Different machining methods can be selected according to the materials and requirements of machining workpieces. Knowing common machining types and machining knowledge can enable us to choose more suitable machining methods and applicable ranges. Then how to choose machining methods and applicable ranges?

I. turning

The method of machining parts with lathes is referred to as turning.In turning, the workpiece rotates to form the main cutting motion.When the cutter moves along the parallel axis of rotation, the inner and outer cylindrical surfaces are formed.The cutter moves along the diagonal line that intersects the axis, forming a cone.In a copying or numerical control lathe, the cutting tool can be fed along a curve to form a specific surface of rotation.Using the molding tool, when the transverse feed, can also be processed to the rotation surface.Turning can also process thread surface, end plane and eccentric shaft.Generally, the machining accuracy is IT11 -- IT6, and the surface roughness is 12.5 -- 0.8 prospectus m.When finished, it can reach IT6 -- IT5, and roughness 0.4-0.1 displacement m.The productivity of turning is high, the cutting process is relatively smooth and the cutting tool is simple.

Scope of application: drilling center hole, drilling hole, reaming hole, tapping thread, turning circle, boring hole, end face, groove, shaping surface, taper surface, knurling and thread

Second, milling machining

The main cutting motion is the rotation of the cutter.In horizontal milling, the plane is formed by the edge of the circular surface of the milling cutter.In vertical milling, the surface is formed by the end edge of the milling cutter.The higher cutting speed can be obtained by increasing the rotation speed of the milling cutter, thus the higher productivity can be obtained.However, due to the cutting and cutting of the teeth of the milling cutter, the cutting process is prone to vibration, which limits the surface quality of the workpiece. Such impact also aggravates the tool wear and damage.Milling machining accuracy is generally up to IT8 -- IT7, with surface roughness of 6.3 -- 1.6 refugee m.General milling can only process the plane, with the shape of milling cutter can also process a fixed surface.Numerical control milling machine can be controlled by software through numerical control system several axes according to a certain relationship to milling complex surface, at this time commonly used ball head milling cutter.The numerical control milling machine is of special significance to machining the complicated shape of the blade, die core and cavity of the impeller.In the general time of cutting off workpiece, certain cooling can be obtained, so the heat dissipation condition is better.According to the main movement speed direction and the workpiece feed direction of the same or opposite, also divided into milling forward and reverse.

(1) milling

The horizontal component of milling force is the same as the feed direction of the workpiece. Generally, there is a gap between the feed screw and the fixed nut on the workpiece table. Therefore, the cutting force can easily cause the workpiece and the worktable to move forward together, which causes the sudden increase of feed quantity and causes the punching.In the process of milling the workpiece with hardness on the surface such as casting or forging, the milling cutter teeth first contact the workpiece with hard skin, which aggravates the wear of the milling cutter. 

(2) reverse milling

It can avoid the phenomenon of channeling when milling.In reverse milling, the cutting thickness increases gradually from zero, so the blade begins to undergo a stage of extrusion sliding on the machined surface of hardened cutting, which accelerates the tool wear.At the same time, the milling force will lift the workpiece, easy to cause vibration, which is the disadvantage of reverse milling. 

Scope of application: milling plane, milling step, milling groove, milling forming surface, milling spiral groove, milling gear, cutting

3. Planing

Planing generally refers to the machining method of cutting excess material by making linear reciprocating movement of planer knife relative to workpiece on the planer.When planing, the reciprocating linear motion of the cutter is the main motion of cutting.Therefore, the planing speed is slow and the productivity is low.Planer machining is more stable than milling processing. Planer machining is rough machining, which can reach semi-finishing degree in some cases. Its precision is lower than milling machining, and its machining accuracy is generally up to IT8 -- IT7.However, it has advantages for the processing of large casting.

