MSE508 Lecture Spring 2008 –Week 4 – I. Costea, Ph.D.

Rapid Prototyping and Manufacturing

Rapid Prototyping and Manufacturing

• Rapid Prototyping Overview

• Lab 1128 3D Systems RP Printer

Rapid Prototyping Overview

• Rapid Prototyping (RP): A one step process of building a prototype directly from the geometric model of the part to be manufactured

• Rapid Prototyping is also known as: layered manufacturing, 3D printing, desktop manufacturing, and solid freeform manufacturing

Solid freeform fabrication (SFF)

• is a technique for manufacturing solid objects by the sequential delivery of energy and/or material to specified points in space to produce that solid.

• SFF is sometimes referred to as rapid prototyping, rapid manufacturing, layered manufacturing and additive fabrication.

Open Wikipedia page: http://en.wikipedia.org/wiki/Solid_freeform_fabrication

What is Rapid Prototyping?Copyright 2005 by Wohlers Associates, Inc

Rapid prototyping is an additive fabrication technology used for building physical models and prototype parts from 3D computer-aided design (CAD) and medical scan data. Unlike CNC machines tools, which are subtractive in nature, these systems join together liquid, powder, and sheet materials to form complex parts. Layer by layer, they fabricate plastic, wood,  ceramic, and metal objects based on thin horizontal cross sections taken from a computer model.

Open Wohlers’ page:http://wohlersassociates.com/rapid-prototyping.html

• http://en.wikipedia.org/wiki/Rapid_prototyping

Very good page on RP; has some good references

Rapid Prototyping Overview

• Basic steps in RP (3 steps):– Form the cross sections of the object– Lay the cross sections layer by layer– Combine the layers

• Therefore– Only cross sectional data is needed for each layer– Common problems with mold and dies are avoided

Forming diesare typically made by tool and die makers and put into production after mounting into a press. The die is a metal block that is used for forming materials like sheet metal and plastic. For the vacuum forming of plastic sheet only a single form is used, typically to form transparent plastic containers (called blister packs) for merchandise. Vacuum forming is considered a simple molding thermoforming process but uses the same principles as die forming. For the forming of sheet metal, such as automobile body parts, two parts may be used, one, called the punch, performs the stretching, bending, and/or blanking operation, while another part, called the die block, securely clamps the workpiece and provides similar, stretching, bending, and/or blanking operation. The workpiece may pass through several stages using different tools or operations to obtain the final form. In the case of an automotive component there will usually be a shearing operation after the main forming is done and then additional crimping or rolling operations to ensure that all sharp edges are hidden and to add rigidity to the panel.

From:http://en.wikipedia.org/wiki/Die_(manufacturing)

• See the picture of the bending die press animated at:

• http://en.wikipedia.org/wiki/Die_(manufacturing)

Rapid Prototyping Overview

• 3D Printing:– Developed at MIT– Similar to inkjet printing

Open: http://en.wikipedia.org/wiki/3D_Printing

• General process steps:– Ceramic powder is deposited to the proper thickness– Powder is selectively scanned with a liquid binder– See Figure next slide

Fig. 12.6 p. 386

Rapid Prototyping Overview• Stereo Lithography Apparatus (SLA):

– Development by 3 people: A. Herbert of 3M Corporation in Minneapolis, an H. Kodame of Nagoya Prefecture Research Institute, Japan (stopped because of lack of financial support)

– C. Hull of UVP Ultra Violet Products in California completed development starting 3D Systems in 1986 coining the term “stereo lithography”

• General process steps:– Photosensitive polymer held in a liquid state– UV laser scans the profile and solidifies the liquid to form the bottom edge of the

part– A platform is lowered as each layer is created– Post curing to finish part

Open: http://www.efunda.com/processes/rapid_prototyping/sla.cfm(very good explanation of SLA with pictures)

Rapid Prototyping Overview• Solid Ground Curing (SGC) called also Solider Process

