What is non-traditional machining?

First, let’s see the definition of non-traditional machining.

Non-traditional machining, also known as “non-conventional machining” or “modern machining method”, generally refers to the machining method of removing or adding materials with energy of electricity, heat energy, light energy, electrochemical energy, chemical energy, sound energy and special mechanical energy, so as to realize materials being removed, deformed, changing properties or being plated.

Non-traditional machining

I. Development and definition of non-traditional machining

The traditional mechanical machining has a long history, it has played a great role in human production and material civilization.

At present, most of our products are manufactured and assembled by traditional methods, such as:

  • Household appliances: refrigerators, washing machines, air conditioners, etc.;
  • Traffic tools, such as cars, trains, planes, etc
  • All kinds of weapons and equipment: guns, canon, tanks, rockets, etc.

The traditional machining method is to use mechanical energy and cutting force to remove excess metal so that the part has a certain geometric shape, size and surface roughness.

It requires tool material to be harder than workpiece material.

The development of science and technology, especially since the 1950s and the product development, as well as the need of scientific experiment, many industrial sectors, especially the defense industry, require that the cutting-edge science and technology products should be developed toward the high precision, high speed, high temperature, high pressure, high power, miniaturization etc.

The materials have been used to become more and more difficult to machining. The shape of the parts is more and more complex. The requirement for dimensional accuracy, surface roughness, and some special requirements also becomes higher, thus it puts forward some new requirements for mechanical manufacturing department:

  • To solve the machining problem of difficult cutting materials, such as machining of metal materials in high hardness, high strength, high toughness, high brittleness like hard alloy, titanium alloy, heat resistant steel, stainless steel, quenching steel, diamond, precious jade, quartz, germanium, silicon and non-metal material.
  • Solve the machining problem of a special and complex surface, such as:

– Stereo forming surface of the steam turbine blade, integral turbine, engine casing, forging die;

– The hole with a special section on various punching die and cold drawing die;

– The machining of internal rifling, spray nozzle, grid, hole and narrow slit on the spinning nozzle;

  • Solve the machining problem of various parts of superfine, smooth or parts with special requirement. Such as the aerospace, aircraft gyroscope, servo valve which have high requirements on the surface quality and precision, and low-stiffness parts machining, like the slender shaft, thin wall parts, elastic components.

To solve the above series of technical problems, it is difficult to realize or even impossible to realize by the traditional machining method.

People have been exploring and researching new machining methods, and non-traditional machining is put forward and developed under this condition.

Non – Traditional Machining (NTM) or Non – Conventional Machining (NCM), is a kind of machining technology which is different from traditional machining process and equipment. It combines the physical energy (electricity, magnetism, sound, light and heat), chemical energy and even mechanical energy to applied on the machining position directly so as that the material can be removed, deformed and changed.

Non-traditional machining has the following characteristics:

  • The hardness of tool materials can be significantly lower than that of workpiece materials;
  • The material can be processed directly using energy such as electric energy, electrochemical energy, sound energy or light energy.
  • Mechanical forces are not apparent during the machining and the workpiece seldom produces mechanical and thermal deformation, which are helpful to improve machining accuracy and surface quality of workpiece.
  • Various methods can be selectively combined into new process methods to make the production efficiency exponentially growing and machining precision increasing;
  • Almost every new source of energy is produced, a new method of non-traditional machining is possible.

Because of non-traditional machining technology with the above characteristics, so overall, it can process metal or non-metal materials of any hardness, strength, toughness and brittleness, and specialized in the machining of complex, micro-surface and low-stiffness parts. At the same time, some methods can be used for superfinishing, mirror finishing and nanometer (atomic) machining.

 

II. Classifications of non-traditional machining

The classification of non-traditional machining has not been specified.

Generally, it can be divided into the form shown in the following table according to energy source, function form and machining principle.

