Materials & Properties
This page narrows broad material categories down to the grade you actually quote on. Pick by part function, finishing plan, and quote risk, not by which name sounds strongest on the datasheet
| Category | Material | Process | Method | Downloads |
|---|
Aluminum Alloys
6061-T6 is the default we quote for machined aluminum housings, brackets, mounts, fixtures, and bases. It machines cleanly, anodizes evenly (Type II and Type III both behave), and welds with 4043 or 5356 filler without the cracking issues that show up on 7075. Yield around 276 MPa, tensile around 310 MPa in T6, enough for most structural brackets and enclosures.
Quote 6061 first when the part is machined aluminum, the finish is anodize or bead blast, and the service environment is indoor or light outdoor. Move to 7075 only when load testing or stiffness math forces it. Move to 5052 only when the part is bent sheet, not machined.
7075-T6 doubles the tensile strength of 6061-T6 (around 572 MPa vs 310 MPa) and roughly 1.5× the shear strength. Used for structural aerospace fittings, high-load brackets, weapon mounts, and tooling plate.
Two things to flag at quote stage: 7075 is not weldable in any practical production sense, it cracks. And it costs 2–3× more than 6061 per kg of stock. If the drawing calls for welding or for an anodize color match with adjacent 6061 parts, push back before quoting, 7075 anodizes a darker, mottled gray-brown that will not match 6061 in the same batch.
Download Data Sheet ↓
5052-H32 is a sheet alloy. Quote it for bent enclosures, chassis panels, marine hardware, and any part that goes through a press brake. Better corrosion resistance than 6061 in salt-spray, especially with the magnesium content around 2.5%. Not heat-treatable — you cannot strengthen it after forming.
Do not quote 5052 for machined billet parts. It gums up cutters and the surface finish after milling looks dragged.
Download Data Sheet ↓
2024-T3/T351 sits between 6061 and 7075 on strength, with high fatigue resistance — that is why aircraft skins and structural plates use it. Copper-based, so corrosion resistance drops well below 6061 and 7075. Bare 2024 surface will pit outdoors. Clad sheet (Alclad 2024) covers it with pure aluminum on both faces. Quote 2024 only when the drawing calls it out by name (usually aerospace). For general industrial work, 6061 covers the same use case at lower material cost and lower corrosion risk.
Download Data Sheet ↓Default to 6061-T6. Switch only with a reason.
• Sheet bending → 5052-H32
• Strength-driven structural, no welding → 7075-T6
• Fatigue loading per aerospace drawing → 2024
• Outdoor / marine + welded → 5052 or 6061 (not 7075, not 2024)
• Anodize color match across multiple parts → keep them all on 6061
Ready to machine aluminum parts? See Aluminum CNC Machining → | See Sheet Metal Fabrication →
Stainless Steels
- 303 Stainless Steel
- 304 Stainless Steel
- 316 Stainless Steel
- 17-4PH Stainless Steel
- Stainless Selection Logic
303 has sulfur added to break chips short. Machinability index sits around 78% versus 304 at 45%, fewer tool changes, faster cycle times, cleaner threads. Quoted for shafts, bushings, valve bodies, threaded fittings, and turned parts running on Swiss lathes or bar feeders.
Two limits to flag on the RFQ: do not weld 303 (sulfur causes hot cracking at the bead), and do not put it in chloride-heavy service, pitting resistance is worse than 304. For everything else machining-driven and dry, 303 is the cheaper, faster pick.
304 (and the low-carbon 304L) is the food-grade and weld-grade default. Quote it for sheet metal enclosures, welded frames, food and beverage equipment, sinks, and brackets that need passivation. Around 18% Cr, 8% Ni, the classic 18/8. Machines slower than 303 (work-hardens fast, keep feeds aggressive, do not dwell). If the part has weld seams, threads, and a sanitary finish on the same drawing, 304L is the safer choice over 303 even though it costs more per machining hour.
Download Data Sheet ↓
316 adds 2–3% molybdenum to 304. That is the only reason to pay the upgrade cost: pitting resistance in chloride environments: marine, coastal, chemical processing, pharmaceutical, surgical instruments. PREN around 24 vs 304 at 18.
Do not upgrade 304 to 316 just because the part “looks industrial.” Without chloride or harsh chemical exposure, the molybdenum buys nothing and the buyer pays 20–30% more for the same finished part.
