The Additive Manufacturing Technologies Engineering Essay

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This report explains briefly the use of 'Additive Manufacturing Technologies (AMT) for prototypes and low volume production parts in agricultural vehicles'. Rapid product techniques play a major role in manufacturing of prototypes of Agricultural vehicles and its parts.

The prototypes of tractor and its parts easily produced using latest techniques such as Direct Metal Laser Sintering, laminated object manufacturing, three dimensional printing, fused deposition modelling, etc. The CAD designs are transformed into three dimensional models and their analysis and tests are performed by different software such as solid modelling and surface modelling. The three dimensional designs are converted to STL files and are checked for tolerances and errors in software like 'Magic'. The error free designs are the prostecuted into different rapid production machines and prototypes and parts are manufactured at a fast rate.

There are also few limitations of these techniques in agricultural industry. The large parts of the tractor cannot be prototyped as the machines available at present need to develope for large parts formation. However still these techniques are very useful in small parts and prototype formation in fields of science and technology.

2. INTRODUTION

"A tractor is a vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction. Most commonly, the term is used to describe the distinctive farm vehicle: agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised. Another common use of the term, "tractor unit", describes the power unit of a semi-trailer truck (articulated lorry)." [http://en.wikipedia.org/wiki/Tractor 6 November 2009 at 23:52.]

The most of the use of tractors is on farms. The tractor is used as a vehicle to pull or push agricultural equipments say a lorry, chisel plow, harvesting equipments, seed drills, rolls and presses, spreaders, etc. Other than farming tractors are also used for industries, gardening, and hoe loader.

The tractor industry is a developing industry. Lots of Modifications have been made to the old technology and design of Tractors. As the change is inevitable so we can expect lot more changes in the future. Now day's tractor manufacturers are trying level best to make high speed engines with high torque development which are capable of delivering more power and can speed up the work.

Figure 1: DIFFRENT TRACTOR APPLICATIONS

Tractor ploughing field. Tractor used for irrigation Backhoe loader tractor

3. BASIC PRINCIPLES OF RAPID PROTYPING (RP)

A Prototype is nothing but a low volume replica of the design of the part which we have to produce or develop. In simple words we can say "the model" of the original part.

Rapid prototyping (RP) refers to technology/technique or process used to develop these prototypes without any use of tools and dies. It is also known as layered or generative manufacturing. A three dimensional object is created using CAD data. Three dimensional objects are produced by adding material layer after layer.

Few RP processes are:

3D PRINTING

FUSED DEPOSITION MODELLING(FDM)

STEROLITHOGRAPHY (SLA)

LAMINATED OBJECT MANUFACTURING(LOM)

SELECTIVE LASER SINTERING(SLS)

ELECTRON BEAM MELTING(EBM)

Rapid Prototyping technology has made manufacturing so easy such that we can make complex object those too realistic three dimensional objects like making picture or drawing on the paper. This new and fast technology has given a new way to design and manufacture objects.

Figure 2: PROTOTYPES FORMATION (THREE DIMENSIONAL MODELS)

THREE DIMENSIONAL PRINTING(3D PRINTING):

Principle and Process:

This is one of the additive manufacturing technology or technique.

The three dimensional model to be produced is created by addition of successive layers of materials.

The material in the form of fine powder and binder is fed into machine.

The printer head moves in the horizontal direction to print the image.

After each layer formation binder is applied to strength the model formation.

Figure 3: THREE DIMENSIONAL PRINTING (3D PRINTING)

Advantages:

Process is cheap(cost effective)

Good surface finish.

Its a fast technique.

Colour parts can be obtained.

Hole part can be developed at once including the hollow part.

Limitations:

Part strength is weak.

Extra care during despatching the part from the machine.

Changeover of material is difficult.

Fused Deposition Modelling (FDM):

Principle and Process:

• The FDM process takes place by melting and depositing a thin filament of thermoplastic polymer (ABS - engineering and medical grade - plastic, Polycarbonate and investment casting wax) in a cross-hatching ways to develop each layer of the part.

• The material feed is in the form of wire from the fixed spool which is mounted on the machine and the wire is delivered through the FDM head.

• The FDM head moves in the horizontal directions (i.e. X and Y) for producing each layer through zigzag movements.

• The table which supports the part moves in the vertical direction (i.e. Z direction) and is lowered after the completion of each layer.

Figure 4: Fused Deposition Modelling (FDM)

Advantages:

• Variety of materials can be used.

• Post curing cannot be done.

• Environment and home friendly.

• Material changeover is relatively easy.

• It is a very economical machine.

Limitations:

• Poor surface finish.

• Process is slow for large and dense parts.

• For the material and geometries support is a must.