Scope of application: planing plane, planing vertical plane, planing step surface, planing right Angle groove, planing bevel face, planing dovetail groove, shaping groove, shaping V groove, planing surface, planing internal keyway, planing rack, planing composite surface

4. Grinding

Grinding machining is a method of cutting the surface of workpiece on the grinding machine by using artificial grinding wheel (grinding wheel) with high hardness as the cutting tool.The grinding process of grinding wheel is actually the comprehensive effect of abrasive particles on the cutting, cutting and sliding of workpiece surface.In grinding, the grinding grain itself becomes dull gradually by sharp grinding, which makes the cutting action become worse and the cutting force become larger.When the cutting force exceeds the strength of the adhesive, the dull, round abrasive particles fall off, exposing a new layer of abrasive particles to form the "self-sharpening" of the grinding wheel.But chips and shards still clog the wheel.Therefore, after a certain period of grinding, the grinding wheel needs to be dressed with diamond turning tools.When grinding, the cutting speed is high and the machining precision is high because of the many blades.The grinding machine is a finishing machine, with grinding precision up to IT6 -- IT4, surface roughness Ra up to 1.25 -- 0.01, or even 0.1 -- 0.008, respectively.Another feature of grinding is that the hardened metal materials can be processed, belonging to the finishing range, so often as the final machining process.During grinding, heat is generated and sufficient cutting fluid is required for cooling.According to different functions, grinding can be divided into external grinding, internal grinding, flat grinding.

Scope of application: external grinding, internal grinding, surface grinding, shaping grinding, screw grinding, gear grinding

5. Drilling and machining

The process of machining various inner holes on the drilling machine is called drilling machining and is the most commonly used method of drilling.The precision of drilling machining is relatively low, which is generally IT12~IT11, and the surface roughness is generally Ra5.0~6.3um. After drilling machining, reaming and reaming are often used for semi-finishing and finishing.The reamer is used for reaming and the reamer is used for machining.Generally, the machining accuracy is IT9 -- IT6, and the surface roughness is Ra1.6 -- 0.4.When reaming and reaming, the bit and reamer generally follow the axis of the original bottom hole, which cannot improve the position accuracy of the hole.

Scope of application: drilling, reaming, reaming, tapping, strontium hole, scraping plane

6. Boring and machining

Boring machining USES boring machine to enlarge the hole size and improve the quality of machining method.Boring and pin processing can be more positive hole position.Generally, high boring machining accuracy is IT9 -- IT7, and the surface roughness is Ra6.3 -- 0.8mm, but the production efficiency of boring and selling is low.

Scope of application: processing high-precision holes, multi-hole finishing

Tooth surface processing

There are two kinds of machining methods of gear tooth surface: forming method and generating method.In general, the machine tool used for machining the tooth surface by forming method is ordinary milling machine, and the cutter is shaping milling cutter, which requires two simple forming movements: the rotation motion of the cutter and the linear movement of the cutter.The commonly used machine tools for machining tooth surfaces are gear hobbing and gear shaping.

Scope of application: gear, etc

8. Complex surface machining

The machining of 3d curved surface mainly adopts the methods of copying and nc milling or special machining.Profile milling must have a prototype as a template.In the process of the ball head copying head, has been to a certain pressure contact prototype surface.The motion of the copying head is transformed into inductance, and the motion of the three axes of the milling machine is controlled by machining amplification to form the trajectory of the cutter head moving along the surface.Most of the milling cutter with copying first - class radius ball head milling cutter.The appearance of numerical control technology provides a more effective method for surface machining.In the numerical control milling machine or processing center processing, is through the ball head milling cutter point by point according to the coordinate value processing.The advantage of using machining center to process complex curved surface is: machining center has a tool bank, equipped with dozens of cutting tools.For rough and finish machining of curved surface, different curvature radius of concave surface can be used with different cutting tools, and appropriate cutting tools can also be used.At the same time, various auxiliary surfaces, such as holes, threads and grooves, can be processed in a single installation.This fully guarantees the relative position accuracy of each surface. 

