Rapid Freezing Prototyping With Water(4PS09MCM02)

“Rapid freezing prototyping with water”Seminar on

Presented by

CHETAN P.MASKI.(4PS09MCM02)

2nd SEM M Tech, PESCEMandya – 571 401

OVERVIEW

INTODUCTION

PRINCIPLE OF RFP Concept of the technique Experimental system Building strategy

MAIN FEATURES OF RFP

APPLICATIONS OF ICE PATTERNS

ADVANTAGES OF RFP

CASE STUDY

CONCLUSION

1. IntroductionThe Solid Freeform techniques also known as Rapid

Prototyping or Layered Manufacturing . By using water as the material and rapid freezing as the

building method, RFP has the potential to build ice patterns

with good accuracy and surface finish.Easy to build different colorized portions, and transparent

parts are additional properties that are good for both tooling and design visualization applications.

The popular applications of this technique are visual aids, Rapid tooling etc.

2.Principle of Rapid Freezing Prototyping

1. Concept of the technique 2. Experimental system3. Building strategy

Principle of Rapid Freeze Prototyping

2.1. Concept of the technique

In the continuous process, the liquid material is continuously extruded from a nozzle to the surface of the substrate or the previously built layer.

In the drop-on-demand process, the liquid material is ejected to the substrate surface or the previously solidified ice surface drop by drop. When the material touches the surface, it rapidly freezes and firmly sticks to the sur face.

Fig shows, The schematic drawing of strands for different ratios of material flow rate to XY moving speed

In continuous process, the ratio of the in-nozzle material flow rate to the nozzle XY moving speed is critical. A ratio too large may cause failure in controlling its out-nozzle flow along the ice surface; a ratio too small may cause discontinuity in the freezing strands, hence the normal ratio must be maintained in order to achieve the proper deposition.

2.2 Experimental system RFP experimental system structure

1. Material extruding subsystem. 2. Material deposition head.3. Three-dimensional positioning

subsystem.4. Freezing chamber.

The main components of the system are:

Motor driven extrusion head

The material extruding system extrudes and deposit continuously a desired amount of water onto build surface.

In motor driven method , water is contained in the cylinder and is continuously extruded by the piston. The motion control card generates control pulses according the control software program, and the pulses applied to the motor controls the material flow.

Nozzle head design and multi-nozzle arrangementThe material depositing head may have multiple nozzles mounted on one head, which are designed for depositing building material, support material, color material, and have different nozzles to improve build speed.

For the multi-nozzle head, the nozzle selection can be accomplished by activating a certain electro magnet. In order to prevent the material in the head from freezing, some heating components are needed to keep it at the desired temperature.

2.3. Building strategyThree different part build strategiesThe part boundary is built with smaller aperture nozzle (for

part accuracy& surface finish)and interior is built with larger aperture nozzle,(for build speed)both nozzles perform continuous deposition.

The part boundary is built with drop on demand nozzle (for part accuracy& surface finish)and interior is built with continuous nozzle(or build speed).

The part boundary is built with smaller aperture nozzle, the interior weaves built with medium aperture nozzle and then the interior spacing are filled with a large aperture nozzle, here all the three nozzles are of continuous kind.

Main features of rapid freezing prototyping RFP is a cheaper and cleaner prototype

building deposition technique .RFP has the potential to build accurate ice

parts with excellent surface finish.The ice part made by RFP is easy to remove

from a mold simply by warming it up and making the mold dry.

The ice parts are easy to join due to its self welding property. hence a very complex parts can be made in several portions and then joined together.

RFP does not have the problem of heat accumulation.

Main features of rapid freezing prototyping It is easy to build colorized parts with RFP

process. Different portions of a part can be built with different colors of same material.

During material freezing in RFP, the material expands and causes compress stresses in the part. The expansion of the material can be compensated by properly selecting the interior fill spacing.

Applications of ice patterns VisualizationRFP can easily build colorized and transparent ice parts. A

model of diseased organ can help the surgeon to prepare the operation better.

By utilizing RFP, a colorized ice model can be made with the CT scanning information, with different portions in different colors. This colorized ice model can provide the surgeon with more information about a disease focus. The transparent feature of the ice model makes it possible to see the internal structure of the diseased organ.

Rapid tooling Silicone molding with ice patterns at low temperature is

feasible.

Advantages of Rapid freezing prototypingHigh precision, when using ice prototype in

investment casting, as ice pattern shrinks not like wax patterns which expands when heated to losing, it wouldn’t crack the ceramic shell, in turn the precision and smoothness of ceramic shell could be kept to the most extent.

Low cost, because water is so cheap and widely available, so that the material cost is negligible.

No pollution, The building process and building material have no negative impact on the operator and environment.

Case study Background and Introduction During recent ten years, the combination of RP and Investment

Precision Cast technology becomes an effective approach to produce metal tools quickly.

The Center for Laser Rapid Forming (CLRF) of Tsinghua University in China has studied and developed RP and RT technology since 1992. In the course of developing Melt Extrusion Modeling (MEM) process, when applying prototype of MEM to Investment Casting, the thermo-plastic material expands and then cracks the ceramic shell during the course of “losing pattern”, the expansion of the prototype may even breaks the ceramic shell completely. Considering this disadvantage of applying prototype of MEM to investment casting, the CLRF in Tsinghua University started to use water replacing thermo-plastic materials and put forward a new RP process-Rapid Prototyping Technology of Low Temperature Ice Forming.

Cont…Rapid Tooling. Similar to “losing Wax”

Investment Casting, using the ice pattern instead of the wax pattern, metal parts can be cast through Investment Precision Casting at low temperature. Advantages of ice pattern casting include easy pattern.

(a)Ice prototype (b)Ceramic shell

Cont…

Ice link rod, Half curve, Spiral solid in sin curve 

conclusionRapid Freezing Prototyping is a novel solid freeform

fabrication process which has some advantages and disadvantages.

The major disadvantage is that it needs a low temperature operating environment.

However, its advantages including clean and cheap material, good surface finish, potentially good accuracy, easy pattern removal and joining, easy expansion compensation, and fast building speed make it a good choice in some application areas.

Silicone molding with ice patterns at low temperatures is feasible.

Thank you