PES INSTITUTE OF TECHNOLOGY BANGALORE – SOUTH CAMPUS
Hosur Road, (1K.M. Before Electronic City), Bangalore – 560 100
DEPARTMENT OF MECHANICAL ENGINEERING
SCHEME AND SOLUTION – III INTERNAL TEST
Subject :RAPID PROTOTYPING
Sub. Code :10ME837 Section: A,B
Semester
: VIII
Name of the faculty : A. KHANNA
(7 Marks)
1. a) Explain PROMETAL Rapid Tooling Technique in detail.
(3 Marks)
b) What is the difference between Soft Tooling and Hard Tooling?
PROMETAL TOOLING TECHNIQUE
The ProMetal RCT equipment automatically builds sand molds and cores
for casting metal directly from CAD data. Standard foundry industry
materials are used, enabling easy integration of the new equipment into
existing manufacturing and foundry procedures.
The large building volume and high building rate combine to make
patternless production a reality for metal-based prototype castings and
low volume production.
The molds and cores are built in an additive layer-wise fashion using a
printhead, analogous to the ink-jet technology commonly used in desktop
printers.
According to Dan Maas, Director of Business Development for ProMetal,
"This revolutionary ProMetal RCT process allows design freedoms, which
was never available to the casting designer or the foundry. Removing the
requirements for parting lines, draft angles and providing undercuts.
Moreover "Providing nested cores, spiral vents, volute shapes, integration
of multiple components, in-situ cores, and unique rigging geometry to
minimize turbulence are design features that are being utilized today by
advanced companies."
DIFFEREENCE BETWEEN SOFT TOOLING AND HARD TOOLING
Hard Tooling
Delivery of first article samples, 4 weeks (very simple parts) – 12 weeks
(normal complexity) – longer for complex or parts requiring ceramic core
tooling
Delivery of production, 2 – 12 weeks after First Article approval.
Highest tooling expense
Lowest investment casting pattern cost
Hard tooling will have the longest life. Simple tooling will last for hundreds of
thousands of parts. Complex tooling with slides and cores will wear over time
but can generally be refurbished. This is not normally necessary for many
years.
Yields the best surface finish and most consistent dimensional control.
Soft Tooling
Delivery of first article samples, 3 – 6 weeks
Delivery of production, 2 – 12 weeks after First article approval
Soft tooling is less costly than Hard Tooling
Pattern cost is higher than Hard Tooling. This is because the tooling will
cycle slower due to the poor thermal conductivity of mold material
Life of soft tooling is limited. Life will depend upon the complexity of part. The
more complex the shorter the life
Surface finish and dimensional control is not as good as Hard Tooling
A single SLA (stereolithography) or Objet pattern is generally used to
make the tooling
2. a) Write benefits of Collaboration software tools in 3D (6 Marks)
printing.
(4 Marks)
b) Name various websites/web portals offering collaboration
tools?
COLLABORATION TOOLS
Collaboration tools like TeamPlatform web enabled cloud-based,
collaborative design and project management platform allows on
product design, engineering services and manufacturing companies
to share data and collaborate on 3D printing projects.
Autodesk 360 collaboaration tool focuses on features and cloud
services that can help you improve the way you design, visualize
and share your work with others; but TeamPlatform's goal is to help
people and companies work together much more easily and quickly.
It focuses on connecting businesses, sharing and collaborating
designs with the added of workflow tools.
WEBSITE / PORTALS
1.
2.
3.
4.
imaterialize
Shapeway
TeamPlatefor
Autodesk 360
3. a) Explain with neat sketch DMLS rapid tooling process?
(6 Marks)
b) Give its benefit over traditional process?
(4 Marks)
Direct Metal Laser Sintering
Utilizing the DMLS rapid tooling process, metal parts of the most
complex geometries are built layer-by-layer (down to 20
microns) directly from 3D CAD data. Parts built using DMLS
have excellent mechanical properties equivalent to wrought
materials, high detail resolution, and exceptional surface quality.
The metal powder is melted entirely to create a fully dense, fine,
homogenous structure.