• Removal is very difficult.

• Z axis is usually weak.

• Not good for small features, details and thin walls.

STERO-LITHOGRAPHY (SLA):

Principle and Process:

This technique uses polymerisation of photosensitive resin by ultra violet light. This is the most widely used process in RP technology.

Ultraviolet laser is focused on resin which is placed in a vat.

The beam moves in X and Y directions horizontally and polymerises the resin in desired cross-sectional area.

The polymer which has been cured moves down from the platform which is attached to it and the new layer of resin cover up the previously cured layer.

Figure 5: STERO-LITHOGRAPHY (SLA)

Advantages:

High accuracy.

High surface quality/ surface finish.

Small and large parts can be manufactured.

Visual and aesthetic testing possible.

Limitations:

Due to phase change shrinkage and curls.

Post curing of the model is required.

Supports are essential.

Removing supports is a hard task.

Limitation to materials because photo polymer.

LAMINATED OBJECT MANUFACTURING(LOM):

Principle and Process:

In laminated object manufacturing (LOM), the process takes place by paper roll indexes at a constant distance.

A hot roller fixes a new layer over the previous layer by pressing.

Then the laser cuts the outline of the object contours of the layer.

Laser cuts the extra remaining material in a grid pattern.

These grids grow into support structures as the build of the part is keep progressing.

Figure 6: LAMINATED OBJECT MANUFACTURING(LOM)

Advantages:

No supports or any kind of support structure is needed.

In this process only the circumferential area of the part is set for processing whereas in other processes whole area of the part is processed.

High manufacturing speed can be obtained.

Limitations:

It is difficult to produce hollow parts.

Surface finish is poor.

The bonds between layers are weak.

Selective Laser Sintering (SLS):

Principle and Process:

• The process involves a high power laser beam which melts and fuses powdered material spread on a layer.

• The powder is taken in definite portion and allowed to spread on a roller which rests on the table.

• Laser beam fuses the powder within the prescribed boundary.

• The table is lowered by a distance to the layer thickness and then the roller spreads the next layer of powder on the previous layer. (Layer thickness is usually 0.01 mm).

• The support for overhanging portions is served by unsintered powder.

Advantages:

• The main advantage of SLS is that the prototypes produced are porous hence impairing their strength and surface finish.

• Variety of materials can be used

• Build time is fast.

• Post curing is not required.

• Very Limited use of support required for structure.

• Nylon & Polycarbonate parts offer good mechanical property.

Figure 7: Selective Laser Sintering (SLS)

Limitations:

• Mechanical properties below those achieved in injection moulding process for same material.

• Poor surface finish.

• Finishing and post processing required.

• Material changeover is relatively difficult as compared to FDM/SLA.

• Operation is complex with build variables.

ELECTRON BEAM MELTING(EBM):

Principle and Process:

Electron beam welding is the one of the cleanest welding. It's a fusion joining process.

It uses a beam of electrons with high energy to join the parts.

The high energy electron beam is focused on the joint to be welded.

The high energy beam melts the metal and joins it with fine finish.

The electron beam is produced in vacuum chamber.

This kind of welding gives high purity.

Figure 8: ELECTRON BEAM MELTING(EBM)

Advantages:

It requires no filler material.

Narrow weld area.

Thick joints can be welded.

Takes place in vacuum hence low distortions.

Distortions are very low.

Narrow heat effected zone.

Dissimilar metals can be welded

Limitations:

During welding harmful X-rays are produced.

Welding cost is very high.

Equipment cost is high.

Delay in welding when operation in vacuum.

4. POTENTIAL BENIFTS OF RP

Better visualization can be achieved as the model is quite realistic.

Concept models can be made with different ideas and modifications.

The prepared models can be put for market survey and we can know its

Market demand and drawbacks.

Form and fit test of the model can be performed.

Model functional tests can be performed.

Wind tunnel tests of models can be performed.

Design review of the model can be done which allows designers to ensure that customer needs are met.

Stress analysis using photo-elasticity.

Number of joints in assemblies can be reduced. Moreover many of the them can be made joint free. This is impossible by any other process or technique.

RP can short the time for the product to be launched in market.

Time of production time is quite less in rapid tooling so production can be at faster rate.

Models can be sent along with the inquiries.

Models can be submitted along with the quotations.

5. USE OF RP & AM IN AGRICULTURAL VEHICLES (TRACTORS)

In today's fast growing world, technology has advanced to the core and in coming time we can see all computer design and manufacturing techniques. Humans just have to give an idea to the machine and it will do the rest.