Scope of application: components of complex curved surface

9. Electric spark machining

Edm is achieved by using high temperature molten workpiece surface material produced by the instantaneous spark discharge between tool electrode and workpiece electrode.Edm machine generally consists of pulse power supply, automatic feeding mechanism, machine body and working fluid circulating filtration system.The workpiece is fixed on the machine table.The pulse power supply provides the energy required for machining, and the two poles are connected to the tool electrode and the workpiece respectively.When the tool electrode and the workpiece are close to each other in the working fluid driven by the feed mechanism, the voltage breakdown gap between the electrodes produces spark discharge, releasing a lot of heat.Workpiece surface to absorb heat after high temperature (above 10000 ℃), its local materials for melting gasification even removal in down, forming a small pit.The working fluid circulating filtration system forces the cleaning working fluid to pass a certain pressure through the gap between tool electrode and workpiece, remove the electro-erosion products in time, and filter the electro-corrosion products out of the working fluid.As a result of multiple discharge, a large number of pits were produced on the surface of the workpiece.The tool electrode is driven down by the feed mechanism and its profile is "copied" onto the workpiece (although the tool electrode material is also eroded

Scope of application

Electroconductive materials of hard, brittle, tough, soft and high melting point are processed by rheo.

(1) processing semiconductor materials and non-conductive materials;

Various types of holes, curved holes and tiny holes are machined on the surface.

Surface machining of various three-dimensional curved cavity, such as forging mold, die-casting mold, plastic mold of the chamber;

Mulch is used for cutting, cutting and surface enhancement, engraving, printing nameplate and marking, etc. 

10. electrolytic machining

Electrochemical machining is a method of forming a workpiece by using the electrochemical principle of metal producing anodic dissolution in electrolyte.The workpiece is connected to the positive pole of dc power supply, the tool is connected to the negative pole, and a small gap (0.1mm ~ 0.8mm) is maintained between the two poles.The electrolyte with a certain pressure (0.5mpa ~ 2.5mpa) flows through the gap between the poles at a high speed of 15m/s ~ 60m/s.When the tool cathode is continuously fed into the workpiece, on the workpiece surface facing the cathode, the metal material dissolves continuously according to the shape of the cathode surface, and the electrolyte is taken away by the high-speed electrolyte, so the shape of the tool surface is "copied" on the workpiece accordingly. 

Scope of application: machining holes, cavity, complex surface, small and deep holes, rifling and deburring, engraving, etc.

11. Laser processing

The laser processing of the workpiece is completed by the laser processing machine.Laser processing machine usually consists of laser, power supply, optical system and mechanical system.The laser (usually solid-state and gaseous lasers) converts electrical energy into light energy, producing the desired laser beam, which is focused by the optical system and irradiated on the workpiece for processing.The workpiece is fixed on the three-coordinate precision worktable, controlled and driven by the numerical control system to complete the feeding motion required for machining. 

Scope of application: diamond drawing die, clock bearing, porous skin of divergent air-cooled blanking sheet, small hole processing of engine oil nozzle, aero-engine blade, and cutting of various metal and non-metal materials.

12. Ultrasonic machining

Ultrasonic machining is a method of machining the workpiece by impinging and polishing the workpiece by the abrasive particles.The ultrasonic generator transforms the alternating energy of power frequency into the ultrasonic vibration with a certain power output. The ultrasonic vibration is transformed into the mechanical vibration of ultrasonic through the transducer. The displacement amplitude of the vibration is amplified from 0.005mm ~ 0.01mm to 0.01 ~ 0.15mm by means of amplitude expansion bar.The end of the tool vibrates against the suspended abrasive particles in the working fluid, which makes it constantly crash against and polishing the processed surface at a great speed. The materials in the processed area are smashed into very fine particles and then knocked down.Although each hit the material is very few, but because of the high frequency of hit, there is still a certain processing speed.As the working fluid circulates, the material particles that are knocked down are taken away in time.As the tool insinuates, its shape is "copied" onto the workpiece. 

Scope of application: hard cutting materials

With the development of science and technology, mechanical processing method are also gradually increase, when choosing machining methods will be in many respects, including machining surface shape, dimensional accuracy, position accuracy, surface roughness, etc., choose the appropriate machining method, can guarantee the quality of the workpiece under the minimum investment and the processing efficiency, can produce benefit maximization.