1. What is a star wheel?
The Star Wheel, also known as the Geneva Wheel, is the core component of the Geneva Mechanism. This mechanism is an intermittent motion mechanism.
Working principle: It usually consists of a continuous, uniformly rotating dial (or pin wheel) and a star wheel with radial grooves. When the round pin on the dial enters the radial groove of the star wheel, it drives the star wheel to rotate; When the circular pin disengages from the radial groove, the concave arc on the star wheel is locked by the convex arc on the dial, making the star wheel stationary.
2. Material selection for star wheel plastic parts
Choosing plastic to manufacture star wheels is mainly based on the following characteristics of plastic, and material selection is crucial:
Polyoxymethylene (POM/DuPont) ™ Delrin ®):
Commonly known as "Sai Gang" or "Diao Gang", it means that its performance is comparable to that of metals.
Nylon (PA66, PA12, PA46, etc.):
Advantages: Good toughness, excellent wear resistance and self-lubricating properties, able to withstand high loads. Glass fiber (GF) or MoS2 (molybdenum disulfide) is usually added to enhance its strength, rigidity, and wear resistance.
Disadvantages: Strong moisture absorption, size may change with humidity, and attention should be paid in precision applications.
Polyether ether ketone (PEEK):
Advantages: Top grade high-performance engineering plastics with excellent high temperature resistance, chemical corrosion resistance, mechanical strength, and wear resistance.
Disadvantage: Extremely expensive price.
Application: Only used for extreme working conditions, such as high temperature, high load, or situations requiring extremely high cleanliness.
3. Advantages and disadvantages of plastic star wheels vs. metal star wheels
Characteristics: Plastic star wheel, metal star wheel (such as steel, brass)
Extremely lightweight, conducive to high-speed operation and reducing inertia weight
Low noise, quieter operation, plastic can absorb vibration noise and larger vibrations
Wear resistant and self-lubricating, many engineering plastics have inherent lubricity and do not require additional oil. Regular lubrication is necessary, otherwise they are prone to wear and tear
Low cost, with lower material and injection molding costs, and higher material and machining costs