Which Dalian CNC machining factory is stronger?

Metal cutting is a processing method that uses cutting tools to remove excess metal from a blank to obtain parts with the required shape, size and surface accuracy.

Processing methods such as casting, forging and welding can usually only be used to manufacture blanks and rougher parts. All parts that require higher precision generally require cutting. Therefore, cutting processing occupies an important position in the machinery manufacturing industry. Although there are various forms of metal cutting, such as turning, planing, milling, grinding, and gear processing, there are also the same phenomena and rules, that is, cutting excess metal from the blank. Mastering these phenomena and laws is of great significance to correctly perform cutting processing, ensure the processing quality of parts, improve productivity and reduce costs.

Metal cutting processes include different types such as turning, planing, drilling, and milling, but in summary, any tool that uses a tool to remove a certain thickness of metal layer from a blank or semi-finished product is obtained in shape. The processing technology that meets the requirements in terms of surface roughness and surface roughness is all cutting processing. When the workpiece comes into contact with the tool, the process in which the metal in the cutting layer turns into chips through elastic deformation, slippage, and separation is called metal cutting.

Motion forms and cutting methods of metal cutting machine tools. The motion of machine tools can be divided into main motion and feed motion. The main motion is the most basic motion for cutting metal. It promotes relative motion between the tool and the workpiece, so that the front of the tool is close to the workpiece; the feed motion causes additional relative motion between the tool and the workpiece, plus the main motion, it can Cut continuously or continuously and produce a machined surface with the desired geometric properties. Different types of machine tools have different cutting methods, movement forms of workpieces and tools, and different safety requirements. Some cutting methods use the workpiece as the main movement and the tool as the feed movement; some use the tool as the main movement and the workpiece as the feed movement. Common cutting methods are:

(1) Turning: the workpiece rotates as the main movement, and the turning tool performs the feed movement.

(2) Milling: The milling cutter rotates as the main movement, and the workpiece or the milling cutter makes the feed movement.

(3) Planing: Use the planer to make horizontal and linear reciprocating motions on the workpiece. For example, the ram of a planer drives the tool to make the main movement, and the workbench drives the workpiece to make intermittent feed movements.

(4) Drilling: The drill bit or reamer is processed on the workpiece. Generally, the drill bit makes main movement and feed movement, while the workpiece does not move.

(5) Reaming: Use a reamer to remove a trace amount of metal layer from the wall of the workpiece hole to improve its dimensional accuracy and surface finish. The rotation of the reamer is the main movement, and the workpiece or the reamer is the feed movement.

(6) Boring: The boring tool rotates as the main movement, and the workpiece or the boring tool makes the feed movement.

(7) Plugging: The inserting tool makes a vertical and relatively linear reciprocating motion on the workpiece, and the workpiece or the inserting tool makes a feeding motion.

(8) Grinding: Use abrasive tools such as grinding wheels to grind the workpiece surface at a relatively high linear speed. The grinding tool rotates as the main movement and the workpiece performs feed motion.

The cutting processing methods also include honing, super-finishing, broaching, pushing, shoveling, scraping, etc. Among the above cutting methods, turning and grinding are the most commonly used.

Cutting is the most important processing method in mechanical manufacturing. Although the manufacturing precision of blanks continues to improve, and processing technologies such as precision casting, precision forging, extrusion, and powder metallurgy are increasingly used, due to the wide adaptability of cutting processing and the ability to achieve high precision and low surface roughness, in It still plays an important role in the machinery manufacturing process.

With the continuous development of machine tools and cutting tools, the precision, efficiency and automation of cutting processing are constantly improving, and the scope of application is also expanding, thus greatly promoting the development of modern machinery manufacturing industry.

There are many classification methods for the cutting processing of metal materials. The three common classification methods are based on process characteristics, based on material removal rate and processing accuracy, and based on surface forming methods.

The process characteristics of cutting processing are determined by the structure of the cutting tool and the relative motion form of the cutting tool and the workpiece.

Therefore, according to process characteristics, cutting processing can generally be divided into: turning, milling, drilling, boring, reaming, planing, slotting, broaching, sawing, grinding, grinding, honing, super-finishing, polishing, Gear machining, worm gear machining, thread machining, ultra-precision machining, benchwork and scraping, etc.

According to material removal rate and processing accuracy, cutting processing can be divided into rough processing, semi-finishing processing, finishing processing, finishing processing, modification processing, ultra-precision processing, etc.

Roughing is a processing method that uses a large cutting depth to remove most or all of the machining allowance from the workpiece in one or a few passes, such as rough turning, rough planing, and rough milling. , drilling and sawing, etc., roughing has high efficiency but low precision, and is generally used as pre-processing; semi-finishing is generally used as an intermediate process between roughing and finishing; finishing uses fine cutting to make the processing The surface reaches high precision and surface quality, such as fine turning, fine planing, fine reaming, fine grinding, etc. Finishing is generally the final processing.