Rapid Production and additive manufacturing is such an advanced process which is widely used in all sectors of manufacturing, design and technology worldwide now days. Rapid prototyping can be used in TRACTOR industry in many ways but it is limited to prototyping, not actual production. The main reason to this is size of the tractor. Still technology has to develop and large machines need to be produced for production of large and heavy parts especially like that of tractor. Tractors are manufactured quite large in design and heavy in weight so that can perform better in fields. But still we can use RP technology in this sector to increase rate and parts of assemblies to be produced.

Gears and gearbox, radiators. Valves, housing of the engines, hydraulic system, pistons and piston rods, hubs and cams, etc can be manufactured with ease using RP Technology. Also design and analysis can be done and performed using solid modelling and CAD software.

Figure 9: LOM MODEL OF A TRACTOR

Figure 10: FLOW CHART FOR RP PROCESS IN INDUSRTY

[http://www.digstrat.com/Downloads/Injection%20Molding%20Technology/rapid_prototyping_process_flow.gif]

6. TECHNOLOGIES IDENTIFICATION FOR DIFFERNT APPLICATION AREA

Going through all the details of different processes and their roles, we can use several techniques in the agricultural vehicle industry. But we need to select the most appropriate processes for different roles in the industry sector. As tractor industry is a very vast and production rate is high, use of suitable techniques is very important for the industry to progress.

As we are known by the fact that tractor is a bulky machine and has almost heavy and has large parts. So production of tractor is not yet possible by these techniques. But there are many other roles which suit these techniques and can increase rate of production in this sector.

Some key roles are:

Design and analysis.

Production of parts.

DESIGN AND ANALYSIS:

Prototypes of different designs can be formed for tractors. New designs can attract customers and it can be very useful for the industry sector.

The best processes for these roles are:

Laminated Object Manufacturing (LOM).

The laminated object manufacturing is limited to small prototypes formation and it can be a quick guide to have an idea of the design. Also prototypes of tractor parts can be manufactured by this technology. The assemblies can be made easily and joint free.

Figure 11: LOM MANUFACTURED MODELS

Three dimensional printing (3D printing).

The three dimensional technique is the one cheap process for producing prototypes. This process gives varieties of experiments in design field and is suitable for conceptual designs of machines or vehicles.

The main advantage it covers is the overall three dimensional model or prototype can be developed at once and very complex and hollow shapes can be easily formed using this technique. As it uses inkjet printer part developed is of desired colour and give better idea for its production.

Figure 12: A CONCEPT AGRICULTURAL VEHICLE PROTOTYPE BY 3 D PRINTER

PRODUCTION OF PARTS:

The most use of RP technology in this sector is in production of elements and parts of tractor. The parts can be produced and assembled together to form a tractor. As the tractor is mostly made of ferrous material and its parts need to have more strength in order to prevent the machine (TRACTOR) failure in fields during heavy works such as ploughing the field or pulling heavy loaded lorry.

The best technology suited for such role is:

Direct Metal Laser Sintering(DMLS):

This process is most suitable for metallic parts. With this technique different prototypes of metals parts can be produced in just single process. With DMLS, metal powder which is free from any binder is melted by focusing high power laser beam to build the part and the welded part has the same properties as that of original material. The mechanical properties are excellent which gives an added advantage to the parts which are to be subjected to heavy loads and jerks as that of tractor.

Figure 13: A FOUR CYLINDER TRACTOR ENGINE WITH VARIOUS PARTS

"The most of the parts of engine in the above shown can be easily produced using this technique and modifications can be done in order to achieve good results. Very large parts such as crank shaft, oil pan and cylinder head cannot be produced because of their large size."

SELECTION OF TECHNOLOGY FOR TRACTOR INDUSTRY

As tractors are basically used on farms and for heavy works. We can have an idea that attractive design of the tractor won't be the preference for the people. Tractor is known for its power and strength and that is what a customer except from the manufacturer.

Making concept designs and modifications in tractor body can decrease the capacity of tractor. Conceptual models are produced using more fibres and plastic on the body and making design attractive to look at. But the fact is addition of all this into such a machine reduces weight and thereby decreasing load carrying capacity of the tractor. Also the slip during ploughing will be more and which increases fuel cost. And most importantly investing too much on design and looks will also increase the price of the tractors and it will be almost difficult for the customer to invest on such a machine. Hence keeping all these factors in mind design of the tractor should be made. For such a risk we can't experiment too much with body and design.

Now we can think of any best suited and fast mode technique for production of prototype of tractor.

What I have opted is

THREE DIMENSIONAL PRINTING.

The reason to choose this process for design and analysis is because it's the cheap and also very fast process as compared with LAMINATED OBJECT MANUFACTURING. Also it can build large prototypes for better visualisation relatively. The idea behind selecting this technique is its ability to produce complex shapes with ease. And tractor shape and design can be produced at once. Design gives an idea how an object will look like and where actually will its parts be fitted on the body for the better performance of the tractor. A designer gets an overview of the parts and it becomes easy for him to understand the whole concept to be applied for the production in an industry.