– More accurate than SLA– Needs no support structure for large voids– Each layer is cured by a UV lamps… no UV laser

• General process steps:– Platform covered with thin layer of liquid photopolymer– Optical mask positioned and UV lamp exposes polymer– Residual liquid is wiped away– Layer of wax fills voids and is solidified by a cold plate– Layer is trimmed by a mill to desired height– Process repeated and wax is melted away on completion

Open: http://www.efunda.com/processes/rapid_prototyping/sgc.cfmVery good introduction (with pictures) of SGC

See Figure 12.4 p. 385

Rapid Prototyping Overview

• Selective Laser Sintering (SLS):– Developed by DTM in the United States– Any meltable powder may be used if laser strong enough

• General process steps:– Chamber is heated to aid in laser sintering– Powdered material is applied from feed cylinder– Powder is selectively heated with a laser causing binding– The part cylinder is lowered and a new layer of powder is rolled

and heated– Upon completion unused material is simply brushed away– See Figure next slide

http://en.wikipedia.org/wiki/Selective_laser_sintering

• Picture 12.X for previous text slide

Rapid Prototyping Overview• Laminated-Object Manufacturing (LOM):

– Commercialized by Helisys, Inc.– Laser trims material in sheet form one sheet at a time

• General process steps:– A sheet attached to the block from a material supply rol then is

laminated with a heated roller– A laser trims the profile … only the edges are scanned– The unused areas are sliced into pieces– The part is now broken into pieces with the resulting part to be revealed– The final part may be sealed to keep out moisture

http://www.efunda.com/processes/rapid_prototyping/lom.cfmVery nice intro with picture

LOM

– See Figure 12.7, 12.8

Rapid Prototyping Overview

• Fused-Deposition Modeling (FDM):– Commercialized by Stratasys, Inc.

http://www.stratasys.com– It’s an additive process– Layers generated by extruding thermoplastic material– Analogous to depositing chocolate cream on a cake

• General Process steps:– Thermoplastic material is deposited on the table just

above solidification temperature– The table or head moves to create the next layer

FDM

– See Figure 12.9

http://www.stratasys.com/media.aspx?id=76

Rapid Manufacturing at BMW: Rapid Manufacturing Jigs and Fixtures with FDM

• Read about BMW use of Stratasys – The plant’s department of jigs and fixtures uses FDM to build hand-tools

for automobile assembly and testing – Rapid prototyping has become a standard practice in product

development. At the BMW AG plant in Regensburg, Germany, FDM (fused deposition modeling) continues to be an important component in vehicle design prototyping. But moving beyond prototyping, BMW is extending the application of FDM to other areas and functions, including rapid manufacturing.

– FDM to make ergonomically designed assembly aids that perform better than conventionally made tools; FDM process can be an alternative to the conventional metal-cutting manufacturing methods like milling,

turning, and boring

• and look at several other case studies

http://www.stratasys.com/fdm_materials.aspx?id=729

• Stratasys FDM systems use a variety of production-grade thermoplastics, including ABS, PC (polycarbonates), PPSF (polyphenylsulfones) and blends to manufacture Real Parts TM . Because Real Parts from a Stratasys FDM system are composed of production thermoplastics, your parts will more closely predict end-product performance. These materials allow you to manufacture Real Parts that are tough enough for functional testing, installation, and most importantly — end use. 

Real production thermoplastics are stable and have no appreciable warpage, shrinkage or moisture absorption, like the resins (and powders) in competitive processes. Because thermoplastics are environmentally stable, part accuracy (or tolerance) doesn’t change with ambient conditions or time. This enables FDM parts to be among the most dimensionally accurate.

FDM Material Guide

http://www.stratasys.com/fdm_materials.aspx?id=729

Stratasys FDM advantagesin BWM case study

• Enhance the ergonomics of hand-held assembly devices used in the plant - to improve productivity, worker comfort, ease-of-use, and process repeatabilityThe freedom of design allows engineers to create configurations that improve handling, reduce weight, and improve balance.

