Direct Answer
CNC fabrication uses computer-controlled machines to drill, cut, cope, and mark structural steel members automatically from digital files (DSTV/NC1). Common equipment includes CNC beam lines (drill and cope in one pass), drill lines (drilling only), profile saws (automated angle cuts), and plasma/oxy-fuel cutting tables (for plates). CNC automation reduces manual layout errors and dramatically increases throughput.
Full Explanation
A CNC beam line (e.g., Peddinghaus FPB, Ficep Endeavour, Voortman V630) processes a W-shape or HSS from end to end: loading from a roller conveyor, auto-measuring the section, drilling all holes simultaneously with multiple spindles, burning or sawing copes, and marking the piece with a peen or scribe. Setup time per member is measured in minutes, not hours. A shop running DSTV files from a Tekla model can process 20–30 members per shift with minimal manual intervention.
What This Means for Your Shop
Shops without CNC equipment are at a significant cost and speed disadvantage on large projects. Manual layout and drilling is 5–10× slower and more error-prone. If you're quoting against CNC shops, factor in the labor difference.
Common Mistakes
Assuming CNC eliminates the need for shop drawings. CNC programs must be verified against the approved drawings before running. DSTV files can have errors if the Tekla model is not fully coordinated.
Recommended Process
Implement a CNC program verification step: the lead technician reviews the first member's NC1 file in the CNC software, visually confirms it matches the shop drawing, then approves for production. First-article inspection of a machined member before running the quantity.