Download Data Sheet ↓
17-4PH is precipitation-hardenable, heat treat after rough machining to lock in strength around 1,310 MPa tensile (H900 condition). Quote it for valve stems, pump shafts, aerospace fittings, mold inserts, and structural stainless parts that need both strength and corrosion resistance. Two things buyers miss: machining in the annealed (Condition A) state and heat treating to H900/H1025/H1150 after rough cut is standard, not optional. And dimensional growth during aging is small but real (about 0.0004–0.0006 in/in). Hold critical tolerances after the final heat treat, not before.
Download Data Sheet ↓• Turned bar parts, no welding, no chloride → 303
• Welded sheet, sanitary, indoor → 304 / 304L
• Marine, chloride, chemical → 316 / 316L
• High strength stainless with corrosion resistance → 17-4PH
• Decorative-only stainless (no real corrosion need) → 304, do not upgrade
Machining stainless steel parts? See Stainless CNC Machining →
Engineering Plastics
- ABS
- Nylon (PA6 / PA12)
- POM (Acetal / Delrin)
- PC (Polycarbonate)
- PEEK
- PMMA (Acrylic)
- Engineering Plastic Selection Logic
ABS is the cheap default for opaque injection-molded housings, covers, and consumer enclosures. Glass transition around 105°C, heat deflection around 88°C at 0.45 MPa. Molds easily, sands and paints well, and bonds with cyanoacrylate or solvent cement. Drop ABS once the part sees sustained temperatures over 80°C, gasoline or strong solvents, or outdoor UV without paint. PC is the next step up for impact and heat; nylon or POM for moving parts and wear
Download Data Sheet ↓
Nylon for gears, bushings, snap fits, cable glands, and any part with sliding contact. PA6 absorbs more moisture (up to 9% at saturation) and shifts dimensions with humidity, flag this for any tight-tolerance application. PA12 absorbs about 1.5% and holds dimensions better, which is why SLS prototypes and fuel-line fittings use it. Glass-filled nylon (PA6-GF30) doubles tensile strength but loses impact toughness and makes the part more abrasive on cutters during machining of stock.
Download Data Sheet ↓
POM machines like a soft metal, clean chips, sharp edges, dimensional stability after cutting. Quote it for precision gears, slides, bearings, lead-screw nuts, and any part where a plastic needs to hold tolerance within ±0.05 mm. Two things to call out at quote stage: POM does not bond well with adhesives without surface treatment (flame or chemical etch), and it releases formaldehyde above 230°C, not a process risk in injection molding, but a problem if the buyer plans to laser-mark or hot-stamp.
Download Data Sheet ↓
PC is transparent, impact-resistant (notched Izod around 600–850 J/m), and rated to about 130°C continuous service. Quoted for clear covers, light guides, safety shields, and impact-rated housings. Optical-grade PC holds about 88% light transmission. Limits: PC cracks under contact with gasoline, brake fluid, and most ketones. It also yellows under UV without a coating. For outdoor optical parts, specify UV-stabilized grade (Makrolon 2207 or Lexan 104R) on the RFQ.
Download Data Sheet ↓
PEEK runs to 250°C continuous, resists most solvents and acids, and holds mechanical properties through autoclave cycles. Quote it for aerospace bushings, semiconductor wafer carriers, medical implants, and high-temperature seal rings. Material cost is 50–100× ABS per kg. Quote PEEK only when the heat, chemical, or biocompatibility requirement is written on the drawing, never as a “better” upgrade from nylon. Machined PEEK also requires annealing after roughing to relieve internal stress before final cuts, which adds process time.
Download Data Sheet ↓
PMMA is the clear-plastic pick for display covers, light pipes, signage, and machine viewing windows. Light transmission around 92%, higher than PC. Scratches more easily than PC and cracks under impact, do not use it for safety guards or anywhere a drop test exists. Cast PMMA machines and polishes better than extruded PMMA. Specify cast grade on the RFQ if the part needs flame-polished or vapor-polished edges.
Download Data Sheet ↓• Opaque housing, low cost → ABS
• Clear and impact-rated → PC
• Clear and display-only → PMMA
• Gears, bushings, tight tolerance → POM
• Wear, snap fits, moisture-stable → PA12 (not PA6 for tight tolerance)
• High heat or aggressive chemicals → PEEK (and only with a stated reason)
Molding plastic parts? See Rapid Injection Molding →
Surface Finishing Options
As Machined
Toolmarks visible. Edges deburred and chamfered 0.2–0.5 mm. Surface roughness around Ra 1.6–3.2 µm depending on tool and feed. Lowest cost, no cosmetic guarantee
Bead Blasting
Glass bead blast (#80–#220 grit) gives a uniform matte surface. Hides minor toolmarks. Ra around 0.8–1.6 µm. Common pre-step before anodizing for an even matte tone.
