CDS10 Response RTC

8/9/2019 CDS10 Response RTC

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Casting Design and Simulation

10Response Competitiveness:

Rapid Tooling & Casting

• Need for rapid casting development

• Tooling routes for casting

• Rapid prototyping (1-step)• Rapid tooling (multi-step)

© 2008 Prof. B. Ravi, Mechanical Engineering Department, Indian Institute of Technology Bombay.


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Need for Rapid Casting Development

First Sample Casting

• For approval before regular production

• Main order often goes to the fastest supplier

•• Who pays for tooling costs if main order is not placed?

rototype ast ngs

• For new product development and testing purpose; time is critical!

, , , …

• Indian suppliers (foundries) take 3-6 months for prototype castings

• Foreign vendors (ex. ACTech) expensive: typically $20K per casting.

Replacement Parts

• For obsolete but workin roducts where inventor is infeasible

• Users from defence, vintage automobiles, large machine tools

• Starting point: broken/worn-out part; drawings may be unavailable

• Conventional route: high cost and delay.


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Conventional Casting Development

Avera e lead time for castin roduction 12 weeks

1 1 6 3 1

Tool Manufacture

and Inspection

amp e

Approval

Tool

Design

r a

Production

,Casting development time can be reduced by over 50%


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Tooling for Casting

(Intermediate Tooling) Final Tooling

Die Casting MOLD

PATTERN MOLD

an as ng

CORE BOX CORE

Investmentast ng

Permanent Consumable


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Conventional Tooling Production

• Tool Material:

Metal: cast iron, steel, aluminum.

Non-metal: wood, plastic.

Metal corebox and core


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Conventional Tooling Production

• Tool Manufacture:

Simple: Manual machining (lathe, milling, grinding)

Complex: CNC machining: multi-axis milling, EDM, HSM.

.


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Tooling Materials

*

• Soft plaster 100 - 500

Epoxy resin

core box for trials

• Hard wood 500 - 1,000

• Plastic plaster 1,000 - 5,000

• Epoxy resin 5,000 - 50,000

• Polyurethane resin 20,000 - 60,000

, - ,

• Copper alloys 40,000 - 60,000

• Gre cast iron 200 000 - 300 000

• Low alloy steel 300,000 - 500,000

*

Production core box


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Rapid Manufacture

Characteristics:

• Minimum number of steps

• Minimum process time for each step

• Minimum supervision requirement• Minimum iterations/trials for quality

Foundation technologies:

Courtesy: Kirloslar

Copeland, Karad

• rec anu ac ure

CAD to part, for intricate shapes (single or multiple).

-

+ Investment casting

• r ua r a s

Predicting and preventing casting defects by simulation


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Rapid Tooling for Casting

•

• Challenge: tooling development for intricate shapes.

single

RPPATTERN

PART CADMODEL

SANDMOULD

METALPOURING

few

few

MOULDPATTERN

METAL many


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Rapid Tooling

Rapid Tooling: Tooling fabricated using Rapid Prototypingsys ems, rec y or n rec y.

p a r t s 1000 Hard

b e

r o f

100 Bridge

( n u m

Using secondary processes

l L i f

e suc as nves men cas ng,

using RP model as master.

T o

Direct Indirect1

Number of steps


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Rapid Prototyping: Principle

or Free Form Fabrication

3D modeling Virtual slicing Layer by layer


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Rapid Prototyping Systems

qu - ase o - ase ee - ase

Stereolithography Selective Laser Laminated Object

(STL)

Fused Deposition

Sintering (SLS)

Laser Engineered

Manufacturing (LOM)

Sha e Makero e ng

Shape Deposition

e ap ng

3-Dimensional


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Rapid Prototyping: Complexity

• Overhanging features (undercuts)

can be produced in RP without any special tooling

but require a support structure during fabrication.

• Material

same: liquid, solid, powder

different: solid

• Support Removal

machining

dissolving / melting

loose owder - shake off

support structure


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Rapid Prototyping: Accuracy

Accuracy depends on:

• Errors in the model

missing elements (edges, facets)

• Model slicing (number)

Slice thickness (staircase effect) Adaptive slicing

Cross hatch / contour parallel

Coarse fine

Hybrid schemes


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Rapid Tooling – Sand Casting

CAD Model of Pattern RP Model of Pattern Metal Cast Part

Courtesy: Thermojet


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Rapid Tooling – Investment Casting

PU RP Pattern

Courtesy: EOS Cast Part

Shell-making Pouring of Al


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Rapid Tooling – Metal Molds

Courtesy: Thermojet


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Secondary Processes: Vacuum Casting

RP master part (or mould) can e conver e o mou or par

by secondary processes:

• Mass casting(Epoxy/PU)

• Vacuum casting

• Metal spraying

(Keltool, low m.p. metals)

• nves men cas ng.

