A practical guide for mold engineers and buyers on the core elements of stamping processes, from die design to cost estimation.

In daily stamping production, the first thing to lock down is the process sequence—blanking, piercing, forming, flanging, and trimming are the five basic operations that define every die layout. For a typical sheet metal part, the number of stations directly drives tooling cost and cycle time. A simple flat blank with two holes might run on a single-stage die, but a deep-drawn housing with multiple flanges often requires a progressive die with 6 to 12 stations. The rule of thumb we use in quoting is that each additional station adds roughly 8–12% to the die build cost, while the press tonnage must be checked against the sum of cutting force and forming force. Cutting force is calculated as perimeter × thickness × shear strength (for mild steel, about 345 MPa), and we always add a 20–30% safety margin for press selection. Never forget the strip layout—material utilization below 65% means you are throwing money away on scrap, so rotate the part or nest it in two-up layout before finalizing the die design.

On the tooling side, the clearance between punch and die is the most overlooked variable. For 1.0 mm thick SPCC, a typical clearance of 5–8% of material thickness per side gives a clean shear edge, but going too tight causes excessive burr and punch wear, while too loose produces a large rollover and a torn edge. In production, we also watch the stripper force—a spring-loaded stripper should provide at least 15–20% of the cutting force to keep the strip flat and prevent distortion. For high-volume runs, use carbide inserts on the piercing punches and die buttons; they cost about 2.5× more than tool steel but last 4–6 times longer, which pays off above 100,000 strokes. Also, check the die shut height and press stroke—a common mistake is using a press with too short a stroke for deep drawing, causing the punch to hit the die plate. Always set the die tryout with a 0.05 mm shim under the stripper to verify the clearance before production.

When quoting a stamping job, break down the cost into four blocks: material, tooling amortization, press time, and secondary operations. Material cost is simply blank weight × coil price per kg, but do not forget the scrap credit—selling the skeleton and offal can recover 10–15% of material cost. Press time is the cycle rate (strokes per minute) divided by the number of hits per part, plus a 5% allowance for loading and unloading. Secondary operations like deburring, tapping, or welding often add 20–30% to the total part cost, so try to design them out. For a realistic quote, always run a quick simulation of the strip layout and estimate the die life—a progressive die for 0.8 mm galvanized steel should hit 500,000 strokes before major maintenance. If you need a reliable mold partner or want to compare stamping die quotes from verified suppliers, visit MoldWorld at www.moldw.com for more mold sourcing information.