CNC Machining and CNC Machine Tools

[dry goods] turning experience and technology summary!

Turning refers to lathe processing is a part of mechanical machining. Lathe processing mainly uses turning tools to turn the workpiece. The lathe is mainly used for machining shafts, discs, sleeves and other workpieces with rotary surfaces. It is the most widely used type of machine tool processing in machinery manufacturing and repair factories. metal fab shops near me

As the technology is a never-ending study, the most common lathe does not need too high technology can be divided into 5 categories. This Turner, society is currently the most common. metal fab shops near me

1. ordinary mechanical sewing, easy to learn, find a lathe, better than you at school

2. die Turner, especially plastic mould precision lathe! Strict requirements for tools, precise size

It is good to know what steel has a good polish, that is, mirror surface

This set of mold products is ABS material or what materials, flexible plastic parts are wire = = = many common knowledge, plasticine is a necessary tool of the lathe work!!! metal fab shops near me

The car is smooth and smooth. It is easy to polish and achieve the mirror effect. It needs plastic mold foundation. The 4 jaw is very commonly used. Generally, several templates are added together. The knowledge of thread must be mastered. The difficulty is high. metal fab shops near me

3. cutter lathe work, drill, reamer, = tool cutter = stem alloy, this Turner is the most simple, is the best, the most tiring

Is usually the mass production, the most commonly used is the double top car, taper, and flow modulus should be the fastest and most simple, the tool wear is reduced to the minimum, because this kind of lathe processing products, hardness than your white steel low alloy knife grinding much! You will all affect you results!! metal fab shops near me

4. large equipment to the Turner, Turner senior technology, young people did not dare to car!!

Teach more when using a car. metal fab shops near me

Car a crankshaft, you want to read the drawings again and again n times, first which and the rear car which, is the amount of grinding, or directly to the size, thread is positive or reverse… = = = some advanced techniques

5. CNC lathe, the lathe is the simplest, and most difficult, first you have to look at the drawings, the conversion formula, application programming, tool!!!

As long as you will be the master Turner and a certain mathematical theory, mechanical, CAD knowledge learned quickly. metal fab shops near me

1 synopsis


It is to change the shape and size of the blank and make it conform to the requirement of the drawing on lathe.

Turning the workpiece in a lathe using the method of cutting tool rotation of the workpiece. The cutting turning is mainly composed of workpiece and not provide tools. Turning is the most basic, the most common method of cutting, occupies a very important position in the production. metal fab shops near me The car cut for processing rotary surface, most of which has a rotating workpiece the surface of the turning method of processing can be used, such as the external cylindrical surface, conical surface, inner and outer, groove, screw and rotary forming surface, the tool is mainly used tools.

In all kinds of metal cutting machine, lathe is one of the most widely used, accounting for about 50%. metal fab shops near me of the total number of lathe machine can be used for machining of the workpiece, and the available bits, reamers, taps and knurling knife drilling, reaming, tapping and knurling operation. According to the process characteristics, layout the structure and characteristics of different lathe can be divided into horizontal lathe, landing lathe, vertical lathe, turret lathe, lathe, horizontal lathe with most of them。

Security technology issues

Turning on the machine manufacturing industry is used most widely, lathe large number of personnel, the processing scope, use tools, fixtures and very numerous, so the safety problems of turning, is particularly important, the focus of the work are as follows:

1, harm and protective measures of chip. All steel parts lathe machining, good toughness, the chip produced by turning a plastic curl, edge is sharp. In high speed cutting of steel will be formed when the red chip, very long, very easy to hurt, and often wrapped around the work piece the turret tool, and so the work, often should use hook clean or broken, when necessary, should stop clearance, but no hand to remove or pull off. To prevent chip damage often take off chip, chip flow control measures and adding a variety of protective baffle. Chip breaking measures in turning grind chipbreaker or step; using appropriate chipbreaker, using mechanical clamping tool. metal fab shops near me

2, workpiece clamping. In the process of turning, because the workpiece clamping improper damaged machine, broken or damaged tool and workpiece drop or flying away accident number. So, in order to ensure the safe production of turning, clamping workpiece must be paid more attention. The size, shapes the parts need to choose the suitable fixture, regardless of the three connecting claw, four claw chuck or special fixture and the shaft must be stable and reliable. The work card is clamped, large workpiece clamping sleeve available, guarantee not to shift workpiece to rotate at high speed and cutting force, and do not fall off and thrown out when necessary. Can top, center frame reinforced fastening clamp. Immediately after remove the spanner.

