Cost

Cost Estimation and Quoting for Weighing, Dosing, and LIW Feeding Lines

What actually drives cost per unit on dosing and loss-in-weight lines, how to build a quote that holds, and the estimating mistakes that quietly erode margin.

On a dosing line the single largest hidden cost is ingredient give-away, not labor. If you consistently over-dose to stay above a minimum weight, a 0.8% average over-fill on a material costing $2.40/kg across 4,000 t/year is $76,800 in product handed away for free. Tightening the setpoint from +0.8% to +0.2% recovers roughly $57,600. Quote every job with the target bias in the model, not the nameplate tolerance. The Ingredient Variance Cost calculator converts a give-away percentage and material price directly into annual dollars so the number is visible before you sign.

Build cost per batch from five buckets: material, labor, feeder time, scrap, and overhead. For a 500 kg batch of eight ingredients averaging $1.90/kg, material is $950. Labor for staging, dosing, and cleanout might be 0.35 h at $38/h loaded, so $13.30. Feeder and mixer time at a $95/h machine rate for 0.30 h is $28.50. Add scrap and overhead below. Costing at the batch level, then dividing by good output, gives a defensible unit cost. The Recipe Cost calculator rolls per-ingredient prices and inclusion rates into a batch total you can quote line by line.

Microingredients distort quotes because their cost concentration is inverted. A 0.05% vitamin premix at $180/kg contributes only $0.09 per 1,000 kg batch in material, but the micro-feeder to dose it accurately, cleaning between colors or allergens, and QC retains can add $6 to $12 per batch in handling. Estimators who price micros purely on inclusion mass understate the true cost by an order of magnitude. Use the Microingredient Usage output to attach a realistic handling and accuracy surcharge rather than a straight material multiply.

Scrap and rework are a tolerance-driven cost. If your batch reject rate on a plus or minus 1.5% window is 2.0%, then 2 of every 100 batches are reworked or dumped. On a 500 kg batch at $950 material plus $42 conversion, a dumped batch is about $992; at 2% across 5,000 batches/year that is roughly $99,200. Half of it usually traces to feeder scatter, not operators. Feed the reject rate and batch cost into the model explicitly rather than burying scrap in a flat 3% adder that hides the real driver.

Labor cost per unit hinges on changeover, not run time. A line doing 40 recipe changes per shift with 12-minute cleanouts burns 8 h of labor purely on transitions. At $38/h loaded that is $304/shift, or about $79,000/year on a two-shift operation. Quoting a short-run, high-mix customer at the same per-kg labor rate as a long-run commodity job is the most common margin leak. Separate a fixed changeover charge from the variable dosing rate so mix complexity is priced honestly.

Machine time should carry a true hourly rate, not just depreciation. A gravimetric feeder plus loadcell, mixer, and controls at $180,000 installed over a 7-year life is about $25,700/year in depreciation, but add maintenance, calibration checks, spare loadcells, and 4 to 6% energy, and the loaded machine rate lands near $85 to $110/h. Utilization decides the per-batch burden: at 78% utilization versus 55%, the same fixed cost spreads across 40% more batches, cutting machine cost per batch from roughly $38 to $27. Underutilized lines quietly inflate every quote.

Where estimates go wrong is treating volumetric fallback and refill dwell as free. Every refill forces 10 to 40 seconds of volumetric operation, and if density drifts, the give-away during that window is real product. A feeder refilling 4 times per hour on an 18-minute cycle spends 2 to 3% of run time in open loop. On a $2.40/kg material at 300 kg/h, even a 1% over-delivery during those windows is $17 to $22 per hour of pure loss. Model this instead of assuming gravimetric control is always active.

Assemble the quote as a stack you can defend line by line: material at recipe cost, plus a named give-away allowance, plus variable labor, plus a fixed changeover charge, plus loaded machine time at real utilization, plus scrap at the measured reject rate, plus overhead as a percentage of the first six. For the 500 kg example, that is roughly $950 material, $19 give-away, $13 labor, $12 changeover, $27 machine, $20 scrap, and 14% overhead, near $1,181 per batch, or $2.36/kg. Every buyer question then maps to one visible line.

Published 2026-07-01.