Unique geometric freedom of design enables DMLS to form
cavities and undercuts, which with conventional machining
methods, can only be produced with great difficulty, if at all.
DMLS produces parts that are extremely high quality and can
be built in a matter of hours or days rather than weeks. The
ability to generate functional metal prototypes in short order
radically impacts design processes, accelerating design cycles
and
time
to
market.
Depending on size and geometries, in some cases the
turnaround time for a part can be as little as a few hours.
Benefits Over Traditional Processes
Additionally, when a part needs to be tested and re-designed
over and over, the lead time for receiving a traditionally tooled
part can create a large bottleneck in the final production
process.
Furthermore, these parts can undergo functional testing in the
environment for which they were designed. This technology
delivers unlimited potential for engineers to create previously
impossible solutions, embracing a new era of design-driven
manufactureing.
4. a) Write briefly about MAGIC, SOLID VIEW and MIMICS
software tools. (4 Marks)
b) Write the process of design and manufacturing a
Jewellery product
(6 Marks)
using RP tools, software and techniques?
, SOLID VIEW and MIMICS software tools:
MIMICS
Mimics is software specially developed by Materialise for medical
image processing. Use Mimics for the segmentation of 3D medical
images (coming from CT, MRI, micro-CT, CBCT, 3D Ultrasound,
Confocal Microscopy) and the result will be highly accurate 3D
models of your MAGIC patient’s anatomy. You can then use these
patient-specific models for a variety of engineering applications
directly in Mimics or 3-matic, or export the 3D models and
anatomical landmark points to 3rd party software, like statistical,
CAD, or FEA packages.
Use Mimics to:
Easily and quickly create accurate 3D models from imaging data
Accurately measure in 2D and 3D
Export 3D models in STL format for additive manufacturing
Export 3D models to 3-matic to optimize the mesh for FEA or
CFD
MAGIC
Magics, a user-friendly data preparation software package and
STL editor, can guide you through every step of your Additive
Manufacturing or 3D
Printing workflow.
1. Import Files
With Magics, you can
import nearly all file formats and native color information, and
stay in control of your original data.
2. Fix and Prepare STL
Files
The STL editor in Magics
allows you to correct problems, as well as create watertight data
and shortcuts to suit your workflow, all in a user-friendly
interface. STL File fixing includes repair of flipped triangles, bad
edges, holes and other defects.
3. Enhance and Edit Data
With Magics, you can also take your designs to the next level: add
logos, serial numbers, and hollow parts; apply textures; and
perform Boolean operations and
advanced cuts.
4. Prepare the Platform
Magics has the tools you need to duplicate parts, orient them in an
ideal way, and create no-build zones.
SolidView/Pro RP is the most robust of the SolidView family of products
and is designed for companies doing their own rapid prototyping work.
SolidView/Pro RP offers all SolidView/Pro features as well as advanced
rapid prototyping tools; compound cutting, file repair, z-correction,
shelling, offset, and automatic or manual object layout. Optional CAD
formats and network licenses are also available for SolidView/Pro RP.
The following features are included with SolidView/Pro RP:
View and Print STL, SVD, and SolidWorks formats
Print STL, SVD, and SolidWorks formats
Measure SVD, STL, and SolidWorks formats
Create PLY files
Create SVD files
View 2D drawings
Translate
Scale
Rotate
Mirror
Copy
Combine
CAD Formats Available
Network Licenses Available
Cut (cross-section)
Shell
Repair
Manual RP Layout
Auto RP Layout
Jewellery Manufacturing
Rapid Prototyping (RP) and Additive Manufacturing (AM) techniques
are usually widely used into those sectors into which complex shapes
and relatively low production are required. Due to its peculiarities
Jewellery industry is perfectly matching
In many manufacturing companies CAD data are then transferred to
Rapid Prototyping equipment which allows for fabrication of pattern
directly from the CAD data . The RP processes, mainly represented by
wax 3D printers and stereo-lithographic apparatuses, are most of the
times fully integrated into the traditional process, either to produce the
master model or to produce replicas to be directly assembled on the
tree. This last process, commonly referred to as “direct casting” is
highly interesting opening several possibilities in terms of shapes and
production flexibility
Flow Chart for Jewellery Making is as follows
5 a) What are various part building errors in RP Technologies?