Example: The tool designs created with FDM often cannot be matched by machined or molded parts. In one example, BMW reduced the weight of a device by 72 percent with a sparse-fill build technique. Replacing the solid core with internal ribs cut 1.3 kg (2.9 lbs) from the device. This may not seem like much, but when a worker uses the tool hundreds of times in a shift, it makes a big difference.

• Improved functionalitySince the additive process can easily produce organic shapes that sweep and flow, the tool designers can maximize performance while improving ergonomic and handling characteristics. The layered FDM manufacturing process is well suited for the production of complex bodies that, when using conventional metal-cutting processes, would be very difficult and costly to produce.

An example is a tool created for attaching bumper supports, which features a convoluted tube that bends around obstructions and places fixturing magnets exactly where needed.

BMW case study

• FDM is taking on increasing importance as an alternative manufacturing method for components made in small numbers

• the jigs and fixtures department has developed a simple flow chart to determine when FDM is a fitting option. The criteria are temperature, chemical exposure, precision, and mechanical load. With FDM’s ABS material, which the engineers find comparable to polyamide (PA 6), many tools for vehicle assembly satisfy the criteria.

Applications to Design• Rapid Tooling (RT): Quickly creating tools for manufacturing

http://www.efunda.com/processes/rapid_prototyping/rt.cfmVery good intro – open page

• RT has 4 distinct types:• Direct tooling: Tools are made directly from RP process, Figure

12.12• Single-reverse tooling: Investment casting, sand casting, spray

metal casting, and silicon RTV rubber molds. Converts different RP patterns into castings with other materials, Figure 12.14

• Double-reverse tooling: Combines single reverse and double reverse process often using a plaster mold. Figure 12.21

Applications to Manufacturing

• Prototyping for Design Evaluation

• Prototyping for Function Verification

• Modeling for further manufacturing processes

Rapid Prototyping Overview

Source:

CAD/CAM Principles, Practice and Manufacturing, 2nd Edition by Chris McMahon, and Jimmie Browne. Addison Wesley Longman Limited 1996, pp. 3-13

http://www.tagrimm.com/benchmarks/download_exec_1005.html

• In an evaluation of rapid prototyping systems, please rate the following in order of importance (e.g. 1 being the most important, 12 the least important)

Material selection: Ease of use:

Surface finish: Dimensional accuracy:

Material cost: Feature resolution:

Complex geometry: Process speed:

Minimal post processing:

Office compatibility:

Initial purchase price: Maintenance expense:

Predictions for RP for 2008http://www.deskeng.com/articles/aaagtb.htm

• Direct Digital Manufacturing (DDM)

• Low cost RP systems

• Materials

• Economy– Less service bureaus– physical prototyping replaced by

http://www.deskeng.com/articles/aaagtb.htm

T. A. Grimm & Associates in Edgewood, Kentucky, an independent consulting firm

Direct Digital Manufacturing (DDM)

“DDM is still new and very immature with respect to technology adoption, but it’s getting some traction and people are starting to take it seriously,” said Grimm. “We might see some interesting DDM developments in 2008.”

Predictions for RP for 2008http://www.deskeng.com/articles/aaagtb.htm

• nothing that promises to be earth shattering • from prototyping to manufacturing to low end

printers to high end systems, from plastics to metals

• commercialization of two low cost systems in early 2008 - one from 3D Systems and one from Desktop Factory, both promised at below $10,000

Todd Grimm

Predictions for RP 2008

• 2007 ushered in new classes of materials with some big advances.

• announcement of Objet’s new Digital Materials, which he has written about for DE (see Special RP&M section, February 2008, p. 50). “The technology allows you to take two of their photopolymers and combine them on the fly to make a unique third material, which means you can make a single part with multiple material characteristics, not previously available in the plastics world.”

http://www.designnews.com/article/CA6524502.html

• In December 2007, Objet Geometries announced its new PolyJet Matrix technology for creating rapid prototype models using multiple materials. The technology and the Connex500 RP system that uses it made its U.S. debut on the show floor at SolidWorks World 2008.

