July 2019 – Page 14 – CNC Machining & Turning, Milling, Metal parts

How to remove wax from aluminium and other metal surfaces

Wax removal, such as polishing wax, is often required in the treatment of aluminium and other metal surfaces. So what is the principle of wax removal? What are the ingredients of wax removal water and what effect do you need to achieve?

Metal surface dewaxing usually uses dewaxing water, such as ht425 super dewaxing water and so on. Wax removal water is mainly composed of surfactants, auxiliaries, corrosion inhibitors and cosolvents, which are scientifically blended by special technology. Wax removal water is a water-based multi-functional cleaning agent, mainly composed of surfactants, metal corrosion inhibitors and solvents. It has the emulsifying ability to wax fouling. As well as the cleaning power of oil contamination, it can not only remove wax thoroughly, but also clean oil, no corrosion to the workpiece, no color change, no oxidation and rust after cleaning.

Usually polishing wax is used to produce and process metal surface wax. The wax scale of polishing wax is mainly composed of paraffin, fatty acid, rosin soap, metal oxide and some inorganic solid polishing particles such as corundum, silicon carbide, high alumina ceramics, etc. Solid particles are distributed uniformly in the polishing wax system in powder form, as well as some grinding cloth reel debris, grinding metal matrix powder and its oxides. Wax scale and workpiece are mainly adhered by mechanical adhesion, intermolecular force adhesion and electrostatic force adhesion. It is difficult to remove wax scale particles when the mechanical adhesion is less than 011 micron. This is based on a long time observation of various wax scale. The key to the preparation of ht425 super dewaxing water and other reagents commonly used on the market is the rational mixing of various surfactants, additives and corrosion inhibitors. By reducing surface tension, wetting permeability and emulsifying, dissolving and solubilizing properties can be improved, so as to enhance the permeability and solubility. The compounding of nonionic surfactants and anionic surfactants has been widely used for a long time. Adding ionic surfactants can make the cloud point of nonionic surfactants have a wide range and form mixed micelles. It is easier to form micelles by weakening the interaction between the hydrophobic chains of the two surfactants, which decreases the CMC of the mixed liquids, the surface tension and the surface activity of the mixed liquids. Therefore, the wax removal water must be of high quality and have good comprehensive performance. Its wax removal ability, rust prevention, defoaming and stability are the four important technical indicators for evaluating the quality of wax removal water. After the rust-proof, defoaming and stability meet the application requirements, the wax removal ability is the decisive index to evaluate the quality of the wax removal water. The wax removal ability is determined by the type, quantity and composition of surfactants in the wax removal water formula.

Generally speaking, wax removal water is a kind of product which can efficiently clean the residual polishing wax of metal surface in the process of grinding and polishing. Its significance is also extraordinary. Its cleaning speed and thoroughness of wax removal will directly affect the production of follow-up products.

Design Machining of Die Casting

1. According to the material category, shape and precision of the product, the process of the product is analyzed and the process is worked out.

2. Determine the position of the product in the die cavity, and analyze and design the parting surface, overflow system and gating system.

3. Design the assembling and fixing modes of each movable core.

4. Design of core-pulling distance and force.

5. Design of ejection mechanism.

6. Determine the die-casting machine and design the mould frame and cooling system.

7. Check the size of the die and die casting machine, and draw the technological drawings of the die and parts.

8, the design is completed.

Different Classification of Punch Press

According to the driving force

The driving force of slider can be divided into mechanical type and hydraulic type, so the punch press can be divided into two types according to the driving force used:

(1) Mechanical Power Press

(2) Hydraulic Press

The mechanical punch is mostly used in the stamping process of common sheet metal. Hydraulic punch press according to the use of different liquids, there are hydraulic punch and hydraulic punch, the use of hydraulic punch is the majority, hydraulic punch is mostly used for giant machinery or special machinery.

Classification by slider motion

There are single-action, double-action and triple-action punches classified according to the movement mode of slider. Nowadays, the single-action punch with one slider is the most widely used. The double-action and triple-action punches are mainly used in the extension processing of automobile body and large-scale processing parts, and the number of them is very small.

