What is an Atomic Force Microscope (AFM)?

The full name of AFM is Atomic Force Microscope, which is an atomic force microscope. It is a new type of atomic-level high-resolution instrument invented after Scanning Tunneling Microscope. It can nanometer a variety of materials and samples in the atmosphere and liquid environment. The physical properties of the area include the detection of topography, or direct nano-manipulation; it has been widely used in semiconductors, nano-functional materials, biology, chemical engineering, food, pharmaceutical research, and research in various nano-related disciplines and research fields , Become a basic tool for nanoscience research.

AFM

(atomic force microscope)

AFM is a surface observation instrument invented by G. Binning based on STM in 1986.

AFM = Atomic Force Microscope (

AFM = Air Force Manual

Air Force Manual ([US] USAF publication);

AFM = Antifrictional Metel

Antifrictional Metel

AFM = Abrasive Flow Machining

Abrasive Flow Machining (AFM) technology is the latest machining method.It uses an abrasive medium (a flowable mixture mixed with abrasive particles) to flow over the surface to be processed under pressure. Deburring, deburring, and rounding to reduce the waviness and roughness of the surface of the workpiece, and to achieve the precision processing precision. The AFM method is the best alternative processing method in parts that require complicated manual finishing or complex shapes, and other parts that are difficult to process. The AFM method can also be applied to workpieces that are unsatisfactory with high-volume machining or are injured during processing. In addition, it can effectively remove the delamination regenerated after electrical discharge machining or laser beam machining and the residual stress remaining on the processed surface of the previous process.

The workpiece is held in a jig, and the flowing medium is guided to the part where the workpiece needs to be ground away, while other parts are not affected. The clamp is fastened between the opposite media cylinders to allow the abrasive media to flow back and forth.

AFM process

The Dynaflow Abrasive Flow Process (AFM) developed by the United States and Massachusetts Dynetics Company is a metal finishing process that forces abrasive-containing media to reciprocate on the surface or in the hole of the workpiece. It has a wide range of applications.

When AFM first appeared years ago, it was mainly used to remove burrs in hard-to-reach inner channels and intersections in metal parts. It is particularly suitable for processing complex aerospace components made of difficult-to-machine alloy materials. It has been used for finishing inaccessible inner surfaces with a surface roughness of 0.127 & micro; m in hydrodynamic components.

The basic principle of AFM: when the medium speed is the largest, the polishing ability is also the largest. Here, the structure of the fixture plays an important role, which determines where the media velocity is at its maximum. The fixture is used to position the workpiece and establish the trajectory of the medium. It is the key to finishing the selected part without touching the adjacent part.

AFM = Analyzing Financial Accounting

Analyzing Financial Accounting is a basic course in accounting.

AFM = Active Fuel Management

AFM Introduction

Active Fuel Management, also known as Displacement on Demand, abbreviated AFM or DOD, is an energy-saving and emission-reduction technology for automotive engines. It was first proposed by General Motors and started to be used on GM Cadillac L62 engines in 1981. . This technology can make the engine choose to close part of the cylinders and stop working under low load conditions according to the requirements of the working conditions, so as to achieve the purpose of improving fuel economy and reducing exhaust emissions. It is generally applied to V6 or V8 engines. According to EPA tests, engines using this technology can effectively reduce fuel consumption by 5.5% to 7.5%.

AFM Development Process

When the vehicle is accelerating rapidly or under high load, a higher power output of the multi-cylinder engine is required. However, according to statistics, in the daily use of the vehicle, the engine's power usage is below 25% in most cases, such as when the vehicle is at high speed. When the road is running, only 40 horsepower (30 kW) of power output is needed to meet the vehicle's forward power requirements and necessary accessories to operate, such as turning on the air conditioner. When the gasoline engine is running under low load conditions, the effective compression ratio of the engine is much smaller than the calibrated compression ratio, the throttle valve is not fully opened, and the intake air volume of the engine in each intake stroke is also far less than the maximum load at full load. The amount of gas, therefore, the pressure and temperature generated by the combustion of the mixed gas in the combustion chamber is far less than the full load state. According to the laws of thermodynamics, the thermal efficiency conversion of the engine is also far less than the maximum thermal efficiency value that it can reach, which is the conversion of the engine's combustion heat energy into operation The efficiency of mechanical energy is not high. Therefore, in most daily vehicle use processes, high-power, large-displacement engine equipment has not been used to the extreme, but has caused waste to a certain extent and increased additional fuel consumption. Active fuel management technology is produced in response to this situation. It can intelligently control the engine operation according to the operating conditions of the engine. When the load is low, close some cylinders to reduce fuel consumption and increase heat. Conversion efficiency, when all the cylinders are turned on at high load, the power output can meet the driving demand.

AFM works

Active fuel management technology uses solenoid valves to control the oil supply of hydraulic valve lifters. By adjusting the oil pressure of the valve lifters of selected cylinders, some cylinder valves remain closed, and these cylinders will stop intake air. Or exhaust, the selected cylinder will not participate in the engine power output, thereby achieving the purpose of improving fuel economy. In order to achieve the effect of closing the cylinder, when the engine's combustion power stroke is completed, the exhaust valve will be closed by the solenoid valve. When the engine exhaust stroke, the exhaust gas will remain in the cylinder and be compressed. When the engine enters the intake stroke At this time, the intake valve is also controlled by the solenoid valve to keep it closed, so that the cylinder can not be intake air. In this way, the exhaust gas remaining in the cylinder will be continuously compressed and expanded in each stroke of the engine, similar to a gas spring. According to the distribution of engine cylinders, then multiple cylinders will be closed at the same time (for example, V8 engine 1, 4, 6, and 7 cylinders). When two cylinders of exhaust gas are compressed, the other two cylinders will be expanded. This balance makes the closing of these cylinders not cause additional burden on the engine and will not affect the normal operation of the engine. When the engine operating conditions change and greater power output is required, the exhaust valve of the closed cylinder will open during the exhaust stroke, the exhaust gas will be discharged, and the engine will enter the normal working state of the full cylinder, which will bring greater power to the vehicle. Power.

AFM technical significance

The application of active fuel management technology has a direct effect on improving engine performance and improving fuel economy, and can also effectively reduce engine exhaust emissions. It belongs to an engine technology that saves energy and reduces emissions. GM is the earliest automobile company to use this technology today. It used active fuel management technology on GM's 1981 Cadillac L62 engine.