How ARCNM calculates a price.

The scheme: row, base, formula

ARCNM calculates with the German differentiated surcharge costing (differenzierende Zuschlagskalkulation) with machine-hour rates, sales calculation included. Rows marked = are sub-totals. Every surcharge rate is set in your costing environment; a rate you do not state is zero.

• Machine costs are machine-dependent production overhead. They are charged through machine-hour rates, so the surcharge on wages carries only the remaining production overhead – hence Rest-FGK. A rate that included machine costs would charge them twice.
• Vom Hundert: the base is 100 %. A 25 % Gewinnzuschlag on the Selbstkosten is a 20 % margin on the Barverkaufspreis. The sheet states both.
• Im Hundert: the rate is a share of the price that contains it. Skonto and Provision share one denominator; with s = 2 % and p = 10 % the factor is 1 ÷ 0.88 = 1.1364, not 1.1338 from two chained divisions.
• The offer price is the last price your environment reaches: the Listenverkaufspreis, or the Zielverkaufspreis or Barverkaufspreis when no Rabatt or no sales term is stated.
• Subcontract work, tooling, programming and first-article cost carry neither MGK nor Rest-FGK. Subcontract work carries a procurement overhead only where you state one.

The machine-hour rate

The machine-hour rate recovers a machine's annual cost over its running hours T_L = T_G − T_ST − T_IH: total time less standstill and maintenance time.

Setup time is billed at the machine rate in the Rüsten row. The standstill hours T_ST therefore exclude setup; counting setup as standstill and billing it as well would recover those hours twice.

The time model: setup per lot, run per part

Each row bills the time and the rate of whoever is tied up. Setup occurs once per lot and is divided by the lot size; the machine stands occupied and the operator works for the whole setup time, so the row carries both rates on one time. Run time occurs per part: the machine is billed for the whole run, the operator only for the attended share – one operator can tend several machines – plus the bench work the machine does not do. Allowances are surcharges on the base time. The operator's time carries the distribution allowance and the recovery allowance, composed multiplicatively; the machine's own run – the automatic cutting run and the finishing pass – carries the distribution allowance only, because recovery is a person's allowance. Loading and unloading is paced by the operator, so the machine waits for it and that time carries both allowances on the machine as well. Setup carries both, for machine and operator alike.

Scrap: two methods, one per cause

To deliver n good parts at a reject rate r, a shop starts n ÷ (1 − r) parts. Each good part therefore carries r ÷ (1 − r) of the cost a reject consumed.

• On material: rejects found early cost the material drawn for them. Base: direct material, less a stated scrap credit.
• On the whole part: rejects found at final inspection cost the whole part. Base: the part's cost before scrap, without the lot's one-offs – setup, programming and first-article cost happen once whatever the yield.
• The second method replaces the first. One cause is never charged twice.

Lot size: five supply arrangements

Which annual cost a lot minimises depends on how the part is ordered, delivered and stocked. ARCNM prices five arrangements, each with its published model.

• Order to your own stock: economic order quantity on the price with a cost per order (Harris 1913, Andler 1929).
• Supplier makes to stock: economic production quantity; stock builds up while the lot runs (Taft 1918).
• Make to order, used on arrival: nobody holds finished stock; only the supplier's work in progress counts.
• Frame contract with call-offs: joint economic lot size – your call-off and the supplier's production lot as a multiple of it, in equal shipments (Goyal 1988, Hill 1997).
• Consignment stock: the joint model with capital at the supplier's cost on every unit and storage where the stock sits (Valentini & Zavanella 2003).

Benchmarks

When you cannot see a supplier's books, you can apply published rates. ARCNM ships two benchmark sets, each converted onto the bases above so the price equals the source's own formula. The first is Table C-1 of FEV's cost analysis for the ICCT (2012): mark-ups as percentages of total manufacturing cost. The second is the public-contract profit ceiling: the usual profit is up to 5 % of net total cost (Netto-Selbstkosten), per the official justification to LSP Nr. 52 (BR-Drs. 732/21, p. 11); applying it sets the Netto-Selbstkosten as the profit base. A benchmark applies only when you choose it.

Where the scheme deviates from a textbook layout

The bases and formulas follow the sources below. The layout and a few simplifications do not, and you should know them.

• Row order: the sheet lists all directly priced rows first. The textbook grouping into material costs and production costs is shown in the manufacturing-cost breakdown.
• Administration overhead (VwGK) and sales overhead (VtGK) are one rate on the Herstellkosten.
• Prices are net of VAT; no row adds it.

Sources

No current DIN or VDI document prescribes a costing scheme: VDI 3258 is withdrawn, and VDI 2225 Blatt 1 is current and describes surcharge costing without prescribing one. The rules on this page come from the price law for public contracts, the commercial code, the teaching and exam standard, and the published lot-size literature. Taft (1918), The most economical production lot, Iron Age 101(18), is available in print only.