3, safe operation. To fully examine the machine before work, confirm the good can be used. The workpiece and the clamping tool to ensure the correct position, firm and reliable. The replacement process tool, and must stop handling the workpiece and measuring the workpiece, the workpiece shall not touch or use silk cotton to wipe in the rotation should be appropriate. Selection of cutting speed, feed rate and depth of difficulty, not to overload processing. The bed head and the bed surface shall place the workpiece, fixture and other sundries. Use the file to the tool moving to the safety position, the right front, left behind, to prevent the sleeve involved. The machine tool should have the person responsible for the use and maintenance. Other personnel shall not be used. metal fab shops near me

Matters needing attention

The technology of NC lathe is similar to the processing technology of ordinary lathe. However, because CNC lathes are clamped and processed automatically and continuously, all the turning processes should be completed. Therefore, we should pay attention to the following aspects.

1. reasonable selection of cutting amount:

For the high efficiency of metal machining, material processing, cutting tools, cutting conditions are the three elements. These determine the processing time, tool life and machining quality. Economic and effective processing method is a reasonable choice of cutting conditions. The cutting conditions of three elements: cutting speed, feed rate and cutting depth directly caused the tool damage. With the increase of the cutting speed, the temperature will rise, will produce mechanical, chemical, thermal wear. The cutting speed increased by 20%, the tool life can reduce 1/2. feeding conditions and tool wear relationship behind in a very small range. But the large amount of feed, cutting temperature rise, wear it is the influence of cutting speed on tool cutting tool for deep influence. Although there is no cutting speed and feed, but in small cutting depth and cutting, cutting material to produce hardened layer, the same will influence The tool life. The user is processed according to the material hardness, cutting condition, material type, feed rate, cutting speed, depth of cut and choose to use. Select the most suitable processing conditions are selected on the basis of these factors. The regular, stable wear reaches life ideal condition. However, in actual operation, the choice of tool life and tool wear, machining size change, surface quality, cutting noise, heat and other related processing. In determining the processing condition, the need to study the actual situation. For stainless steel and heat-resistant alloy hard processing materials, the coolant can be used or to choose a good blade rigid. metal fab shops near me

2. reasonable choice of cutting tools:

(1) rough car, to choose high strength, good durability of the tool, to meet the rough car large cutting depth, large feed requirements.

(2) when a fine car is refined, a tool with high precision and good durability is needed to ensure the requirements of machining precision.

(3) in order to reduce the cutting time and facilitate the knife, we should try to use the machine clip knife and the machine clip blade as much as possible.

3. select the jig reasonably:

(1) try to choose the common fixture to clamp the workpiece, so as to avoid the use of special fixture.

(2) part positioning datum coincide in order to reduce the positioning error.

4. determine the processing route: the machining route refers to the movement track and direction of the tool relative to the parts during the machining process of CNC machine tools.

(1) the processing precision and the surface roughness should be guaranteed.

(2) the machining route should be shortened as far as possible, and the cutting time of the cutter should be reduced.

5. the connection between processing line and processing allowance:

At present, the CNC lathe is not to popularize the use of conditions, the general should be too rough on the margin, especially with forging, casting hard layer cushion placed in ordinary lathe. If you must use the CNC lathe machining, should pay attention to the flexible program.

6. key installation points:

The current connection hydraulic chuck, hydraulic clamping cylinder is * rod to achieve the following points: first, using hydraulic chuck spanner nut on the hydraulic cylinder under unloading, unloading tube, and pulled out from the rear end of the main shaft, and then move hand unloaded Chuck Screw, can remove chuck

General code

General process Code for turning / processing / JB / T9168.2-1998)

Tool clamping

1) the tool holder should not be too long, and the general length should not exceed 1.5 times of the height of the tool rod (except the hole, slot, etc.)

2) the centerline of the tool rod should be perpendicular to or parallel to the walking direction.

