CNC Machining Melbourne Service: 7 Checks Before You Order
This guide is for Melbourne engineers and buyers sourcing metal or plastic parts. It lists the checks that separate a workable supplier from one that costs you a re-run, and it shows where offshore capacity fits a local project. Read it before you send an RFQ.
In this article
- 1
- 2
- 3
- 4
- 5
- 6
- 7
Key takeaways
What to check against what it actually controls
Match your part to the column that governs it. If two columns disagree, the tighter one wins.
| Check | What it controls | Good sign | Red flag |
|---|---|---|---|
| Tolerance | Fit and function | ±0.005 mm stated with machine list | “As tight as needed” with no number |
| Machine mix | Geometry and setups | 5-axis and mill-turn in-house | All work subcontracted out |
| Lead time | Schedule risk | Quote in 12 h, production in 24 h | Quote only after chasing |
| MOQ | Prototype cost | One piece accepted | 500-piece minimum on a first order |
| Certifications | Audit and traceability | ISO 9001 + IATF 16949 + ISO 13485 | Certificate images only, no scope |
| Inspection | Incoming quality | 100% before shipment, reports on request | Sampling only, no reports |
| Max part size | Whether it fits | 4,000 mm envelope confirmed | Size quoted before checking travel |
| Confidentiality | IP exposure | NDA on request, secure uploads | Files sent by plain email |
The short verdict
If your part needs ±0.005 mm, several faces, or a certified supply chain, pick the supplier that answers all seven checks in writing. If it is a simple bracket and you need it tomorrow, keep it local. Send the drawing and we will tell you which side you are on.
Tolerance and machine mix decide the part, not the price
Start with the tightest tolerance on your drawing. If it is ±0.005 mm (±0.0002 in), the supplier needs 5-axis or mill-turn capacity to hold it in one setup. A shop that moves the part between three fixtures will stack error and drift on the second or third face. Ask which machine will run the job and how many setups it needs.
Setup count also drives geometry. A part with features on five faces, deep pockets, or an angled bore is a 5-axis job by default. A simple bracket with holes on one face is not, and paying a 5-axis rate for it is waste. GreatLight runs 16 simultaneous 5-axis centers, 12 four-axis mills, 27 three-axis machines, 16 mill-turn centers and a Ø400 mm rotary table, so the quote can match the part instead of forcing it onto one platform.
Surface finish follows the same logic. Ra 0.8–1.6 μm is a normal machined finish for most aluminium and steel parts. Ra 0.2–0.8 μm needs finer stepovers, sharper tooling and slower feed, which raises cycle time. Say which surfaces actually matter. A cosmetic face and a sealing face rarely need the same number.
- 1Send the tolerance callout, not the title block defaultA general ±0.1 mm note and a local ±0.005 mm callout are different jobs.
- 2Mark datum surfacesIt tells the programmer where to start and cuts a setup.
- 3Say if the finish is cosmetic or functionalIt changes the toolpath and the price.
Lead time, MOQ and what a quote should actually contain
A CNC machining Melbourne service can only promise what it controls. Ask when the clock starts: at PO, at drawing release, or at material arrival. A shop that quotes and returns a DFM analysis within 12 hours and can start production within 24 hours is telling you the programming and material pipeline are already in place. Parts ship in 3–5 days on that basis.
MOQ is the next filter. If you are prototyping, a supplier with a 500-piece minimum forces you to buy parts you have not validated. No minimum order quantity means one piece or a 10,000+ part run goes through the same process. That matters more for complex parts, where the first article usually reveals a drawing problem.
Read the quote line by line. A usable quote lists material grade, machine, tolerance, finish, inspection method and shipping terms. If it only shows a price and a date, you cannot compare it to a second quote, and you cannot prove later that a part was out of spec.
Certifications, inspection and material choice
Certifications answer different questions. ISO 9001:2015 covers a working quality system. IATF 16949:2016 is what automotive and EV programs ask for. ISO 13485:2016 applies to medical devices. ISO 27001:2022 covers information security, which matters when you upload proprietary CAD. Check the scope on the certificate, not just the logo.
Inspection is where the numbers either hold or do not. 100% inspection before shipment, with raw material check, in-process monitoring and final inspection, is the baseline for anything functional. Reports are available on request. If a supplier samples only and cannot send dimensional data, you are the inspection department.
Material availability sets the ceiling on what is practical. Aluminium 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075 and ADC12 cover most housings and brackets. Stainless 303, 304, 316, 316L, 17-4PH and 440C cover food, marine and medical parts. Steels 1018, 1045, 4130, 4140 and 4340 handle shafts and structural work. Copper C101, C110 and C36000 brass suit electrical and fluid parts. Titanium TA2, TC4 (Ti-6Al-4V), Inconel and magnesium AZ31B are available when weight or heat matters.
