Commonly used measuring tools
(I) Caliper
Vernier caliper
Vernier caliper is a commonly used measuring tool, which consists of a main scale and a vernier. The main scale is used to read the size of the integer part, and the vernier is used to read the size of the decimal part. Its measurement accuracy is generally 0.02mm, 0.05mm and 0.1mm. It can measure dimensions such as outer diameter, inner diameter, length, depth, etc. For example, when measuring the outer diameter of a shaft, clamp the outer measuring claw of the caliper on the outer surface of the shaft, and determine the outer diameter of the shaft by reading the scales on the main scale and the vernier.
Ordinary vernier caliper
Digital caliper
Digital caliper is developed on the basis of vernier caliper. It uses electronic sensors to display the measurement data directly on the display in digital form. It is more convenient and quick to use, and avoids the human error that may be caused by the reading of the vernier caliper. Its accuracy is also high, generally up to 0.01mm.
Digital caliper
(II) Micrometer
Outside micrometer
Outside micrometer is mainly used to measure the outside diameter, and its accuracy is higher than that of caliper. Its working principle is to use the screw pair transmission to convert the rotational motion into linear motion for measurement. Usually its measurement accuracy can reach 0.01mm. When measuring, place the workpiece between the anvil and the micrometer screw, and move the micrometer screw forward by rotating the ratchet until it touches the workpiece lightly, and then read the scale value to determine the outside diameter of the workpiece.
External micrometer
Inside micrometer
Inside micrometer is used to measure the inside diameter. Its structure is relatively complex, generally composed of a fixed probe and a movable probe. By replacing the extension rod of different lengths, the inside diameter of different size ranges can be measured. The measurement accuracy of the inside micrometer is also high and can meet the requirements of precision measurement.
Inside micrometer
(III) Dial indicator
Structure and principle
The dial indicator is mainly composed of a head, a body and a measuring rod. It is a comparative measuring tool. Through the linear displacement of the measuring rod, it is amplified by gear transmission, so that the pointer indicates the corresponding value on the dial. The dial is usually divided into 100 grids, each grid represents 0.01mm, so it is called a dial gauge. It is mainly used to measure shape and position errors, such as runout and flatness.
When measuring the radial runout of the shaft, the dial gauge head is in contact with the outer surface of the shaft, and then the shaft is rotated. The swing range of the dial gauge pointer is the radial runout of the shaft. When measuring flatness, move the dial gauge head on the plane and observe the change of the pointer to judge the flatness.
Dial gauge
(IV) Tape measure
Structure and principle
The tape measure is mainly composed of a tape, a ruler box, a brake button and a reel. The tape is the core component of the measurement, usually made of thin steel sheets with scales marked on it. The ruler box is used to store the tape, and the reel allows the tape to be smoothly retracted after stretching. The brake button is used to fix the tape for easy reading.
When the tape is pulled out, it stretches against the spring force of the reel; after the measurement is completed, the tape is released, and the spring force causes the reel to automatically retract the tape into the tape box. The scale marks are distributed along the length of the tape, and the measurement size is determined by reading the scale value corresponding to the length of the tape extended.
Tape structure
Application field
YINGYONGLINGYU
1. Aerospace field
Machining is used to manufacture key parts of aircraft engines (such as blades, turbine discs), fuselage frames and landing gear. These parts have extremely high requirements for accuracy, strength and quality, and require advanced processing technology and high-precision equipment.
Aviation field
2. Automobile manufacturing field
The core parts of automobile engines such as cylinder blocks, cylinder heads, crankshafts, as well as body frames and some precision interior parts all need machining. The large-scale production characteristics of the automotive industry also place high demands on the efficiency and cost control of machining.
Automotive field
3. Medical device field
Surgical instruments (such as scalpels, tweezers), implants (such as artificial joints, dental implants) and parts of medical equipment (such as rotating parts of CT scanners) are all manufactured through precision machining to meet the strict requirements of medical devices for accuracy, safety and biocompatibility.
Medical devices
4. Electronic equipment manufacturing field
The processing of parts such as shells, internal frames and heat sinks of electronic devices such as mobile phones and computers is also inseparable from machining. In order to meet the requirements of thinness and high performance of electronic equipment, machining needs to be continuously improved in terms of accuracy and efficiency.
