Monthly Archive June 2021

Bychengcg

ypes of machining methods

In the field of mechanical processing industry, most of the manufacturers are engaged in the processing of ordinary milling machines and lathes, and there are also precision machining manufacturers. Because it is a more detailed industry, its production corresponds to the processing of other machine tools, the processing process is relatively complex, and the requirements for product quality error are very strict, Ordinary machine tools can’t do it. The following is a brief description of the precision machining method:

Classification of machining process: corresponding to different mechanical parts processing, there are different processing machine tools, the most common are lathe (general lathe), milling machine (general milling), grinder, wire cutting, desktop lathe and so on. The processing of complex mechanical equipment parts needs high precision machine tools.

The method of precision machining mainly depends on the process steps: the processing technology of precision parts is reasonable, improving the quality of parts processing, at the same time, it can also create efficiency for enterprises. Generally provide precision machining machine tools and equipment are: CNC processing (computer gong), CNC lathe, compound turning and milling processing, precision parts with special accuracy requirements, can be processed with four axis, five axis CNC, and finally according to the customer’s drawing processing requirements!

The above is how many kinds of precision machining methods, thank you for your attention!

ken. tang@chengcg.com

Bychengcg

Plane accuracy of ordinary milling machine

Completely rely on technicians independently operate x, y, Z axis coordinates, simple mechanical equipment parts, hardware parts hole, plane, step, keyway processing, such processing machine is called ordinary milling machine. In the field of mechanical processing industry, the status of ordinary milling machine was very important in the early days. At that time, the CNC processing equipment was not extended, and the processing of mechanical parts, hardware parts, fixture and fixture all depended on ordinary milling machine, lathe and grinder. At any time, the mechanical equipment manufacturing industry continued to progress, and the ordinary processing machine tool could not meet the needs of the mechanical processing industry.

At present, the ordinary milling machine is mainly for single piece, small batch parts processing, although the processing accuracy requirements are not high, but has advantages. Especially for the plane machining of mechanical equipment parts, it can be rough machining, finish machining, and can also help to clamp the workpiece. The precision of the plane machining of the workpiece depends on the size of the workpiece platform. Generally, the plane machining precision of mechanical parts can be controlled within 0.1 mm, and finally it can be processed according to the customer’s drawing.

The above is the ordinary milling machine processing plane precision can achieve how much, thank you for sharing!

ken. tang@chengcg.com

Bychengcg

Hardness requirements of CNC machining materials

In the field of mechanical processing industry, the hardness requirements of non-standard accessories, fixture, automation equipment parts and so on are determined according to the selected materials. Generally, aluminum alloy, POM saigang, Q235, brass and other materials do not need quenching treatment, so they are suitable for machining fixture accessories and mechanical equipment parts and so on. There are no material hardness requirements for parts processing.

In metal materials, there are many materials, such as Cr12, 45, 50, SKD11, SKD61, which can meet certain hardness requirements according to the surface heat treatment process, such as equipment shaft fittings or mold blade, The main role is to extend the life of spare parts and achieve the corresponding effect! In the machining line, we always choose different heat treatment process to achieve the required hardness according to the processing process requirements on the production drawings. The hardness requirement of equipment parts after processing directly affects the selection of materials.

The above is the concept of material hardness requirements for mechanical parts processing, thank you for sharing.

ken. tang@chengcg.com

Bychengcg

Methods of improving CNC machining accuracy

In the machining process of mechanical parts, the quality precision control firstly improves the geometric precision of the machine tool, the precision of measuring tools and tools, controls the error caused by the force and thermal deformation of the process system, reduces the deformation error caused by the cutting tool wear and internal stress, and reduces the measurement error as far as possible, all of which belong to the direct reduction of the original error. Improve the machining accuracy of mechanical parts, analyze the original errors of machining errors, and take corresponding measures to solve the main original errors according to different situations. For the processing of precision mechanical parts, the geometric accuracy, stiffness and thermal deformation of precision machine tools should be improved as much as possible; For the parts with forming surface, the main problem is how to reduce the shape error and installation error of forming tool.

