There are many ways to attach the sole to the upper but some methods are more commonly used in mass production. Over the period of time Technology has introduced new materials and mechanised much of the process but the manufacture of shoes is still labour intensive.There are two main operations in shoe construction Lasting and Bottoming.
Lasting described as when the shoe upper sections are shaped to the last and insole. Followed by Bottoming where the sole is attached to the upper. The process of bottoming also determine price, quality and performance of the shoe.
Cemented Construction OR Stuck On Construction is A way to attach the outsole and midsole to the upper body using “cement”, or more commonly known as glue. In this process the upper is attached to the insole by cement and the lasting margin is roughened. The sole is attached with lasted upper by means of adhesive. This results in a permanent bond between three components upper, insole, sole. There is no stitch. Many women, children and Men's dress and casual type of shoes are made in this process.
Insole Board Lasting Construction
Insole lasting board is attached to the last. Then the upper is fixed to the Insole lasting board with glue, surrounding the last. A heating process is activating the glue and the upper is tightened by a worker’s manual pull force and a hammer. This process is done in mechanised factories by machines.Cemented production line generally has a set of machines namely - Toe lasting M/c, Seat Side Lasting, Heat Setter, Counter Moulding, Pounding, Sole Attaching and Reactivator. There can be more additions of machines depending on the requirement and cost.
Due to the board the shoe will not become as flexible as with strobel lasting. The stiffness is also dependent on the choice of other components such as outsole and upper material. Though there are options of Texon and other types of flexible Insole materials available.
Strobel / California / Slip lasting / Force lasting
This process has many different names, Strobel, California, Slip or Force Lasting.
The upper is stitched to a strobel insock creating a sock of the insock and upper material. This stich is called “strobel stitch” and is a type of chain stich.The last is put into the sock and then the package is attached to the sole by glue.Since the insock is stitched and not cemented together with the upper it´s creating a more flexible shoe.
This construction is commonly used for majority of athletic footwear due to the elastic and soft properties in some cases where you want to ensure a smooth toe cap the strobel stitch is attached to the inner lining instead of upper. The toe area is extended and pulled around the strobel insock. This toe lasting is usually done with a machine to ensure a smooth toe cap and strong lasting.
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