Using this technique in prototypes and low volume production parts can be very effective. The CAD data can be used to design and solid modelling can be used for analyses. It's a fast process and changes can be made rapidly and any desired change can be added to increase the rate of production. Also the prototype will give an approx idea of how the tractor is going to look like. Customers and market feedback can be achieved and changes can be done accordingly. Also prototypes of large parts of maximum size 59.00 x 29.50 x 27.60 (Inches) can be produced using this technique. The number of joints can be reduced and complex assemblies can be made by Three Dimensional Printing.

The second technology option I have opted for production of metallic parts is

Direct Metal Laser Sintering (DMLS)

As we know tractor is mostly made up of iron and steel. Hence the most use of this technique is in this industry. As we have already discussed this process is most suitable for metallic parts. And it produces good surface finish. The parts can be cut or welded with moving laser which is produced by high energy moving electron beam in vacuum. The parts welded usually have good mechanical properties as that of original part and the most important use of this technology is that dissimilar metals can be easily joined and good mechanical properties parts can be produced which can be strong enough to bear any applied or excess load.

Figure 14: TRACTOR PARTS THAT CAN BE PRODUCED BY DIRECT METAL LASER SENTERING

The Fig. 14 shows the few tractor parts. These small parts can be easily produced by Direct Metal laser Sintering process. This process use both metals as well as powder to develop prototypes production. It is widely used in automobile industries as well as other relevant industries. The process is fast as compared to other additive manufacturing process. The process is costly so its preferred for large scale production such as tractor or automobile industries. It does not require any filler material the laser beam melts the metal and desired shapes and joints can be produced using this technique of rapid production (RP).

Process Comparison

Property Name

Laminated Object Manufacturing

Direct Metal Laser Sintering

Three Dimensional Printing

Abbreviation

LOM

DMLS

3DP

Material type

Solid (Sheets)

Powder (Metal)

Powder

Materials

Thermoplastics such as PVC; Paper; Composites (Ferrous metals; Non-ferrous metals; Ceramics)

Ferrous metals such as Steel alloys, Stainless steel, Tool steel; Non-ferrous metals such as Aluminum, Bronze, Cobalt-chrome, Titanium; Ceramics

Ferrous metals such as Stainless steel; Non-ferrous metals such as Bronze; Elastomers; Composites; Ceramics

Max part size (in.)

32.00 x 22.00 x 20.00

10.00 x 10.00 x 8.70

59.00 x 29.50 x 27.60

Min feature size (in.)

0.008

0.005

0.008

Min layer thickness (in.)

0.0020

0.0010

0.0020

Tolerance (in.)

±0.0040

±0.0100

±0.0040

Surface finish

Rough

Average

Rough

Build speed

Fast

Fast

Very Fast

Applications

Form/fit testing, Less detailed parts, Rapid tooling patterns

Form/fit testing, Functional testing, Rapid tooling, High heat applications, Medical implants, Aerospace parts

Concept models, Limited functional testing, Architectural & landscape models, Color industrial design models, Consumer goods & packaging

[http://www.custompartnet.com/rapid-process-compare?p=94,91,90,89,93]

CAD REQUIREMENTS FOR RP

As you can see, CAD in rapid prototyping really incorporates some high technology and this technology is very beneficial to many different industries in today's society. Not just anyone can operate this software. It requires well trained person, usually with an engineering background to design these products through the use of CAD data.

There are different CAD softwares which are available today for designing a prototype or model. Few CAD Packages for designing, modelling and analysis are:

AUTO CAD

AUTO DESK INVENTOR

SOLID EDGE

MAYA

CATIA

PRO-E

MAGIC

ANSYS

In the field of Rapid Prototyping the initial step is designing which is done by different CAD software's. Here the 3D Modelling is done and the file is converted into STL format. The STL file is then prepared by

Validation and Repair

Orientation

Design and Generation of Model Supports

The model and supports are then sliced and then it is subjected for part formation or building.

CONCLUSION

From the information collected on use of rapid prototyping plays an important role in agricultural industry. The parts of the tractors or any agricultural equipment can be manufactured and subjected to various tests can be done by using this advanced technology. Prototypes of parts can be produced according to the customer satisfaction by using RP technology. Various joint free assemblies can be produced and we can reduce number of joints therefore decreasing the number of parts which increases production rate.

By using RP technology we can produce parts in less time and at cheapest way which can attract customers. New design and ideas can be put and experimented and also we can modify old designs by the use of Rapid production technology.

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