"What will this part cost?" has no single answer, but the items that make up the answer are well defined. This article walks through the four main cost items of a die casting, why volume changes everything, and how design decisions land on the price. The aim is to let you see inside the box while you wait for a quote.
The four cost items
1. The die — one-off and up front
The die is an investment separate from the part itself, made before production starts. What sets its price: how many cavities the part can be cast in, the number of cores, how hard the die steel is to machine, the surface quality expected and the life required from the die. A core is a moving element of the die, and every core raises both die cost and maintenance load.
Die cost is spread over the total quantity produced. That is why the same die is the largest item in the piece price on a 5,000 part job, yet becomes almost invisible on a long running project. Decisions on the die manufacturing side therefore have to be taken early.
2. Material — not just the weight of the part
The material item is not simply the net weight of the part. Every shot also casts the runner system and overflows; these are cut off and returned. So what enters the calculation is the shot weight. A well laid out gating system reduces the share of returned metal, which lowers melting load and with it energy consumption.
The alloy itself is another variable: the alloy choice affects both raw material price and castability, and those two effects do not always pull in the same direction.
3. Cycle time — the machine time each part consumes
The machine is an hourly cost; the share per part depends on cycle time. The main thing that stretches a cycle is the solidification time of the part's thickest section. A heavy boss or a region that is hard to feed holds up the entire cycle. The layout of cooling circuits in the die feeds directly into this.
Machine tonnage belongs here too: as the projected area of the part grows, so does the force needed to hold the die closed, and the job moves to a larger press.
4. Secondary operations — usually the biggest surprise
Everything done after the casting comes out is a separate cost: deburring, machining, surface treatment, leak testing, assembly and packing. Individually small, together they can rival the casting itself.
The critical point here: every surface to be machined means a fixturing operation. A part machined from two different directions needs a second set-up and a second datum reference, and that adds more to cost than simply doubling the cutting time.
Why volume changes everything
Of the four items above, two scale with volume (material, cycle) and two do not (the die is one-off, secondary operations only partly automate). The practical consequence: the piece price falls as volume rises, but not forever — beyond a certain point the price approaches material plus cycle cost and settles there.
So when asking for a quote it helps to ask in volume steps rather than for a single number: separate prices for 5,000, 20,000 and 50,000 per year show clearly where the die investment pays for itself.
How design moves the price
Most of a part's cost is already decided while it is still a drawing. The headings that make the biggest difference:
- Wall thickness balance. Even walls solidify faster (shorter cycle) and reduce porosity risk (less scrap).
- Number of cores. Every undercut means a core. Sometimes a small change to the part removes a core entirely.
- Tolerance and surface demands. Writing a tight tolerance on every dimension turns surfaces that need no machining into machined ones. Marking only what is critical is the cheapest improvement available.
- Draft angle. Insufficient draft increases both die wear and scrap; both turn into price over time.
- The surface treatment decision. If the part will be anodised, alloy and surface preparation must be planned for it; an anodising decision taken late can change the alloy and with it the whole calculation.
A common mistake
Comparing unit prices alone. The gap between two quotes is sometimes a gap in scope: one prices a deburred, machined and tested part, the other prices a raw casting. For the comparison to mean anything, the quotes have to cover the same level of completion. The second common mistake is treating die cost as separate from total cost of ownership; a cheap die can repay itself many times over in maintenance and scrap across its life.
What to send with a quote request
What we need for a sound price is a short list:
- A 3D model (STEP preferred) or a drawing — best of all, both
- Expected annual volume, in steps if possible
- Alloy preference, or the service conditions of the part (load, temperature, environment)
- Surfaces to be machined and the critical tolerances
- Surface treatment and any testing expectations (leak, X-ray)
You may not have all of it; starting with a model and a volume expectation is enough, and we clarify the rest together. You can share it through the contact page.