--- title: "Anodising Cost Per Piece for Small Parts — Converting from Per Square Metre | Saravana Consultancy" description: >- Anodising is quoted per square metre, which is useless for high-volume small parts. How to convert to cost per piece, a worked example on a cabinet knob, where the money actually goes on a basket line, and the make-or-buy threshold. canonical: "https://www.saravanaconsultancy.in/blog/anodising-cost-per-piece-small-parts" source_url: html: "https://www.saravanaconsultancy.in/blog/anodising-cost-per-piece-small-parts" md: "https://www.saravanaconsultancy.in/blog/anodising-cost-per-piece-small-parts.md" last_modified: 2026-08-20 --- # Anodising cost per piece for small parts — converting from per square metre Balasubramanian Iyer · August 2026 Anodising is quoted per square metre. That unit works for an extruder buying six-metre profiles and is close to useless for a hardware maker in Aligarh deciding whether a knob costs him two rupees to finish or five. If you are making high volumes of small parts, the first thing to do with any anodising quotation is convert it — and most people never do. ## Why the industry unit does not fit small parts Per square metre is the natural unit when surface area and handling effort rise together, which is true for profiles: a longer extrusion has more area and takes proportionally more effort to rack. For small parts that relationship breaks. A basket holds thousands of pieces with a very large combined surface area, and the handling effort is **one basket**, not one part. That is why bulk processing is cheap, and it is also why quoting it per square metre hides where the money actually goes. ## Converting a quotation to cost per piece Three numbers do it: - **Surface area of one part**, in square metres. For simple shapes, calculate it. For irregular ones, take the area of the enclosing solid and add roughly 20–30%. - **Pieces per basket load.** From your packing density, which you should be weighing anyway. - **The quoted rate** per square metre. Cost per piece is then simply part area × rate. The basket count tells you throughput and therefore how many loads a day the job shop has to run for you — which is where lead time and minimum lot size come from. ### A worked example Take a cabinet knob, roughly 30 mm diameter and 25 mm tall. Enclosing cylinder area is about 0.0035 m²; call it 0.0045 m² with the fillets and the underside. At a job-work rate of ₹190 per m², that is **about 85 paise of anodising per knob**. If your knob sells for ₹40, anodising is around 2% of the selling price. That single number reorganises the conversation: it tells you that chasing a 10% discount on the anodising rate is worth 8 paise a piece, while a 3% contact-mark reject rate is costing you far more than that. Most hardware makers negotiate the first and never measure the second. ## Where the money actually goes on a basket line Run the same logic on your own plant and the cost structure looks nothing like a profile line: ### Handling dominates Loading and unloading baskets is the labour, and it is per basket, not per piece. This is why cost per piece falls steeply with pieces per load and why packing density is a commercial variable, not just a technical one. ### Power is modest Type II sulphuric anodising runs around 3.5 kWh per square metre. On small parts with a low area per piece, the power cost per piece is often under twenty paise. ### Chemicals track area Roughly ₹20–25 per square metre for Type II. Predictable, and it scales exactly with the area you calculated. ### Rejects are the swing factor A contact-mark reject costs the revenue *and* the power, chemicals and labour already spent. At high volume this dwarfs the rate negotiation. ## The make-or-buy threshold Hardware makers are usually the easiest of the four archetypes to model, because **you already know your outsourced spend to the rupee** — you pay it monthly. That is the number a captive line earns back, and it is far more reliable than the market-rate guesswork an extruder has to do. Set the archetype to **Bulk / basket** and the mode to **Captive** in our [plant cost and payback calculator](/calculators/anodizing-plant-cost), and enter what the job shop charges you today. A basket line is the cheapest of the four plants to build — small tanks, no long rails, a transporter at roughly half the cost — so the payback arithmetic is often better than owners expect. Two things that usually decide it before the payback number does: - **Lead time and queue position.** If your anodising sits behind an extruder's order at the job shop, your delivery promise is not yours to make. - **Minimum lot sizes.** If the shop will not run below a certain load, you carry inventory to suit their economics rather than yours. For the plant itself, see [bulk anodising for small parts](/applications/small-parts-anodising-plant). For the reject rate that dominates the arithmetic, see [contact marks in bulk anodising](/blog/contact-marks-bulk-anodising). ## Frequently asked questions ### How do I convert an anodising rate per square metre to cost per piece? Multiply the surface area of one part in square metres by the quoted rate. For simple shapes calculate the area; for irregular parts take the area of the enclosing solid and add roughly 20 to 30 per cent. For a 30 mm cabinet knob at about 0.0045 square metres and a rate of ₹190 per square metre, anodising costs around 85 paise per piece. ### What does anodising cost per piece for small hardware in India? It depends almost entirely on surface area per piece. A small knob or fitting of a few thousandths of a square metre typically costs well under a rupee to anodise at Indian job-work rates, which is usually one to three per cent of the selling price. That ratio matters more than the rate itself, because it shows that reject rate normally costs more than any discount you could negotiate. ### Why is bulk anodising cheaper than rack anodising? Because handling is per basket rather than per part. A basket can hold thousands of small pieces with a very large combined surface area, but loading and unloading it is one operation. Labour, which dominates the cost of finishing small parts, therefore falls steeply as pieces per load rise, which makes packing density a commercial variable as much as a technical one. ### Is it worth setting up my own anodising line for hardware? Hardware makers are the easiest case to model, because the outsourced spend is already known to the rupee. A basket line is also the cheapest of the four plant types to build: small tanks, no long rails and a transporter at roughly half the cost. Lead time and minimum lot size at the job shop often decide it before the payback number does.