Here is a part that will sail through every check you run on it. The file is complete. The drawing matches the model. Every feature can be machined. There is just one problem: a hole meant to sit at the centre of a face is 0.1mm off centre, and on screen it looks centred.
A machine shop will build exactly what you drew. The error surfaces weeks later, when someone programming the job looks at the part as a whole and wonders whether that hole was really meant to sit there. By then the price is locked, the schedule is committed, and the question lands in your inbox with a delivery date attached.
Design for manufacturing is usually taught as a checklist of features to avoid. The more useful question is where in the workflow errors are actually detected, because that determines what they cost. Caught before the quotation, an error costs a short conversation. Caught after the purchase order, it costs days. Caught after production, it costs a reorder.
Why so much gets caught so late
A supplier's closest read of your drawing happens when programming begins, because that is when every line has to be translated into toolpaths. And there is a commercial incentive at work: where an issue looks unlikely to affect cost, many suppliers will accept the order first and ask questions afterwards. Efficient for them. For you, it means clarification requests arrive after pricing is fixed and the delivery clock has started.
Across more than 9,000 parts verified on Factorem's platform, the same few issues account for most of these late surprises. Drawings missing a dimension the part cannot be made without. Features that cannot be produced as drawn, like a perfectly square internal corner that no round cutting tool can reach. And the hardest category of all: parts where the file is correct but the design is not, which no automated check can detect, because measured against the file itself there is nothing wrong.
What actually prevents it
Not better software alone. The pattern that works pairs an automated check, which scans every 3D model for known problems with a consistency no person can match, with an engineer who makes the judgement calls the file cannot answer: whether a demanding feature is intentional, whether an odd dimension is a decision or a slip, and when to ask rather than assume.
There are also specific numbers that prevent most of these issues at the design stage: minimum corner radii, wall thicknesses, bend allowances, and the thresholds that separate a part that machines cleanly from one that triggers a week of emails. Factorem has put all of them, along with the reasoning behind each, into a full guide with a one-page pre-submission checklist you can run in the five minutes before you upload.
Download the full guide and DFM Pre-Submission Checklist, or upload a part at app.factorem.co/getquotenow and see the review in action.
