The insole, as mentioned in the previous post, can be thought of as the insole of a shoe, in simple terms. It is a crucial component of the shoe that is attached to the strobel of the upper and is one of the important parts that come into direct contact with the sole of the foot.
In this section, we will explore how the insole is manufactured in the shoe manufacturing process and what equipment is used.
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| shoe manufacturing process |
Definition of Insole : shoe manufacturing process
Definition of Insole:
As mentioned earlier, the insole is one of the most crucial parts of the shoe structure that comes into direct contact with the sole of the foot, as mentioned earlier. It forms the bottom of the shoe when combined with the strobel.
The insole is responsible for providing support when the shoe is worn according to the shape of the foot, absorbing shocks during walking or exercise to provide a comfortable fit. In addition, it has the function of absorbing and expelling sweat and odor from the feet, and it also has a significant impact on the durability and hygiene of the shoe. Understanding these factors will help you understand the manufacturing process better.
Key Materials for Insoles:
In most athletic shoes, insoles are made from EVA foam. Dress shoes or other types of shoes use suitable materials such as leather or other materials. The characteristics of each material are as follows:
- EVA Foam: Lightweight and excellent shock absorption capability.
- Leather: Durable and provides natural breathability.
- Gel: Provides excellent shock absorption and support.
- Memory Foam: Provides a comfortable fit that conforms to the shape of the foot.
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| 나이키 인솔 / Nike Insole |
Insole Manufacturing Process
The process of manufacturing insoles goes through the following stages:
- Raw Material Processing
- EVA Processing
- Insole Lamination
- Pressing
- Cutting/Trimming
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| Insole manufacturing process |
Raw Material Processing (EVA):
- EVA Material Preparation
- Extrusion
- Mixing EVA and Additives
- EVA Sheet Production
EVA is a copolymer of Ethylene and Vinyl Acetate, which is lightweight, flexible, and has excellent shock absorption capabilities. Typically, EVA is supplied in pellet form. It is melted and extruded based on the appropriate mixture, mixed with EVA material and additives, and prepared to meet the requirements of insole production.
EVA Processing:
- EVA Molding and Foaming
- Roll Sheet Work and Skiving
- Band Knife
In this process, the prepared EVA sheets are heated and foamed for a certain period. After foaming, they expand to the size of a calendar sheet. The foamed EVA sheet is then skived to the thickness of the insole, completing the preparation of the EVA surface of the insole.
refer below video for your more better understanding.
Insole Lamination:
- EVA Sheet Cutting
- Hot Melt Adhesion
- Hot Press
The large-sized EVA sheet processed in the previous stage is cut to the appropriate size for making insoles. After cutting, a hot melt film is placed between the fabric and the EVA sheet to prepare it for adhesion. The set of fabric/hot melt film/EVA sheet is placed in a hot press, completing it as one insole sheet.
Pressing:
- Insole Pressing
Insoles can be divided into two main types: flat insoles and slightly 3D-shaped insoles. For flat insoles, the insole sheet is cut according to the size of each shoe using a die-cutting machine. However, for insoles with 3D shapes, additional molding work is required to reshape them using a molding press.
Cutting/Trimming:
- Cutting
- Label/Logo Adhesion
- Trimming
Once the insole is shaped according to the shoe design, it is cut to the size of each shoe and the brand’s logo or label is adhered to the part where the insole material is located. Trimming or finishing work may also be added to ensure there are no quality issues with the product.
refer below video for your more better understanding.
Equipment for Insole Manufacturing
The key manufacturing equipment needed for insole production includes:
Raw Material Processing (EVA):
- Kneader Machine: Equipment for extruding pellet raw materials with heat.
- Bucket Conveyor: Transfers extruded raw materials to a blender (mixing roll) by placing them in buckets.
- Mill Blender: Mixes materials such as EVA and additives.
- Calendar Machine: Shapes mixed materials into calendar sheets.
EVA Processing:
- EVA Heating Press: Press equipment for foaming and expanding EVA sheets.
- Roll Skiving Machine: Thins the foamed material into sheets.
Insole Lamination:
- Die Cutting Machine: Cuts EVA sheets into smaller sizes.
- Heat Press: Presses the set of fabric/hot melt film/EVA to create one insole sheet.
Pressing:
- Insole Press (Molding Press): Shapes insoles, especially for 3D-shaped ones.
Cutting/Trimming:
- Cutting Machine: Cuts insoles to the size required for each shoe.
The shoe manufacturing process consists of three main parts: insole, outsole, and midsole. Reviewing the information on these three processes will provide a more detailed understanding of sole or bottom manufacturing processes.
Taking another look at the overall process of making shoes from the beginning will be even more helpful for better understanding.