3) Adjustment of the height of the knife tip:

The end face, cone face, thread, forming surface and cutting off solid workpiece, the tip of the cutter should be high with the axis of the workpiece.

Rough car outside circle, finish hole, knife tip should be slightly higher than the axis of the workpiece.

When cutting the hollow workpiece, the tool tip should be slightly lower than the workpiece axis. metal fab shops near me

4) the parallel angle of the thread turning tool should be perpendicular to the axis of the workpiece.

5) when installing the cutter, the gasket under the tool rod should be less and flat, and the screw under the tool should be tight.

Clamping of the workpiece

1) workpiece with three jaw self centering chuck with coarse or fine car car, if the workpiece diameter less than 30 mm, the overhang length should be less than 5 times the diameter, if the workpiece diameter greater than 30 mm, the suspension length should be less than 3 times the diameter.

2) chuck, four claw disc, angle (bending) and clamping on irregular workpiece, must add weight.

3) when machining axis workpieces at the top, the top axis of the tail seat should be adjusted to coincide with the axis of the lathe spindle before turning.

4) during the processing of slender shaft between the two top centers, we should use a knife rest or a central rack. During the processing, we should pay attention to the adjustment of the top tightening force of the top, so we should pay attention to the lubrication of the dead center and the center frame.

5) when the tail seat is used, the sleeve is extended as short as possible to reduce the vibration.

6) when installing a small, high – height workpiece on a vertical car, a high claw should be used and the workpiece should be pressed with a pull rod or a press plate in the appropriate part.

7) turning wheel type, when casting and forging, it should be found on the unmachined surface to ensure that the wall thickness of the workpiece is uniform after processing.


1) when turning the bench shaft, in order to ensure the rigidity of the turning, the larger part of the vehicle and the smaller diameter of the rear car should be first.

2) when cutting the grooves on the workpiece on the axis, it should be carried out before the finishing car to prevent the deformation of the workpiece.

3) when the spindle is threaded with the thread, it is usually the thread free part after the thread is processed.

4) before drilling, the end face of the workpiece should be flat. If necessary, the center hole should be hit first.

5) when drilling in a deep hole, the guide hole is usually drilled first.

6 (10) turning Phi Phi 20) mm hole, the cutter bar diameter should be 0.6 to 0.7 times the cutting diameter; diameter greater than 20 mm diameter machining holes, the general should adopt the cutter bar clamping head.

7) when turning a multi head or multi head worm, it should be cut after adjusting the exchange gear.

8) when using automatic lathe, we should adjust the relative position between tool and workpiece according to the adjustment card of machine tool. After adjusting, we must carry out trial cutting, and the first part can be processed after qualification. At any time, we should pay attention to tool wear and workpiece size and surface roughness at any time.

9) when turning on a vertical lathe, when the tool holder is adjusted, it is not allowed to move the beam at will.

10) when the relevant surface of the workpiece has a position tolerance requirement, it is possible to complete the turning in a clip.

11) when turning the gear blank of a cylindrical gear, the hole and the datum end face must be processed in one clip. When necessary, the marking line should be drawn near the gear degree circle of the end face.

4 error compensation

The modern machinery manufacturing technology is moving towards high efficiency, high quality, high accuracy, high integration and high intelligent direction. The precision and ultra precision processing technology has become the most important part and the direction of development of modern machinery manufacturing, and has become a key technology to improve the ability of international competition. With the wide application of machining error on precision machining is has become a hot topic of research. Due to all kinds of machine errors, thermal error and geometric error which occupy the most, so as to reduce the two error especially the thermal error which become the main target. Error compensation technology (Error Compensation Technjque, referred to as ECT) with the development of science and technology and the emergence and development. By the thermal deformation of machine tool caused by the loss is considerable. So it is necessary to develop the factory actual production can satisfy high precision requirements, low cost thermal compensation system error The thermal error between the spindle (or the workpiece) and the cutting tool is corrected in order to improve the machining precision of the machine tool, reduce the waste, increase the production efficiency and economic benefit.

The basic definition and characteristics of error compensation

Basic definition

The basic definition of error compensation is artificially created a new error to offset or weaken the current into the original error, the problem through the analysis, statistics, induction and grasp the characteristics and rules of the original error and establish the error model, try to make the same value and the error caused by human error and the original two opposite directions, thus to reduce machining error, improve the dimension accuracy of the parts.