Electronic manufacturing
Industry development
HANGYEFAZHAN
1. Intelligence and automation
With the advancement of Industry 4.0, the machining industry is developing towards intelligence and automation. By introducing robots, automated production lines and intelligent control systems, automatic operation, monitoring and adjustment of the machining process can be achieved, and production efficiency and quality stability can be improved.
Intelligence and automation
2. High-speed and high-precision machining
The market's requirements for product quality and production efficiency are constantly increasing, prompting machining to develop in the direction of high speed and high precision. For example, ultra-precision machining technology can produce parts with nanometer-level precision to meet the needs of high-end manufacturing industries (such as the semiconductor industry).
High precision
3. Green and environmentally friendly machining
The increased awareness of environmental protection has promoted the use of green and environmentally friendly technologies in the machining industry, such as dry cutting, micro-lubrication cutting and green cleaning technology, to reduce pollutant emissions and energy consumption.
Green and environmental protection
4. Composite machining technology
Composite machining technology (such as turning and milling, grinding and milling) integrates multiple machining processes on one machine tool, reduces the number of workpiece clamping times, and improves machining efficiency and precision. It is an important development trend of future machining.
Composite machining
Machining: The core technology of precision manufacturing
Turning
CHE XUE
Principle: The workpiece rotates, and the turning tool makes linear or curved motion in the plane to change the shape of the workpiece. This is the most basic processing method, used to process rotating parts, such as shafts, discs, and sleeves.
Application case: The crankshaft of an automobile engine, its journal part is turned to achieve precise dimensions and good surface quality, laying the foundation for subsequent processes.
Accuracy range: The ordinary turning accuracy can reach IT8-IT7, and the surface roughness Ra value is 1.6-3.2μm; the precision turning accuracy can reach IT6-IT5, and the Ra value can reach 0.8-0.2μm.
Turning process
Milling
XI XUE
Principle: Use a rotating milling cutter to cut on the workpiece. There are many milling methods, such as peripheral milling (milling cutter circumferential edge cutting) and end milling (milling cutter end face edge cutting), which can process various shapes such as planes, grooves, and curved surfaces.
Application case: In mold manufacturing, complex shapes are obtained by milling the cavity using different types of milling cutters (such as end mills, ball end mills, etc.).
Accuracy range: General milling accuracy can reach IT9 - IT8, Ra value is 3.2 - 1.6μm; precision milling accuracy can reach IT7 - IT6, Ra value is 0.8 - 0.2μm.
Milling process
Grinding
MO XUE
Principle: Use grinding wheel as cutting tool, remove the excess through the relative movement of grinding wheel and workpiece, mainly used to improve surface quality and accuracy.
Application case: The inner and outer ring surfaces of high-precision bearings are ground to make the surface roughness reach micron level to ensure the rotation accuracy and service life of the bearings.
Precision range: Ordinary grinding precision can reach IT7 - IT6, and the surface roughness Ra value is 0.8 - 0.2μm; ultra-precision grinding precision can reach IT5 - IT4, and the Ra value can reach 0.025 - 0.01μm.
Grinding process
Drilling and boring
ZUAN XUE YUTANG XUE
Drilling principle: The drill bit rotates and feeds axially to machine a hole on the workpiece. It is the most common hole processing method.
Boring principle: The boring tool expands or corrects the existing hole to improve the accuracy and quality of the hole.
Application case: In mechanical processing, the initial hole is first processed by drilling, and then boring is used to ensure the size accuracy, shape accuracy and position accuracy of the hole, such as the cylinder hole processing of the engine block.
Accuracy range: Drilling accuracy is generally IT10 - IT9, Ra value is 12.5 - 6.3μm; boring accuracy can reach IT7 - IT6, Ra value is 1.6 - 0.8μm.
Drilling and boring pin process
Machining: the core process of precision manufacturing
Lathe
CHE CHUANG
Types: There are ordinary lathes, CNC lathes, etc. Ordinary lathes control the movement of the tool through manual operation handles; CNC lathes automatically control the movement of the tool according to pre-programmed programs, with higher processing accuracy and efficiency.
Main components and functions: The bed is the basic component of the lathe and provides support; the spindle box is used to install the spindle and drive the workpiece to rotate; the feed box controls the feed movement of the tool; the slide box enables the tool holder to move longitudinally or horizontally.