Plastics behave differently. POM and PA machine cleanly and hold tolerance. PEEK is stable at temperature but expensive and slow to cut. ABS, PC, PMMA and PP are usually better moulded or printed at volume, so use CNC for the prototype and switch process later. Mixing a material that fights the geometry adds cost with no gain.
- 1Match the certificate to the industryIATF for automotive, ISO 13485 for medical, ISO 27001 for IP.
- 2Ask for the inspection report format before orderingFirst-article, in-process or full dimensional.
- 3Pick the cheapest material that meets the spec7075 is not needed where 6061 holds.
Size envelope, finishing and confidentiality risk
Confirm the part fits before you discuss anything else. GreatLight machines up to 4,000 mm, with a 4,000 × 400 × 150 mm travel on the large platform, 750 × 1,150 × 550 mm and 600 × 600 × 600 mm on the medium machines, and 500 × 500 × 450 mm plus 500 × 310 × 200 mm on the compact ones. A long extrusion and a small manifold do not go to the same machine, and treating them as one job creates a fixture problem.
Finishing is often quoted separately and quietly changes the tolerance. Anodizing builds a few micrometres on the surface. Electroless nickel, zinc, silver and gold plating do the same. Hardcoat anodizing is thicker and can close a tight bore. Powder coating and black oxide add more. Bead blasting, tumbling, brushing and polishing remove or move material. If a bore is held at ±0.005 mm, say so and mask it or finish before the final cut.
Laser marking and engraving need a minimum character height of 1.5 mm to stay legible after coating. Anything smaller fills in. For IP, uploads are secure and confidential, and an NDA is available on request. Do not send production CAD through a channel your legal team has not approved.
The practical filter is simple: a supplier that answers these seven points in writing can be compared. One that answers with adjectives cannot.
Step by step: qualifying a supplier in one week
Work through these in order. Each step takes a day or less and removes a class of risk.
- 1Send a real drawing, not a sample photoInclude material, tolerance callouts, datums, finish and quantity. A 2D PDF plus STEP file lets the supplier quote machine and setup correctly.
- 2Time the responseA quotation and free DFM analysis inside 12 hours is the target. Slower is not fatal, but it predicts how the order will run.
- 3Ask which machine and how many setupsFor ±0.005 mm work, expect 5-axis or mill-turn with one or two setups. Three or more setups is a warning.
- 4Confirm MOQ and the first-article pathNo minimum order quantity lets you approve one piece before committing. Ask what changes between piece one and piece 10,000.
- 5Check certificate scope, not certificate namesISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022 all apply to different work. Ask for the scope statement.
- 6Agree the inspection plan in writingState which dimensions are checked, at what frequency, and whether a report ships with the parts.
- 7Separate shipping from deliveryParts ship in 3–5 days once released. Clarify whether the clock starts at PO, drawing release or material arrival.
Questions buyers ask before the first order
Can a supplier outside Melbourne hold ±0.005 mm on my parts?
Yes, if the machine and the inspection match. Tolerance comes from the machine, the fixture and the temperature, not from the postcode. Ask for the machine type and the inspection report from a comparable part.
The trade-off is shipping time and travel. If your line needs parts in hours, keep a local source for emergencies and use a longer pipeline for planned runs.
What does no minimum order quantity actually mean?
It means the supplier will run one piece. The setup, programming and inspection hours are the same whether you order one or ten thousand, so the per-piece price on a single unit is high.
Use it to validate the design and the supplier before committing to a production run.
Which materials are worth machining and which are not?
Aluminium 6061, 7075, stainless 304 and 316, steel 1045 and 4140, and brass C36000 machine well and hold tolerance. Titanium TC4 and Inconel are machinable but slow, so cost rises with removal volume.
Plastics like ABS, PC and PP are usually better moulded at volume. Use CNC for the prototype and switch when the design freezes.
Does anodizing or plating change my dimensions?
Yes. Anodizing, electroless nickel, zinc, silver and gold plating all add a thin layer. Hardcoat anodizing and powder coating add more.
If a bore or shaft is held at ±0.005 mm, mask it or specify a pre-finish dimension so the coated part still fits.
How do I protect my design when I send CAD files?
Uploads are secure and confidential, and an NDA is available on request. Ask which people can open the files and how long they are stored.
For defense or medical work, confirm ISO 27001:2022 scope before sending anything.
What should be in a quote before I compare prices?
Material grade, machine, tolerance, finish, inspection method and shipping terms. Without those, two quotes are not comparable.
A quote that arrives in 12 hours with a DFM note is also a useful signal about how the shop reads drawings.
Send one drawing and test the process
Quotation and free DFM analysis within 12 hours. No minimum order quantity, from one prototype to 10,000+ parts.
12-hour quoteNo MOQ100% inspection before shipmentNDA on request
More from the shop floor
We publish setup notes, tooling trials and inspection data from the factory floor.
