KEVOS® MAKEOS · Materials
Ring Blank Plan (Rolled Ring or Cut from Plate, Mass and Cost)
For this machined ring, is it cheaper to buy a rolled (forged) ring blank or to cut the blank from plate, and how much material does each waste?
Comparison of blank routes for a rectangular-section ring: finished ring volume and mass, and the rolled-ring blank with machining allowance, by Pappus’s theorem (area of the section × path of its centroid, as the Pappus surface and volume tool), against a square plate blank of the same thickness with its offcut credited as scrap; mass, cost and material yield for each and the cheaper route, checked against your budget.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Finished outside diameter | mm | Outside diameter of the finished ring. |
| Finished inside diameter | mm | Inside diameter of the finished ring. |
| Finished height (thickness) | mm | Axial height of the finished ring. |
| Machining allowance per surface | mm | Material left on each machined surface. |
| Extra on the plate square (cutting edge) | mm | Extra added to the square plate blank for flame or saw cutting. |
| Density | kg/m³ | Density of the material. |
| Prices | ||
| Rolled ring price | $/kg | Price per kilogram of a rolled or forged ring blank. |
| Plate price | $/kg | Price per kilogram of plate. |
| Scrap credit | $/kg | Value per kilogram of the plate offcut and centre disc returned as scrap. |
| Budget per blank | $ | Most you will pay for the blank. |
Method and formulas
- Ring volume = section area × 2π × radius of the section centroid (as the Pappus surface and volume tool).
- Rolled blank: section (OD + 2a − ID + 2a) ÷ 2 × (h + 2a) on its centroid radius; cost = mass × ring price.
- Plate blank: square of side OD + 2a + edge, thickness h + 2a; cost = mass × plate price − scrap × scrap credit; yield = finished mass ÷ blank mass.
- Example: the finished ring weighs 21.579 kg; a rolled blank costs 94.74 $ against 99.411 $ from plate.
Limitations
- Rectangular ring section; contoured rings need their own section area and centroid.
- Plate offcut assumed sold as scrap, not reused.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Choose between a rolled ring and a plate cut-out
- Estimate material for a large machined ring
- Quote a ring part
Who it is for
- Estimators
- Buyers
- Manufacturing engineers
What you get
- Finished ring and rolled blank volume and mass
- Plate blank mass and scrap
- Cost, yield and the cheaper route
Interpreting the result
- Thin, large-diameter rings waste most of a plate blank, so rolled rings usually win as the ring gets thinner.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 66–67. Topic reference; no source tables or recommended settings are reproduced.
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Open the Ring Blank Plan (Rolled Ring or Cut from Plate, Mass and Cost) calculator