Error compensation is the earliest by hardware. The hardware compensation belongs to a mechanical fixed compensation in machine error changes to change the amount of compensation must be re produced parts, calibration ruler or re adjustment of compensation mechanism and compensation. Hardware can not solve the random error, the lack of flexibility of the shortcomings. The recent development of the characteristics of software compensation is there won’t be any changes to the machine itself, advanced technology and comprehensive use of various disciplines of contemporary computer control technology to improve the machining accuracy of machine tool. The software compensation has overcome many difficulties and lack of hardware compensation, the compensation technology to a new stage.


Error compensation (Technology) has two main characteristics: scientific and engineering.

The rapid development of science and technology of error compensation has greatly enriched the theory of precision machinery design, precision measurement and the precision engineering, become an important branch of the subject. And error compensation technology detection technology, sensor technology, signal processing technology, photoelectric technology, material technology, computer technology and control technology as. A new technology of error compensation technology with independent branch, content and features of their own. Further research on error compensation technology, the theoretical, systematic, has very important scientific significance.

The error compensation technique of the engineering significance is very significant, it contains 3 meanings: one is the use of error compensation technology can more easily achieve the level of precision hard technology “to spend a great price to reach two; the error compensation technology, can solve the” level of precision hard technology “cannot achieve; the three is in certain circumstances if the accuracy of error compensation technology can greatly reduce the manufacturing cost of instruments and equipment, has very significant economic benefits.

Generation and classification of thermal error in turning

With the higher requirement on the precision of the machine tool, the proportion of thermal error in total error will continue to increase, has become the main obstacle to improve the machining accuracy of machine tool thermal deformation. The thermal error is mainly composed of motor, bearings, transmission parts, hydraulic system, environment temperature, caused by thermal deformation of machine components caused by the cooling fluid inside and outside heat source machine the geometric error of machine tool manufacturing defects from the machine, with the error between machine parts, machine tool parts, static displacement and so on.

Basic method of error compensation

In summary and related references, we can see that the turning error is generally caused by the following factors:

Machine tool thermal deformation error;

Geometric errors of machine tool parts and structures;

Error caused by cutting force;

Tool wear error;

Other error sources, such as machine tool shafting servo error, NC interpolation algorithm error and so on.

There are two basic methods to improve the accuracy of machine tools: error prevention method and error compensation method.

The error prevention method is an attempt to eliminate or reduce the possible error sources through the design and manufacture. The error prevention method can reduce the temperature rise of the heat source to a certain extent. It is effective to equalize the temperature field and reduce the thermal deformation of machine tools, but it can not completely eliminate the thermal deformation, and the cost is very expensive.

The application of thermal error compensation rule opens up an effective and economical way to improve the accuracy of machine tools.

Relevant conclusions

The research of turning error is the most important component and development direction in modern machinery manufacturing, and it becomes the key technology to improve the international competition ability. The analysis and research of thermal error is helpful to improve the turning accuracy and technical requirements.

The error compensation technology can meet the requirements of high precision and low cost in the actual production of the factory. The thermal error compensation technology can correct the thermal drift error between the spindle (or workpiece) and the cutting tool and improve the machining accuracy of the machine tool. Reduce waste products and increase production efficiency and economic benefits.

Frequently asked questions

Common lathe in the strong turning of large pitch thread, sometimes will appear bed saddle vibration, light surface to produce ripples, heavy cutter break. And cut when. The students often have the phenomenon of cutting or breaking the knife. There are many reasons for the above problems. This phenomenon and its solution are mainly discussed by analyzing the force of the cutting tool.

1. The origin and cause of the problem

We know: when turning thread with small pitch, we usually use the straight feed cutting method (make straight feed tool in the direction of perpendicular to the axis of the workpiece; In order to reduce the cutting force when turning the thread with larger pitch, the cutting method of left and right borrowing tool is often adopted (the thread turning tool is made to use the left and right cutting edge to cut the thread tool separately by moving the small skateboard.