Classification by slider driving mechanism

(1) Crank Press

A punch using crankshaft mechanism is called a crankshaft punch. Firstly, a crankshaft punch and most of the mechanical punches.

Use this institution. The reason why crankshaft mechanism is used most is that it is easy to make, and can correctly determine the end position under the stroke, and the slider movement curve is basically applicable to various processing. Therefore, this type of stamping is applicable to punching, bending, stretching, hot forging, warm forging, cold forging and almost all other punching processes.

(2) Crankless Press

Crankless punch is also called eccentric gear punch. Fig. 2 is eccentric gear punch. As shown in Table 2, the function of crankshaft punch and eccentric gear punch is better than that of crankshaft in shaft rigidity, lubrication, appearance and maintenance, but the disadvantage is that the price is higher. The eccentric gear punch is more advantageous when the stroke is longer, and the crankshaft punch is better when the stroke of the special punch is shorter, so the small machine and the high-speed punch are also the fields of the crankshaft punch.

(3) Knuckle Press

The use of elbow mechanism in slider drive is called elbow punch, as shown in Fig. 3. This kind of punch has a unique slider movement curve that the slider speed near the lower dead point will become extremely slow (as measured by the crankshaft punch), as shown in Figure 4. It also correctly determines the dead-point position under the stroke. Therefore, this kind of punch is suitable for compression processing such as embossing and finishing, and nowadays cold forging is the most widely used.

(4) Friction Press

The punch which uses friction drive and screw mechanism in track drive is called friction punch. This kind of punch is the most suitable for forging and crushing operations. It can also be used for bending, forming, stretching and other processing. It has a versatile function. Because of its low price, it was widely used before the war. Nowadays, it is gradually being eliminated because it is impossible to determine the terminal position under the stroke, poor processing accuracy, slow production speed, overload when controlling operation errors, and skilled technology is needed in use.

(5) Screw Press

The use of screw mechanism in slider drive mechanism is called screw punch (or screw punch).

(6) Rack Press

Rack punch is used in slider drive mechanism with rack and pinion mechanism. Spiral punch and rack punch have almost the same characteristics, and their characteristics are roughly the same as those of hydraulic punch. Formerly used for pressing bushes, debris and other articles, squeezing oil, bundles, and cartridge case extrusion (hot extrusion processing), but now has been replaced by hydraulic punch, unless very special circumstances are no longer used.

(7) Link Press

The punch which uses various connecting rod mechanisms in slider driving mechanism is called connecting rod punch. The purpose of using linkage mechanism is to keep the stretching speed within the limit while reducing the processing cycle. By reducing the speed change of the stretching process, the speed of approaching the stroke from the top dead point to the starting point of the processing and returning stroke from the bottom dead point to the top dead point can be accelerated, so that it has a higher speed than the crankshaft punch. Shorter cycle to improve productivity. Since ancient times, this kind of punch has been used for the deep extension of cylindrical containers, with narrow bed surface, and for the processing of automobile body panels and wider bed surface.

(8) Cam Press

The punch which uses the cam mechanism in the slider driving mechanism is called the cam punch. This punch is characterized by a properly made cam shape so that the desired slider motion curve can be easily obtained. But because the nature of the cam mechanism is difficult to convey greater strength, so this kind of punch ability is very small.

Classification performance of metal bellows

The performance, material selection and use of metal bellows are as follows:

Brass bellows

H80 H -60 -60 ~ +100 C has lower elasticity, greater hysteresis and greater aftereffect, and better solderability. It can be used as a measuring element in non corrosive media and instruments with low accuracy.

Tin bronze bellows

QSn6.5-0.1 *-60 ~+100 (?) has good elasticity, strength and corrosion resistance, less hysteresis and elastic aftereffect, better brazing performance, and is widely used as measuring elements.

Beryllium bronze bellows

QBe2 P-60 ~+150 (?) has little hysteresis and elastic aftereffect, high elastic stability, corrosion resistance and no magnetism. It is mostly used in high-precision measuring instruments.

stainless steel bellows

1Cr18Ni9Ti G -194 C ~ +400 C has high bending fatigue strength and corrosion resistance, and good weldability. It can be used as measuring, sealing, connecting and compensating elements in corrosive medium.

