Week 13. MOLDING AND CASTING

Objectives

group assignment:review the safety data sheets for each of your molding and casting materials, then make and compare test casts with each of them. Compare mold making processes

individual assignment: design a mold around the process you'll be using, produce it with a smooth surface finish that does not show the production process toolpath, and use it to cast parts

Group Assignment:

As part of the group assignment, we reviewed the materials available in the lab and went through their safety information, mixing ratios, curing times, and handling requirements. The materials we worked with were Aditya Silicone Rubber RTV - 1010, Aditya Ultra Clear Cast Epoxy - 37, and Mould Releasing Spray 1083.

We also made test molds and casts to compare how the different materials behave. I learned how important accurate measurement, thorough mixing, and vacuum degassing are for achieving good results. Aditya Silicone Rubber RTV - 1010 produced flexible molds with good detail capture and Aditya Ultra Clear Cast Epoxy - 37 created clear casts but required extra care to avoid trapped air bubbles. Mould Releasing Spray helped with easy demolding and prevented the cast from sticking to the mold.

Material	Purpose	Mixing Ratio	Working Time	Curing Time	Hardness	Notes
Aditya Silicone Rubber RTV – 1010	Mold Making	Silicone + 2.5–3% Hardener	8–10 min	12–24 hrs	Shore A 10	Flexible mold material with excellent detail capture and easy demolding.
Aditya Ultra Clear Cast Epoxy – 37	Casting Material	Part A : Part B = 100 : 50	Moderate	12–24 hrs*	Rigid after cure	Transparent, low-viscosity resin that produces clear casts with a smooth finish.

Curing time may vary depending on the volume of resin being cast and ambient conditions.

This activity helped me understand the differences between mold-making materials and casting materials, along with the practical workflow involved in molding and casting before moving on to my individual assignment. It also helped me understand the importance of material selection-typically using a harder mold to cast softer materials for easier demolding, and using flexible mold materials such as silicone when casting harder materials with complex geometries or undercuts, allowing the finished part to be removed without damage.

To know more, visitGroup Assignment.

Individual Assignment:

Design a mold around the process you'll be using, produce it with a smooth surface finish that does not show the production process toolpath, and use it to cast parts

Extra credit: use more then two mold parts

— Types of Molding

TYPE OF MOLDING	DESCRIPTION
Injection Molding	Molten plastic is injected into a mold under pressure and cooled before ejection.
Blow Molding	Used for hollow plastic products such as bottles and containers.
Compression Molding	Material is placed in a heated cavity and compressed into shape.
Rotational Molding	Creates hollow parts by rotating a mold while resin coats the interior.
Extrusion Molding	Material is pushed through a die to create continuous profiles.
Thermoforming	Heated plastic sheet is shaped over a mold and cooled.
Casting	Liquid material is poured into a mold and solidified.
Die Casting	Molten metal is injected into a die under pressure.

— Materials Used for Molding

MATERIAL	DESCRIPTION
Plastics	Thermoplastics: PE, PP, PS, PVC can be melted and remolded. Thermosetting Plastics: Epoxy, phenolic and melamine become permanently set after molding.
Rubbers	Natural Rubber: High elasticity and resilience. Synthetic Rubbers: Silicone, neoprene, nitrile and EPDM for heat, oil and weather resistance.
Metals	Aluminum: Lightweight and corrosion resistant. Steel: Strong and wear resistant for molds. Zinc / Magnesium / Copper Alloys: Used in die casting for precision parts.
Ceramics	Porcelain: Heat resistant ceramic for specialized products. Alumina & Zirconia: Used where hardness and thermal stability are needed.
Composites	Fiber Reinforced Polymers (FRP): Fiberglass, carbon fiber and aramid composites with high strength-to-weight ratio.
Foams	Polyurethane Foam: Cushioning and insulation products. Polystyrene Foam: Used for packaging and insulation boards.
Glass	Borosilicate Glass: High thermal and chemical resistance for labware, optics and lighting components.

Designing Molds

When designing molds, consider the following factors:

Important Things to Remember for Silicone Mold Making

• Use a simple design so the mold can be removed easily.
• Avoid shapes that can get stuck inside the mold.
• Make sure the master model has a smooth surface.
• Keep the mold thick enough so it does not tear.
• Add small air vents to help remove trapped air bubbles.

For Molding and Casting iam trying to make Stamp . to make mold i created a simple design through fusion 360

Fusion

using circle spline tool i created a simple shape of stamp

using revolve option i created 360 degree of model

I give fillet for avoiding sharp cut i give fillet 5mm

then i created new component of 5mm height for making stamp logo

for creating logo on stamp I imported svg file using import svg's

To insert svg select folder from my computer to insert

next need to arrange svg accordingly

then I extroded svg 1mm

then i planed to 3d print logo using 3d printer.then i made 2 components

Slicing and Printing

Here, I am trying SLA printing, so I used the ELEGOO Satellite application for the mold-making process. This process was carried out by Amaljith A.M.

I imported the mold design files into the slicer software and arranged them on the build plate for printing

I generated automatic supports to hold the models securely during the resin printing process

I checked the support placement from different angles to make sure all parts of the models were properly supported

After confirming the model orientation and support settings, I sliced the files to generate the printer-ready output

I reviewed the support structure closely to ensure the models would print successfully without deformation or failure

I previewed the sliced layers to verify that the models and supports would print correctly before saving the final file

I examined the layer-by-layer preview to confirm that the sliced model would be printed accurately from start to finish.

The slicing settings were finalized with a layer thickness of 50 um, resulting in a total of 1201 layers for the print.

volume:22.100 ml

Weight:25.416 g

Layers:1201

Layer thickness: 50 um

Print time: 1 hours 23 minutes

I selected the ELEGOO Saturn 4 Ultra printer and Black ABS-Like 3.0 Pro resin from esun before starting the slicing process.

