When it comes to creating the sole of a shoe, one of the indispensable components at the bottom is the outsole. In the process of making shoes, this is also a crucial aspect. The outsole significantly impacts the performance, quality, and even the design of the shoes.
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| 아웃솔 : 신발제조공정, 나이키 Air Max 90 / Outsole |
In this section, we will explore how the manufacturing process of the outsole is structured. From materials to design, manufacturing equipment, and the production process itself, we will delve into the overall aspects of outsole manufacturing.
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| shoe manufacturing process |
Definition of Outsole in the Shoe Manufacturing Process
What is an Outsole?
The outsole is the part of the shoe that is located at the very bottom, directly in contact with the ground. It plays an extremely important role in the overall structure of the shoe, determining factors such as the shoe’s durability, stability, and comfortable fit. Outsoles are manufactured through various materials, technologies, and processes, with their form and design varying depending on the intended purpose of the shoe and the brand’s identity.
Functions of the Outsole
The outsole performs the following functions:
- Durability: The outsole must withstand continuous wear and tear and resist abrasion and corrosion.
- Traction: It prevents slipping and provides stability during walking or sports activities.
- Shock Absorption: It absorbs the impact generated when walking or running, reducing the strain on the legs and feet.
- Comfortable Fit: The outsole is designed to provide a comfortable fit based on the shape of the foot when the shoe is worn.
Materials Used for Outsoles
Commonly Used Materials Materials used for outsole manufacturing vary depending on the shoe’s purpose, price range, and brand preferences. Common materials include rubber, polyurethane (PU), ethylene-vinyl acetate (EVA), and thermoplastic rubber (TPR).
Characteristics and Applications by Material
- Rubber
- Characteristics: High durability and excellent grip. Rubber is commonly used in most athletic shoes.
- Applications: Trekking boots, running shoes, work boots, and more.
- Polyurethane (PU)
- Characteristics: Lightweight, durable, and versatile, allowing for various designs.
- Applications: Casual shoes, sports shoes, and more.
- Ethylene-Vinyl Acetate (EVA)
- Characteristics: Extremely lightweight with excellent shock absorption.
- Applications: Running shoes, training shoes, and more.
- Thermoplastic Rubber (TPR)
- Characteristics: Similar to rubber in properties but with excellent processability.
- Applications: Casual shoes, slippers, sandals, and more.
Outsole Design
Importance of Design
Outsole design goes beyond mere aesthetics; it plays a crucial role in determining the functionality of the outsole. The visible part of the design consists of the toe and the bottom when viewed from the side. However, design affects the functionality of the outsole and represents an essential element of the shoe’s overall style and the brand’s identity and image.
Key Design Types and Features
- Wave Pattern
- Characteristics: Features a wavy pattern that provides excellent grip and stability.
- Applications: Mainly used in running shoes and trekking boots.
- Hexagon Pattern
- Characteristics: Consists of hexagonal shapes, offering flexibility and grip.
- Applications: Suitable for basketball shoes and training shoes.
- Spikes
- Characteristics: Features small protrusions on the sole, providing high grip, especially on slippery surfaces.
- Applications: Commonly used in soccer shoes and golf shoes.
- Flat
- Characteristics: Smooth surface for comfortable everyday wear.
- Applications: Suitable for casual shoes and slippers.
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| 출처 : RunRepeat, 다양한 아웃솔 형태 / source from RunRepeat, Outsole shapes |
Outsole Manufacturing Equipment
Essential Manufacturing Equipment
Various equipment is required for outsole manufacturing, used for processing raw materials, shaping the outsole, and completing the final product.
Key Manufacturing Equipment and Their Functions
- Banbury Mixer
- Function: Mixes high-density rubber materials in batch units.
- Characteristics: Capable of rapidly mixing solid rubber materials.
- Roll Mixer
- Function: Secondary mixing of rubber materials initially mixed in the Banbury mixer.
- Characteristics: Uses additives such as fillers, plasticizers, processing aids, and coloring agents during mixing.
- Calendar Machine
- Function: Extrudes materials initially mixed in the roll mixer into a calendar sheet.
- Characteristics: Shapes rubber uniformly, maintains consistent thickness, and completes the drying process.
- Cutting Machine
- Function: In the first step, cuts the calendar into uniform pieces, and in the second step, cuts them to the appropriate size for the mold.
- Characteristics: Ensures materials are cut uniformly for the outsole press.
- Outsole Press
- Function: Produces the outsole in the final design and pattern.
- Characteristics: Applies uniform temperature and pressure for a specific duration, determining the outsole’s design.
- Trimmer
- Function: Removes fur or burrs from the molded outsole.
- Characteristics: Enhances the visual quality of the outsole.
- Outsole Washing Machine
- Function: Removes impurities and foreign substances from the surface of the outsole.
- Characteristics: Enhances the quality of the outsole through hot water washing.
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| 아웃솔 제조설비 / Machinery for Outsole Manufacturing |
Materials for Outsole
Design Phase
- Use of Computer Programs: Detailed design of the outsole is performed using CAD (Computer-Aided Design) programs. This is typically carried out in development or design centers, and manufacturing facilities often skip this step.
- Material Selection: The choice of materials is made based on how the outsole will be manufactured in terms of shape and design. Factors such as the shoe’s purpose, durability, grip, etc., are considered.
Raw Material Preparation
- Material Verification: Suitable rubber materials with the desired properties for outsoles are selected and verified for quality.
- Material Sorting and Storage: Verified materials are categorized and stored under appropriate conditions.
Manufacturing Process
- Mixing Process: High-density rubber materials are batch-mixed using Banbury and roll mixers, forming them into shapes suitable for shoe production.
- Calendar Sheet Manufacturing Process: Properly mixed materials are processed into calendar sheets with consistent thickness and size.
- Cutting Process: The calendar sheets are cut into uniform pieces in the first step and further cut to the mold’s appropriate size in the second step.
- Curing Process: Rubber is injected into the outsole press mold, and the outsole is produced by curing at a specific temperature and pressure for a defined time.
- Finishing Process: The outsole’s appearance is refined, burrs are removed, and a washing process enhances the outsole’s quality.
In this way, we have briefly examined the process of producing outsoles in the shoe manufacturing process. To gain a broader understanding of the sole, it may be helpful to review the midsole manufacturing process, which will further enhance your understanding of the sole’s production process.
Next, we will explore the preparation process (StockFit) for attaching the midsole and outsole.
Taking another look at the overall process of making shoes from the beginning will be even more helpful for better understanding.