(5 Marks)
b) Explain parameters for dimensional accuracy of 3D
component?
(5 Marks)
SEVEN Part Building Errors in RP Technologies are as follows
1. The part design has thin features or walls that are less than
.030” for standard resolution or .015” – .020” for high resolution
machines.
Due to the ―layer by layer‖ approach of the additive manufacturing
process, anything smaller or thinner that this will often times not build
and will not be present in the final model. Pay very close attention to
raised or recessed logos and areas of small text, ―knife edge‖ features
which taper down to zero thickness, and curvy sections of any design
where thickness can fluctuate.
2. The native CAD model is converted to .STL format with a very
low resolution, resulting in heavy faceting in the model.
If the resolution of the .STL file is too low, the model will be faceted
instead of having smooth surfaces and curves. This can be quite
common and produces unattractive parts. Typically, to achieve a
smooth finish on a model there should be an edge-to-edge distance of
less than .020‖ between facets on the .STL file. Check the parameters
on the native CAD program being used to determine the best method
of exporting acceptable .STL files.
3. The original CAD data has numerous unstitched surfaces
(rather than solids), resulting in errors when converting to .STL
format.
Make sure that the surfaces in the original CAD model are ―water
tight‖, in that only solids are modeled. The .STL file can also be
inspected to ensure that all dimensions, part volume, and surface area
all appear to be correct.
4. The part design has an enclosed hollow space from which
support
and
build
materials
cannot
be
removed.
Any enclosed hollow void in the design will contain support materials
which cannot be removed through the finishing process. This area
may also be filled with unused resin or powder depending on the
selected prototyping process. Consider filling in voids to be solid,
building the design in halves to allow access to the enclosed space, or
adding a hole of some kind in the model to allow for the removal of the
support materials.
5. Assemblies, threads, and mating features are designed with
improper
clearance.
The standard tolerances for most additive manufacturing processes
start at +/- .005‖ and compound from there as the design increases in
size. It is not uncommon for first time customers to receive parts that,
while within the published tolerances of the manufacturing process, do
not ―fit together‖ or mate up as intended. Typically, there should be a
.015‖ – .020‖ clearance between mating parts, which is different from
what is required for traditional injection molding. This is an important
point to remember when the success of the project depends on how
well different designs mate up or assemble with one another.
6. The design includes a living hinge which needs to function.
Living hinge designs on most parts produced via additive
manufacturing don’t typically function as intended. The build material
involved is often too rigid, especially in such a thin section, and will
break. While there have been a few materials developed that look to
address this need (the Duraform EX material using the SLS process
can often work well), expect limited usage from a living hinge design
produced via additive methods.
7. The units of measurement for the .STL file differ from what was
intended.
Double check the .STL files properties to ensure that the correct unit of
measurement is selected. This is especially true when there is more
than one design with varying units of measurement being built
together. Some CAD packages also have default settings where .STL
files may be exported in a different unit of measurement from what
was used during the design process. When there is a tight time line
and the project is on the line, it can be difficult to see the comedy in
dramatically oversized or undersized parts as they come out of the
box.
Keep these seven common mistakes in mind when considering any
additive manufacturing project. Be careful to confirm the integrity of the
original CAD data, and be mindful of living hinge designs, enclosed or
trapped hollow spaces, clearance between mating features, and any
features or walls that are smaller or thinner than .030‖. After exporting
the .STL file from the native CAD file, take time to confirm that the
overall resolution of the file is sufficient and that the selected units of
measurement are correct.
Parameters For Dimensional Accuracy of 3D Component
Dimensional accuracy of a component part represents the degree of
agreement between the manufactured dimension and its designed
specification. It is the most critical aspect to ensure dimensional
repeatability of manufactured component parts.
