12 modi per ridurre i costi di lavorazione CNC senza cambiare la funzione

A machined part's price breaks down roughly like this:

• Machine time — 40 – 60 %
• Material — 15 – 35 %, more for titanium or large billets
• Setup and programming — 10 – 25 %, dominant at low volume
• Inspection — 5 – 15 %, rising steeply with tight tolerances
• Finishing, handling and packing — 5 – 10 %

Every item below attacks one of those lines. None of them require you to compromise the function of the part.

1. Reduce the number of setups

Each setup means a new fixture, a new datum alignment and a new tolerance stack. Going from four setups to two can cut the price by 25 % on a low-volume part.

Look at your model and ask: can the features on the fifth face move to one of the other four? Can a feature be open rather than blind?

2. Open internal corner radii

A square corner cannot be milled. The radius you specify sets the cutter diameter, and cutter diameter sets how fast material comes off.

Going from R2 to R3 lets us use a 6 mm cutter instead of a 4 mm one — typically 25 – 30 % less cycle time in the pocket. Going from R3 to R5 saves again.

3. Use one corner radius throughout

Three different internal radii mean three cutters and three tool changes per setup. One radius everywhere means one cutter, one tool path strategy, one set of cutting data.

4. Relax tolerances that do not do anything

Apply ISO 2768-m as the default and call out only the dimensions that matter. On a part with 40 dimensions, typically 4 or 5 are functionally critical. Tightening the other 35 adds inspection time and rejection risk for no benefit.

5. Avoid deep, narrow pockets

Beyond 4× cutter diameter in depth, tool deflection forces lighter cuts. Beyond 6× you need a special tool. A 40 mm deep, 8 mm wide slot can cost more than the rest of the part combined.

6. Limit thread depth to 2× diameter

The first three engaged threads carry most of the load. M8 threads 30 mm deep cost more than M8 threads 16 mm deep and hold no better — but they do increase the risk of a broken tap, which scraps a part that has already had all its value added.

7. Choose the right stock form

Machining a 60 mm diameter shaft from 80 mm bar wastes material and time. Buying closer-to-size bar, tube instead of solid, or extruded profile instead of plate can remove both.

For a hollow part, starting from tube instead of solid bar can halve the machining time and cut material cost by 60 %.

8. Reconsider the material

6061 cuts roughly twice as fast as 316L and three times as fast as titanium. If corrosion is the reason for stainless, check whether anodised or nickel-plated aluminium would survive the environment — often it would, at a fraction of the cost.

Conversely, 303 stainless cuts far faster than 304 and costs about the same. If your part does not need to be welded, 303 is usually the better choice.

9. Order in sensible batch sizes

Setup cost is spread across the batch. On a typical milled part:

• 1 piece: setup is ~60 % of the unit price
• 10 pieces: ~15 %
• 50 pieces: ~4 %
• 200 pieces: ~1 %

The step from 1 to 10 is where most of the saving lives. If you know you will need ten over the next year, buying ten now usually costs barely more than buying three.

10. Release a family of parts together

Parts that share material and setup type can be nested and run consecutively, sharing material and setup. Ordering six different brackets in one release rather than six separate releases across two months can save 10 – 20 %.

11. Specify the finish you need, not the finish you like

Ra 1.6 µm is standard. Ra 0.8 µm adds a finishing pass. Ra 0.4 µm usually means an additional operation. Bead blasting to hide tool marks costs less than machining to a better finish, and on a non-functional surface it looks better too.

12. Send a complete enquiry the first time

This one is free. An enquiry with a STEP file, a dimensioned drawing, quantity, material, finish and required certifications gets quoted in hours. An enquiry with just a model triggers a round of questions, and when the quotation finally arrives it carries more contingency because the engineer had to assume.

What this adds up to

On a typical aluminium housing, applying items 1, 2, 4, 7 and 9 together routinely takes 30 – 45 % out of the price. On a stainless manifold, adding item 8 can double that.

Send us the model before it is frozen and we will mark up exactly which of these apply to your part, with the saving attached to each one. There is no charge for that review.