Finishing is performed after finishing, and its purpose is to obtain smaller surface roughness and slightly improve accuracy. The machining allowance of finishing processing is small, such as honing, grinding, super-fine grinding and super-finishing, etc.; the purpose of modification processing is to reduce surface roughness, improve corrosion protection, dust-proof performance and improve appearance, and does not There is no requirement to improve precision, such as polishing, sanding, etc.; ultra-precision machining is mainly used for processing of aerospace, laser, electronics, nuclear energy, etc. that require certain particularly precise parts, and its accuracy is as high as IT4 or above, such as mirror turning, mirror grinding, soft grinding Granular mechanical chemical polishing, etc.

Machining precision is mainly used to characterize the fineness of produced products and is a term used to evaluate the geometric parameters of the machined surface. Machining accuracy is measured by tolerance levels. The smaller the level value, the higher the accuracy. There are 20 tolerance levels ranging from IT01, IT0, IT1, IT2, IT3 to IT18. Among them, IT01 represents the highest processing accuracy of the part, and IT18 represents the lowest processing accuracy. Generally, factory and mining machinery belongs to IT7 level. , general agricultural machinery belongs to IT8 level.

According to different functions, product parts require different processing accuracy, and the selected processing forms and processing techniques are also different. The following introduces the machining accuracy that can be achieved by several common machining forms such as discharging, milling, planing, grinding, drilling, and boring.

1. Turning

The workpiece rotates and the turning tool moves linearly or curvedly in the plane. Turning is generally performed on a lathe to process the internal and external cylindrical surfaces, end surfaces, conical surfaces, formed surfaces and threads of the workpiece.

The turning precision is generally IT8-IT7, and the surface roughness is 1.6-0.8μm.

1. Rough turning strives to use large cutting depth and large feed amount to improve turning efficiency without reducing the cutting speed, but the machining accuracy can only reach IT11, and the surface roughness is Rα20— 10μm.

2. For semi-finishing and finishing turning, try to use high speed and smaller feed and cutting depth. The processing accuracy can reach IT10-IT7, and the surface roughness is Rα10-0.16μm.

3. Using finely ground diamond turning tools for high-speed precision turning of non-ferrous metal parts on high-precision lathes can achieve a processing accuracy of IT7-IT5 and a surface roughness of Rα0.04-0.01μm. This This type of turning is called mirror turning.

2. Milling

Milling refers to the use of rotating multi-edged tools to cut workpieces. It is a highly efficient processing method. Suitable for processing flat surfaces, grooves, various forming surfaces (such as splines, gears and threads) and special shaped surfaces of molds, etc. According to whether the main movement speed direction during milling is the same as or opposite to the feed direction of the workpiece, it is divided into down milling and uphill milling.

The processing accuracy of milling can generally reach IT8-IT7, and the surface roughness is 6.3-1.6μm.

1. The processing accuracy during rough milling is IT11-IT13, and the surface roughness is 5-20μm.

2. The processing accuracy during semi-finishing milling is IT8-IT11, and the surface roughness is 2.5-10μm.

3. The processing accuracy during fine milling is IT16-IT8, and the surface roughness is 0.63-5μm.

3. Planing

Planing is a cutting processing method that uses a planer to make horizontal and linear reciprocating motions on the workpiece. It is mainly used for the shape processing of parts. The planing precision can generally reach IT9-IT7, and the surface roughness is Ra6.3-1.6μm.

1. The rough planing processing accuracy can reach IT12-IT11, and the surface roughness is 25-12.5μm.

2. The processing accuracy of semi-precision planing can reach IT10-IT9, and the surface roughness is 6.2-3.2μm.

3. The precision of fine planing can reach IT8-IT7, and the surface roughness is 3.2-1.6μm.

4. Grinding

Grinding refers to a processing method that uses abrasives and abrasive tools to remove excess material from the workpiece. It is a finishing process and is widely used in the machinery manufacturing industry. Grinding is usually used for semi-finishing and finishing, the accuracy can reach IT8-IT5 or even higher, and the surface roughness is generally 1.25-0.16μm.

1. The surface roughness of precision grinding is 0.16-0.04μm.

2. The surface roughness of ultra-precision grinding is 0.04-0.01μm.

3. The surface roughness of mirror grinding can reach less than 0.01μm.

5. Drilling

Drilling is a basic method of hole processing. Drilling is often performed on drill machines and lathes, and can also be performed on boring machines or milling machines. The machining accuracy of drilling is low, generally only reaching IT10, and the surface roughness is generally 12.5-6.3μm. After drilling, enlarging and reaming are often used for semi-finishing and finishing.

6. Boring

Boring is an inner diameter cutting process that uses a tool to enlarge a hole or other circular contour. Its application range generally ranges from semi-roughing to finishing. The tool is usually a single-edged boring tool (called a boring bar).

1. The boring accuracy of steel materials can generally reach IT9-IT7, and the surface roughness is 2.5-0.16μm.

2. The processing accuracy of precision boring can reach IT7-IT6, and the surface roughness is 0.63-0.08μm.