Leather calculation¶
The calculation for the leather is performed in three steps: scale area, first waste and second waste computation.
Scale area¶
The first step consists in computing the scale area for each part which is assigned a leather material.
Based on the kind of assigned leather (restrictive or not), the application automatically evaluates several strategies and the best one is picked.
First waste¶
The first waste is calculated as second step, which depends on the following factors:
- S: the scale area of the pieces assigned to the specific piece of leather
- A: the size of the skin where the parts will be cut
- Adj: this is a constant factor that indicates an area adjustment for a particular kind of skin
The gross area is calculated then with the following equation:
$$G = S * ((1.0 + Adj / 100) + S / A)$$
Second waste¶
This third step relates to the cuttability grade of the leather, which depends on the quality that the supplier can offer.
The table for SATRA's five-point grading system for leather is given below:
| Quality coefficient | Grade | Representative coefficient |
|---|---|---|
| 100 to 95.1 | A | 97 per cent |
| 95 to 90.1 | B | 93 per cent |
| 90 to 85.1 | C | 88 per cent |
| 85 to 80.1 | D | 83 per cent |
| 80 to 75.1 | E | 78 per cent |
| 75 to 70 | F | 73 per cent |
Final result¶
The Second Waste is finally weighted against the gross area (G) computed for the pieces to calculate the yield.