The resolution and accuracy of porous 3DP samples are determined by many
factors, including print head resolution, material used, printing delay, build
orientation, geometric features and their topology, post treatment
procedures, precision of the linear stage positioning, binder drop volume,
binder–powder interaction, particle size and last but not least, the layer
thickness.
Unfortunately, the efforts to determine these effects are often hampered by
the limitations set by the commercial printers. In order to achieve a
breakthrough in 3DP for scaffold engineering, accuracy (the mismatch
between the model and the 3DP specimen) and resolution (smallest feature
size) need to be substantially improved .
6 a) Write with neat sketch quick cast process?
(7 Marks)
b) Name the industry were this techniques is used
successfully.
(3Marks)
Quick Cast Process
QuickCast® Investment Casting Patterns are accurate,
consistent, strong, fully drained and completely sealed patterns
that are 10 to 35% lighter than those built with other polymers and
ordinary build styles.
Advantages and Industries Using This Technology
Lower Cost
Lower Cost is achieved with our SC 1000
material. 1) Our cost is lower—we pass along
the savings. 2) This material is more stable,
reducing the over-all cost of operation. 3)
Patterns made with SC 1000 demonstrate
higher yield both in SLA part building and more importantly
during flash firing. We offer aggressive pricing to encourage
higher volumes; often demonstrating that a
tooling/wax approach is more expensive and
a higher risk.
Lighter Weight
Lighter Weight patterns are sought after by
knowledgeable foundries. These QuickCast® patterns are up
to 35% lighter than conventional stereolithography patterns.
This translates directly to higher yield in the casting process.
Proportionately less ash is produced and thermal expansion
forces are minimized during flash firing.
Production Capacity
Production Capacity is a given at Solid
Concepts. We have twenty five SLA Systems
including both large (20″ cube build envelope)
and smaller (10″ cube) sized machines. Capacity
translates to better on time delivery. All of these systems are kept
at peak performance by regular maintenance.
Large Part ExpertiseLarge Part Expertise has
come with over twenty years in the business. We
take on large projects that others cannot or will
not. We have assembled and inspected even
larger parts. For large parts, experience with
custom assembly fixtures and large part
packaging is a must.
New Build Style
New Build Style and SC 1000 make these patterns truly unique.
This build style and photopolymer combination has already been
approved by most major US foundries. This
proprietary build style offers complete internal
draining and excellent final surface sealing.
7 a) What is process optimization important in RP Technologies?
( 6 Marks)
b) What’s part building error? How you can control it?
(4 Marks)
Rapid prototyping (RP) has evolved as frontier technology in the recent times,
which allows direct transformation of CAD files into functional prototypes where it
tremendously reduces the lead-time to produce physical prototypes necessary for
design verification, fit and functional analysis by generating the prototypes directly
from the CAD data.
Part quality in the rapid prototyping process is a function of build parameters such
as hatch cure depth, layer thickness, orientation, hatch file, hatch spacing and part
characteristics. Thus an attempt was made to identify study and optimize the
process parameters governing the system which are related to part characteristics
using Taguchi experimental design techniques-quality.
The part characteristics can be divided into part physical characteristics and
mechanical characteristics. The physical characteristics are surface finish,
dimensional accuracy, distortion, layer thickness, hatch cure, and hatch file
whereas, mechanical characteristics are flexural strength, ultimate tensile strength
and impact strength.
Thus, the paper proposes to characterize the influence of the physical build
parameters over the part quality. An orthogonal array of experiment was
developed which has the least number of experimental runs with desired process
parameter settings and also by analysis tools such as ANOVA (Analysis of
Variance). Establishment of experimentally verified correlations between the
physical part characteristics and mechanical part characteristics to obtain an
optimal process parameter level for betterment of part quality is obtained. The
process model obtained by the empirical relation can be used to determine the
strength of the prototype for the given set of parameters that shows the
dependency of strength, which are essential for designers and RP machine users.
8 Write notes on
a) Build Orientation
(5 Marks)
b) Layer Thickness
(5 marks)