Extrusion Math

How to Calculate Extrusion Ratio, Billet Yield, and Press Output in Aluminum Extrusion

Work through the core aluminum extrusion formulas: extrusion ratio, billet yield, pounds per foot, and press cycle output, each with real units and worked examples.

Start with extrusion ratio, the single number that governs whether a die will run. It is the billet cross-sectional area divided by the total die opening area. A 7-inch billet has an area of pi/4 times 7 squared, or 38.48 sq in. If the profile openings total 0.55 sq in, the ratio is 38.48 / 0.55 = 70:1. For 6xxx alloys most presses live between 20:1 and 60:1; below about 10:1 you get poor weld consolidation, and above 100:1 pressure demand spikes. The Aluminum Extrusion Ratio Practicality Calculator flags where your ratio falls versus press tonnage.

Billet yield tells you how much of the log you actually sell. Yield equals net shipped weight divided by billet charge weight. A 7-inch by 30-inch 6063 billet weighs area 38.48 sq in times 30 in times 0.098 lb/cu in, roughly 113 lb. Subtract butt (typically 10 to 15 percent of billet length), front-end and back-end transverse cuts, and stretcher grip loss (6 to 12 in per end). If usable profile is 92 lb, yield is 92 / 113 = 81 percent. The Aluminum Billet Yield Calculator lets you model butt length and crop loss to hit an 82 to 88 percent target.

Pounds per foot converts a profile drawing into a weight you can price and schedule. Weight per foot equals cross-sectional area in sq in times 12 in times 0.098 lb/cu in for 6063. A profile with a 0.42 sq in section runs 0.42 times 12 times 0.098 = 0.494 lb/ft. Use 0.0975 for 6061 and 0.098 for 6063; the difference is under 1 percent but matters at volume. The Aluminum Profile Pounds per Foot Calculator does this from area or from a weight-per-meter spec, and it back-solves area if you only know shipped weight and length.

Press cycle output ties dead-cycle time to throughput. Cycle time equals ram advance time plus dead time (shear, billet load, die slide, butt removal), commonly 8 to 20 seconds dead plus the push. Runout length per cycle equals billet volume times yield divided by profile area. For our 113 lb billet at 81 percent yield and 0.494 lb/ft, useful length is 92 / 0.494 = 186 ft per cycle. At a 45-second total cycle that is 186 ft times 80 cycles/hr = 14,880 ft/hr. The Extrusion Press Cycle Output Calculator converts this to lb/hr.

Runout table and puller capacity cap what those cycles can physically handle. Table capacity in feet equals table length divided by (profile length plus gap). A 150-ft table pulling 40-ft lengths with a 3-ft gap holds 150 / 43 = 3.4, so 3 lengths staged before cutoff. Exit speed for 6063 typically runs 20 to 80 ft/min; at 60 ft/min a 40-ft length exits in 40 seconds, which must fit your cycle. The Extrusion Runout Table Capacity Calculator checks length staging against table length and puller travel.

Aging oven load sets your batch heat-treat throughput. Load capacity equals oven usable volume or basket weight limit divided by per-part footprint or weight. A T5 age at 350 to 375 F for 6 to 8 hours means the oven, not the press, can bottleneck. If a basket holds 4,000 lb and you run 6-hour cycles, that is 4,000 / 6 = 667 lb/hr of aging capacity per oven. The Aluminum Aging Oven Load Capacity calculator matches basket count and cycle time to upstream press lb/hr so you do not strand extruded stock.

Finish by reconciling scrap and metal balance. Metal in equals billet weight; metal out equals shipped profile plus recoverable scrap (butts, crops, offcuts). At 81 percent yield, the other 19 percent, about 21 lb per billet, is recoverable extrusion scrap that returns to remelt at a discount to prime. Track it as a running percentage: total scrap weight divided by total billet charged should sit near 15 to 20 percent for solid profiles. Use these five formulas together and every number, from die design to shipped weight, closes to the metal balance.

Published 2026-07-01.