Machining method Major energy form Functional form
Electrical discharge machining EDM forming machining Electricity, Thermal energy Melting, gasification
EDM cutting machining Electricity, Thermal energy Melting, gasification
Electrochemical machining Electrochemical machining Electrochemical energy Ion transfer
Electroforming machining Electrochemical energy Ion transfer
Plating machining Electrochemical energy Ion transfer
High energy beam machining Laser beam machining Light, Thermal energy Melting, gasification
Electron beam machining Electricity, Thermal energy Melting, gasification
Ion beam machining Electricity, Mechanical energy Abscission
Plasma arc machining Electricity, Thermal energy Melting, gasification
Material cutting and erosion machining Ultrasonic machining Acoustic, mechanical energy Abscission
Abrasive flow machining Mechanical energy Abscission
Chemical machining Chemical milling machining Chemical energy Corrosion
Photographic plate making Chemical energy

Light energy

Corrosion
Lithography process Light, Chemical energy Photochemical, corrosion
Photoelectroforming plating Light, Chemical energy Photochemical, corrosion
Etching machining Chemical energy corrosion
Bonding Chemical energy Chemical bonds
Explosion machining Chemical energy, Mechanical energy explosion
Forming machining Powder metallurgy Thermal energy

Mechanical energy

Thermoforming
Superplastic forming Mechanical energy Superplastic
Rapid prototyping Thermal energy

Mechanical energy

Hot melt forming
Composite machining Electrochemical arc machining Electrochemical energy Melting and gasification corrosion
Electro-discharge mechanical grinding Electricity, Thermal energy Ion transfer, melting, cutting
Electrochemical etching Electrochemical energy, Thermal energy Melting, Gasification corrosion
Ultrasonic EDM Sound, heat, electricity Melting, Abscission
Complex electrolytic machining Electrochemical energy, mechanical energy Abscission
Cutting Base Combined Machining Mechanical, acoustic and magnetic energy Cutting

III. Common non-traditional machining methods

Electrical discharge machining (EDM):

Electrical discharge machining

Basic principle:

EDM is a kind of non-traditional machining method which is used to etch conductive material by electric erosion which is produced by the pulse discharge between two poles immersed in working liquid, also known as discharge machining or electroerosion machining.

Basic equipment: electro-discharge machine tool

Main features:

  • Able to process materials which is difficult to be cut by conventional machining method and complex-shaped workpieces.
  • Machining without cutting force;
  • No defects such as burrs and tool marks and grooves, etc.
  • Tool electrode materials do not need to be harder than the workpiece material;
  • Directly using electricity machining, easy to realize automation;
  • Metamorphic layer generated on the surface after treatment needs to be further removed in some applications
  • The treatment of smoke pollution produced during the purification and processing of working fluid is troublesome

The range of application:

  • Machiningmolds and parts with complex shaped holes and cavities;
  • Machining various hard and brittle materials such as hard alloy and hardened steel
  • Processing deep fine holes, shaped holes, deep grooves, narrow slits and cutting thin slices, etc.
  • Machining all kinds of tools and measuring tools such as cutting tools, sample plate and thread ring gauge.

Electrolytic machining:

Electrolytic machining

Basic principle:

Based on the principle of anodic dissolution in the electrolytic process and with the help of the molded cathode, the workpiece is machined according to certain shape and size.

The range of application:

Electrolytic machining has significant advantages for those materials which are difficult to machining, in complex shape or thin-walled parts.

Electrolytic machining has been widely used, such as gun barrel rifling, blade, integral impeller, mold, profiled hole and parts, chamfering and deburring.

And in the machining of many parts, the electrolytic machining technology has occupied an important or even irreplaceable position.

