How much more expensive is 7075 than 6061 to machine?

Raw 7075-T6 bar or plate typically costs several times more per kilogram than 6061-T6, while cutting time is only modestly higher — 7075 machines well, slightly harder and with marginally faster tool wear. For a small part where material weight is a fraction of a kilogram, the alloy choice usually shifts the unit price by tens of percent, not multiples; the material delta matters far more on large solid parts where most of the billet becomes chips.

Why does batch size change the unit price so much?

One-time engineering — CAM programming, fixturing, first-article inspection and set-up — is spread across the batch. A part needing 90 minutes of set-up and programming costs that hour once: divided across 10 pieces it adds 9 minutes per piece, divided across 500 it becomes seconds. Machine time per piece then drops further as operators optimise feeds and multi-part fixtures over the run.

What design changes most reliably cut aluminium machining cost?

In order of impact: reduce deep narrow pockets and long internal radii that force small slow tools; allow standard end-mill corner radii instead of sharp internal corners (or move those corners to a wire EDM route); avoid tolerances tighter than the function needs, especially on non-critical faces; choose 6061 over 7075 where strength allows; and accept a standard finish such as clear anodise rather than cosmetic multi-step treatment.

Aluminum CNC Machining Cost: Machine Time Drives the Price, Not the Metal

Cost structure of aluminium CNC parts · Boyang Hardware, Zhongshan, Guangdong, China

Direct answer For an aluminium CNC part, machine time is the largest cost component — often more than half the unit price — even though the raw alloy itself is cheap. The ranking of drivers: geometry that forces small slow tools (deep narrow pockets, tight internal radii), batch size (set-up amortisation), tolerance specification (inspection and precision operations), surface finish, and only then the alloy choice. Between the two common grades, 6061-T6 is the cheaper buy and faster to cut; 7075-T6 stock costs several times more per kilogram with only slightly higher cutting time, so the alloy delta is material-volume dependent — small for a 50 g part, significant for a solid block.

>50%typical share of machine time in cost
×4–87075 vs 6061 raw stock price
1×spread set-up across 500 parts
±0.01 mmachievable without cost penalty
1–2 daysquotation
100%CMM inspection included

What an aluminium part actually costs, item by item

Table 1 — Cost components for a typical small-to-medium aluminium CNC part. Percentages are indicative for a 100-piece order and shift with geometry and quantity.
Cost component	Typical share	What moves it
Machine time (milling/turning)	45–65%	Pocket depth, tool diameters, tool changes, chip volume
Raw stock	10–30%	Alloy (6061 vs 7075), billet oversize, stock form (bar vs plate)
Set-up & programming (amortised)	5–30%	Batch size — collapses as quantity rises
Surface finish	5–15%	Clear anodise cheap; hard anodise, colour matching, masking higher
Inspection & documentation	5–10%	100% CMM is included; 0.001 mm critical features add grinding/EDM routing
Logistics & packaging	3–8%	Order size, shipping terms

The headline: on cheap metal, you are essentially buying spindle minutes. Anything that lets the tool cut faster, deeper and with fewer changes directly lowers the price — see our aluminium machining services and the materials guide for how other alloys change this picture.

6061 vs 7075 — where the alloy money actually goes

Table 2 — The two aluminium grades compared on cost-relevant properties. Prices are relative, not quoted; both are machined routinely at Boyang Hardware.
Factor	6061-T6	7075-T6
Raw stock price	Reference (lowest common alloy)	~4–8× higher per kg
Cutting behaviour	Excellent — high speeds, long tool life	Very good — slightly harder, modest tool-wear increase
Strength	Moderate (~310 MPa tensile)	High (~570 MPa tensile)
Weldability	Good	Poor — design around it
Anodising	Straightforward, good appearance	Machines well but anodised finish can appear slightly less bright
Cost impact on a small part (<200 g)	Cheapest overall	Unit price rises mainly via stock cost — often tens of percent
Cost impact on a large solid part	Cheapest overall	Stock cost dominates — can rival or exceed machine time
Best use	General parts, welded assemblies, budget projects	High-load, low-weight structures — 7075 capability

Practical rule: specify 7075 only where the strength calculation demands it, because its price premium is paid per kilogram of billet — including the kilograms removed as chips. A solid-block design in 7075 pays twice; a design that starts from plate near net shape pays once.

How batch size reshapes the unit price

One-time costs do not scale with pieces: CAM programming, fixture build, first-article inspection and machine set-up happen once per run. On a job needing ~90 minutes of that engineering:

10 pieces: engineering adds roughly 9 minutes of cost per part — often the majority of the unit price.
100 pieces: under 1 minute per part — engineering becomes a rounding error.
500 pieces: seconds per part — and multi-part fixtures then cut machine time itself, the second saving.

This is why repeated small orders cost disproportionately more than one consolidated order, and why quoting "same part, three quantities" usually shows a steep initial drop then a flattening curve. Prototypes and small batches remain available with no minimum order — just expect the per-piece economics above.

Design and sourcing levers that reliably lower unit cost

Table 3 — Ranked levers. Each is checked and quantified at quotation, not guessed.
Lever	Why it cuts cost	Typical effect
Relax non-functional tolerances to ISO 2768-m general block	Removes extra passes and 100% inspection burden per feature	High on over-toleranced drawings
Avoid deep narrow pockets & small internal radii	Permits larger, faster tools	High — machine time is the main driver
Standard corner radii; sharp corners only where functional	Sharp corners need EDM or special tooling — wire EDM route	Medium-high
Consolidate orders or schedule framework batches	Amortises set-up once instead of per order	High for small quantities
6061 instead of 7075 where strength allows	Stock price delta disappears	Medium; large on big parts
Standard clear anodise; skip cosmetic colour matching	Finish step simplified, masking avoided	Medium
Start from plate near net shape on solid parts	Fewer kilograms converted to chips	Medium; large in 7075
Very high volumes with simple constant profiles	Consider die casting break-even instead of machining	Case-dependent — evaluated honestly at quote

Honest limits: we publish no per-hour machine rates or instant online price calculators — every aluminium part is quoted from the actual drawing because geometry, not a catalogue formula, sets the price. Cost figures on this page are structural explanations, not quotations. Batch-price curves assume repeatable drawings; engineering changes restart the one-time costs. And where the cheapest route for your part is not CNC machining at all — casting, stamping or moulding — we will say so at quotation rather than sell you the wrong process.

FAQs

Why did a reorder of the same part cost more than the first batch?

Usually one of three causes: a smaller quantity this time (set-up re-spent across fewer pieces), a drawing change (programming redone), or raw-alloy market movement — aluminium billet prices fluctuate with the LME and are locked at quotation, not at order date.

Do tighter tolerances on aluminium cost much extra?

Up to ±0.01 mm, usually not — it is within normal milling and turning capability. Beyond that, cost rises per feature: critical dimensions routed through grinding or EDM plus dedicated measurement. Specify 0.001 mm only where function requires it.

Is it cheaper to machine aluminium in China despite shipping?

For many part families yes — machine time and set-up costs are the dominant components, and they are priced lower here. The honest answer depends on your part and logistics: send the drawing and we quote the full landed picture including shipping terms, typically within 1–2 working days.