Two-Stage Polyurethane Insole Casting Process
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Solution Overview
Problem
Current methods for producing shoe insoles with polyurethane materials are inefficient due to long production times, high waste rates, and incorporation of moulding defects, leading to uncompetitive production and unaesthetic products.
Innovation Solution
A process involving the use of two polyurethane materials with different Shore A hardness levels, where the first material has a Shore A hardness of 25-55 and the second 5-30, cast in separate moulds with a stabilisation time, allowing for defect removal and reduced overall production time, and incorporating inserts for enhanced comfort and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double casting technique in a single mould is used to make an insole with two polyurethane materials, then the insole provides both comfort and structural stiffness, but the production time becomes too long (at least 6 minutes) making the process uncompetitive
Solution Approach 1:
The patent divides the insole manufacturing process into two separate casting operations using two different moulds. The first mould casts the comfort layer, which is then removed and inspected for defects. The second mould casts the stiffness layer. This segmentation allows each layer to be independently manufactured and quality-checked, reducing overall production time while maintaining product performance.
Solution Approach 2:
The first casting operation and quality inspection are completed and the first mould is removed before starting the second casting. This preliminary completion and removal of the first mould allows the second casting to begin without waiting for the first to fully stabilize, significantly reducing the total production cycle time from over 6 minutes to under 4 minutes.
2Productivity
If the mould opening time is reduced in the first or second casting step to shorten production time, then productivity increases, but a very high quantity of waste is generated
Solution Approach 1:
The first mould is completely removed and the first casting is inspected for defects before the second casting begins. This preliminary removal and inspection allow adequate stabilization time for the first layer without extending the total production time, as the second casting proceeds independently. This prevents premature mould opening that would cause defects and waste.
3Productivity
If the first casting product is removed from the mould before stabilization to reduce production time, then productivity increases, but casting burrs and moulding defects cannot be removed and are incorporated into the final product
Solution Approach 1:
The patent segments the manufacturing process so that the first casting is completely removed from the first mould and inspected for defects before the second casting begins. This separation allows thorough quality inspection and defect removal of the first layer without delaying the overall production, as the second casting proceeds independently in a separate mould.
Solution Approach 2:
The first casting is allowed to stabilize completely before the mould is opened and the product is removed for inspection. This preliminary stabilization ensures the casting is ready for defect removal and prevents burrs from being incorporated into the final product, while the independent second mould maintains production efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process reduces production time, minimizes waste, and allows for the removal of moulding defects, resulting in a more efficient and aesthetically pleasing insole production with improved comfort and structural stiffness.
Implementation Method 1
a first foamable polyurethane and/or thermoplastic polyurethane material is cast into a first mould to make a first supporting element
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
Process for making an insole and/or fussbet (10) composed of at least two components of foamable polyurethane and/or thermoplastic polyurethane materials having different density, comprising the steps of: - casting in a first mould (20) a first foamable polyurethane and/or thermoplastic polyurethane material with a Shore A hardness greater than 25 to make a first supporting element comprising at least one hull-shaped portion extending for at least 40% of the first supporting element (2) at a rear portion of said first supporting element (2); said hull- shaped portion (4) comprising a cavity defined at least partially by perimeter edges having a height greater than 2 mm; - closing the first mould (20) with a lid (20'); - opening said first mould (20) after at least one stabilisation time of at least 120 seconds; - extracting the first supporting element (2) from said first mould (20); - inserting the first supporting element (2) into a second mould (21); - casting in said second mould (21) a second foamable polyurethane and/or thermoplastic polyurethane material with hardness less than at least 15 % with respect to the hardness of the first foamable polyurethane and/or thermoplastic polyurethane material so that said hull-shaped portion (4) of the first supporting element (2) accommodates, at least partially, said second foamable polyurethane and/or thermoplastic polyurethane material to make a second supporting element (3) coupled to the first supporting element (2).