Pattern Area measurement: Manual method – Part 4
..Continued from Part-3
5. Square board method: In this method a board is used to calculate the area. The board may be wood, paper or hard board in rectangular with a size of 24” X 12” with rules (half and full inch). Lay the complete one pair of patterns on the board in the most compact and economical way. Find the area covered by the area for one Pair, which includes the first waste (Inter locking wastage).
To adjust for the actual cutting value, allowances will be made for:
• Leather type and grade.
• Variations in size range and fittings.
6. Graph paper: This is almost same as above. The complete patterns for one pair/odd are laid out in the most compact and economical arrangement on graph paper.
The following assumptions are takes while tracing the patterns
• Assuming that material is endless.
• Material contains no directions and the properties are same through out.
• Material contains no defects
The area of the rectangle is calculated by multiplying the length with width and counting up the number of squares covered. Then uncovered squares (full/half) are deducted from this. An allowance is added to this area to calculate the consumption for a pair. The allowance will usually vary according to
• Material type and quality
• Average pattern area in relation to average material area.
• Variations in size and fittings.
The percentages are usually based on previous experience and some companies apply the same percentage for all styles and materials.
1. While calculating the area for one odd there should be at least 2 patterns. Otherwise it is difficult to find out the interlocking wastage
2. if you are using different types of colors and materials, you have to find the area for different sets of patterns
(Generally percentage allowance are 15% for buff and cow leathers, 20-25% for Kid, goat and calf leathers, depending on the design and size of the components. An allowance of 10% is added for lining material. For remaining materials an approximation value is taken by considering the pattern shape, size etc at the time of cutting.)
• Reasonably quick and easy to use.
• Permanent record of the calculation method
• The same base area can be used for different materials, qualities and sizes
• Less skill is required than the marking-up method.
• Area will depend on the interlocking skills of the assessor.
• The percentages applied are based on previous cutting history which may result to uneconomical cutting,
• The lay-out does not reflect usual cutting practice i.e. Vamps to be cut together from the butt, quarters from belly etc.,
Ex: Rectangle area = 20 X 50 cm =1000 sq.cm
Empty Squares = 150 sq.cm ( 100 full squares + 100 half squares i.e 50 full squares)
Net area (odd) = 1000-150 = 850 sq.cm = 8.5 sq.dm
Net area for pair= 8.5 sq.dm X 2= 17 sq.dm.
Assume that the leather is cow, 15 % allowances are added.
Then total gross area = 17 + (17 X 15/100)= 17+2. 55 = 19.55 sq.dm.
7. Rubber band method: This is almost same as of small square method . The only difference is finding the area. After laying the pattern a smooth line is drawn around the pattern…Assume you placed a rubber band around the patterns laid out. The area enclosed inside the rubber band is the area of patterns.