Advantages

  • A wide range of machining. Almost all conductive materials can be processed by electrochemical machining without the limitation of mechanical and physical properties such as strength, hardness, toughness of materials, and the metallographic structure of materials basically remains unchanged after machining. It is often used for machining hard alloy, high-temperature alloys, hardened steel, stainless steel and other hard machining materials.
  • A high rate of production
  • Good machining quality, especially the surface quality.
  • It can be used to machining thin wall and deformable parts. There is no contact between tool and workpiece, no mechanical cutting force, no residual stress and deformation, no burr and flashing during the electrochemical machining process.
  • The tool cathode is free of losses

Limitations:

  • Low machining precision and machining
  • High machining cost. The smaller the batch, the higher the additional cost per piece.

Laser machining:

Laser machining

Basic principles:

Laser machining is to use the energy of light to reach high energy density at the focal point after being focused by the lens, to melt or vaporize the material and remove it in a very short time to realize the machining.

Basic principle:

Laser machining technology has the advantages of less waste of materials, obvious cost effect in large-scale production and strong adaptability to the machining object. In Europe, the welding of special materials such as high-grade automobile body and base, aircraft wing and spacecraft fuselage is basically based on laser technology.

The range of application:

As the most commonly used application, the technologies of laser machining mainly include laser welding, laser cutting, surface modification, laser marking, laser drilling, micro-machining and photochemical deposition, stereolithography, laser etching and so on.

Electron beam machining:

Electron beam machining

Basic principles:

Electron beam machining (EBM) is the machining of materials by using the thermal or ionization effects of high energy convergent electron beam.

Main features:

High energy density, strong penetration, a wide range of one-time melting depth, large weld width ratio, fast welding speed, small thermal impact zone, small working deformation.

The range of application:

The electron beam machining has a wide range of machining materials and the machining area can be very small. The machining accuracy can reach the nanometer level and realize molecular or atomic machining; High productivity; The pollution produced by machining is small, but the cost of machining equipment is high.

It can be used for the machining of microholes, narrow slits, etc. It can also be used for welding and fine lithography.

Vacuum electron beam welding bridge shell technology is the main application of electron beam machining in the automobile manufacturing industry.

Ion beam machining:

Ion beam machining

Basic principles:

The ion beam machining is realized by accelerating and focusing the ion stream generated by the ion source to the surface of the workpiece in a vacuum state.

Main features:

Due to the precise control of ionic flow density and ionic energy, the machining effect can be precisely controlled to achieve ultra-precision machining at the nanometer level, as well as the molecular level and atomic level.

Ion beam machining produces little pollution, little stress and deformation, and is adaptable to the processed materials, but the machining cost is high.

The range of application:

Ion beam machining can be divided into two types: etching and coating.

  • Etching machining:

Ion etching is used to machining the air bearing of gyroscope and grooves on dynamic pressure motor, with high resolution, high precision and good repetition consistency.

Another aspect of ion beam etching applications is the etching of high-precision graphics, such as integrated circuits, optoelectronic devices and optical integrated devices, etc.

Ion beam etching is also used to thin out materials to make penetrating electron microscopy specimens.

  • Ion beam coating machining:

Ion beam coating machining has two forms: sputtering deposition and ion plating.

The ionic coating can be applied to a wide range of materials, metal or non-metal films can be plated on metal or non-metal surfaces, and various alloys, compounds, or certain synthetic materials, semiconductor materials, and high-melting-point materials can also be plated.

Ion beam coating technology can be used for coating lubricating film, heat-resistant film, wear-resistant film, decorative film and electrical film.

Plasma arc machining:

Plasma arc machining

Basic principles:

Plasma arc machining is a non-traditional machining method to cut, weld and sprays metal or non-metal by the heat energy of the plasma arc.

Main features:

  • Microbeam plasma arc welding can weld foil and thin sheet.
  • It has the keyhole effect and can realize single side welding and double side free forming.
  • The plasma arc has a high energy density, high temperature on the arc column, and strong penetration ability. There is no need to beveling for 10~12mm thick steel and can realize complete weld penetration and double-sided forming in one time, with fast welding speed, high productivity, and small stress deformation.
  • The equipment is complex, with large gas consumption, so it’s only suitable for indoor welding.