I transferred the sliced file to the ELEGOO Saturn 4 Ultra printer through the network connection to begin the printing process.

printing started

mold after printing

Using a scraper and isopropyl alcohol, the model was removed from the build

while removing from the build plate some damage was caused by the scraping process.

after removing the model from the build plate next need to keep model in uv chamber to cure the model with out cure model may get soft or deform

for cureing the model i put temperature at 35°C and exposure time at 5 minutes

this is how looks after curing

after curing I made rectangular shape box for molding silicone size of 55mm x 55mm x 60mm after that i 3d printed the box with 1mm wall thickness 5% infill with esun pla white filament

using double side tape to secure the model in the mold i stick the model to the base

Remove the sticker from the model and fix model centre of the box

Silicone Molding

1st we need to know the volume of silicone required for the mold

add water into box

keep a plastic transparent drinking glass on top of measuring scale make sure scale is in 0 position

then transefer water to the glass

then using permenent marker mark the water level on the glass

then remove the water from the glass and fill it with silicone up to the marked level

next we will mix the silicone with the curing agent

for that we need to find the correct mixing ratio for that Calculator Soup

To calculate the required hardener amount, I used a ratio calculator. The original silicone mixing ratio was 1000 g silicone : 25 g hardener. Since I only needed 168.3 g of silicone, I calculated the corresponding hardener amount using the same ratio.

Calculation:
1000 : 25 = 168.3 : X
X = (168.3 × 25) / 1000
X = 4.21 g

Therefore, for 168.3 g of silicone, I added 4.21 g of hardener to maintain the correct mixing ratio.

Now I will proceed with the silicone molding process.Here Iam using Aditya Silicone

Mixing ratio: 1000:25

Viscosity=10000

Curing Agent / Hardener Ratio=2.5 to 3 %

Working Time 8-10 Minutes approx

Curing Time 12 to 24 Hours

Colour Milky

then i added 4.21 g of hardener to the silicone

then i mixed the silicone and hardener properly for 5 minutes with a stirrer

next we need remove the air bubbles from the mixture so that we need to keep mixture in a vacuum chamber. to keep clean chamber iam using food wraping film

then i put the mixture in vacuum chamber for 3 minutes to remove air bubbles

i sparyed releasing agent to the mold it will help to remove the cured silicone

Note: I forgot to take image of the releasing agent sparying

after removing air bubbles, I will pour the mixture into the mold

pour the mixture into the mold slowly to avoid trapping air bubbles

after filling the mold, I will tap the sides of the mold gently to help any remaining air bubbles rise to the surface and escape

after filling the mold, I will let it cure for 12 to 24 hours

after 24 hours, I will remove the cured silicone from the mold,for removing using pen knife I cut 3d printed mold

using air compressor to remove the cured silicone from the mold

this how I removed the cured silicone from the mold

Next we need to fill water inside silicone mold for resin casting

Repeat the process done for silicone molding

fill water into small containers to identify volume

then mark using papper tape for refference

next we need to fill resin up to marking

then i added hardener to the resin 2 droup

Note: here in resin i added 2 drops of black pigment iforgot to take a picture then i fill resin to silicone mold

after filling the resin, I will let it cure for 12 to 24 hours

after 24 hours, I will remove the cured resin from the mold it will come out simple we can remove it by hand itself

Hero Shot 1

mistakes

there are some air bubbles trapped in silicone mold. it effect the final project

how to improve

while filling silicone mold shake well to avoid air bubbles

while designing the mold ensure proper venting to allow air to escape

while filling resin into silicone mold shake well to avoid air bubbles

next time i will take care of this mistakes

Method 2 FDM Printing

Note:

For the Molding and Casting assignment, I tried two approaches for mold making: FDM and SLA printing. I created two different products, but I made a silicone mold for only one of them (sla)

Here iam trying to print a part using FDM printing For that Here I choosed

Now I will proceed with the silicone molding process.Here Iam using Bambulab A1 printer

Esun

Pla Filament is used to print

For slicing and printing here iam using Bambu Studio

3D Printing Strength Settings

• Sparse Infill Density: 15%
• Sparse Infill Pattern: Grid

Advanced Settings

• Infill/Wall Overlap: 15%

I used a 15% grid infill pattern to provide sufficient strength while reducing material usage and print time. The infill direction was set to 45° to distribute internal support evenly throughout the model.

Support Settings

• Support Enabled: Yes
• Support Type: Tree (Auto)

I enabled tree supports with a threshold angle of 40° to provide support for overhanging areas while minimizing material usage and making support removal easier after printing.

ready for printing

after printing

Note:

saheen instructed me to paste resin on top of the printed part

Resin Casting

I used gloves and safety equipment while handling the resin.

I ensured proper ventilation in the workspace.

for casting i took Stratasys J55 Primeexpired resin took for casting

before pasting i cleaned mold with isopropyl alcohol

I took small container for mixing the resin and took only the required amount resin

on top of table I sticked paper tape to avoid resin from spilling

Using uv light i tryed to cure the resin but it didn't work as expected

I put model in uv chamber in different temperatures and times still didn't work

Note:

the resin didn't cure I dont know exactly why but i Think it's due to the expired resin and the wavelength of the uv light need to cure also may different

Note:

I again 3d printed the part to try again with out resin coating but I didnt get enough time to do.i will do in future

then I take my resin mold and 3d printed fablogo I stick together useing double sided tape makeing stamp.Note:I dint take sla printed logo because the logo didnt come i expected and finshing of it was not ok for me

I put small clay on top of a plane plate then ipressed to create the desired shape and it workes

Final Output

Download Files

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