POM Assembly Composition for Low-Friction Squeak-Free Sliding
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Solution Overview
Problem
Polyoxymethylene polymers used in tribological applications often require tribological modifiers that are temperature-sensitive, leading to reduced effectiveness at high or low temperatures, and they can generate noise due to the stick-slip phenomenon when sliding against other components, which is undesirable in consumer products.
Innovation Solution
A polymer composition combining polyoxymethylene polymer with ultrahigh molecular weight silicone as a tribological modifier, which maintains low friction and reduces noise generation across a wide temperature range, even when sliding against similar components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional tribological modifiers are used with polyoxymethylene polymers, then friction is reduced at room temperature, but effectiveness is lost at high or low temperatures
Solution Approach 1:
The patent uses a composite tribological system combining ultra-high molecular weight polyethylene (UHMWPE) and polytetrafluoroethylene (PTFE) particles. This composite approach allows the modifiers to complement each other's strengths, with UHMWPE providing low-temperature performance and PTFE providing high-temperature stability, thereby achieving effective friction reduction across an extended temperature range from -40°C to 100°C
Solution Approach 2:
The patent modifies the molecular weight parameter of the polyethylene component by using ultra-high molecular weight polyethylene (molecular weight > 1,000,000) instead of conventional polyethylene. This parameter change significantly improves the temperature resistance and friction reduction capability, particularly at lower temperatures where traditional modifiers fail
2Speed
If polyoxymethylene components slide against each other, then movement is achieved, but noise is generated due to the stick-slip phenomenon
Solution Approach 1:
The patent introduces UHMWPE and PTFE particles as intermediary lubricating layers between the sliding polyoxymethylene surfaces. These intermediary materials form a low-friction transfer film that prevents direct stick-slip contact between the polymer surfaces, thereby eliminating the characteristic squeaking noise while maintaining smooth sliding movement
Solution Approach 2:
The tribological modifier system is designed to be self-lubricating, where the UHMWPE and PTFE particles automatically form protective lubricating films during the sliding process. This self-service mechanism continuously suppresses the stick-slip phenomenon and associated noise generation without requiring external intervention or additional components
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 polymer composition exhibits a dynamic coefficient of friction of less than 0.06 and minimal wear track width, ensuring quiet operation and reduced noise over a broad temperature range, making it suitable for applications in consumer appliances and other moving parts.
Implementation Method 1
The first sliding member is made from a first polymer composition comprising a polyoxymethylene polymer combined with an ultrahigh molecular weight silicone. The second sliding member is made from a second polymer composition also containing a polyoxymethylene polymer combined with an ultrahigh molecular weight silicone. The ultrahigh molecular weight silicone can be present in the first polymer composition and the second polymer composition such that when the polymer compositions are tested against each other, the compositions exhibit a dynamic coefficient of friction of less than about 0.06
Data Source
AI summary
A tribologically modified polyoxymethylene polymer composition is disclosed. The polyoxymethylene polymer composition is comprised of a polyoxymethylene polymer and at least one tribological modifier. The tribological modifier may comprise an ultra-high molecular weight silicone having a kinematic viscosity of greater than 100,000 mm2 s−1. When tested against itself, the composition of the present disclosure exhibits an extremely low dynamic coefficient of friction and produces no discernible noise over a very broad temperature range, such as from −20° C. to 60° C.