Investment Casting in Australia: How It Compares to CNC Machining and Sand Casting
Investment casting, also called lost-wax casting, makes complex steel and stainless parts close to their final shape, so far less material is machined away. Compare it with the alternatives, see where it pays off, and learn how to source it.
The short answer
Choose the process by quantity, material and complexity:
- Investment casting for complex steel or stainless parts at medium volumes, machined only on critical features.
- CNC machining from solid for prototypes and small batches, with no tooling cost.
- Sand casting for large, heavy parts in small numbers where finish matters less.
- Die casting for high-volume aluminium and zinc parts. It is not used for steel.
Investment casting vs CNC machining, sand casting and die casting
How the four most common ways to make a metal part compare on cost, detail and material.
Swipe the table sideways to see every option →
| Comparison | Investment castingThis page | CNC machining from solid | Sand casting | Die casting |
|---|---|---|---|---|
| Best for | Complex steel parts at medium volumes | Prototypes, small batches and the tightest tolerances | Large, heavy parts in small numbers | Repeat production of aluminium and zinc parts |
| Materials | Carbon, alloy and stainless steels | Almost any metal or engineering plastic | Iron, steel, aluminium and bronze | Aluminium and zinc alloys only |
| Tooling cost | Medium: wax pattern tool | None | Low: pattern | High: hardened steel die |
| Cost per part at volume | Medium | Highest | Medium, plus more machining | Lowest |
| Detail and thin walls | Excellent | Excellent, but cost rises with complexity | Limited | Excellent |
| Material removed after casting | Little, near-net shape | Most of the bar is cut away | A lot, rough surfaces machined | Little |
| Time to first parts | Medium | Shortest | Short to medium | Longest, die build first |
Ratings are general guidance. Your manufacturing advisor confirms the best option for your drawing.
When does investment casting become the cheapest option?
Drag the slider to change the order quantity and see which process gives the lowest cost per part.
Illustrative example for a mid-sized stainless steel part, not real prices. Crossover points depend on your part's size, material and complexity, so your quote shows unit prices at several quantities.
Carbon and alloy steel vs stainless steel castings
Both are investment cast the same way, but they suit different conditions.
Carbon and alloy steel
Strong, tough and lower cost. Can be heat treated for hardness and usually painted or plated.
- Grades such as WCB, 4140 and 8620
- Machine parts, brackets, levers and wear parts
- Heat treated to the hardness on your drawing
Stainless steel
Resists corrosion without coating, for wet, food-contact, marine and chemical service.
- Grades such as CF8M (316) and CF8 (304)
- Valve bodies, pump parts and marine fittings
- Passivated or polished finish
Relative ratings out of 5, for comparison between the two options only.
Where to get investment casting for an Australian business
Once you have chosen investment casting, the next decision is who casts and machines your parts.
Swipe the table sideways to see every option →
| Comparison | Local Australian foundry | Overseas marketplace | RTech factory-direct |
|---|---|---|---|
| Who makes your part | The local foundry | Whichever supplier takes the job | Our own factory |
| Wax tool price | Typically the highest | Varies by supplier, plus platform margin | Factory-direct, no markup |
| Price per part | Typically higher | Lower, plus platform margin | Factory-direct, no markup |
| Heat treatment and machining | Often sent out to other suppliers | Varies by supplier | Arranged in the same order |
| Freight, customs and duty | Not needed | Often quoted separately | Included, one price to your door |
| Inspection report and certificates | Varies by foundry | Varies by supplier | With every order |
| Face-to-face visits | Easiest | Not usually possible | Dedicated advisor in Sydney |
General comparison. Individual suppliers vary.
From drawing to cast part
One price agreed up front, and one manufacturing advisor the whole way.
Send your drawing
CAD or PDF drawing, with quantity, steel grade, heat treatment and finish.
Casting design review
Wall thickness, gating and machining allowances checked. Price and lead time within 48 hours.
Wax tool and samples
The wax pattern tool is made and first-article castings are measured against your drawing.
Casting and machining
Parts are cast, heat treated, and finish machined on critical features.
Delivered duty paid
Shipped, cleared and delivered to your door with the inspection report and material certificates.
Investment casting questions
What is investment casting?
Investment casting, or lost-wax casting, makes a wax copy of your part, coats it in ceramic to form a shell, melts the wax out, and pours molten metal into the shell. The shell is broken away to leave a part very close to its final shape.
Is investment casting cheaper than CNC machining?
Per part, usually yes once quantities reach the tens or hundreds, because far less material is machined away. For prototypes and very small batches, machining from solid is often cheaper because there is no wax tool to pay for.
What steels can be investment cast?
Carbon, alloy and stainless steels, including grades such as WCB, 4140, 8620, CF8 (304) and CF8M (316). Your advisor will recommend a grade for your part’s load and environment.
Can investment castings be machined and heat treated?
Yes. Castings are heat treated to the hardness on your drawing and critical faces, bores and threads are finish machined, typically to ±0.05 mm, in the same order.
Who owns the wax pattern tool?
You do. When you pay for tooling, it belongs to you. We store and maintain it for your repeat runs, and release it to you on request.
How long does investment casting take?
Most orders arrive 4–8 weeks after you approve the quote. A new wax tool adds tool build and sample approval before production, and your quote gives a confirmed delivery date.
Do I pay customs duty on cast parts?
No. Prices are delivered duty paid: freight, customs clearance and import duty are included in one price, so there is no separate bill when the parts arrive.
Related guides
Ready to price your cast part?
Send your drawing and we will come back with one price delivered duty paid, a lead time and any design notes.