• The system is yet another leap forward for the rapid prototyping industry by enabling the simultaneous jetting of multiple model materials in a single build process.

• The system provides 600 x 600 dpi models in both the x and y axes, with model walls as little as 0.6mm. The company claims the highly precise printing delivers 0.3-mm tolerance across large models. There are up to 21 materials to choose from that deliver such features as translucent parts, the ability to coat parts for a rubber-like appearance and parts with combined rigid body and flexible material.

• The machine is 55 x 44 inches wide and 44 inches high.

http://www.tenlinks.com/news/PR/objet/111907_polyjey_matrix.htm

• REHOVOT, Israel, Nov 19, 2007 – Objet Geometries Ltd., the world leader in jetting ultra-thin layers of photopolymer, today announced its new PolyJet Matrix Technology, the first method that enables the simultaneous jetting of different types of model materials.

• This innovation opens up virtually unlimited opportunities for closely emulating the look, feel and function of final products, pioneering an entirely new direction in the 3D printing of models, prototypes and manufactured parts.

Predictions for RPTodd Grimm

• If the economy is down and investments in prototypes and prototyping equipment are impacted, people may turn to virtual prototyping, such as that which Autodesk has been promoting.

• If someone feels they need RP during a recession, obviously they’ll be more likely to consider low cost systems, and now they’ll have an option below $10K.

• Service bureaus will be affected by downturns in the market; once down it will take 3 years to go back to the same use

Applications –

3D printer provides dental models • 3D Systems' ProJet DP 3000 3D Production

System is a 3D Printer that accurately, consistently and economically manufactures precision wax-ups for dental professionals. The user of the ProJet DP Production System scans a model, designs a virtual wax-up using 3D software, then sends the data to the ProJet Production System to 'print' wax-ups in layers.

http://www.engineeringtalk.com/news/dsy/dsy177.html

Applications –3D printer provides dental models (Ctnd.)

• The system can generate hundreds of units each cycle.• Built in VisiJet DP 200 Material, the wax-ups have a smooth surface

finish and can be cast or pressed with conventional techniques.• The specially formulated material for dental applications is virtually

ash-free and can be used with traditional laboratory waxes.• The printer's large build volume and optional part stacking and

nesting capabilities enable unattended operation, suitable for high-volume production.

• The open architecture allows file transfer from any open scanner on or off site.

• Current material applications include full cast crowns, bridges, partial frameworks and full contour units to be pressed over metal and zirconia copings.

• Other potential applications include the rapid production of surgical guides and models.

Rapid manufacturing system rivals CNC accuracy

Precision Prototyping (APP) has added a Viper Pro SLA System to its fleet of

3D Systems' large-part manufacturing systems.

• The Viper Pro SLA System delivers strong parts with high surface smoothness, feature and edge definition and tolerances, with accuracy rivaling that of CNC-machined plastic parts.

• This system enables customers to consistently and economically mass customize and produce high-quality, end-use parts, patterns, wind tunnel models, functional prototypes, fixtures and tools.

• speed, accuracy, superior surface finish and expanded build envelope = rapid manufacturing equipment

Nanocomposite material for Stereolithography

• 3D Systems Corp has developed a new engineered nanocomposite material

• Designed for motorsport and aerospace applications, Accura Greystone material delivers exceptional accuracy, stiffness, thermal performance as well as long-term stability.

• The grey-coloured nanocomposite material was developed for

rigorous, high-pressure wind-tunnel testing, under-the-bonnet automotive applications and other uses requiring high thermal resistance, insulating electrical components, and building accurate and stable jigs and fixtures.

http://www.engineeringtalk.com/news/dsy/dsy174.html