During thread turning, the movement of the bed saddle is realized by the rotation of the long lead screw and the movement of the opening and closing nuts. There is an axial clearance in the bearing of the long lead screw. There is also an axial gap between the long lead screw and the opening and closing nut. When cutting the right-hand worm with the right main cutting edge, the tool bears the force P from the workpiece. (ignoring the friction between chip and front cutter surface, as shown in figure 1, the force P is decomposed into axial and radial forces, where the axial component force Px is the same as the tool’s feed direction. The tool transmits the axial force PX to the bed saddle, thus pushing the bed saddle to move quickly and violently back and forth to the side with clearance. The result is that the tool moves back and forth and the machined surface produces ripples. But this is not the case when cutting with the left main blade. When cutting with the left main blade, the axial force PX of the tool is opposite to the direction of the feed, moving in the direction of eliminating the gap. The bed saddle was in uniform motion.

When cutting off, the movement of the middle slide plate is realized by the rotation of the screw screw and the movement of the nut. There is an axial clearance between the lead screw bearing and the screw screw and the nut. When cutting off on the lathe, there is also an axial gap between the lead screw and the nut. The front face of the tool (with the front angle) bears the force given to it by the workpiece (neglecting the friction between the chip and the front cutter surface, as shown in figure 2), the force P is decomposed into force Pz and radial force. The radial component force is the same as the feed direction of the cutting tool, pointing to the workpiece, pushing the tool into the workpiece, which will pull the skateboard into the gap direction and make the cutting knife suddenly prick the workpiece. Cause the knife or workpiece to bend.

2. Solution

When turning the screw thread with the right and left cutter cutting method, the fit gap between the bed saddle and the bed guide rail should be adjusted in addition to adjusting the relevant parameters of the lathe, so that it is slightly tighter. In order to increase the friction when moving, reduce the possibility of the bed saddle moving, but this gap can not be adjusted too tight, in order to be able to shake the bed saddle smoothly.

Adjust the clearance of the skateboard and minimize the gap as far as possible; Adjust the fastness of the small skateboard so as to prevent the turning tool shift. The length of the workpiece and pole should be shortened as far as possible, and the left main cutting edge should be used as far as possible; When cutting with the right main blade, we should reduce the amount of knife eaten by the back; Increase the front angle of the right main blade, the edge should be straight and sharp, to reduce the axial force Px. theoretically, the bigger the front angle of the right main blade, the better.

Tips for turning tool sharpening operation

Selection of Common kinds and Materials of turning tools and Grinding Wheel

There are five categories of common turning tools, which have different cutting uses.

The outer circle inner hole and thread, cut off the forming also commonly used;

There are three kinds of cutting edge, linear curve and compound;

There are many kinds of turning tool materials, commonly used carbon steel alumina,

Carbide silicon carbide, according to the material selected grinding wheel;

Grinding wheel granularity, different thickness do not use;

Rough grinding wheel grinding rough turning tool, fine grinding wheel selection.

7 turning tool sharpening operation skill and matters needing attention

Grinding machine first check, equipment safety is the most important;

After the rotational speed of the grinding wheel is stabilized, the vertical wheel side of the knife is held by both hands;

Two elbows clamp waist place, grinding smooth and anti-jitter;

Turning tool height must be controlled, grinding wheel horizontal center;

The tool press grinding wheel force is moderate, the reaction force is too big easy to slide;

The handheld turning tool moves evenly, the warm high scald hand is temporarily left;

Knife off the wheel should be careful to protect the tip of the knife first lift;

High speed steel knife can be water-cooled to prevent annealing to maintain hardness;

Do not quench cemented carbide, quench easily make tool crack;

Stop grinding first, shut down and power off the machine room

Grinding step of 90 °75 °45 °external Circular turning tool

First grinding the main behind the rod tail to the left side of the main deviation;

The tip of the knife is up to 38 degrees and the rear angle is reduced by friction.

Then grinding the back of the pair, finally sharpening the front face;

The front of the front corner is ground out together, the first is coarse and then the fine sequence is clear;

The finishing mill firstly grinds the front and then the main rear and the secondary;

When grinding the arc of the knife tip, the left hand holds the front fulcrum;

The right hand turns the end of the rod and the tip of the knife is naturally formed by a circular arc;

The correct angle is the key to the straight stabilization of the flat edge.

The pattern plate angle ruler fine inspection, the rich experience may be measured visually.

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