The range of application:

It is widely used in industrial production, especially for the welding of copper and copper alloy, titanium and titanium alloy, alloy steel, stainless steel, molybdenum used in military industry and cutting-edge industrial technology such as aerospace, such as titanium alloy missile shell, some of the aircraft thin-walled containers.

Ultrasonic machining:

Ultrasonic machining

Basic principles:

Ultrasonic machining makes the surface of the workpiece gradually break by the use of ultrasonic frequency as the tool for small amplitude vibration and punch on the processed surface by free-abrasive in the liquid between it and the workpiece.

Ultrasonic machining is often used for piercing, cutting, welding, nesting and polishing.

Main features:

Can machining any material, especially suitable for machining of various hard, brittle non-conductive material, with high precision, good surface quality, but in low productivity.

The range of application:

Ultrasonic machining is mainly used for perforation (including round holes, shaped holes and curved holes, etc.), cutting, slotting, nesting, carving of various hard and brittle materials, such as glass, quartz, ceramics, silicon, germanium, ferrite, gemstone and jade, deburring small parts in batches, polishing of mold surface and grinding wheel dressing.

Chemical machining:

Chemical machining

Basic principles:

Chemical machining makes use of acid, alkali or salt solution to corrode or dissolve the material of the parts to obtain the desired shape, size or surface of the workpiece.

Main features:

  • Can process any metal materials that can be cut, free from hardness, strength.
  • It is suitable for large area machining and can process many pieces at the same time.
  • The surface roughness reaches Ra1.25~2.5μmwithout any stress, crack or burr.
  • Easy to operate.
  • Not suitable for machining narrow slots and holes
  • Not suitable for eliminating defects such as surface roughness and scratches.

The range of application:

  • Suitable for large area thinning;
  • Suitable for machining complex holes on thin-walled parts

Rapid prototyping:

Rapid prototyping

RP technology is integrated and developed on the basis of modern CAD/CAM technology, laser technology, computer numerical control technology, precision servo drive technology and new material technology.

Different kinds of rapid prototyping systems have different forming principles and system characteristics due to different forming materials.

However, the basic principle is the same, which is “manufacturing by layers, overlapping layer by layer”. It’s kind of like a mathematical integration process.

Graphically, the rapid prototyping system is like a “3d printer”.

Basic principles:

It can directly receive the product design (CAD) data and rapid manufacture of new product samples, molds or models without having to prepare any mold, cutter and fixture.

Therefore, the popularization and application of RP technology can greatly shorten the development cycle of new products, reduce development cost and improve development quality.

From the traditional “elimination method” to today’s “growth method”, from mold manufacturing to mold-free manufacturing, this is the revolutionary significance of RP technology to the manufacturing industry.

Main features:

RP technology disperses a solid complex three-dimensional machining into a series of laminated machining, which greatly reducing the machining difficulty. It has the following characteristics:

  • The fast speed of the whole forming process is suitable for the fierce product market in modern times;
  • Can make three-dimensional entities of any complex shape;
  • No special fixture, die, or cutter is needed during molding, which not only saves the cost but also shortens the production cycle.
  • The high integration of technology is not only the inevitable product of the development of modern science and technology but also the comprehensive application of them, with distinctive high-tech characteristics.

The above characteristics determine that RP technology is mainly suitable for new product development, rapid manufacturing of single and small batch parts, complex shape parts, design and manufacturing of mold and model.

It also suitable for manufacturing of materials which is difficult to machining, and inspection of shape design, assembly and rapid reverse engineering.

The range of application:

Rapid prototyping technology can be applied in the fields of aviation, aerospace, automobile, communications, medical treatment, electronics, household appliances, toys, military equipment, industrial modeling (sculpture), building model, machinery industry, etc.

Conclusion

In this article, we listed the 9 types of non-traditional machining technique. I believe it can be the handbook for most of you who want to learn the non-traditional machining process, advantages, classifications etc.

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