Application of titanium bar

Titanium is a kind of corrosion-resistant material with excellent corrosion resistance, so the titanium bar rolled by it has been widely used in chemical industry, medical industry and so on. Here is a brief introduction of some characteristics and application of titanium bar in chemical industry.

I. implementation criteria for titanium rods

Commonly used standards in chemical industry GB/T2965 and ASTMB348.

(2) high temperature mechanical properties

Grade test temperature c

High temperature mechanical properties are not less than

Tensile strength Sigma bMPa endurance strength 100hMPa

TC4

Four hundred

Six hundred and thirty

Five hundred and eighty

Four. Processing and surface quality requirements

The roundness of the hot rolled pass bar should not be greater than half of its dimensional tolerance.

The indefinite length of the titanium rod is 300-6000MM, the indefinite length of the annealed titanium rod is 300-2000MM, and the allowable deviation of the indefinite length or the double length is + 20MM. The length of the double length should be included in the cutting quantity of the titanium rod, and the length of the fixed length or the double length should be specified in the contract.

Titanium bars should be sawed at both ends smoothly, and bars with diameter or edge length less than 35MM should not be cut more than 3MM; bars with diameter or edge length greater than 35MM should not be cut more than 5MM.

The transverse macrostructure of titanium bars does not permit cracks, pore, metallic or non-metallic inclusions, segregation affecting use and other metallurgical defects visible to the naked eye.

The surface of titanium rod is allowed to have slight scratches, indentations, pitting and wrinkles which are not more than half of the allowable deviation of diameter or side length.

Local defects on the surface of titanium rod can be removed. The ratio of width to depth of the removal site should be greater than 6, and the depth of the removal site should meet the following requirements:

The bar for hot working will not exceed the allowable deviation of the size.

Bars for continuous cold working; the minimum size of bars should be guaranteed after cleaning.

The surface roughness of the bar required for flaw detection should meet the requirements of flaw detection.

Five. Application of titanium bar

In recent years, with the continuous development of science and technology, the superior properties of titanium have attracted more and more attention and been applied in many fields. Like the automobile industry, the use of titanium rods, especially those made of Ti-6AL-4V alloy rods, in automobile engines not only wear-resisting but also lightweight, which reduces the weight of automobiles, has attracted the attention of many well-known automobile companies. The following titanium springs, silencers, exhaust drums and so on are all used in titanium. Of course, titanium rods are used as stir rods, fasteners, etc. in chemical industry due to their corrosion resistance and wear resistance. Titanium rod filter is widely used in food industry because of its low toxicity and pollution-free characteristics. In addition, the superior performance of titanium has also attracted the attention of the medical community, contributing its strength to the development of medicine and human health. Specific instructions to be continued.

What kind of die steel is used for metal stamping dies

Stamping die is a special process equipment which processes materials into parts (or semi-finished products) in cold stamping process. It is called cold stamping die. Stamping is a kind of pressure processing method which uses the die installed on the press to exert pressure on the material at room temperature to produce separation or plastic deformation so as to obtain the required parts. Stamping die materials include die steel, cemented carbide, steel-bonded cemented carbide, zinc-based alloy, low melting point alloy, aluminum bronze and so on. At present, most of the materials for stamping die are die steel. The common types of die working parts are: carbon tool steel, low alloy tool steel, high carbon and high chromium or medium chromium tool steel, medium carbon alloy steel, high speed steel, matrix steel and cemented carbide, etc.

1. carbon tool steel

T8A and T10A are the most widely used carbon tool steels in dies, which have the advantages of good processing performance and low price. But the hardenability and red hardness are poor, the heat treatment deformation is large, and the bearing capacity is low.

2. low alloy tool steel

Low alloy tool steel is based on carbon tool steel with a suitable amount of alloying elements. Compared with carbon tool steel, it reduces the tendency of quenching deformation and cracking, improves the hardenability and wear resistance of steel. The low alloy steels used for making moulds are CrWMn, 9Mn2V, 7CrSiMnMoV, 6CrNiSiMnMoV and so on.

