Aluminum CNC machining, and the rest of the stocked library.
Praetore is a precision manufacturer with a distributed factory floor — one engineering core, a network of American shops on one standard, a price in minutes and a date backed by money.
Material choice sets a part's cost, weight, service life, and lead time before a single chip is cut. Most of what we make is aluminum, and most of that is 6061-T6 — because it is the right engineering answer more often than any other metal, not because it is the easy one.
The Catalog library is fixed and stocked. That is not a limitation we apologize for; it is the reason a price can be instant and a date can be underwritten. Below is every material in it, what each one is for, and where we would tell you to pick something else.
- GRADES
- 13, FIXED
- INSTANT PRICE
- 11
- FLAGGED TIER
- Ti 6Al-4V · PEEK
- STOCK LADDER
- 0.25 – 4.5 IN THICK
- SUPPLIED STOCK
- ACCEPTED WITH CERT
A count of the published library below — two aluminums in section 01 and eleven more in section 02 — not a claim about inventory on a given day. A material joins the library only under the rule in section 05.
Two aluminums cover almost everything.
Nearly every aluminum decision we see comes down to these two. 6061 unless the part is highly loaded; 7075 when it is and weight still matters. Both are stocked across the ladder, both price instantly, and both anodize.
Aluminum 6061-T6
T6 · Start here unless you have a reason not to
Strong enough for most structural parts, about a third the density of steel, excellent thermal conductivity, and it cuts fast — which is why it is also the cheapest to machine. It anodizes cleanly in clear or black, and it is the material stocked across the widest range of the ladder.
- Typical use
- Enclosures, brackets, plates, manifolds, heat sinks, robotics and drone structure
- Watch out
- Not the call above roughly 300 °F sustained, or where surface hardness matters more than weight.
Aluminum 7075-T651
T651 · When 6061 is not strong enough
Roughly double the tensile strength of 6061 — into the range of many steels — while staying light. The default for aircraft structure and for anything highly loaded that still has to fly, ride, or be carried. It machines well, though it is less forgiving in thin sections.
- Typical use
- Aerospace structure, suspension and linkage parts, high-stress brackets
- Watch out
- Costs more, welds poorly, and corrodes more readily than 6061. Anodize or coat it.
Minimum wall in metals is 0.030 in and the minimum internal corner radius is 0.031 in, which accepts a 1/16 in end mill. Thin ribs and sharp internal corners are the two aluminum features most likely to flag a job for an engineer — usually with a one-line redesign suggestion attached.
Eleven more materials, and nothing hiding behind “and more.”
Everything below is held on the standard stock ladder and prices from the same engine, and each entered the library under the rule in section 05 — proven feeds and speeds, real stock supply, and a committed recurring buyer. Two of them — titanium and PEEK — sit in a flagged tier, which means an engineer sizes the stock and confirms the price rather than a machine guessing at it.
Stainless 303
Annealed · The free-machining stainless
Sulfur additions make 303 cut far more easily than the rest of the 300 series, at the cost of weldability. Pick it when the part is mostly machined features and never sees a weld.
- Typical use
- Fittings, shafts, fasteners, instrument bodies, machined hardware in wet service
- Watch out
- Do not weld it, and expect slightly lower corrosion resistance than 304. It work-hardens.
Stainless 304
Annealed · The one you weld
Tougher and more corrosion resistant than 303, and it welds cleanly. Pick it for welded assemblies, wet service, and anything a food-safety or marine spec is written against.
- Typical use
- Food and beverage equipment, marine hardware, weldments, enclosures in wet service
- Watch out
- Work-hardens harder than 303 and cuts slower. Tight tolerances on thin features cost more here than in aluminum.
Stainless 17-4 PH
Cond A · H900 · Stainless that behaves like tool steel
Precipitation-hardening stainless that heat-treats to roughly 44 HRC in H900 while keeping its corrosion resistance. When a part must be hard, strong, and rust-proof at once, this is usually the answer.
- Typical use
- Valve internals, instrument components, high-load pins and shafts
- Watch out
- Call out the condition on your print. Condition A and H900 machine and measure differently.
Steel 1018
Cold rolled · Cheap strength, honest work
Weldable, predictable, and inexpensive. The right answer for fixtures, brackets, and structural parts where cost wins and corrosion is handled by a coating.
- Typical use
- Fixtures, weldment components, spacers, tooling plates
- Watch out
- No corrosion resistance at all. Budget for plating, black oxide, paint, or oil from day one.
Steel 4140
Annealed · pre-hard · Real mechanical strength
Chrome-moly steel with genuine strength and the option to harden. Pre-hard stock arrives at usable hardness, which removes a heat-treat leg from the schedule.
- Typical use
- Shafts, gears, tooling, high-load mechanical components
- Watch out
- Heavier cuts and slower cycles than aluminum. Specify annealed or pre-hard — they are different jobs.
Brass 360
Half hard · The fastest metal through the machine
Free-machining brass cuts faster than anything else in the library, which often makes a brass part cheaper than the same geometry in steel despite the higher material cost. Naturally corrosion resistant and non-sparking.