CNC lathe and ordinary lathe
Milling machine
XI CHUANG
Types: Including vertical milling machine, horizontal milling machine, gantry milling machine, etc. Vertical milling machines are suitable for processing planes, step surfaces and grooves, etc.; horizontal milling machines are convenient for processing long-axis parts; gantry milling machines are used for processing large workpieces.
Main components and functions: The spindle of the milling machine is used to install the milling cutter and provide rotational power; the worktable can achieve longitudinal, lateral and lifting movements to adjust the relative position of the workpiece and the milling cutter.
Gantry milling machine and vertical milling machine
Grinding machine
MO CHUANG
Types: Cylindrical grinders are used to process cylindrical and conical surfaces; internal grinders process the inner surface of holes; surface grinders process planes.
Main components and functions: The grinding wheel frame of the grinder is used to install the grinding wheel and realize the high-speed rotation of the grinding wheel; the headstock and tailstock are used to clamp the workpiece; the worktable drives the workpiece to reciprocate.
Cylindrical grinder and internal grinder
Drilling machine ZUAN CHUANG
Drilling machine types: There are bench drilling machines, vertical drilling machines and radial drilling machines. The main components of a drilling machine include a spindle, a worktable, and a column. The spindle drives the drill bit to rotate, and the worktable is used to place the workpiece.
Main components and functions: The main components of a drilling machine are composed of a spindle, a worktable, and a column. The spindle drives the drill bit to rotate, the worktable is used to place the workpiece, and the column plays a supporting role.
Vertical drilling machine and boom drilling machine
Boring machine
TANG CHUANG
Types of boring machines: There are horizontal boring machines, coordinate boring machines, etc. The boring bar of the boring machine is used to install the boring tool, and the boring process is realized through the movement of the worktable, spindle box and other components.
Main components and functions: The main components of a boring machine include a boring bar, a spindle box, a worktable, and a column. The boring bar is used to install the boring tool, the spindle box is driven, the worktable is loaded with the workpiece, and the column is supported.
Horizontal boring machine and jig boring machine
Processing materials
JIA GONG CAI LIAO
Metal materials:
Such as steel, cast iron, aluminum alloy, copper alloy, etc.
1. Steel has high strength and toughness and is widely used in machinery manufacturing;
2. Cast iron has good casting performance and is often used to manufacture parts with complex shapes;
3. Aluminum alloy has low density and high strength and is widely used in aerospace and automobile manufacturing.
Metal materials
Non-metal materials:
Including plastics, ceramics, composite materials, etc.
1. Plastics have good processing performance and are often used to manufacture some shell parts;
2. Ceramic materials have high hardness and good wear resistance and are used to manufacture tools and wear-resistant parts;
3. Composite materials combine the advantages of multiple materials and are used in occasions with high performance requirements.
Ceramic and composite materials
Processing tools
JIA GONG DAO JU
Tool materials:
There are high-speed steel, cemented carbide, ceramics, cubic boron nitride (CBN) and diamond, etc.
1. High-speed steel tools have good toughness and are suitable for processing some softer materials;
2. Carbide tools have high hardness and good wear resistance and are widely used;
3. Ceramic tools are suitable for high-speed cutting and processing of materials with higher hardness;
4. CBN and diamond tools are mainly used for processing superhard materials.
Machining tools
Tool geometry:
Different processing technologies require tools with different geometric shapes.
1. There are many types of turning tools, such as external turning tools and internal turning tools. Their blade angles and tool head shapes are designed according to processing requirements;
2. Parameters such as the number of teeth and helix angle of the milling cutter will also affect the milling effect.
Machining tools
Dimensional accuracy
CHI CUNJING DU
Dimensional accuracy refers to the degree of closeness between the actual size of the part after processing and the ideal size, which is regulated by the tolerance grade.
ISO standards:
The standards formulated by the International Organization for Standardization (ISO) are widely used worldwide. ISO specifies a series of tolerance grades, such as IT01, IT0, IT1 to IT18, etc. The smaller the number, the higher the tolerance grade, that is, the higher the dimensional accuracy requirement.
IT01 and IT0: These two grades have extremely high accuracy requirements and are usually used in the manufacture of precision measuring tools such as gauge blocks, and the processing cost is also very high.
IT1 to IT5: Suitable for high-precision mechanical parts, such as key components of aerospace engines, core parts of precision instruments, etc. These parts need to ensure accurate dimensions within a very small tolerance range to ensure their performance and reliability.
IT6 to IT11: Widely used, covering many important parts in ordinary mechanical products, such as some parts of automobile engines, some key components of machine tools, etc.
IT12 to IT18: Used for parts with relatively low dimensional accuracy requirements, such as some less important structural parts, appearance parts, etc.
IT tolerance zone
GB standard (China National Standard):
There is a certain correspondence between my country's GB standard and ISO standard. For example, GB/T 1800.1-2009 specifies the tolerance grade of linear dimensions, which also has similar grade divisions.
Such as IT01, IT0, IT1, etc. to IT18. In actual production, enterprises will select appropriate tolerance grades according to GB standards to control the dimensional accuracy of parts based on the specific needs of the products.
Shape accuracy
XING ZHUANG JING DU
Shape accuracy refers to the degree of conformity between the actual shape of the surface or axis of the part and the ideal shape. Common shape accuracy indicators include roundness, straightness, flatness, etc.
Roundness:
Definition: Roundness refers to the degree of deviation between the contour of the actual circle and the ideal circle on the same cross section. It reflects the accuracy of the surface shape of circular parts (such as shafts, holes, etc.).
ISO and GB standards: Both ISO and GB standards specify the measurement method of roundness and the allowable error range. The roundness value is generally measured by professional measuring equipment such as roundness gauges. For example, for the inner ring of a high-precision rolling bearing, the roundness requirement may be in the micron level or even smaller to ensure the good running performance of the bearing.
Roundness
Straightness:
Definition: Straightness refers to the degree of deviation between the actual straight line profile of a part and the ideal straight line, and is often used to measure the shape accuracy of slender parts such as shafts and rods.
ISO and GB standards: The standards specify the evaluation methods for straightness, such as the minimum area method and the two-end point connection method. Different application scenarios have different requirements for straightness. For example, in the manufacture of high-precision machine tool guides, the straightness requirement is very high, and the straightness deviation may be required to be no more than a few microns per meter in length to ensure the motion accuracy of the machine tool tool.
Straightness
Flatness:
Definition: Flatness refers to the degree of deviation between the actual plane and the ideal plane, and is mainly used to measure the surface shape accuracy of flat and box-type parts.
ISO and GB standards: The measurement method and allowable error range of flatness are also specified. For example, in precision mold manufacturing, the flatness of key planes such as the mold parting surface is required to be very high to ensure the tightness of the mold when closing the mold and the quality of the molded parts.
Flatness
Position accuracy
WEI ZHI JING DU
Position accuracy refers to the degree of conformity between the actual position relationship between the elements on the part and the ideal position relationship. Common position accuracy indicators include parallelism, verticality, coaxiality, etc.
Parallelism:
Definition: Parallelism refers to the degree of parallelism between two planes or two straight lines. For example, between the workbench and the guide rail of the machine tool, the moving plane of the workbench is required to maintain a high degree of parallelism with the guide rail plane to ensure processing accuracy.
ISO and GB standards: The standards specify the measurement method of parallelism and the allowable error range. Measuring parallelism usually requires the use of some special measuring tools, such as dial indicators, micrometers, etc., and the parallelism is evaluated by measuring the deviation values of two planes or two straight lines at different positions.
Perpendicularity:
Definition: Perpendicularity refers to the degree of perpendicularity between two planes or two straight lines. Widely used in construction, machinery manufacturing and other fields. For example, between the columns of a building and the ground, the columns are required to be perpendicular to the ground; in mechanical parts, such as the mounting surface and the bottom surface of the box, a high degree of verticality is required to ensure the installation accuracy and overall performance of the parts.
ISO and GB standards: also specify the measurement method of verticality and the allowable error range. The measurement of verticality also often uses tools such as dial indicators and micrometers to obtain the vertical deviation value of two planes or two lines through specific measurement methods.
Coaxiality:
Definition: Coaxiality refers to the degree to which the axes of two rotating bodies remain coaxial. It is often used for the matching of shaft parts and hole parts, such as the engine crankshaft and the bearing hole require a high degree of coaxiality to ensure the normal operation of the engine.
ISO and GB standards: The standards specify the measurement method of coaxiality and the allowable error range. The measurement of coaxiality usually uses some special measuring instruments, such as three-coordinate measuring instruments, etc., and the coaxiality is evaluated by measuring the position deviation of the two axes in space.
