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Rapid Prototyping?

Rapid Prototyping?

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Rapid Prototyping?

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  1. Rapid Prototyping? • RP (Rapid prototyping) ? • 3차원 CAD모델로 부터, 실물 모형을 신속히 제작하는 기술 • 주로 Layered manufacturing technology 사용 (2차원으로 단면 형상들을 적층하여 3차원 형상을 제작) • 기능성 모형(Functional prototyping)을 만들기 위해서는 2차 처리 필요 • Coating, 가공등 • RP & M : Rapid Prototyping & Manufacturing • RT : Rapid Tooling  RP를 이용한 간이 금형의 제작 RP system (광경화 시스템)

  2. 대표적인 RP 시스템

  3. Basic process of RP Solid model Slicing into a series of parallel cross-section pieces Model building

  4. XY Scanning UV Laser Beam Elevator Top of the Liquid Photo-curable Resin (Liquid) Cured Resin Vat SLA (StereoLithography Apparatus) • Vat filled with photo-curable liquid resin and the elevator table set just below the surface of the liquid • Computer controlled optical scanning system directs and focuses the laser beam so that it solidifies a two dimensional cross-section on the surface of the photopolymer • Elevator drops enough to cover the solid polymer with another layer of liquid • Process continues building the part from bottom up, layer by layer until the part is completed Platform

  5. SLA Process

  6. Support structures (SLA)

  7. SLA 특징 • Most popular • Undercut 형상  support structure • Post-curing 필요

  8. SLS (Selective Laser Sintering) • Mechanical roller spreads powder across the top of the elevator • Heat generating CO2 laser traces the shape of each cross-section, fusing powder in the thin layer. Unsintered power thus acts as support for the part • Mechanical roller then spreads more powder across the top of the finished part and the laser traces the next cross-section • Process continues till the part is formed

  9. SLS process • Powder 사용 • Metal or plastic • Support structure 불필요 • 사출금형 등의 제작 가능

  10. Solid Ground Curing - 1 • The image is electrostatically created on a erasable glass plate and developed using a recyclable toner (or LCD 이용 가능) • Image mask is then aligned with the work piece • High power light shines through curing all unmasked area • Meanwhile glass plate is cleaned and ready for new image • Aerodynamic wiper removed all uncured resign

  11. Solid Ground Curing - 2 • Liquid wax is then applied to fill up all the gaps left behind by uncured resin • A plate press then instantly solidifies the wax • The layer is then milled through to give a constant increase in height • The rest is lowered by 1 layer height before another layer of solidifiable resin is applied • Process is repeated until the prototype is complete

  12. Solider system (SGC) • Laser beam 대신 lamp 사용 • Post-curing 불필요 • Support structure 불필요 (빈공간은 wax로 채움) • SLA 보다 정밀, 복잡함.

  13. FDM (Fused Deposition Manufacturing) • Filament in dispenser heats and melts the wax/plastic • Dispenser extrudes a thin layer of wax/plastic just above of its melting point • Computer signal to the dispenser to deposit the wax/plastic at the desired position • Deposited wax/plastic solidifies to form a hardened layer • Process is repeated till the part is formed • Support is then removed to reveal the prototype

  14. FDM process

  15. 3D Printing

  16. LOM (Laminated Object Manufacturing) • Laser cuts profile of 2-D shape and external boundary • Hot roller presses over paper onto a previous layer and melts glue so that the two layers are adhered together • Platform lowers and process repeats till the entire part is built • Excess blocks of material are removed to reveal desired part

  17. LOM process • Subtractive process • 재료와 접착제 교번  불균질 • High potential accuracy (수축없음) • Relatively larger size part

  18. Removing tiles (LOM)

  19. RP 응용 사례 SLA로 제작된 펌프 임펠러 (impeller)의 test functional model SLS로 제작된 주조용 core

  20. RP 응용 사례 생체 폐의 CT 촬영자료 에서 얻어낸 SLA 모형 Alumina part produced in LOM process

  21. RP process from CAD model to RP machine 대상 모델  단면화 작업 (slicing)  주사경로 생성작업 (scanning)

  22. 단면화 (slicing) 방법의 발전 Uniform 단면화 단면간의 간격 일정 Adaptive 단면화 cusp height가 일정하게 단면 두께 조정 Direct 단면화 CAD 데이터에서 직접 단면정보 생성 Direct & adaptive 단면화 정밀도 및 build time 향상

  23. Adaptive slice thickness Effect of adaptive slicing on part accuracy Build direction Constant slice thickness

  24. Uniform & Adaptive 단면화 방법 비교 Sample model : Crank model(폭 98mm 높이 21mm) • Uniform 단면화 • Adaptive 단면화

  25. Scanning pattern Raster scanning Model-based scanning Directional scanning

  26. RP Data Format: STL (STereoLithography) • STL File Format Tessellation of a sphere

  27. Limitations of current RP systems • Size of part • 대형 부품의 제작이 어려움 • Accuracy • 계단 형상, 수축, 왜곡, 비틀림 • Material • 실제 부품에 사용할 소재와의 차이 • Functional model로서의 역할 부족 • Durability • Cost • Equipment is still expensive • Operating cost • Laser • Resin • Model preparation • Operator • Speed : really rapid?