- Typical use
- Fittings, valve bodies, electrical contacts, decorative hardware
- Watch out
- Soft. Do not specify it for wear surfaces or heavily loaded structure.
Titanium 6Al-4V
Grade 5 · When the part matters more than the price
The best strength-to-weight ratio of any common engineering metal, biocompatible, and effectively corrosion-proof. Machining it is slow and hard on tooling — that is most of what you are paying for, and it is why titanium sits in a flagged pricing tier rather than the instant one.
- Typical use
- Aerospace, medical instruments and implantable components, motorsport
- Watch out
- Prototype in 6061 and cut over once the design settles. The geometry lessons transfer; the cost does not.
Delrin 150
Acetal homopolymer · The default engineering plastic
The most dimensionally stable of the common machinable plastics, it machines beautifully and needs no lubrication to run against metal. If a plastic part has to behave like a part, this is where to start.
- Typical use
- Bushings, gears, wear pads, insulators, manifold bodies
- Watch out
- Moves with temperature and moisture. Tolerance expectations should account for it.
UHMW
Sheet · bar · Impact and abrasion, cheaply
Extremely tough, low friction, and nearly impossible to abrade. The right answer for wear strips, guides, and anything that gets hit.
- Typical use
- Wear strips, chain guides, impact pads, conveyor components
- Watch out
- Not dimensionally stable enough for precision fits. Loose tolerances only.
PEEK
Unfilled · Plastic that survives the autoclave
High-temperature, chemically inert, sterilizable, and strong. Specified when metal is out for weight, electrical, or chemical reasons and ordinary plastics will not survive the environment.
- Typical use
- Semiconductor handling, medical instruments, chemical service, insulators
- Watch out
- Material cost dominates the part cost. Flagged so an engineer sizes the stock before you are quoted.
Polycarbonate
Machine grade · Transparent and tough
Impact resistant and optically clear. Used where someone has to see the mechanism, or where a guard has to survive being hit.
- Typical use
- Guards, windows, light pipes, fixtures for visual inspection
- Watch out
- Scratches easily and can stress-craze near solvents. Not a bearing surface.
Need something the library does not hold — Inconel, copper, magnesium, a specific temper, a mill-certified customer lot? Send it anyway. It routes to the Sourcing lane, where a human comes back within 2 business days with a real answer and a committed date. Not a rejection, and not silence.
A shared ladder is what makes your part cheaper.
Standard stock runs in defined increments from 0.25 in to 4.5 in of thickness, in plate and bar. Every network shop draws from the same ladder, which means your part and a stranger's part can share a plate, a lot cert, a fixture family, and one setup.
No single shop sees enough order flow to do that. A network does. It is the machining equivalent of nesting several customers' parts on one sheet, and it is the reason staying on the ladder and inside the library shows up in your price rather than in a brochure.
Customer-supplied material is accepted with a cert. It flags the job and forfeits the batching discount, because we no longer control the lot, the size, or when it lands on the dock. That is a real trade, not a penalty — sometimes your lot is the whole point.
Anodize is a spec, not a color swatch.
Aluminum leaves the machine at 125 µin Ra by default, or 63 µin as a premium surface. What happens after that is a fixed menu, scheduled inside your order rather than handed to you as a second project to manage.
- Anodize Type II — clearThe default aluminum finish. Thin, hard, corrosion resistant.
- Anodize Type II — blackSame process, dyed. Other colors are flagged.
- Anodize Type IIIHardcoat. Thicker, for wear surfaces and sliding fits.
- Bead blastUniform matte, usually before anodize.
- Powder coatStandard RAL subset, for parts that live outdoors.
- Chem filmFlagged. Partner-routed, and it adds days we state up front.
Passivation, zinc plate, and black oxide cover the stainless and steel side of the library. The full finish menu lives on the capabilities page.
A material enters the library by proof, not by request.
Adding a material to the Catalog means three things have to be true at once: proven feeds and speeds in the network, a real stock supply on the ladder, and at least one committed recurring buyer. Miss any of them and the material stays in the Sourcing lane, where a human quotes it honestly, until it doesn't.
Every out-of-library request is logged by class. That log is the expansion roadmap — the envelope grows from delivered evidence, never from marketing pressure. So tell us what you wish were instant.
What the shop receives
The material spec and its lot requirement are two of the twelve artifacts inside every Job Packet, alongside the verified programs, the setup sheets, the tool list, the fixture plan, the probing routines and the inspection plan. A shop never has to decide what to cut it from — or chase a cert after the fact.
Apply as a shopStill not sure which one? Send the part and say what it has to survive.
Loading, environment, temperature, budget. In-envelope parts come back with a price and a guaranteed date in minutes, and the DFM feedback names any feature that would flag — in plain language, with the fix where one exists.
Upload a partYou never have to guess what to cut it from.
The material spec and its lot requirement arrive inside the packet, on stock from the shared ladder. We send you the job, not the RFQ — no quoting, no programming, no fees.
Apply as a shop