Multilayered Part ROM Process Soft Seal Integration
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Solution Overview
Problem
Current ROM processes for producing interior trim parts in the automotive industry face challenges in achieving a soft tactile feel and suffer from issues related to the manual handling and inefficiencies of flexible seals, leading to variable skin thickness and increased scrap rates.
Innovation Solution
Incorporating a softer moulded part with a Shore A hardness lower than 60 into the core, which overlaps with the substrate layer or forms a seal, allowing for the production of a multilayered part with a softer feel and eliminating the need for a separate flexible seal, using a multicomponent molding process to reduce costs and improve sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flexible seal is used in the ROM process to position the substrate layer, then sealing and positioning are achieved, but the seal requires manual handling which increases production time and causes variable skin thickness
Solution Approach 1:
The softer moulded part integrates the sealing function directly into the core structure, eliminating the need for separate manual seal installation. The softer material automatically provides sealing when the mould closes, as it deforms to fill gaps between the substrate layer and mould wall, making the system self-sealing without manual intervention.
Solution Approach 2:
The sealing function is merged with the core structure by incorporating the softer moulded part directly into the substrate layer. This combines the structural support function with the sealing function, eliminating the need for separate seal components and manual assembly steps.
2Reliability
If a flexible seal is used to delimit the polyurethane injection area, then sealing is achieved, but positioning accuracy varies leading to variable skin thickness and increased scrap rates
Solution Approach 1:
The solution changes the physical parameter of the sealing element from a rigid or semi-rigid seal to a softer material with Shore A hardness lower than 60. This softer material can deform under mould closing force to achieve consistent sealing and uniform positioning, eliminating variability in skin thickness caused by rigid seal tolerances.
Solution Approach 2:
The softer moulded part acts as a flexible sealing element that deforms to conform to the mould cavity and substrate layer positioning. This flexibility allows the sealing interface to adapt to minor positioning variations, ensuring consistent sealing and uniform polyurethane skin thickness throughout the part.
3Reliability
If manual seal installation is used in the ROM process, then sealing is achieved, but labor costs increase and positioning consistency decreases
Solution Approach 1:
The softer moulded part automatically performs the sealing function when the mould closes, without requiring manual installation or positioning. The material's inherent softness allows it to deform and seal gaps automatically, making the process self-service and eliminating manual labor while maintaining reliable sealing.
Solution Approach 2:
The sealing function is extracted from the separate manual seal installation process and integrated directly into the core structure through the softer moulded part. This eliminates the separate sealing step and manual handling, simplifying the overall process while maintaining sealing reliability.
4Ease of operation
If a backfoam system is used to produce interior trim parts, then a soft tactile feel is achieved, but production costs increase and scrap rates are high due to air bubbles
Solution Approach 1:
Instead of using a backfoam system throughout the entire part, the softer moulded part is applied locally only in specific areas where tactile softness is required. This localized application maintains the soft feel where needed while avoiding the complexity and defects associated with full backfoaming, reducing scrap rates.
Solution Approach 2:
The solution uses a composite structure combining the rigid substrate layer with localized softer moulded parts. This composite approach provides the hard structural support where needed while adding soft tactile areas only where required, avoiding the uniform softness and associated defects of backfoam systems.
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
The method achieves a softer feel comparable to backfoam layers while reducing production costs and minimizing scrap rates by integrating a softer material into the core, ensuring accurate positioning and effective sealing during the ROM process.
Implementation Method 1
introducing a polyurethane reaction mixture in said gap between the surface of the core and the internal wall of the mould to overmould at least a first area of the core surface with the polyurethane reaction mixture; allowing the polyurethane reaction mixture to cure in said gap to produce the flexible polyurethane layer therein
Data Source
AI summary
The invention relates to a method for producing a multilayered part which comprises a moulded core (5) and a flexible polyurethane skin layer (4). The core itself comprises a moulded substrate layer (1) which is made of a substrate material, in particular a thermoplastic material, having a Shore A hardness higher than 60. The flexible polyurethane skin (4) is produced by a reaction overmoulding (ROM) process wherein a polyurethane reaction mixture is moulded in a closed mould (11, 12) over at least a first area of the core surface. The moulded core (5) comprises in addition to said substrate layer (1) a softer material which is moulded onto the substrate layer (1) and/or onto which the substrate layer (1) is moulded. This moulded softer material has a Shore A hardness lower than 60 and forms a softer layer (2) between the flexible polyurethane layer (4) and the substrate layer (1) and/or a seal (3) engaging the internal wall of the mould (11, 12) during the ROM process.