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Typical application scenario matching
1. Scenarios where copper-based friction plates are preferred
- Heavy-load, high-torque equipment: such as winches of mining machinery, slewing mechanisms of excavators, and ship propulsion systems, need to withstand large instantaneous loads. The high load-bearing capacity of the copper base can avoid slipping or damage.
- High temperature and harsh working conditions: such as rolling mills in the metallurgical industry and crushers in cement production lines. The high temperatures generated by continuous operation can easily cause the failure of paper-based friction pads, and the temperature resistance of copper-based friction pads is more suitable.
- Scenarios with low maintenance requirements: such as the braking system of wind turbines and the gearbox of large construction machinery. If the equipment is installed in a remote location or has high maintenance costs, the long life of the copper base can reduce the frequency of replacement.
2. Scenarios where paper-based friction discs are preferred
- Medium to light load, high-frequency shifting equipment: such as automobile automatic transmissions and motorcycle clutches. The paper-based friction coefficient is high and the shifting is smooth, which can improve operating comfort and cause less wear on the steel counterpart parts.
- Normal temperature, low impact working conditions: such as the transmission system of printing machines and textile machinery, the operating temperature is stable, the load fluctuation is small, and the low cost and adaptability of the paper base are more advantageous.
- Scenarios that require high protection of paired parts: such as the braking mechanism of precision machine tools. The soft nature of the paper base can avoid scratching the expensive mating friction disc and reduce overall maintenance costs.
The friction coefficient is a physical quantity that measures the ability of two contact surfaces to hinder relative movement. There is no absolute "good" or "bad" value in its value. The core depends on the functional requirements of the application scenario. Blindly pursuing a high friction coefficient may cause problems.
In scenarios where "stable grip" or "efficient braking" is required, a higher friction coefficient is necessary. For example, the friction coefficient between car brake pads and brake discs needs to be maintained at 0.3-0.6 to quickly reduce the vehicle speed through sufficient friction and ensure driving safety; the texture design of the soles of sports shoes is also designed to increase the friction coefficient with the ground and avoid slipping when walking or exercising.
However, in scenarios where it is necessary to "reduce resistance", "reduce wear" or "achieve smooth movement", a high friction coefficient will become an obstacle. Take the piston and cylinder inside the engine as an example. If the friction coefficient between the two is too high, it will increase parts wear and consume more power. Therefore, the friction coefficient must be reduced to an extremely low level through engine oil lubrication. The blades of skates can form a thin layer of water film on the ice surface. It is the water film that is used to reduce the friction coefficient, allowing athletes to glide at high speeds.
In addition, an excessively high friction coefficient may also be accompanied by problems such as "large energy loss" and "serious heating". For example, if the friction coefficient of an industrial conveyor belt is too high, the drive motor will consume more electricity to drive the conveyor belt. At the same time, the high temperature generated by the continuous friction of the contact surface will shorten the service life of the equipment.
In summary, the selection of friction coefficient needs to accurately match the purpose of use and be comprehensively judged based on safety, efficiency, loss and other factors. There is no absolute conclusion that "the higher the better".
As the core braking/transmission component in high-load scenarios, copper-based friction plates need to take into account friction performance, structural strength and stability. The core adopts the "powder metallurgy" process route. The specific process is as follows:
1. Raw material ratio and mixing
This is the basic link that determines the performance of the friction pad. It requires precise mixing of multiple raw materials according to the formula.
- Core raw materials include copper powder (matrix, accounting for 50%-70%, providing strength and thermal conductivity), friction performance modifiers (such as graphite, antimony sulfide, controlling the stability of the friction coefficient), reinforcing agents (such as iron powder, silicon carbide, improving wear resistance) and binders (such as phenolic resin, auxiliary molding).
- Put all the raw materials into the high-speed mixer and stir in a closed environment for 1-2 hours to ensure that the ingredients are evenly dispersed, avoid local performance deviations, and finally form a uniform mixed powder.
2. Press molding (cold pressing)
The mixed powder is transformed by pressure into a "green body" with a preliminary shape.
- Fill the mixed powder quantitatively into the customized mold (corresponding to the final size of the friction plate) and put it into the hydraulic press.
- Apply a pressure of 15-30MPa and hold it for 30-60 seconds to tightly combine the powder particles to form a green body with a dense structure and regular shape. This link requires strict control of pressure and pressure holding time to prevent cracks or uneven density in the green body.
3. Sintering and solidification
Through high-temperature heating, the components in the green body undergo physical and chemical changes to form a stable metal matrix structure.
- Put the green body into the continuous sintering furnace and raise the temperature according to the preset curve: first remove the volatile matter in the binder at 200-400°C, then raise the temperature to 850-950°C (the critical temperature for sintering copper-based materials), and keep it warm for 2-4 hours.
- During the sintering process, the copper powder particles melt and combine to form a metal skeleton, in which friction modifiers and reinforcing agents are evenly embedded, ultimately forming a high-strength, high-stability friction plate matrix.
4. Subsequent processing and processing
The sintered semi-finished products are finely processed to meet assembly and performance requirements.
- Mechanical processing: Use lathes, milling machines and other equipment to process the inner and outer circles, mounting holes, chamfers and other structures of the friction plate to ensure that the dimensional accuracy meets the drawing requirements (the tolerance is usually controlled within ±0.05mm).
- Surface treatment: In some scenarios, the friction surface needs to be sandblasted or grinded to remove the surface oxide layer and burrs to improve the flatness of the friction surface; the non-friction surface may undergo anti-rust treatment (such as galvanizing).
- Performance testing: Sampling testing of friction coefficient (under high and low temperature environments), hardness, density and compressive strength, eliminating unqualified products to ensure that the performance of factory products meets standards.
The entire process takes "powder metallurgy" as the core, and by accurately controlling the three key parameters of raw materials, pressure, and temperature, it finally produces copper-based friction plates with high wear resistance, high temperature resistance, and stable friction performance, which are suitable for high-intensity scenarios such as automobile braking and engineering machinery transmission.