Vacuum casting machine


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Benchmarking of Routes

• Large number of direct and indirect routes for rapid tooling • Eac route i ers in terms o i e ity, inis , time an cost

• Systematic approach required to select the appropriate route.

SLA QC FDM Thermojet LOM Rubber mold

Courtesy: Naval Dockyard, Mumbai


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Benchmarking of Routes

• RP-based Tooling Routes: - enc mar ng rou es: s ep, or san cas ng .

- RT route capability database: accuracy, finish, time, cost.

- Route selection methodology.


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SLA:PP UV):S

Stereo LithographySLA 5000 (3D Systems Inc.)

Layer Thickness: 0.10 mm

Material

Part Liquid Photo-Polymers(UV curable Resins)

Support part material itself

Characteristics

Tolerance + - 0.36 mm

Roughness 6 μm

Time 4 hrs

Cost Rs. 8548


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SLA:PP UV):H

Stereo LithographySLA 5000 (3D Systems Inc.)


Material

Part Liquid Photo-Polymers(UV curable Resins)


Characteristics


Roughness 6 μm

Time 2.5 hrs

Cost Rs. 6628


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FDM:ABS/PC/PPS:S/H

Fused Deposition ModellingFDM Maxum (Stratasys, Inc.)


Material

Part ABS, Polycarbonate,Polyphenylsulfone

Support Water soluble

Characteristics:Tolerance + - 0.127 mm

Roughness 20 μm

Time 7 hrs

Cost Rs. 7230


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OBJ:PP:S

ObJet (PolyJet Modeling)Eden 500V (Objet geometries ltd.)


Resolution 600 D i

MaterialPart Photo polymer resins

Support Gel like proprietary material

CharacteristicsTolerance + - 0.46 mm

Roughness 15 μm

Time 7.16 hrs

Cost Rs. 5700


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TJP:WAX:S

ThermoJet PrinterThermoJet® (3D Systems Inc.)


Resolution 300 x 400 x 600 D i

MaterialPart Wax, Thermoplastic material

Support Part material itself


Roughness 3 μm

Time 6 hrs

Cost Rs. 3897


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SD:PVC:S

SoliDimension – 3D PrinterSD 300 (Solidimension Ltd.)


Material

Part Engineered Plastic(Polyvinylchloride)



Roughness 4 μm

Time 7.4 hrs

Cost Rs. 1654


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SLA:PP UV):S/H-VC:RTV:S-MC:EP:S

1. Stereo Lithography2. Vacuum casting with Silicone

3. Mass casting with Epoxy

Characteristics:


Roughness same as RP Part

Time 30 hrs (typical)Cost Rs. 2100


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Rapid Manufacture- Metal moulds

Direct Metal Laser Sintering

Distortion ± 0.2-0.5 mm

Roughness 1.6-2.1 µm

. - .

S ra Metal Toolin

Mold failed at 65KN clamping force.

Metal shell peeled off after 150 shots.

.

Courtesy: CMERI, Durgapur


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Case Study: Separator body

• Separator body of hydraulic filter assembly of armoured vehicle

Courtesy: CQAE, Pune

• Original part broken, drawings not available, replacement needed.


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Case Study: Art object


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Case Study: Pendant jewellery

• 22 Feb 2006, 2 p.m.: Start of modelling on FreeForm system• 23 Feb 2006, 3 p.m.: STL file transferred to Viper RP system

• 24 Feb 2006, 4 p.m.: RP model used for investment casting.

Gold jewellery pieces

use n ou n a

circa 1st century AD

Fine Jewellery,

Mumbai]


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Example- Hip prosthesis

Pelvic bone part

fabricated on

Resection line

,fit-checked withmatching saddle

.

Tumour boundary [Courtesy: Sushrut Surgicals, Mumbai]

• Surgery performed on schedule,

successful (first time in India).


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SUMMARY

Conventional route: machining: takes several weeks.

Rapid tooling can reduce lead time by 50% or more.

Types: direct (from RP), or indirect (RP+secondary process)

Issues: tool life (soft, bridge, hard), complexity, accuracy.

Techno-economic benchmarking to select the best route.

Future developments: better materials, speed, accuracy.

Documents

CDS10 Response RTC