3. high carbon and high chromium tool steel

Commonly used high-carbon and high-chromium tool steels are Cr12 and Cr12MoV, Cr12Mo1V1 (D2) Cr12Mo1V (SKD11), Cr8Mo1VSi (DC53), etc. They have good hardenability, hardenability and wear resistance. The heat treatment deformation is very small. They are high wear-resistant micro-deformation die steels, and their bearing capacity is only inferior to high-speed steel.

4. high carbon medium chromium tool steel

High carbon medium chromium tool steels used for dies include Cr4W2MoV, Cr6WV and Cr5MoV. They have low chromium content, few eutectic carbides, uniform distribution of carbides, small heat treatment deformation, and good hardenability and dimensional stability.

Classification of fishing gear

Generally, it can be divided into net fishing gear, fishing gear and other fishing gear.

According to China’s national standards, it can be divided into 12 categories: gill nets, trawls, purse nets, ground pulling nets, stretching nets, laying nets, copying nets, masks, traps, fishing tackles, rakes and cages.

Some also include the use of sound, light, electricity, bubble curtain and other devices to play an auxiliary role in the fishing process tools.

International fishing gear standards:

International standard for fishing gear statistical classification developed by the world food and Agriculture Organization (FAO) in 1980 (ISSCFG)

Chinese fishing gear standards:

The National Standard of Classification, Naming and Coding of Fishing Gear (GB/T5147-85) was formally promulgated and implemented in 1985, and revised in 2003 (GB/T5147-2003).

Development of die casting industry

New alloy die casting die products are well sold in China, but this phenomenon does not mean that they are well sold all over the world. The demand of foreign market is often different from that of domestic market. According to the experts concerned, there are three main reasons that restrict the export of die-casting die in China. First, there are still many shortcomings in the use of raw materials in domestic die-casting die; second, the backward technology is one of the obstacles to the development of die-casting die industry in China; third, the supporting system of die-casting die industry in China is not perfect. These are the bottlenecks that restrict the development of die-casting die industry in our country. Our die-casting die industry has only broken through these bottlenecks, and its share in the international market will be greatly improved.

Die-casting and die-casting have both differences and connections. The birth of die-casting die industry is the most perfect combination of the two. In other words, die-casting, die-casting and die-casting die are three different industries. The relationship mainly exists in several ways: die-casting, die-casting integration, die-making, and seldom for other enterprises. Mold; professional die casting mold manufacturing, there is no die casting; only die casting, no mold manufacturing capability. With the aggravation of industrial division, the gradual blurring of industrial boundaries and the development of industrial overlapping, the three industries should strengthen links, learn from each other, integrate the three industries into one and exist in the form of “integration”. It is believed that China’s die casting die industry will usher in more and more opportunities and space for development in the later period.

How to choose milling cutters for milling thread technology

Traditional thread processing methods mainly include turning threads with thread turning tools or manual tapping with taps, plate teeth and sockets. With the development of NC machining technology, NC milling of threads has been realized. Compared with traditional thread processing, thread milling has great advantages in processing accuracy and efficiency, and it is not restricted by thread structure and thread rotation direction. For example, a thread milling cutter can process various internal and external threads with different rotation directions. The following is a brief introduction of how to choose the milling cutter for the thread milling process.

I. advantages of thread milling

(1) For threads with no transition buckle or withdrawal groove structure, it is difficult to machine by traditional turning method or tap or plate teeth, but it is very easy to realize by CNC milling.

(2) The durability of threaded milling cutter is more than ten times or even tens of times that of tap, and in the process of NC milling threads, it is very convenient to adjust the diameter and size of threads, which is difficult to achieve by using taps and plate teeth.

Two. Thread milling process

(1) thread milling cutter runs quickly to the safety plane of the workpiece, and the thread drill is drilled to the hole depth.

(2) the thread milling cutter is rapidly raised to the thread depth dimension, and the thread milling cutter enters the starting point of the thread by circular arc.

(3) The threaded milling cutter interpolates around the threaded axis, and simultaneously moves parallel to the axis and raises a pitch along the direction. The three-axis linkage trajectory is a helix.

