Laminated Object Manufacturing(LOM)

8/10/2019 Laminated Object Manufacturing(LOM)

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ACKNOWLEDGEMENTI most humbly surrender with gratitude before my

teachers. They are my guiding inspiration who awaked my sub

conscious mind & engineering talents through the inspiration,

sincerity, spending precious time & imparting

knowledge presenting a success system before

which difficulties, failures & obstacles are powerless but stepping

stones to success under extra stress. My professor taught me to

relentlessly work hard under pressure to improve my capacity

which I understand is incredible, formidable &impossible.

Circumstances cannot change us but we can change the

circumstance forgetting physical & mental pains to achieve the goal

accurately within time with zero tolerance with genuine desire for

success and inspiration.

My emeritus professor changed my negative attitude to

positive result oriented action with preference directing me tounderstanding, acceptance & direction.

I express my genuine gratitude to staff & lab technicians

for their co-operation. I am much delighted and obliged to this

campus, lab & immaculate library, multicultural but friendly

colleagues. By changing the attitude we can change the life for

positive results.

I have boundless love & obligation to my parents for

arranging me education in this esteemed & prestigious University. I

am proud of being a student of a prestigious institution.


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ABSTRACTThe laminated object manufacturing (LOM) process is an

effective rapid prototyping technology with a variety of possible

applications. It is developed by Helisys Inc. The main process of the

LOM consists of at first, a slice material such as paper is

transported onto the work table, the work table raise, and then a

hot beam press and heat ups the shape into small piece in order to

wipe them off after build all layers; after cutting is finished, the

work table fall and repeat the first step. An alternate method is to

collect all the cut layers of the prototype first and then stacking is

done layer by layer with gluing them properly.

As rapid prototyping also includes developing complex

prototypes, LOM being a rapid prototyping process face difficulties

in making complex prototypes as a cubing methods used to support

prototype being made. But the cubes cannot support the

overhanging or island structures in the prototype due to itsstructure. The removal process of cubes known as de-cubing is

tedious, time consuming, labor intensive and also causes damages

to the prototype during its removal. The LOM process here is

developed by adopting powder as the support material eliminating

the de-cubing method, as powder provides support to

the prototype being made and also the overhanging structures in it.

Two complex prototypes have been made and compare with the

current Rapid prototyping technologies proving this process to be

cost effective and time efficient.


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CONTENTTOPIC PAGE NO

1 - Introduction 4

2 - Process of LOM 6

3 - Aim 7

4 - Objective 7

5 -

Deliverables 86 - LOM 9

7 - Machine Structure 10

8 - Procedure 11

9 - Software 13

10- Advantages 15

11- Disadvantages 16

12- Application 17

13-Conclusion 18


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INTRODUCTION

In past decade, a lot of important breakthroughs have

been made in the theoretical research and its application about

the rapid prototyping and manufacturing (RP/M) technology.

Although there are some reports in which the ceramic

is used as the modeling materials, in the most case the

modeling materials used are those such as plastics, paper orwood. During its initial development stage, RP/M technique is

usually used to evaluate the correctness of the three

dimensional model resulted from CAD, the materials such as

plastics used as modeling materials are good enough for that

purpose. With its application extending to the fields such as the

check of design, the evaluation of performance, the trial

fabrication or the manufacturing of the functional parts, RP/M

technique must be further improved with the effort to use

some other materials rather than the ones mentioned above.

One of the attempts is to use metal as the modeling materials.

There are some reports using the sheet metal as

modeling materials by laminated object manufacturing (LOM)

for manufacturing the metallic functional parts. Afterexamining on the available results, we have realized that there

are some problems to be solved when using the sheet metal as

the modeling materials in LOM process, one of them is how to

get the expected laminating accuracy. It is well known that the


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thinner the laminating layer is, the higher the modeling

accuracy is. The thickness of laminating layer for the available

LOM processes, which use paper, plastics or wood plate as

modeling materials, is usually only 0.05-0.1mm. For using metalplate as modeling material, there is a research report of using

sheet steel of 0.2mm thick, and the attempt would be made to

use thinner sheet metal plates. But using thinner sheet metal

brings about other problems, for example, the strength of steel

decreases with the increase of the modeling time. In addition,

the sheet steel thinner than 0.2 mm with the bond coated onits both surface is difficult to be made practically.

