Shenzhen Alu Rapid Prototype Precision Co., Ltd.
Industry News
Short answer: Start with 6061 aluminum for metal parts and POM (Delrin) for plastic parts — they are the cheapest, fastest, and most forgiving options. Move to stainless, titanium, or engineering plastics only when strength, temperature, chemical resistance, or regulatory requirements demand it.
This guide compares the materials we machine most often, ranked by cost, machinability, and typical use.
Metals Compared
| Material | Cost | Machinability | Strength | Typical use |
|---|---|---|---|---|
| Aluminum 6061 | $ | Excellent | Medium | Enclosures, brackets, general parts |
| Aluminum 7075 | $$$ | Good | Very high | Aerospace, high-load parts |
| Aluminum 2024 | $$$ | Good | High | Aircraft structures, fatigue parts |
| Brass | $$ | Excellent | Medium | Fittings, connectors, decorative |
| Copper | $$$ | Good | Low | Busbars, heat sinks, RF parts |
| Mild steel 1018 | $ | Good | High | Brackets, shafts, structural parts |
| Alloy steel 4140 | $$ | Moderate | Very high | Tooling, shafts, high-stress parts |
| Stainless 303 | $$ | Good | High | Free-machining fittings, fasteners |
| Stainless 304 / 316 | $$ | Moderate | High | Food, medical, marine, chemical |
| Stainless 17-4 PH | $$$ | Moderate | Very high | Aerospace, medical, valves |
| Titanium Ti-6Al-4V | $$$$$ | Poor | Very high | Aerospace, implants, racing |
| Inconel 718 | $$$$$ | Very poor | Extreme | Jet engines, high-temperature service |
Plastics Compared
| Material | Cost | Machinability | Key property | Typical use |
|---|---|---|---|---|
| ABS | $ | Good | Cheap, tough | Housings, covers, prototypes |
| POM (Delrin) | $ | Excellent | Low friction, stable | Gears, bushings, sliding parts |
| Acrylic (PMMA) | $ | Good | Optically clear | Light guides, windows, displays |
| PC (polycarbonate) | $$ | Good | Impact resistant, clear | Lenses, guards, housings |
| Nylon (PA) | $$ | Moderate | Wear resistant, absorbs moisture | Gears, rollers, wear pads |
| PTFE (Teflon) | $$$ | Moderate | Chemical resistance, low friction | Seals, liners, lab equipment |
| PEEK | $$$$ | Good | High temp + chemical resistance | Aerospace, medical, semiconductors |
| PEI (Ultem) | $$$$ | Good | High temp, flame retardant | Electrical, aerospace interiors |
| PPSU / PSU | $$$ | Good | Sterilizable, transparent | Medical trays, sterilizable parts |
How to Choose
Strength and stiffness — does the part carry load? If not, stay with aluminum or POM
Operating temperature — above about 120 °C, standard plastics are out; consider PEEK or PPSU
Chemical exposure — solvents, fuels, and acids rule out many plastics; PTFE and PEEK resist best
Corrosion requirements — stainless 304/316 or anodized aluminum for outdoor and marine
Regulatory constraints — medical and food contact require specific grades and certifications
Cost — always ask whether a cheaper material meets the requirement before choosing a premium one
Cost Ranking at a Glance
| Rank | Metals | Plastics |
|---|---|---|
| Cheapest | 6061 aluminum, mild steel, brass | ABS, POM, acrylic |
| Mid | 7075, 2024, stainless 303/304/316, 4140 | PC, nylon, PTFE |
| Expensive | 17-4 PH, titanium | PPSU, PSU |
| Most expensive | Inconel, specialty alloys | PEEK, PEI |
Note that machinability matters as much as material price. Titanium stock is costly, but the real expense is that it machines 5–10× slower than aluminum and destroys tooling. See our 6061 vs 7075 comparison for a deeper look at the two most common aluminum alloys.
Quick Selection Guide
| Requirement | Choose |
|---|---|
| Cheapest functional metal part | 6061 aluminum |
| Highest strength aluminum | 7075-T6 |
| Corrosion / food / medical | 316L stainless |
| Light weight + strength | Titanium Ti-6Al-4V |
| Cheap low-friction plastic | POM (Delrin) |
| High temperature plastic | PEEK or PEI |
| Transparent plastic | Acrylic or polycarbonate |
See our CNC machining capabilities for the materials we keep in stock and machine routinely.
FAQ
What is the best material for CNC machining?
6061 aluminum for metal parts and POM for plastic parts — they are the cheapest, fastest to machine, and most widely available.
Why is titanium so expensive to machine?
The raw stock is costly, it conducts heat poorly so tools overheat, it work-hardens, and it must be cut slowly with frequent tool changes.
Which plastic is strongest?
PEEK offers the best combination of strength, temperature, and chemical resistance, but it costs several times more than POM or nylon.
Can I machine food-safe or medical parts?
Yes — typically 316L stainless, titanium, PEEK, or PPSU. Certification and cleanliness requirements must be specified up front.
Should I prototype in the production material?
Yes, at least once. Material behaviour is the most common source of late-stage design problems.
Get Your Material Quoted
Send your drawing with the material and finish you have in mind. If a cheaper material would work, we will tell you.