The method of error compensation can be used to control the influence of some original errors in the processing of mechanical parts. Sometimes a new kind of original error will be created by human, so as to compensate or offset the original error inherent in the original process system, so as to reduce the machining error and improve the machining accuracy. Using one original error to partially or completely offset the original error or another original error. In order to improve the machining accuracy of a batch of mechanical parts, the method of dividing some original errors can be adopted. For the part surface with high machining accuracy, the method of homogenizing the original error step by step can be adopted in the process of continuous trial cutting.

After the basic understanding of the machining process, according to the error reflection law, the workpiece size of the blank or process is divided into n groups according to the size, and the size range of each group of workpiece is reduced to the original 1n. Then, according to the error range of each group, the accurate position of the cutter relative to the workpiece is adjusted respectively, so that the center of the size dispersion range of each group of workpieces is basically the same, so that the size dispersion range of batch workpieces is greatly reduced.

The process of reducing and equalizing the original error of machined surface by machining. The principle of homogenization is to find out the differences between the closely related workpieces or tool surfaces through mutual comparison and inspection, and then carry out mutual correction machining or benchmark machining.

In the machining process, the original error is transferred from the error sensitive direction to the error insensitive direction, and the original error is transferred to the error insensitive direction. The degree of various original errors reflected in the machining errors of parts is directly related to whether they are in the error sensitive direction. If we try to transfer it to the non sensitive direction of machining error, the machining accuracy can be greatly improved. Transfer the original error to other aspects that have no effect on the machining accuracy.

The above is to share how to improve the machining accuracy of mechanical parts, thank you for your attention!

ken. tang@chengcg.com

Bychengcg

Introduction of CNC machining accuracy

In the process of machining precision mechanical parts, there are the following points to control the machining accuracy: geometric accuracy: geometric accuracy refers to the accuracy of the geometric shape of each surface or axis of the component, such as whether the line is straight, whether the surface is flat, whether the normal section on the cylinder is round, etc. The smaller the number of geometric tolerance is, the higher the shape accuracy is; Dimensional accuracy: dimensional accuracy refers to the accuracy of the size of parts after processing, expressed by “dimensional tolerance”. When the dimensions of parts are the same, the higher the accuracy is, the smaller the tolerance number is; Position accuracy: position accuracy refers to the accuracy of the mutual position between the surfaces of components, such as whether the two planes are parallel, vertical, and whether the two axes are coaxial, which is expressed by “position tolerance”. Hold these points, precision machining accuracy of mechanical parts is easier to control.

The above is the processing precision of precision mechanical parts, thank you for sharing!

ken. tang@chengcg.com

Bychengcg

Basic steps of CNC processing quotation

The basic steps of quotation for mechanical parts processing are as follows: raw materials + processing time + mechanical wear and tear + surface treatment + packaging fee + tax = price. Quotation for mechanical processing is a relatively technical work, which requires not only rich machining technology, but also a certain understanding of machining process. Honghai machinery has many years of experience in machining mechanical parts. Now let’s look at the basic steps of quotation for machining mechanical parts

Calculate the processing cost of mechanical parts. First of all, consider the various processes and related aspects in the machining process, and take the machining process as the starting point to calculate the processing cost, and the price of raw materials should also be calculated clearly; Thirdly, clear processing ideas and process arrangement are set for the machining of mechanical parts, and each process is analyzed in depth. The processing cost is calculated according to the working hours required by each process and its price; How much is the surface treatment fee? Then according to the proportion, plus the packaging and transportation, management costs, tooling tools, machine tool wear, profit can be regarded as the machining quotation; Finally, with 17% VAT, the price is equal to the machining price.

For example, in the case of large quantities of parts, the processing price is more favorable, because the efficiency of processing large quantities of parts will be improved, thus reducing the cost. The above is the basic steps to share the quotation of mechanical parts processing, thank you for your attention!

ken. tang@chengcg.com

Bychengcg

CNC machining raw material cutting grade

In the field of mechanical processing industry, the main raw materials are aluminum, copper, POM steel, stainless steel, die steel, Unilever rubber and so on. According to the hardness of materials, reasonable cutting tools and processing technology will be selected. The processing of raw materials for general equipment spare parts is divided into grades. Take a look at the following grades:

  1. General non-ferrous metals: machinability grade (1), machinability of materials. Easy to process, relative machinability K: 8-20, representative materials: aluminum magnesium alloy, 5-5-5 copper lead alloy;
  2. Free cutting steel: machinability grade (2), machinability of material. Free cutting, relative machinability K: 2.5 ~ 3, representative material: automaton steel( σ b=400~500MPa);
  3. Free cutting steel: machinability grade (3), machinability of material. Free cutting, relative machinability K: 1.6 ~ 2.5, representative material, 30 steel normalizing( σ b=500~580MPa);
  4. Machinability grade of general carbon steel and cast iron (4), machinability of materials, general relative machinability K: 1.0-1.5, representative materials, 45 steel and gray cast iron;

5, machinability grade (5) of slightly difficult cutting materials, machinability of materials, common relative machinability K: 0.7-0.9, representative materials, 85 rolling, 2Cr13 quenching and tempering( σ b=850MPa)

6, machinability grade (6), machinability, relative machinability K: 0.5-0.65, representative material, 65Mn quenching and tempering( σ B = 950-1000mpa), free cutting stainless steel;

7, machinability grade of hard cutting material (7), machinability of material, relative machinability K: 0.15-0.5, representative material, stainless steel (1Cr18Ni9Ti); 8, it is difficult to cut the material to be machinability grade

(8) The representative materials are heat resistant alloy steel and titanium alloy

The above is the raw material cutting grade sharing, thank you for your attention!

ken. tang@chengcg.com

Bychengcg

Introduction of CNC milling cutter

In the process of precision machining, the common milling machine tools are dial indicator, minute bar, center drill, drill and milling cutter, etc. the milling cutter used in precision machining has a variety of commonly used types according to the use classification.

  1. Cylindrical milling cutter: used for machining plane on horizontal milling machine. The cutter teeth are distributed on the circumference of the milling cutter and can be divided into straight teeth and spiral teeth according to the tooth shape. According to the number of teeth, it can be divided into coarse teeth and fine teeth. The helical coarse tooth milling cutter is suitable for rough machining because of its small number of teeth, high tooth strength and large chip space; Fine tooth milling cutter is suitable for finishing after grinding.
  2. Face milling cutter: it is used for vertical milling machine, end milling machine, gantry milling machine and upper machining plane. There are cutter teeth on the end face and circumference, as well as coarse teeth and fine teeth. Its structure has three types: integral type, inlaid type and indexable type.
  3. End milling cutter: it is used for machining groove and step surface. The cutter teeth are on the circumference and end face, and cannot feed along the axial direction when working. When the end milling cutter has an end tooth passing through the center, it can be fed axially (usually the double-edged end milling cutter is also called “keyway milling cutter” which can be fed axially).
  4. Three side milling cutter: it is used to process all kinds of grooves and step surfaces, with cutter teeth on both sides and circumference.
  5. Angle milling cutter: it is used for milling groove with certain angle. There are two kinds of single angle milling cutter and double angle milling cutter. Generally, it processes dovetail groove.
  6. Saw blade milling cutter: it is used for machining deep groove and cutting workpiece, with more cutter teeth on the circumference. In order to reduce the friction during milling, there are 15 ‘- 1 ° The secondary deflection angle of the system. In addition, there are keyway milling cutter, dovetail milling cutter, T-groove milling cutter and various forming milling cutters. According to the different parts processing technology, choose the appropriate milling tool.

There are four kinds of milling cutter structures that are often used.

  1. Integral type: the cutter body and cutter teeth are integrated.
  2. Integral welding tooth type: the cutter teeth are made of cemented carbide or other wear-resistant tool materials and brazed on the cutter body.
  3. Inlaid type: the cutter teeth are fixed on the cutter body by mechanical clamping. The replaceable cutter teeth can be the cutter head of the whole cutter material or the cutter head of the welding cutter material. The milling cutter with the cutter head mounted on the cutter body for grinding is called internal grinding type; If the cutter head is grinded separately on the fixture, it is called external grinding.

4, indexable: this structure has been widely used in face milling cutter, end milling cutter and three face edge milling cutter, etc.

