Similar weight does not mean similar cost
A plain bush and a fitting with cross-holes and precision mating surfaces may start from almost the same weight of stock. Their operation counts, workholding and inspection requirements are different. That is why we cannot price a machined part reliably by weight or cutting time alone.
The quotation is for a finished part meeting agreed requirements. Programming, tool setting, first-piece inspection, deburring and packing all contribute to that result, even when the machine is not cutting.
Separate setup from recurring work
Much of the programming and workholding preparation happens once per batch. Machining and some inspection work repeat with each part. A simple cost breakdown therefore separates setup, quantity-dependent production and additional services. Scrap allowances, purchasing terms and commercial conditions may also affect the final price.
Multiplying a ten-piece unit price by a thousand is rarely a sound production estimate. Higher quantities spread setup costs, but they do not make tooling consumption, quality requirements or capacity disappear. The saving is not necessarily proportional to the increase in quantity.
Material cost goes beyond the stock invoice
A change of material can alter cutting conditions, tool life and deburring time. Stock diameter matters too: an oversized bar creates extra chips and machining time. The availability of a suitable stock size belongs in the quotation review.
Specify the material condition and whether dimensions apply before or after heat treatment or coating. One supplier may be quoting the finished component while another has priced machining only.
Make inspection requirements visible
Checking selected dimensions on a sample of parts is different from reporting specified features on every piece. State which features, how many parts and what report format you need. A material certificate is not a dimensional inspection report.
Before asking for a discount, discuss alternative batch sizes, separately priced operations and tolerances that may be tighter than the function requires. Any drawing change needs design approval. Our design-for-cost guide covers geometry-related savings in more detail.
Related guides
- Designing CNC parts for lower cost
- Choosing machining tolerances
- Ordering CNC Parts to a Drawing: Your First Order
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