Thermoplastic Mounting Boss Structure to Prevent Show-Surface Sink Marks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermoplastic articles used for appliance handles face issues with sink marks on the show surface due to increased thickness variations, which weaken the attachment bosses and compromise structural integrity under external forces.
Innovation Solution
A thermoplastic article design featuring a molded body with an interior channel and an attachment boss that extends through the attachment surface into the channel, reinforcing the boss and preventing sink marks by distributing forces more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the size of the attachment bosses is increased to increase strength, then the strength of the attachment boss is improved, but sink marks are formed in the show surface
Solution Approach 1:
The patent divides the attachment boss into multiple segments: a first portion extending from the attachment surface, a second portion extending into the interior channel, and a web connecting them. This segmentation allows the boss to extend deeper into the article body without increasing the visible size at the attachment surface, thereby preventing sink marks while maintaining strength
Solution Approach 2:
The attachment boss extends into the interior channel in the depth dimension rather than only extending laterally at the attachment surface. This dimensional change allows the boss to gain strength through increased material volume without increasing the surface footprint that would cause sink marks
2Strength
If the thickness of the thermoplastic material is increased to strengthen the attachment boss, then the strength is improved, but sink marks occur due to slower cooling rate
Solution Approach 1:
The attachment boss is segmented into portions at different depths, with the second portion extending into the interior channel. This allows the boss to access thicker material zones for strength while keeping the visible attachment surface portion thin to prevent sink marks during molding
Solution Approach 2:
The web acts as an intermediary element connecting the first and second portions of the attachment boss, distributing stresses and allowing the boss to leverage material at different thicknesses without creating concentration points that would cause sink marks
Data Source
AI summary
A thermoplastic article can be mounted to a support structure by a fastener. The article includes a molded body having a length. The molded body also has an attachment surface configured to face the support structure and a show surface opposite the attachment surface. The molded body defines an interior channel separating the attachment surface and the show surface. The article also includes a attachment boss coupled to and extending from the attachment surface for receiving the fastener to mount the article to the support structure. The attachment boss extends through the attachment surface and into the interior channel of the molded body for reinforcing the attachment boss at the attachment surface.