In this paper the accuracy study on LOM is presented. Authors

have done a basic analysis on theoretical manufacturing error

for LOM in reference. Based on the further analysis of the

theoretical manufacturing error and the quantity of remaining

material to be removed by finish process (that is said as

remaining quantity) caused by LOM process and 3-D numerical

control manufacturing (that is said as 3-D NC process), a new

LOM process to reduce the theoretical manufacturing error and

remaining quantity is proposed.


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The Process of Laminated

Object Manufacturing:-

The Laminated Object Manufacturing is the process which

consist of laser (or cutter), heated roller, a support, a platform, and

a roll of paper or material used for making prototype.

The process starts with a paper material which is brought

onto a work table, the work table then tend to rise. The paper or

the material is brought in-front of laser such that the laser cuts the

paper or material layer by layer. These layers have adhesives

underneath it or could be applied under it so that they are stacked

after they are cut (cut and bond process). After cutting each layer

the build platform goes down and the layer comes on for it to be

cut. As these layers cannot be made into a prototype in air

without any support, thus they were supported by cubes and

after the whole process of cutting was over the build platform is

made to rise above and the prototype is taken after the time

consuming and tedious de-cubing process.


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The main purpose (Aim):-The purpose of this project is to develop a process for the

laminated object manufacturing without the process of de-cubing.

Thus, the main aim is to develop

the process to create any type of complex prototype using the Lami

nated ObjectManufacturing process without de-cubing.

Objectives:-

Getting knowledge of Laminated Object Manufacturing

(L.O.M) and the theory on it.

Developing the process to show the prototype can be created

without the de-cubing process in Laminated Object

Manufacturing.

Developing the process to save time and cost and making the

prototype with proper accuracy.

Making complex prototypes with proper accuracy using the

methods that will save time and be cost effective.

Finding and applying the methods to support island objects or

overhanging structures in complex prototypes.


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Deliverables:-

To provide a cost effective method of making prototypes

To provide a process that is time consuming when compared

to the current Laminated Object Manufacturing process and

other rapid prototyping processes

A report regarding the problems, solution, the methods of

solving the problems and the comparison of the prototype

being made with that of other rapid prototyping systems

A log book with updated research details and changes made

in the project methodology.

A poster describing the project at a glance

Complex prototypes to show prototypes that are complex in

nature can be built without the process of de-cubing.


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Laminated Object Manufacturing

(LOM):-

The Laminated Object Manufacturing (LOM) system

was introduced in 1991 by Helisys, CA. The mechanism of the

system starts with a sheet placed over a build platform, a laser

to cut the sheets in the designed way as in the CAD model or in

the STL file, a roller to put pressure on the sheets on the

previous one which is cut by applying glue in between the

sheets or using adhesive coated sheets so as to stack the layers

properly. After the completion of cutting each layer the built

platform lowers and then the new layer of sheet again sits on

the previous one and the process continues. After the layers

are cut the waste material around it supports the model and

can be removed once the model is built. LOM is one of thecheapest systems in Rapid Prototyping to make parts of

complex geometry.

Machine Structure:-The mechanical part of the system contains an unwinding and a

rewinding roll connected by a ribbon of sheet material routed

through several idler rollers. These rolls store and supply the

material. The laminated part is grown on a platform capable of

a vertical incremental movement under the action of a stepper


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motor. Above the platform is located a heated roller capable of

heating and compressing the ribbon between itself and the

stack of laminations on the platform. As a result of a single

reciprocal motion of the heated roller the ribbon material isbonded to the top of the stack. An X-Y positioning table carries

two mirrors which reflect a beam from a C02 laser and a lens

which focuses the beam on the upper surface of the laminated

stack so as to cut the very top layer. Scrap pieces remain on the

platform as the part is being built. They are diced by the laser

beam into crosshatched squares and serve as a supportstructure for the part. A picture of a LOM machine is shown

billow.


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PROCEDURE:-A computer which runs the system is capable of slicing a 3-D

solid model into thin two-dimensional cross-sections.

The thickness of each cross-section is equal to the thickness

of the material used in the process.

At first, the geometry of a cross section is generated by the

computer.


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The geometrical information is fed into the LOM system

which guides the laser beam cutting around the periphery of

the cross-section.

The laser cuts to the depth of one layer of the material. Thematerial which surrounds the cross-section is usually

crosshatched by the laser beam into squares to facilitate

separation at the completion of the process.

In the areas where attachment of the material which

belongs to the part to the material which surrounds it is

undesirable the laser beam ablates the portions of thebottom layer to prevent bonding. Sometimes fine crosshatch

of these portions can achieve virtually the same effect.