Brushing
Abrasive belt or pad pulled in one direction. Produces parallel lines (#180, #240, #320 grit specifiable). Used on stainless trim, aluminum panels, and consumer-facing flat faces.
Anodizing
Type II for color and corrosion (5–25 µm thick). Type III hard-coat for wear (25–75 µm, much harder, color limited to dark gray/black). 6061 anodizes cleanly; 7075 turns mottled. See all Surface Finishing Services →
Material Comparison Guides
Aluminum vs Stainless
Aluminum 6061 is roughly one-third the density of 304 stainless (2.70 vs 8.00 g/cm³) and machines 3–5× faster. Quote aluminum for brackets, enclosures, and structural parts where weight, machining cost, and anodizing matter more than chemical exposure.
Move to stainless when the part sees daily washdown, food contact, chloride exposure, or sustained temperatures over 200°C, aluminum cannot hold its properties there. Stainless also takes a polished or brushed finish that stays bright without coating, which aluminum does not.
Mixed-metal note: do not bolt aluminum directly to stainless in wet service without an isolator. Galvanic corrosion eats the aluminum at the interface
ABS vs PC
ABS molds easier, costs about half as much per kg, and sands and paints well. PC is roughly 5–10× more impact-resistant (notched Izod) and holds dimensional stability up to about 130°C versus ABS at 80°C. PC is also transparent in optical grades.
Upgrade ABS to PC when a drop test fails, when the part runs above 80°C continuously, or when transparency is required. Skip the upgrade for indoor consumer housings that do not see impact or heat , the buyer pays more for performance the part never uses.
ABS/PC blend (Cycoloy / Bayblend) sits in between and is often the answer when ABS fails impact but PC is overkill on cost
PEEK vs Nylon
Nylon holds up to about 80–100°C continuous service. PEEK holds 250°C. Nylon absorbs moisture and shifts dimensions; PEEK is dimensionally stable in steam and water. Nylon costs around $5–10/kg in stock; PEEK runs $90–150/kg.
Quote PEEK only when the drawing specifies a temperature over 120°C, autoclave cycles, aggressive chemical contact (concentrated acids, ketones, brake fluid), or implantable/aerospace certification. Everything else, gears, bushings, snap fits, cable glands, quote nylon.
A common over-spec we see: PEEK quoted for a part that runs at 90°C in clean air. Glass-filled PA66 or PPS would have solved it at one-tenth the material cost
6061 vs 7075
7075-T6 has tensile strength around 572 MPa versus 6061-T6 at 310 MPa, nearly double. Shear strength runs about 1.5× higher. 7075 also costs 2–3× more per kg of stock and is not weldable in production.
Stay on 6061 unless the load calculation, the FEA, or a failed prototype proves 7075 is needed. The drawings we see most often over-specifying 7075: enclosure walls, cosmetic brackets, mounting plates under 5 mm thick, and anodized consumer parts where the buyer wanted “aerospace grade” on the spec sheet.
If the part is welded, formed, or anodized for color matching, 7075 is the wrong answer no matter the load
Cost vs Strength
Stronger material earns its cost when there is a failure mode on record, a cracked bracket from the last batch, a part that warped at 90°C, a thread that stripped at torque spec. Without a failure or a calculated load, the upgrade only shows up on the invoice. The pattern we see most: 7075 specified for parts that 6061 ran fine for years, 316 specified for parts that never see chloride, PEEK specified for parts running at room temperature. The cheaper grade is the right grade until the part proves otherwise
Typical Applications
Concept Models
Early visual and tactile models that lock in form, proportion, and styling before any tooling is committed.
Functional Prototypes
Working parts in production-intent materials, built to verify fit, function, and mechanical performance under real loads.
Engineering Validation
Rigorous testing of strength, durability, and environmental resistance to confirm the design meets performance and safety targets.
Fit & assembly testing
Dimensional and mating checks across components to verify tolerances, clearances, and assembly before scale-up.
Market testing samples
Near-final, cosmetically finished units in small batches for customer, retailer, and certification feedback.
Bridge production
Limited pre-mass runs on near-final tooling that keep you shipping while hard tooling and full production ramp up.
Related Engineering Resources
Material selected. Next, make sure your design is ready to machine.
