There are almost 800 known ways to construct a shoe, but usually, they are variations of a few basic techniques or constructions. The term sole attaching is simply the technique used to attach the sole to the upper of safety footwear. Let’s now discuss the most common sole attaching techniques for safety footwear.
Goodyear Welt Construction
This technique is considered the conventional construction for robust, well-made footwear. It is used almost entirely on better shoes and most men’s shoes. Goodyear Welt Construction employs an insole with a rib or wall that is sited close to the edge of the insole. Throughout lasting, the upper is protected to this wall. The welt is then stitched in and confers to the wall of the insole. The sole is then attached with an adhesive to the bottom of the shoe and is stitched through the welt. With the technological advancements, the sole is usually attached in an automatic sole attaching machine for better assembly. This makes an indirect attachment as the sole is not directly attached to the upper. This is considered the most labor-intensive technique of shoemaking and thus the most expensive.
Cement Construction
Cement construction was originated in 1928. It is considered the most commonly used construction for safety footwear. With cement construction, the outsole is fixed to the insole and upper material with a very stable bonding adhesive and pressed together. Cement assembled shoes are generally flexible, light, and make for better-looking dress shoes.
Heat Sealing Construction
Heat-sealing construction is of two types, and that is vulcanized and injection molded. The main variance is that vulcanized soles are rubber, and injection-molded soles are of a plastic material. In any case, the sole is very long-wearing, which exceeds the life of the footwear.
Vulcanizing
The upper and outsole are combined and molded together with a soft rubber band, which is then pressed in part, heated in a vulcanizing kiln, and permitted to cool.
Injection Molded
Outsoles begin as a soft plastic substance that is dispensed into a sole-shaped metal mold. The shoe’s upper is then constrained down against the mold. The soling material then hardens quickly and is molded in an enduring bond to the upper.
