy steel | 1045, 4140, 4340 | High strength, hardenable | Shafts, gears, structural |
| Titanium | Gr 2, Gr 5 (Ti-6Al-4V) | Best strength-to-weight, biocompatible | Aerospace, medical implants |
| Brass / copper | C360, C110 | Conductivity, machinability | Electrical, plumbing, decorative |
| Tool steel | D2, A2, H13 | Wear resistant, holds edge | Dies, molds, cutting tools |
Engineering plastics
| Material | Strengths | Typical use |
|---|---|---|
| ABS | Tough, impact resistant, low cost | Enclosures, consumer goods |
| Nylon (PA6/66) | Strong, wear resistant | Gears, bearings, bushings |
| POM (Delrin) | Low friction, dimensionally stable | Precision moving parts |
| Polycarbonate | Transparent, impact resistant | Lenses, guards, housings |
| PEEK | High temp & chemical resistance | Aerospace, medical, semiconductor |
Accepted file formats
3D models (preferred)
2D drawings
10 ways to cut part cost
Loosen non-critical tolerances to ISO 2768-m
Reduce the number of setups & tool changes
Use standard stock sizes & common materials
Add radii instead of sharp internal corners
Avoid deep pockets and thin tall walls
Choose as-machined or bead-blast over premium finishes
Standardize hole sizes to common drill diameters
Increase quantity — unit price drops with volume
Avoid tight surface-finish callouts unless required
Send a clean 2D drawing to avoid quoting delays
Put these into practice
Upload your CAD — we return pricing and a free DFM review within 24 hours.