Accuracy and quality control
Accuracy
The amount by which a measurement can vary without affecting the ability of the product to be manufactured accurately. in textiles is the amount of acceptable variation from the specified measurement from which you can cut out pattern pieces, add A part that when put together makes a product. or sew seams.
The amount of material between the edge of a fabric and the seam line. is the amount of material between the edge of the fabric and the seam, and it is tested to check it meets the tolerance stated in the Document containing clear and detailed instructions for the manufacture of a product..
Example
A factory may say that a seam allowance of 20 mm is needed, with an acceptable tolerance of +/- 5%.
5% = 20 × 0.05
= 1
The seam can have a tolerance of 1 mm either side of the 20 mm.
20 + 1 = 21 mm maximum
20 - 1 = 19 mm minimum
If this were the case, then the seam allowance could range from 19 mm to 21 mm.
Question
A factory has specified that a seam allowance of 25 mm is needed, with an acceptable tolerance of +/- 8%.
What is the possible range of tolerance?
8% = 25 × 0.08
= 2
The seam can have a tolerance of 2 mm either side of the 25 mm.
25 + 2 = 27 mm maximum
25 - 2 = 23 mm minimum
The seam allowance can range from 23 mm to 27 mm.
Quality control
During the manufacturing process, quality control (QC) checks are carried out - for example, to check whether:
- seams are sewn straight
- components are sewn on straight and strong
- fabric has no faults or misprints
- stitching is straight and neat
Although quality control checks can increase waste, with faulty products being thrown away, if a factory develops a reputation for being reliably high in quality, money is saved in the long term through products being reordered.
In a manufacturing flow chart, quality control checks are placed as decisions in diamonds to show where a step would need repeating if there was a mistake:
