China Shenzhen Perfect Precision Product Co., Ltd. company news

Any parts are processed with precision requirements, and if the parts are found to be processed with poor precision during inspection, such products are likely to become substandard. Then for the parts, its processing accuracy why it will become poor? Non-standard precision parts machining accuracy is poor to a large extent because in the equipment installation and adjustment, the feed dynamic tracking error between the axes is not adjusted; or because the machine use after wear, the machine tool axis drive chain has changed. In this case, can be re-adjusted and modify the amount of clearance compensation to solve. So when the non-standard precision parts processing ready dynamic tracking error is too large and alarm, can check its servo motor speed is too high; position detection components are good; position feedback cable connector is good contact; the corresponding analog output latch, gain potentiometer is good; the corresponding servo drive device is normal, and timely maintenance. Of course, if the machine tool movement overshoot will also cause parts processing accuracy is not good, for example, is too short acceleration and deceleration time, can be appropriate to extend the speed change time; may also be the servo motor and screw between the connection is loose or rigid is too poor, can be appropriate to reduce the position ring gain. In addition, when the non-standard precision parts processing equipment of the two-axis linkage, the circle of axial deformation and oblique ellipse error and other factors under the influence of the parts processing accuracy will also become poor. Among the deformation may be caused by the machinery is not well adjusted; and oblique ellipse error need to first check the position deviation value of each axis, if the deviation is too large, can adjust the position ring gain to exclude. Then check whether the rotary drive or induction synchronizer interface plate is well adjusted, and then check whether the mechanical drive vice clearance is too large, whether the clearance compensation is appropriate, etc., to determine the root cause of poor machining accuracy of the parts.

A common application in design is the analogous approach, which is simple, fast and reasonable. The application requires adequate references and a wide range of materials and references are given in various current mechanical design guides. Commonly, surface roughness is compatible with dimensional tolerance levels. Generally speaking, the smaller the standard tolerances specified for machining and production of mechanical parts, the smaller the surface roughness value of mechanical parts, but there is no fixed functional relationship between them. Mechanical parts machining strength is the ability of the part not to break or undergo more than the allowed plastic deformation during work, and is the most basic provision for all normal operation and production safety of the equipment. Standard countermeasures to improve the strength of the parts are: in order to expand the specifications of the part risk cross-section, expand the moment of inertia of the cross-section, effectively design the cross-section of the case; the use of high-strength raw materials, the raw materials to expand the heat treatment process to improve the strength and reduce thermal stress, operation manufacturing process to reduce or eliminate microscopic shortcomings, etc.; in order to reduce the load of the parts to reduce the stress level, etc., should be properly involved in the structure of the parts. 1, positioning error: positioning error mainly includes the benchmark does not overlap error and positioning vice manufacturing inaccuracy error. 2, measurement error: parts in the processing or measurement after processing, due to the measurement method, gauge accuracy, as well as the workpiece and subjective and objective factors are directly affected by the measurement accuracy. 3, tool error: any tool in the cutting process is inevitable to produce wear and tear, and thus cause the size and shape of the workpiece to change. 4, fixture error: the role of the fixture is to make the workpiece equivalent to the tool and machine tool has the correct position, so the geometric error of the fixture on the machining error (especially the position error) has a great impact 5, the machine tool error: including spindle rotation error, guide error and drive chain error. Spindle rotation error refers to the actual axis of rotation of the spindle moment relative to its average axis of rotation of the amount of change, it will directly affect the accuracy of the workpiece being machined.

The conventional CNC lathe processing relies on the movement of the tool to complete the turning of the excess blank material, but in the processing of precision slender shafts, the conventional lathe is obviously unable to satisfy the processing needs, and the emergence of longitudinal cutting lathe makes the batch processing of precision shaft workpiece possible. Longitudinal cutting lathe, as it is called, means that in metal cutting processing, the activity trajectory of the tool is perpendicular to the middle axis of the workpiece instead of moving axially, that is, the workpiece is rotating and moving during processing, and the turning tool unnecessarily follows the movement of the workpiece, which is different from the conventional lathe in nature. This machine tool can also be called walking center type CNC lathe, spindle box moving type CNC automatic lathe or economic turning and milling compound heart. The Z-large processing diameter of longitudinal cutting lathe in the market now is 32mm, which has a great advantage in the market of precision shaft processing. This series of machine tools can be equipped with automatic feeding device to realize the fully automatic production of single machine tool and reduce the labor cost and product defect rate. CNC lathes are used for precision composite processing of various high-precision, multi-volume and complex-shaped shaft parts in the industries of aviation, aerospace, military, automobile, motorcycle, communication, refrigeration, optics, home appliances, electronics, microelectronics, clocks and watches, office equipment, etc.

Shaking cutter is very common during turning, which is generally shown as: uneven and rough surface of parts, accompanied by harsh sound, unstable dimensions, etc In order to better solve these common problems, we have to understand the root cause of this problem: resonance point On Wikipedia, it is explained as follows: Resonance point (acoustics is called resonance) refers to the situation when a physical system vibrates with greater amplitude than other frequencies at a specific frequency; These specific frequencies are called resonance frequencies. Under the resonance frequency, a small periodic driving force can produce huge vibration, because the system stores vibration energy as damping. There is a very small chance that the resonance frequency is approximately equal to the natural frequency of the system, or called natural frequency, which is the frequency of free oscillation. In the previous video, we used tuning forks and table tennis balls to show the effect of resonance on vibration amplitude. In a normal cutting environment, the spindle speed remains stable, and the frequency and amplitude of vibration are also maintained within an acceptable range. With the increase of vibration frequency, the vibration amplitude will also increase accordingly. The most obvious examples are: In some intermittent turning environments, with the increase of spindle speed, the workpiece surface roughness will not be improved, on the contrary, the surface will be rougher. In this case, increasing the speed is equivalent to increasing the frequency of vibration; The rough surface means that when the tool contacts the workpiece, the contact point on the circumference has slightly changed, which also indicates that the amplitude of vibration has been amplified. This does not mean that increasing the frequency of vibration will definitely increase the amplitude of vibration. Only when resonance is excited can this result be more obvious. In essence, to ensure the stable roughness of parts, it is necessary to maintain a stable vibration amplitude. Keep the generated vibration away from the resonant frequency, and no longer increase the amplitude of vibration. If forced, shortening the time of resonance will also have a positive impact on the control of vibration amplitude. The special function SSV (spindle speed floating) of Haas lathe makes use of the changing speed to shorten the time when resonance occurs, so as to improve the roughness.

In the actual production of milling, including machine tool settings, workpiece clamping, tool selection and other aspects of application skills, today we briefly summarized the main points of milling, which is worth a look! 1. Power capacity Check the power capacity and machine rigidity to ensure that the machine tool can use the required milling cutter diameter. 2. Workpiece stability Workpiece clamping conditions and considerations. 3. Overhang Make the tool overhang on the spindle as short as possible during machining. 4. Select the correct milling cutter pitch Use the correct milling cutter pitch suitable for the process to ensure that no too many blades participate in the cutting, otherwise it will cause vibration. 5. Cutting tool When milling narrow workpieces or with gaps, ensure that there are enough blades to feed. 6. Blade slot type selection As far as possible, use an indexable insert with a front angle groove to ensure a smooth cutting effect and minimum power consumption. 7. Use correct feed By using the recommended maximum chip thickness, ensure the correct feed of the used blade to achieve the correct cutting action. 8. Cutting direction Use straight milling as much as possible. 9. Part Considerations Workpiece material and configuration, and quality requirements of the surface to be machined. 10. Blade material selection The groove type and material are selected according to the material type and application type of the workpiece. 11. Vibration reducing milling cutter For longer overhangs that are more than 4 times the tool diameter, the vibration trend will become more obvious, and the use of damping tools can significantly improve productivity. 12. Main deflection angle Select the most appropriate main deflection angle. 13. Milling cutter diameter Select the correct diameter according to the width of the workpiece. 14. Milling cutter position Position the milling cutter correctly. 15. Milling cutter cut in and cut out It can be seen that through arc cutting, the chip thickness is always zero when the tool is retracted, so that higher feed and longer tool life can be achieved. 16. Coolant Use coolant only when you think it is necessary. In general, milling can be performed better without coolant.

How much do you know about machining process? Here comes the interview question! 1. What are the three methods of workpiece clamping? 1. Clamp in the clamp; 2. Directly align the clamp; 3. Marking and aligning clamp 2. What does the process system include? Machine tool, workpiece, fixture, tool 3. What are the components of the machining process? Rough machining, semi finishing, finishing, super finishing 4. How are benchmarks classified? 1. Design datum 2. Process datum: process, measurement, assembly, positioning: (original, additional): (coarse datum, fine datum) What does machining accuracy include? 1. Dimensional accuracy 2. Shape accuracy 3. Position accuracy 5. What are the original errors during processing? Principle error, positioning error, adjustment error, tool error, fixture error, rotation error of machine tool spindle, guide error of machine tool guide, transmission error of machine tool, stress deformation of process system, thermal deformation of process system, tool wear, measurement error, error caused by residual stress of workpiece 6. Influence of process system stiffness on machining accuracy (machine tool deformation, workpiece deformation)? 1. Workpiece shape error caused by position change of cutting force action point 2. Machining error caused by size change of cutting force 3. Machining error caused by clamping force and gravity 4. Influence of transmission force and inertia force on machining accuracy 7. What are the guiding errors and spindle rotation errors of the machine tool guideway? 1. The guide rail mainly includes the relative displacement error of the tool and workpiece in the error sensitive direction caused by the guide rail 2. Radial circular runout of the main shaft · axial circular runout · inclination swing 8. What is the phenomenon of "error remapping"? What is the error remapping coefficient? What are the measures to reduce error remapping? Due to the change of process system error and deformation, the blank error is partly reflected on the workpiece Measures: increase the number of tool passes, increase the process system stiffness, reduce the feed rate, and improve the blank accuracy 9. Transmission error analysis of machine tool transmission chain? Measures to reduce transmission error of transmission chain? Error analysis: that is to use the angle error of the end components of the drive chain Δφ To measure Measures: 1. The smaller the number of drive chains, the shorter the drive chain, Δφ The smaller it is, the higher the accuracy is 10. How are machining errors classified? Which errors are constant errors? Which errors belong to variable systematic errors? Which errors belong to random errors Systematic error: (constant systematic error, variable systematic error) random error Constant systematic error: machining error caused by machining principle error, manufacturing error of machine tool, cutter and fixture, and force deformation of process system Variable systematic error: wear of props; Thermal deformation error of tools, fixtures, machine tools, etc. before thermal balance Random error: copy of blank error, positioning error, tightening error, multiple adjustment error, deformation error caused by residual stress 11. What are the ways to ensure and improve the machining accuracy? 1. Error prevention technology: reasonable use of advanced technology and equipment to directly reduce the transfer of original error The original error is inferior to the original error Average the original error 2. Error compensation technology: online detection of automatic grinding of coupling parts, and active control of error factors that play a decisive role 12. What does the geometric morphology of the machined surface include? Geometric roughness, surface waviness, texture direction, surface defect 13. What are the physical and chemical properties of the surface layer materials? 1. Cold work hardening of surface layer metal 2. Metallographic structure deformation of surface layer metal 3. Residual stress of surface layer metal 14. Try to analyze the factors that affect the surface roughness of cutting? Roughness value consists of: the height of the cutting residual area Main factor: the tool tip arc radius Main deflection angle Secondary deflection angle Feed rate Secondary factor: the cutting speed increases Select the cutting fluid appropriately Increase the rake angle of the tool Improve the grinding quality of the tool 15. Try to analyze the factors that affect the surface roughness of grinding? 1. Geometric factors: the influence of grinding parameters on surface roughness 2. The influence of grinding wheel granularity and grinding wheel dressing on surface roughness 2. The influence of physical factors: plastic deformation of surface layer metal: the selection of grinding wheel 16. Try to analyze the factors that affect the cold work hardening of the cutting surface? Influence of cutting parameters influence of tool geometry influence of material properties 17. What is grinding tempering burn? What is grinding quenching burn? What is grinding annealing burn? Tempering: if the temperature in the grinding area does not exceed the transformation temperature of the quenched steel, but has exceeded the transformation temperature of martensite, the martensite in the metal on the workpiece surface will be transformed into the tempering structure with lower hardness for quenching; if the temperature in the grinding area exceeds the transformation temperature, plus the cooling effect of the coolant, the surface metal will have a secondary quenching martensite structure, with higher hardness than the original martensite; In his lower layer, due to slow cooling, there is tempering structure annealing with lower hardness than the original tempering martensite: if the temperature of the grinding area exceeds the phase transformation temperature and there is no coolant during the grinding process, the surface metal will have annealing structure, and the hardness of the surface metal will drop sharply 18. Prevention and control of machining vibration Eliminate or weaken the conditions that generate machining vibration; Improve the dynamic characteristics of the process system, improve the stability of the process system, and adopt various vibration damping devices 19. This paper briefly describes the main differences and applications of machining process cards, process cards and process cards. Process card: single piece small batch production with common processing method Mechanical process card: medium batch production process card: mass production type requires strict and meticulous organization 20. The principle of selecting rough datum? Principle of precise benchmark selection? Coarse datum: 1. Principle of ensuring mutual position requirements; 2. The principle of ensuring the reasonable distribution of machining allowance on the machined surface; 3. Principle of facilitating workpiece clamping; 4. The principle that the coarse datum shall not be reused generally. The precise datum: 1. The principle of datum coincidence; 2. Principle of unified benchmark; 3. The principle of mutual benchmarking; 4. Self reference principle; 5. Principle of easy clamping 21. What are the principles of process sequence arrangement? 1. First process the datum plane, then process other surfaces; 2. In half cases, the surface shall be machined first and then the hole; 3. First process the main surface, and then process the secondary surface; 4. Arrange the rough machining process first, and then the finishing process 22. How to divide the processing stages? What are the benefits of dividing the processing stages? Machining stage division: 1. Rough machining stage, semi finishing stage, finishing stage, precision finishing stage can ensure that there is sufficient time to eliminate thermal deformation and residual stress generated by rough machining, so as to improve the subsequent machining accuracy. In addition, when defects are found in the rough machining stage, the next processing stage is not necessary to avoid waste. In addition, equipment can also be used reasonably. Low precision machine tools are used for rough machining and precision machine tools are used for precision machining to maintain the precision level of precision machine tools; Reasonably arrange human resources, and highly skilled workers are specialized in precision and ultra precision machining, which is very important to ensure product quality and improve process level.  

Die cutting process - the blanking process of knife die and knife die. The film panel or line is positioned on the bottom plate, the knife die is fixed on the machine template, and the material is cut off by controlling the knife edge with the force provided by the machine. What distinguishes him from the blanking die is that the notch is smoother; At the same time, through the adjustment of cutting pressure and depth, the indentation and half break can be cut. At the same time, the cost of the mold is low, and the operation is more convenient, safe and fast. Centrifugal casting is a technology and method to inject liquid metal into a high-speed rotating mold to fill the mold and form castings under the action of centrifugal force. According to the shape, size and production batch of the castings, the mold used for centrifugal casting can be non-metallic (such as sand mold, shell mold or investment mold shell mold), metal mold or the mold with coating layer or resin sand layer in the metal mold. Lost foam casting is a new casting method that combines paraffin wax or foam models similar in size and shape to form model clusters, applies fire-resistant coatings and dries them, buries them in dry quartz sand for vibration molding, pours them under negative pressure, vaporizes the model, liquid metal occupies the position of the model, and solidifies and cools them to form castings. EPC is a new process with nearly no allowance and accurate molding. This process does not require mold taking, parting surface and sand core, so the casting has no flash, burr and draft angle, and reduces the size error caused by core combination. Squeeze casting, also known as liquid die forging, is a method to directly inject molten metal or semi-solid alloy into the open mold, then close the mold to generate filling flow, reach the external shape of the workpiece, and then apply high pressure to cause plastic deformation of the solidified metal (shell), while the uncured metal bears isostatic pressure, while high-pressure solidification occurs, and finally obtain the workpiece or blank. The above is direct squeeze casting; In addition, indirect squeeze casting refers to the method of injecting molten metal or semi-solid alloy into the closed mold cavity through a punch, and applying high pressure to make it crystallize and solidify under pressure, and finally obtain a workpiece or blank. Continuous casting is a casting method that uses a through mold to continuously pour liquid metal into one end and continuously pull out molding materials from the other end. Drawing is a plastic processing method that uses external force to act on the front end of the metal to pull the metal blank from the die hole smaller than the blank section to obtain products of corresponding shape and size. Because drawing is usually carried out in cold state, it is also called cold drawing or cold drawing. Stamping is a forming processing method of workpieces (stamping parts) with required shape and size by applying external force on plates, strips, pipes and profiles by press and die to cause plastic deformation or separation. Metal injection molding (MIM) is a new powder metallurgy near net forming technology that extends from the plastic injection molding industry. As we all know, plastic injection molding technology produces products of various complex shapes at low prices, but the strength of plastic products is not high. In order to improve its performance, metal or ceramic powders can be added to plastic to obtain products with high strength and good wear resistance. In recent years, this idea has evolved to maximize the content of solid particles and completely remove the binder in the subsequent sintering process and densify the preform. This new powder metallurgy forming method is called metal injection molding. Turning refers to the lathe processing is a part of mechanical processing. The lathe mainly uses turning tools to turn the rotating workpiece. Lathes are mainly used to process shafts, discs, sleeves and other workpieces with rotary surfaces. They are the most widely used machine tools in machinery manufacturing and repair plants. Turning is a method of cutting the workpiece by rotating it relative to the tool on the lathe. The cutting energy for turning is mainly provided by the workpiece rather than the tool. Turning is the most basic and common cutting method, which plays a very important role in production. Turning is suitable for machining rotary surfaces. Most workpieces with rotary surfaces can be machined by turning methods, such as internal and external cylindrical surfaces, internal and external conical surfaces, end faces, grooves, threads and rotary forming surfaces. The tools used are mainly turning tools.

High speed cutting (HSM) refers to the cutting process at a much higher speed than the conventional cutting speed. At present, there is no uniform definition of the speed range of high-speed cutting in various countries. Generally, cutting that is 5~10 times higher than the conventional cutting speed is called high-speed cutting. One of the main goals of high speed cutting is to reduce production costs through high productivity. It is mainly used in the finishing process, often for processing hardened die steel. Another goal is to improve overall competitiveness by reducing production time and delivery time. High speed cutting technology is a very large and complex system engineering. What are its advantages over traditional machining? For machine tools, how can high-speed cutting be met? After the concept of high speed machining was put forward, it was widely used in industrial production in the near future after long-term exploration, research and development. High-speed cutting system is mainly composed of high-speed cutting cnc machine tools, high-performance tool clamping system, high-speed cutting tools, high-speed cutting cam system software and other parts. The reason why high-speed cutting is more and more widely used in industry is that it has significant advantages over traditional machining: What kind of machine tool can satisfy high-speed cutting? 1. Short processing time and high efficiency. 2. The cutting condition of the tool is good, the cutting force is small, and the force on the spindle bearing, the tool and the workpiece is small. 3. The tool and workpiece are less affected by heat. 4. The surface quality of the workpiece is good. 5. High speed cutting tools have good thermal hardness. 6. It can finish the processing of high hardness materials and hrc40-62 hardened steel. In general, what kind of machine tool can meet the requirements of high-speed cutting can be divided into the following requirements: 1. The mechanism is designed for high-speed operation High speed machine tool requires its mechanism to be highly rigid, capable of absorbing high frequency vibration and high inertia G value to ensure high speed cutting precision and stability. 2. Excellent CNC control system CNC numerical control system is the unit that sends the position command. The command is required to be transmitted accurately and quickly. After processing, it sends the position command to each coordinate axis. The servo system must quickly drive the tool or workbench to move accurately according to the command. It requires to be able to process program segments quickly and control the machining error to the minimum. In the field of high-speed processing applications, Siemens 840D and Fanuc18iMB are the most representative. 3. Tool handle and tool suitable for high-speed operation Tools for high-speed cutting, especially high-speed rotary tools, require better quality and performance of tools and tool handles in terms of ensuring machining accuracy and operating safety. 4. Specialized CAD/CAM software Professional CAD/CAM software requires a precise path calculation method, which can not only accurately meet the accuracy requirements of 3DProfile, but also reduce the discharge process, and even meet the surface quality requirements without polishing. It must be able to produce a good cutting path, make the cutting amount stable, not only improve the machining efficiency, but also extend the tool life and save the tool cost.

There are many forms of steel: sheet metal, plates, bars and beams of various geometric shapes, pipes, and of course, solid billets used in CNC steel processing. Steel is widely used, but what is the difference between different types of steel? What is steel? Steel is a general term for iron and carbon alloys. The amount of carbon (0.05% – 2% by weight) and the addition of other elements determine the specific alloy and material properties of the steel. Other alloying elements include manganese, silicon, phosphorus, sulfur and oxygen. Carbon increases the hardness and strength of steel, while other elements can be added to improve corrosion resistance or machinability. Manganese is also frequently present in large quantities (at least 0.30% to 1.5%) to reduce the brittleness of steel and increase its strength. The strength and hardness of steel is one of its most popular characteristics. They make steel suitable for construction and transport applications because the material can be used for a long time under heavy and repeated loads. Some steel alloys, i.e. stainless steel varieties, are corrosion resistant, which makes them the best choice for parts operating in extreme environments. However, this strength and hardness will also lead to longer processing time and increased wear of cutting tools. Steel is a high density material, which makes it too heavy for some applications. However, steel has a high strength to weight ratio, which is why it is one of the most commonly used metals in manufacturing. Steel type Let's take a look at some of the various steels. To become steel, carbon must be added to iron. Although the amount of carbon varies, it leads to great differences in properties. Carbon steel usually refers to steel other than stainless steel, and is identified by the 4-digit grade of steel. It is more widely known as low, medium or high carbon steel. Mild steel: less than 0.30% carbon by weight Medium carbon steel: 0.3 – 0.5% carbon High carbon steel: 0.6% and above The main alloy elements of steel are represented by the first digit in the four digit grade. For example, any 1xxx steel, such as 1018, will use carbon as the main alloying element. 1018 steel contains 0.14 – 0.20% carbon and a small amount of phosphorus and sulfur, as well as manganese. This universal alloy is commonly used to machine gaskets, shafts, gears, and pins. Easy to machine grade carbon steel is re vulcanized and re phosphated, so that the chips break into smaller pieces. This prevents long chips or large chips from becoming entangled with the tool during cutting. Free machining steels can reduce processing time, but may reduce ductility and impact resistance. stainless steel Stainless steel contains carbon, but it also contains about 11% chromium, which increases the corrosion resistance of the material. More chromium means less rust! Adding nickel can also improve rust resistance and tensile strength. In addition, stainless steel has good heat resistance, making it suitable for aerospace and other extreme environmental applications. According to the crystal structure of metals, stainless steels can be divided into five types. The five types are austenite, ferrite, martensite, duplex and precipitation hardening. Stainless steel grades are identified by three digits instead of four. The first number represents the crystal structure and main alloy elements. For example, 300 series stainless steel is austenitic chromium nickel alloy. 304 stainless steel is the most common grade because it contains 18% chromium and 8% nickel. 303 stainless steel is a free machining version of 304 stainless steel. Adding sulfur will reduce its corrosion resistance, so 303 stainless steel is more prone to rust than 304 stainless steel. Stainless steel can be used in a wide range of industries. Type 316 stainless steel can be used in medical equipment, such as valve assemblies in machines and pipelines, if properly processed. 316 stainless steel is also used to machine nuts and bolts, many of which are used in the aerospace and automotive industries. 303 stainless steel is used for gears, shafts and other essential parts of aircraft and automobiles. chisel tool steel Tool steel is used to manufacture tools for various manufacturing processes, including die-casting, injection molding, stamping and cutting. There are many different tool steel alloys tailored for different applications, but they are known for their hardness. Each can withstand the wear of multiple use (the steel mold used for injection molding can withstand one million or more times of material injection) and has high temperature resistance. A common application of tool steel is injection molding tools, which are machined from hardened steel CNC and used to produce the highest quality production parts. H13 steel is usually selected because of its good thermal fatigue performance - its strength and hardness can withstand long exposure to extreme temperatures. H13 mold is very suitable for advanced injection molding materials with high melting temperature, because it provides a longer mold life than other steels - 500000 to 1 million injections. At the same time, S136 is stainless steel, and the tool life exceeds one million times. This material can be polished to the highest level for special applications where parts require high optical transparency.

In order to change the properties of steel and make it easier to process, some additional treatment and process are usually done before the mechanical processing is completed. Hardening the material before processing will prolong processing time and increase tool wear, but the steel can be treated after processing to increase the strength or hardness of the finished product. The following are some common processing technologies of steel. heat treatment Heat treatment refers to several different processes that involve manipulating the temperature of steel to change its material properties. One example is annealing, which is used to reduce hardness and increase ductility, making steel easier to machine. The annealing process slowly heats the steel to the desired temperature and holds it for a period of time. The time and temperature required depend on the specific alloy and decrease with the increase of carbon content. Finally, the metal is cooled slowly in the furnace or surrounded by insulating materials. Normalizing heat treatment can reduce the internal stress in steel, while maintaining higher strength and hardness than annealing steel. In the normalizing process, the steel is heated to a high temperature and then air cooled to obtain higher hardness. Quenched steel is another heat treatment process. You guessed right, it can make steel hard. It also increases strength, but also makes the material more brittle. The hardening process consists of slowly heating the steel, soaking it at high temperatures, and then rapidly cooling it by immersing it in liquids such as water, oil, or saline solutions. Finally, the tempering heat treatment process is used to reduce some brittleness caused by steel hardening. Tempering and normalizing of steel are almost identical: you heat it slowly, keep it at the selected temperature, and then air cool the steel. The difference is that tempering is carried out at a lower temperature than other processes, which reduces the brittleness and hardness of tempered steel. Precipitation hardening Precipitation hardening improves the yield strength of steel. Some grades of stainless steel may contain PH in the designation, which means that they have precipitation hardening properties. The main difference between precipitation hardening steels is that they have additional elements: copper, aluminum, phosphorus, or titanium. Many different alloys are possible here. In order to activate the precipitation hardening characteristics, the steel is formed into the final shape and then the age hardening process is carried out. The aging hardening process will heat the material for a long time, making the added elements precipitate - forming solid particles of different sizes - to increase the strength of the material. 17-4PH (also known as 630 steel) is a common example of a precipitation hardening grade of stainless steel. This alloy contains 17% chromium, 4% nickel, and 4% copper, which is helpful for precipitation hardening. Due to the increased hardness, strength and high corrosion resistance, 17-4PH is used for helideck platforms, turbine blades and nuclear waste drums. Cold working The properties of steel can also be changed without applying a lot of heat. For example, cold worked steel is made stronger by a work hardening process. Work hardening occurs when a metal undergoes plastic deformation. This can be done intentionally by hammering, rolling, or drawing the metal. If the cutting tool or workpiece becomes too hot, work hardening can also occur unintentionally during machining. Cold working can also improve the machinability of steel. Low carbon steel is very suitable for cold working. Precautions for steel structure design When designing steel parts, it is important to remember the unique properties of materials. The features that make it very suitable for your application may require some additional consideration of design for manufacturing (DFM). Because of the hardness of materials, it takes longer to process steel than other softer materials such as aluminum or brass. You can protect your parts and tools by reducing the spindle speed and feed rate. Even if you do not machine yourself, you still need to select the steel type suitable for the project, not only considering hardness and strength, but also considering the difference in machinability. For example, the processing time of stainless steel is about twice that of carbon steel. When determining the different grades, it is also necessary to consider which properties are most important and which steel alloys are readily available. Common grades, such as 304 or 316 stainless steel, have a wider range of stock sizes to choose from, and require less time to find and purchase. Due to the wide application of CNC processing steel and its strong physical properties, steel has become the preferred material for parts manufacturing. When designing your CNC processing steel parts, please remember to balance the properties you need according to the machinability of the materials.