The above is the classification of milling cutters commonly used in precision machining. Thank you for sharing!

ken. tang@chengcg.com

Bychengcg

Introduction of CNC parts processing fixture

In the field of machining industry, some complex parts are difficult to process, and auxiliary fixture will be used. There are many kinds of auxiliary fixtures to be contacted. Let’s see what the difference is

First of all, understand the general fixture: General fixture refers to the standardized fixture that can be used to process different workpieces within a certain range. For example, three jaw chuck and four jaw single action chuck on lathe, flat tongs, dividing head and rotary table on milling machine, etc. This kind of fixture is usually produced by professional factories and is often provided to users as machine tool accessories. It is characterized by wide adaptability and low production efficiency. It is mainly suitable for the production and processing of single and small batch parts; Special fixture: special fixture refers to the fixture specially designed for a certain process of a workpiece. It is characterized by compact structure, fast, convenient and labor-saving operation, which can ensure high machining accuracy and production efficiency of parts, but the design and manufacturing cycle is longer and the manufacturing cost is higher. When the product is changed, the fixture will be scrapped because it can no longer be used. It is only suitable for the production and processing with fixed products and large batch; Universal adjustable fixture and group fixture: its feature is that some components of the fixture can be replaced and some devices can be adjusted to adapt to the processing of different parts. The fixture used for group machining of similar parts is called group fixture. Compared with the group fixture, the general adjustable fixture is not very clear about the processing object and has a wider range of application.

There are modular fixture: modular fixture is a fixture assembled by a set of pre manufactured standard components and parts according to the processing requirements of mechanical parts. It is made by professional manufacturers. It is characterized by flexibility, versatility, short manufacturing cycle and repeated use of components. It is especially suitable for trial production of new products and small batch production and processing of single piece. Accompanying fixture: accompanying fixture is a kind of fixture used in automatic line. The fixture not only plays the role of clamping the workpiece, but also integrates with the workpiece to move from one station to the next along the automatic line for different processes.

In the process of machining mechanical parts, according to the classification of machine tools used: due to the different working characteristics and structural forms of all kinds of machine tools, different requirements are put forward for the structure of fixtures. According to the different machine tools used, fixtures can be divided into: lathe fixture, milling fixture, drilling fixture, boring fixture, grinder fixture, gear fixture and other machine fixture. According to the classification of clamping power source: according to the different clamping power source used by the fixture, it can be divided into: manual fixture, pneumatic fixture, hydraulic fixture, gas-liquid fixture, electric fixture, magnetic fixture, vacuum fixture, etc.

The above is the mechanical parts processing auxiliary fixture introduction, thank you for sharing!

ken. tang@chengcg.com

Bychengcg

Technical problems of milling machine

In the process of mechanical parts processing, general parts processing technology often contact with the completion of turning and milling machine. And turning and milling machine processing mechanical parts, sometimes also encounter technical problems. For example: the blade installed on the lathe tool follows closely and protrudes slightly than the blade for cutting. The purpose is to process good surface roughness of parts. Eccentric turning starts from the center of the rotating workpiece to ensure that the cutting edge cuts into the workpiece slowly.

First of all, the importance of cutting: cutting parts need to remove a lot of machining allowance, turning and milling machine processing should be the best choice. Discontinuous cutting: turning tool is usually not good for discontinuous cutting, but milling cutter can do it well. Milling is often defined as a kind of discontinuous cutting. Therefore, in the case of discontinuous cutting, it should be thought of turning to milling. Excellent chip breaking processing: over the years, machining practice has proved that for some equipment parts, milling instead of turning can eliminate the previous phenomenon of “bird’s nest” shaped chips entangled in the cutter head. Because the milling process with the advantage of natural chip breaking is combined in cutting, the continuous chips are broken into small pieces which are easy to be eliminated.

Flexible shaft machining: when turning long and thin parts which can not be supported in the middle, milling can prevent the parts from bending. Compared with turning, in theory, milling can cut parts under very small pressure. But in fact, a lot of technical problems need to be solved.

Continuous time processing: in the cutting of difficult to machine materials, the service life of a turning tool is very short, while the milling cutter can be used for a long time because it distributes the cutting load through multi edge cutting. Because the milling cutter has a long service life, it can save the trouble of changing the cutter many times during cutting. Eccentric processing or special-shaped processing: the radial (x-axis) movement of milling cutter can be consistent with the rotation movement of workpiece, and it has certain processing advantages to process the contour of complex parts.

The above is about the mechanical parts milling machine processing technical problems, thank you for sharing!

ken. tang@chengcg.com