Guides / Cost
Cost Drivers for Semiconductor Chamber and Wafer Handling Parts
September 26, 2026
A chamber lid and an end effector are priced by the same six factors in different proportions. Knowing which one dominates your part tells you where to push and where you are only annoying the shop.
1. Material and certification level
For a large 6061-T651 plate part, raw stock is a real share of the price, and the plate has to be bought flat and stress relieved or the part will move during machining. Add a mill cert requirement and the shop is buying from a narrower list of suppliers. Add a heat lot traceability requirement and the shop has to keep that lot segregated through the whole job, which is process cost, not material cost.
For a thin 316L end effector the material is almost free and everything else dominates.
Push here when: the part is large and mostly stock removal. Ask whether a near net plate size or a different starting form changes the number.
2. Flatness, geometry and the setup that follows
Large flat sealing faces are the most common cost surprise. Holding flatness across 400 mm is not a cutter problem, it is a fixturing and stress problem. The shop may need to rough, relieve stress, then finish in a second setup, and that is a second fixture and a second program.
Thin walls, deep pockets and wafer handling parts that must not vibrate all bring the same answer: more setups, softer cuts, longer cycle.
Push here when: a datum scheme is forcing an expensive setup and a different one would give the same function.
3. Surface finish, face by face
Ra 0.8 um is a finishing pass. Ra 0.4 um is a slower finishing pass with a sharper tool and an inspection step. Ra 0.2 um and better usually leaves the machining department entirely.
The cost multiplier is not the number, it is the area it applies to. One O-ring groove face at Ra 0.4 um is cheap. The same callout in the title block prices the entire part at Ra 0.4 um.
Push here when: the drawing has a global finish note. Move it to the faces that need it and re-quote.
4. The finishing chain
| Step | Typical schedule impact | What goes wrong |
|---|---|---|
| Type III hard anodize | 5 to 10 working days | Growth on toleranced features, masking errors, rack marks |
| Type II anodize | 3 to 7 working days | Colour variation between lots |
| Electropolish | 5 to 10 working days | Edge rounding on sharp features, over-polish on thin sections |
| Passivation | 2 to 5 working days | Usually none, but it is still a transport leg |
Each outside step is a shipment out, a queue at the vendor and a shipment back, and most of the lead time on a finished part is queue time, not process time. Two coatings on one part means two vendors and two queues unless one house does both.
Push here when: the schedule is tight. Ask which finishing is in house. A shop with an anodize line on site can often beat a cheaper shop on delivery by a week.
5. Cleaning, packing and paperwork
Precision clean, dry, double bag, label outside the bag, and in some cases nitrogen purge. For a small gas delivery part this can be a visible share of the unit price. For a large lid it is small in percentage and still a fixed cost per piece.
Dimensional reports are the same story. A first article report on a 40 feature part is hours of CMM time. Asking for a full report on every piece of a fifty piece order is a decision with a price, and it is sometimes the right decision. Just make it on purpose.
6. Quantity and the repeat
Programming, fixture design and the first article are paid once. On one to five pieces they are most of the price. On fifty they are noise.
Telling the shop that fifty more are expected next quarter often lowers the first quote, because the shop will build a better fixture and amortise it across the expected volume. Leaving it out means every order is priced as a one off.
Reading two quotes that differ
Before you conclude that one shop is expensive, line the two up against these six headings. In most cases the gap is that one shop quoted precision cleaning, controlled packing and a dimensional report, and the other quoted a machined part in a box. Both answers can be honest readings of a drawing that did not say.
If you want the same scope priced by shops that already run this class of part, send the drawing and the notes that go with it.
Frequently asked questions
Why is a second quote for the same part so much higher?
Usually one shop read the finish and cleaning notes and the other did not. Compare the scope line by line before you compare the totals. A quote that leaves out precision cleaning and double bagging is a different product.
Does tightening a tolerance by one step really cost that much?
On a single feature, often not. Applied to the whole part in the title block, yes, because the shop has to hold it everywhere and inspect it everywhere.
Is a big chamber lid cheaper to buy as a weldment?
Sometimes, but a weldment brings distortion and a stress relief cycle before finishing. Ask the shop to price both if the geometry allows it, and compare the lead times as well as the prices.
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