Next, the platform moves down. The ribbon moves by an

increment exceeding the length of a cross-section onto the

rewinding roll.

As the platform moves up, the heated roller moves across

the stack while pressing the ribbon against the stack and

bonding it to the upper layer.

Meanwhile, the height of the stack is measured by the

machine and fed back to the computer where the next layer

is calculated according to the current measurement.

Laser beam cuts a new cross-section. The process continues

until all of the cross sections have been deposited and cut.The product comes out of the machine as a rectangular

block containing the part.


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The material surrounding the part has already been diced

into small cubes due to a "crosshatch" cut by the laser, so

they can be separated easily from the part.

LOM Model: the piece is freed from its orthogonal support matrix. The appearance of the final object is wood like.

Software:-

The control and slicing software for the LOM machines called

LOM Slice, takes files in the STL format as an input. After

receiving a few parameters specified by an operator, the


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software supervises the LOM machine throughout the

unattended operation.

Some features of the current version of the software are shown

as follows:

A proprietary algorithm enables LOM Slice to slice each layer

"on the fly"; in other words, while the LOM machine is

laminating and cutting one layer, LOM Slice is concurrentlycomputing the next slice. Therefore, no extra computing time

is required for slicing and simply an IBM-compatible PC is

needed as the platform.

By constantly receiving feedback of the current height of the

stack from the LOM machine. LOM Slice applies dynamic

height control procedure to eliminate hardware turbulence

and adjust the slicing increment. Thanks to the real-time

slicing capability, every layer is sliced precisely.

LOM Slice has been developed under Microsoft Windows 3.0

environment. The Windows's popularity and user-

friendliness itself makes it easy to learn and operate.

LOM Slice possesses robust capacity of dealing with

imperfect STL files. Not every STL-generating CAD systemdoes a perfect jobs; some STL files are created with

discontinuities which means that the surfaces of STL objects

are not closed completely. LOM Slice can tolerate these cases

and clarify these ambiguities to make a successful slice.


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LOM Slice has a beam compensation ability. Even having

been described as a "zero-diameter tool," a laser beam still

has a thickness of several thousandth of an inch. The

software offsets the center path of the beam so as to cut aprecise outline of each cross sections.

Other utilities such as: translation, scaling, and rotation of

the object; multi-layering. i.e., laminate more than one layer

then cut once; build several objects in one production. Run

from different STL files or duplicate the same object; and so

on.

Advantages:-

Due to its simple and straightforward concept, theLOM process has several advantages:

A variety of organic and inorganic materials can be used in

the LOM process allowing the user to meet various

requirements such as price range, environmental concerns,


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undercut potions of the part. This eliminates extra design

time required to create proper support structures.

Disadvantages:-

Difficulty in producing hollow parts

Traditional manufacturing is usually much faster when mass

producing identical parts

Fire hazard is occasionally happened when the workingchamber becomes too hot

The built parts absorb moisture quickly

The process is restricted to build complex parts

It is very difficult to remove the waste materials from inside

Difficulty in supporting overhanging structures

Applications of LOM Process:-Rapid prototyping machines have developed in Center

for Laser Rapid Forming, Tsinghua University, China, such as M-

RPMS-III, SSM-800 and SSM-1600, they could perform the LOM

process.


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The LOM process can be applied in many field such as

patternmaking, art recurring, toy designing and so on. Figure1

shows a thin-wall part manufactured by LOM process. This part

is very complicated and large. There are many difficultiesmanufacturing this part by other process such as FDM. It is too

large to that process. Figure2 shows a ball part manufactured

by LOM process. If this ball is produced by FDM process, the

support material would be a very serious problem. While in

LOM process, there is no problem.

Figure 1. A thin-wall part manufactured by LOM process

Figure 2. A Taiji ball manufactured by LOM process


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CONCLUSION:-The Laminated Object Manufacturing (L.O.M) can be

regarded as one of the quick rapid prototyping systems where

powder has been adopted as the new support for supporting

the complex prototypes with the elimination of the de-cubing

method. The prototype has been made in this process by eco-

friendly and recyclable materials which are easily available and

are cheaper ingredients as raw materials. It has been proved

that any complex prototype could be made by L.O. M. in a costeffective way and also has proved to be time efficient. The only

problem seen in this method was a poor surface finish which

could be easily sorted out by proper alignment mechanism and

providing improvements in some aspects of the machine where

the built platform has proper dimensions with respect to the

built chamber.

Documents

Laminated Object Manufacturing(LOM)