Insole Cold Press Technology – Room Temperature Molding to Preserve Texture, Creating Core Competitiveness of Comfort Insoles

In the production of comfort insoles (such as daily commuting insoles, cushion insoles, and thin lightweight casual insoles), cold press technology has become the mainstream process in the industry due to its core advantage of “room temperature molding and preserving the original texture of materials”. Different from the high-temperature melting of injection molding process, cold press technology does not require high-temperature heating. Through high-pressure pressing at room temperature, various materials such as EVA, foam, composite fabrics, and breathable mesh are closely bonded and pressed into shape. It can not only ensure the softness and resilience of the insole, but also realize the firm combination of layered materials. It is the key technology to create “skin-friendly, cushioning and fitting” comfort insoles. As a factory specializing in insole production, we have introduced high-precision fully automatic cold press equipment, deeply cultivated the details of cold press technology, and transformed technological advantages into product competitiveness to meet consumers’ high-quality demand for daily wearing comfort.

First of all, let’s explain the core principle and equipment configuration of insole cold press technology in detail. The core logic of insole cold pressing is “high-pressure bonding and room temperature shaping”. The core equipment is a fully automatic cold press, matched with customized insole molds, suitable for the production of insoles of different materials and thicknesses. The cold press used in our factory adopts a four-column structure, the pressure can be precisely adjusted (range 50-150T), the pressing time is adjustable from 0.5-3 minutes, the workbench size can be flexibly adjusted according to the insole specifications, and it is equipped with a PLC control system to realize the full automatic control of pressing pressure, time and stroke, ensuring the consistent molding effect of each insole. The core materials of the cold press process are mainly EVA (ethylene-vinyl acetate copolymer) and high-elastic foam, matched with skin-friendly top layer (such as velvet, BK cloth, breathable mesh) and non-slip bottom layer. Through the high-pressure action of the cold press equipment, the multi-layer materials are closely pressed to form a complete structure and foot-fitting insole.

The working process of cold press technology can be divided into five key steps, each of which directly affects the quality of the insole:

• Step 1: Raw material pretreatment, cutting EVA sheets, foam, top layer fabrics and other raw materials, the cutting size matches the insole mold, and at the same time, dedusting and leveling the fabrics to ensure no wrinkles and impurities during bonding;
• Step 2: Layered placement of materials, according to the order of “bottom non-slip cloth → EVA/foam main body → middle cushion layer → top layer fabric”, accurately place the multi-layer materials in the cold press mold to ensure that each layer of materials is aligned to avoid deviation;
• Step 3: Mold closing and pressing, start the cold press, the mold exerts high pressure on the materials at room temperature, the pressure is adjusted according to the material thickness and hardness (such as the pressure of thin lightweight insoles is controlled at 50-80T, and the pressure of thick cushion insoles is controlled at 100-150T), the pressing time is set according to the material characteristics to ensure that each layer of materials is closely bonded without delamination and bubbles;
• Step 4: Pressure holding and shaping, after pressing, maintain the pressure for 10-30 seconds to fully shape the materials, ensure the stability of the insole’s contour, arc and thickness, and avoid subsequent deformation;
• Step 5: Demolding and trimming, open the mold, take out the formed insole, trim and polish the edges, remove excess corners, ensure the insole edges are flat and smooth, and meet the product specifications.

Compared with traditional hot press technology and manual bonding technology, cold press technology has obvious advantages, which is also the core competitiveness of our factory in producing comfort insoles.

• First, preserve the original texture of materials. The cold press process is carried out at room temperature without high-temperature heating, which will not damage the molecular structure of EVA, foam and other materials, and can maximize the retention of the material’s own softness, resilience and breathability. For example, the cold-pressed EVA insole produced by us has a softness 30% higher than that of hot-pressed EVA insole, and the rebound rate can reach more than 70%. It will not collapse or deform after long stepping, and the foot feel is more comfortable when wearing, fitting the foot without foreign body sensation.
• Second, layered bonding is firm. High-pressure pressing makes each layer of materials closely combined, the peeling strength can reach more than 1.5N/cm, and there will be no problems such as top layer falling off and bottom layer warping. The service life is 2-3 times longer than that of manually bonded insoles. At the same time, it avoids the problems of fabric yellowing and material aging caused by high temperature in the hot press process.
• Third, realize zoned performance customization. The cold press equipment can realize “zoned density cold pressing” by replacing molds or adjusting local pressure. For example, the forefoot area adopts softer foam, the pressure is controlled at 50-70T to ensure flexibility when walking; the arch area adopts harder EVA sheet, the pressure is controlled at 100-120T to provide sufficient support; the heel area adopts high-elastic foam, the pressure is controlled at 80-100T to enhance the cushioning effect. One insole can achieve the triple needs of “softness, support and cushioning”, adapting to different foot force characteristics.
• Fourth, environmental protection, high efficiency and low loss. The cold press process does not require high-temperature heating, the energy consumption is only 1/5 of the hot press process, and there is no waste gas or odor emission during the production process, which conforms to the green production standard; at the same time, the material cutting is precise, there is no extra loss during the pressing process, the raw material utilization rate can reach more than 98%, which reduces the production cost and improves the production efficiency. A single cold press can produce 500-800 insoles per hour, meeting the delivery needs of large-volume orders.
• Fifth, wide adaptability. Cold press technology can produce various types of comfort insoles, whether it is thin lightweight for daily commuting, cushion for people standing for a long time, or soft elastic for casual shoes, mass production can be realized by adjusting materials and process parameters. At the same time, it can flexibly adapt to the insole specifications of different shoe types (sports shoes, casual shoes, leather shoes), with strong compatibility.

In the actual production of the factory, we have continuously optimized the cold press process to further improve product quality. For example, in material selection, we choose high-purity EVA and high-density foam to ensure the resilience and durability of the insole; in the bonding process, we adopt environmentally friendly glue-free bonding technology, realizing physical bonding of materials through high pressure, avoiding odors and environmental hazards caused by glue, and improving bonding firmness; in the shaping stage, we adopt segmented pressure holding technology to make the shaping of each part of the insole more uniform, fit the foot more accurately, and avoid problems such as edge warping and middle collapse. In addition, we are equipped with a professional quality inspection team to test the thickness, hardness, fit, rebound rate and other indicators of each batch of cold-pressed insoles to ensure that the products meet domestic and foreign quality standards.

For consumers, the core charm of cold-pressed insoles is “comfort without burden” – the soft and skin-friendly foot feel, precise fit, and long-lasting resilience make daily walking and standing for a long time get sufficient cushioning and support, relieving foot fatigue. For our factory, cold press technology is not only a production process, but also a reflection of our product concept of “taking comfort as the core”. Through high-precision equipment and refined technology, each cold-pressed insole is made into a high-quality product with both quality and comfort, meeting the high-quality demand of the market for comfort insoles.