The process of one-piece molded shoes
Reading times：1 Update time：2026-04-29
The core of the one-piece shoe craftsmanship lies in directly combining the upper and sole into a single unit through specific technology, thereby eliminating the cumbersome stitching or extensive use of glue in traditional shoe making. This craftsmanship not only enhances production efficiency but also effectively avoids the issue of shoes coming unglued.
Currently, there are primarily the following mainstream integrated molding processes:
Direct Injection
This is a widely used technology at present, employed by numerous renowned sports and casual shoe brands.
Upper preparation: First, place the finished upper (which can be made of canvas, fly-knit material, leather, etc.) onto the shoe last to shape it.
Mold positioning: Place the shoe last, which is covered with the shoe upper, precisely into a closed mold. A cavity will form between the bottom of the shoe upper and the mold, and the shape of this cavity is the shoe sole.
Liquid injection: Inject liquid shoe sole materials (such as polyurethane PU, thermoplastic rubber TPR, etc.) directly into this cavity.
Curing and molding: The liquid material rapidly foams, expands, and solidifies within the mold, tightly integrating with the bottom of the shoe upper. After cooling, a sole that is integral with the shoe upper is formed.
Advantages: High production efficiency, capable of achieving automated assembly line production; no need for glue, environmentally friendly and completely solves the glue cracking problem; flexible sole design.
Representative technologies: ECCO's FLUIDFORM™ direct injection molding process, Red Dragonfly's intelligent workshop for continuous upper injection, etc.
Vulcanization
This is a classic craftsmanship, commonly seen in canvas shoes (such as Converse, Vans, etc.).
Component assembly: Assemble the canvas or fabric upper, rubber sole, and the rubber "Foxing Tape" that wraps around the entire shoe body in advance.
High-temperature vulcanization: The assembled shoes are sent into a large high-temperature oven (vulcanizing tank) for heating.
Chemical fusion: Under high temperature and high pressure conditions, rubber materials undergo vulcanization, transforming from a soft state to a firm and elastic state, and permanently fusing with the upper of the shoe, forming a sturdy whole.
Advantages: The shoes are very flexible, with a good feel on the feet, strong grip, and a unique retro style.
Disadvantages: The sole is usually thin, with relatively weak cushioning and support.
Ultrasonic Welding Process
This technology is commonly used in shoe styles that prioritize environmental protection and lightweight design, such as indoor slippers or certain components of sports shoes.
Material stacking: Stack the upper sheet and sole sheet according to the design in the mold.
High-frequency vibration: Ultrasonic welding heads are utilized to generate high-frequency vibrations, causing instantaneous high temperatures on the contact surface of the materials due to friction.
Fusion welding: The material on the contact surface is locally melted, rapidly cooled under pressure, and then combined into one piece.
Advantages: The production process eliminates the need for glue, resulting in zero waste and emissions, making it highly environmentally friendly; the seams are smooth and aesthetically pleasing, and the product is lightweight
Suction Film Molding
This is a relatively novel technology aimed at producing shoe soles with exquisite appearance and superior performance.
Film preheating: Place a layer of special elastic film (such as TPU film) in the mold and heat it to soften it.
Film suction molding: Through vacuum adsorption, the softened film is made to adhere closely to the inner wall of the mold, forming the outer surface of the shoe.
One-piece infusion: Inject foaming material (inner lining material) into the "shell" formed by the film, and after curing, it combines with the outer film to form a complete shoe sole.
Advantages: The sole appearance can achieve a fully encapsulated effect, with no air holes, making it wear-resistant and less prone to developing creases over time.
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