The cost of sewing thread in footwear production is an important point since it can affect the costability of materials and production planning, inventory management, and overall manufacturing efficiency. There are a variety of seams, curves, stitch types, and thicknesses in footwear construction. Thus, there is more to the calculation of the amount of thread needed than merely measuring a seam.
What Is Sewing Thread Consumption?
Sewing thread consumption is the total amount of thread consumed for the completion of a specific sewing operation or for a complete area of a garment in the choice of footwear style and size. It involves the thread that is used to create stitches and any other thread that is utilized during sewing, such as thread used at the start and finish of seams.
A basic calculation can be expressed as
Whereas, the quantity of thread used is the seam length multiplied by the thread consumption factor.
The consumption factor depends on the kind of stitches being worn, the length of the stitch, the thread construction, the thickness of the materials to be sewn, the sewing conditions, and the use of stitches.
Measure the Total Seam Length
The initial step is to figure out the full extent of all seams that shall be employed to create the footwear structure. This should be seams of the assembly, decoration, re-stitching seams, and other stitches and the pieces.
The importance of this is that although the difference may only be small, it can have a tremendous impact on the overall amount of thread needed when quantities are large. Digital pattern and production-planning systems can also aid manufacturers in acquiring exact measurements of seams.
Consider Stitch Type and Stitch Length
The stitch construction can have a definite impact on thread usage. Depending on the stitch type used, various amounts of threads may be needed to sew an identical seam length with a lockstitch, chain stitch, zigzag, coverstitch, or decorative stitch.
The length of the stitch is also important. A shorter stitch will usually tighten, so more stitches will be formed in a similar distance, hence an increase in the amount of thread used. The longer the stitches, the less the thread will be consumed, but this choice might not be appropriate for the desired strength, look, or construction.
In this way, thread consumption has to be determined based on the actual stitch specification used for production.
Calculate Needle and Bobbin Thread
Where both needle and bobbin threads are used, the use should be calculated for both threads. The amount of needle thread or bobbin thread varies with the types of stitches and machines, their set-up, thread tension, fabric type, and working conditions.
By carrying out controlled sewing trials and accurately measuring the level of thread consumption, manufacturers can well develop the consumption factor. This is more accurate than using theoretical calculations.
Consider Thread and Material Characteristics
Consumption and sewing performance can be impacted by thread size, thread construction, fiber type (bonded nylon thread or polyester embroidery thread), and lubrication. Changing from a finer thread to a heavier thread may cause it to act differently when being stitched.
Additionally, the thickness of the materials can impact how much thread will be used, as thicker footwear materials may necessitate different machine settings and the creation of stitches to maintain the material and its thickness. A number of material layers can contribute to greater requirements for stitching material together in a stable stitch.
Therefore, record some consumption figures for different thread/machine/material/stitch type combinations.
Include Sewing Wastage
The theoretical thread consumption is not the total consumption of thread for production. Other threads used are brought into the workpiece in the process of starting and ending the seams, cutting the threads, machine misadjustments, thread breaks, rejected workpieces, additional reworking, and work interruptions.
The important point for manufacturers is, therefore, to set the wastage allowance in a realistic way, using actual production figures. Calculating and tracking the amount of thread used and comparing it to the actual amount used can help to isolate where possible waste might be occurring.
Calculate Consumption Per Pair
After the thread requirement of each sewing operation is determined, the amount of thread used by all the operations can be added up to obtain the thread requirement for each pair of footwear.
If several threads are used in the same product, the calculation should differentiate between threads by taking into account various thread types and colors. This information can then be utilized for production planning, purchases, inventory, and product costing (production scheduling).
Monitor Actual Consumption
It is critical that production conditions are monitored regularly for product changes if thread consumption changes. Actual usage may be influenced by machine adjustment, operation, stitch settings, shoe designs, materials, and threads.
Manufacturers can recognize overuse and inefficiency with the process and ways in which it can be improved by comparing standard consumption to the actual consumption.
Conclusion
Having to accurately calculate the amount of sewing thread used is vital in an effective shoe production process. These include the measurement of seams, tips on stitch type and stitch length, needles and bobbins needed, and thread and material properties, as well as wastage of production.
The best method is to set standards of consumption on a deliberate basis via production trials and to continually monitor and measure this standard in comparison with actual usage. This will help the shoe manufacturers to better estimate the footwear cost, help them to reduce material waste, optimize material inventory, and help them maintain the homogeneous sewing process of production.