Sunday, May 10, 2015

Standard Operating Procedure For Footwear Industry-Production Process(Sewing)

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Hello everyone. This is the Production part (Sewing) of this SOP. If you don't read yet the Cutting & Prefabrication parts you can read them from the following links. In this part we are talking about Sewing department.



Sewing Department: The Sewing Dept. plays a very important role in shoe making. It has an impact both in terms of functionality and outlook. Maximum value addition in a shoe making happens  in sewing Department. Both for functional and decorative feature , it is important to use number of stitches per cm. Therefore utmost care should be taken in the sewing operations. Besides that the maximum job content, workforce and machinery are involved in the sewing dept. Let's see sewing objective and main functions.

Objective: 
  • To stitch the cut components of uppers as per plan, size assortment and approved sample within the stipulated time.
  • To ensure the best utilization of the manpower and machinery.
  • To ensure the stitching of right quantity of upper in the right quality in the most efficient manner.
Main Functions:
  • TO make an analysis of the file(Production Guide), production plan received from planning and the approved sample. In case of any deviation to be communicated to the person concern and get it corrected.
  • To ensure necessary equipment, machinery and manpower are available well ahead of production start time for avoiding any sort of interruption during production.
Receiving Components:
  • Upper components are checked, counted pair by pair as per style, approved sample, color, size assortment and receive from the cutting dept.
Receiving of auxiliary items:
  • Requirement for the corresponding auxiliary items such as needle, thread, buckle, eyelet, trim, necessary chemicals etc is given to the store and received accordingly as per approved sample. 

Practical Stitching:
  • Preparation: Before starting the job, a preparatory check is done of the approved sample, component, related accessories, guides, gadgets, machinery and the required manpower. Thread color & number to be matched with the approved style. Needle to be set as per thread number, stitch length to be adjusted as per sample. marking ink & cleaner to be selected well ahead of production.
  • Line Setting: Since every style have their uniqueness in sewing, it requires different setting in the sewing line for the sequential operation avoiding repetition of movement.
  • One pair is stitched first following the approved sample to check every technical details.Consult with the product development dept. and get it approved after necessary correction if required.
After getting the approval, the volume production stats, components are sometimes reinforced, laminate and progressively stitched together such as collars are joined to quarters, tongue to vamps, vamps to quarters, eyelets to uppers and so on depending on the style using a wide variety of specialized sewing machines until the upper is completely stitched. Sequential operation of a typical sewing line shown bellow:

a typical sewing process for a stitchdown shoe

Each operator along with the helper is responsible for efficiently producing high quality work. They must follow the approved sample. Proper thread, needle, number of stitches per cm, distances from edges or other raws of stitches to be maintained. Loose threads to be trimmed, shoe components are straight and wrinkle free during attachment. Line supervisor check the quality different point and gives technical solutions.
  • At the end of the sewing process the quality controller inspect the stitched upper pair by pair so that a standard of excellence is maintained. After completion of stitching, the stitched uppers are stored in the section.
  • Delivery: Depending in the style, some of the uppers are directly delivered to the lasting line and some of them to the Hand Sewing for Moccasin Stitch.

Relation Between thread and Needle: Very important for sewing

 THREAD NEEDLE (LR/LL) NEEDLE (DP/PF)
  10               160-180                       22-24
  20               130-140                 20-22
  30               120-130                 20-22
  40               100-110                 18-20
  60                90-100                 12-14


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