(4) the thread milling cutter withdraws from the starting point with the circular arc, and the thread drilling and milling cutter returns to the safety plane of the workpiece quickly.

Three. Types of thread milling cutters

(1) cylindrical thread milling cutter

The shape of cylindrical thread milling cutter is very similar to the combination of cylindrical end milling cutter and thread tap, but its thread cutting edge is different from the tap. There is no spiral lift on the cutter. The spiral lift in processing is realized by the movement of the machine tool. Because of this special structure, the tool can process both right and left threads, but it is not suitable for processing larger pitch threads.

(2) thread milling cutter and blade

Thread milling cutter is suitable for machining large diameter thread. Its characteristic is that the blade is easy to manufacture and the price is low. Some threaded blades can be cut on both sides, but the impact resistance is slightly worse than that of the whole threaded milling cutter. Therefore, the cutter is often recommended for machining aluminum alloy materials.

(3) combined multi station special thread boring and milling cutter

The combined multi-position thread boring and milling cutter is characterized by multi-edge cutter. Completing multi-position processing at one time can save auxiliary time such as tool changing and significantly improve productivity.

Four. Selection of thread cutting oil

(1) Because of the toughness of stainless steel, cutting is not easy to be separated, so cutting oil is required to have a higher cooling performance to take away a lot of heat.

(2) Because of its high viscous and melting property, it is easy to produce chip tumors in the process of cutting threads, so the cutting oil should have high lubricity.

(3) It is required that the cutting oil has good permeability, which can penetrate into the micro-gap lines in the metal area in the cutting process, so that the chips are easy to break off.

(4) Cutting oil should contain sulfide extreme pressure and anti-wear additives, which can effectively protect cutting tools and improve process accuracy.

(5) Compared with rapeseed oil, mechanical oil and regenerated oil, the special cutting oil has good stability and does not harm equipment, human body and environment.

(6) The cutting oil has passed strict tests in viscosity, flash point, dip point and thermal conductivity to meet various cutting process requirements.

CNC machining aluminum, should pay attention to the problem

First of all, under the premise of aluminum material, the following aspects should be considered.

1. Irresistible factors:

1. stability of machine tool itself.

If it is not for the new machine tool or the machine tool has gone through a lot of processing without debugging, there will be the size error caused by the machine tool itself.

The error of the machine tool has the following factors:

(1) mechanical aspects:

A. servo motor and screw loose.

B. ball screw bearing or nut wear.

There is not enough lubrication between the C. screw and the nut.

(2) electrical aspects:

A. servo motor failure.

There is dirt inside the B. grating ruler.

C. servo amplifier failure.

System parameters can be PMC recovery, so do not mention.

2. cooling deformation after workpiece processing.

This is basically unavoidable, pay attention to the use of coolant as much as possible in processing, as well as in-situ measurement, pay attention to the deformation of the cooled workpiece.

Two, avoidable factors:

1. processing technology: CNC Machining

In fact, most of the actual processing errors are caused by unreasonable processing technology, on the basis of ensuring the basic processing technology (such as milling NC processing “first rough then fine, first face then face, first big face then small face” or the use of fixture “reduce clamping times, try to use modular fixture” and other basic processing technology details). For example, in FANUC or Huazhong Machining Center, G83 instruction is used to drill deep holes so that the iron chips can be discharged.

2. cutting three elements:

Cutting speed vc, feed f, cutting depth AP and tool compensation are not very detailed. In a simple word, it is on the premise of guaranteeing processing quality and tool wear, to adjust parameters to give full play to tool cutting performance, so that cutting efficiency is the highest and processing cost is the lowest. In CNC lathes, there are elements such as tool wear compensation.

3. numerical calculation in manual programming and automatic programming:

In manual programming, calculating errors is also a common situation, but now most of the production is automatic programming, so this part is just a reminder, make up a word.

4. accurate tool setting:

The inaccuracy of tool alignment is also the cause of size errors, so try to choose a good edge finder, if the machine tool has an automatic tool alignment, it would be better. If there is no edge finder, try to cut it, this is the operation experience. The above is a summary of several factors that can easily cause errors in NC machining. We hope our partners will benefit.