Moulding & Casting

"Hi everyone ,Week 15 moulding and casting.This moulding and casting week might be very challenging for me.As i am new to 3D design and all .So i am looking forward to learn more about 3D design and then most important thing is how to do mould and cast the given design.Again in this week i will learn the another angle of SRM-20 to used for moulding.Also the material used for moulding as well.Overall this week is one of the challenging for me .So lets start .....!.

    Group assignment

    1. Review the safety data sheets for each of your moulding and casting materials, then make and compare test casts with each of them

    Individual assignment

    1. Design a mould around the stock and tooling that you'll be using, mill it (rough cut + (at least) three-axis finish cut), and use it to cast parts


moulding & Casting

moulding is the process of of manufacturing by shaping liquid or pliable raw materials using a mould or matrix, which have been made using a pattern or model of final object. But, Casting is a manufacturing process in which a molten metal is injected or poured into a mould to form an object of the desired shape.
So just to simplify i classified this week work in four categories.

  • Step 1. Create a Positive mould Model
  • Step 2: Mill the Wax on the SRM20
  • Step 3: Make a mould from the Wax
  • Step 4: Cast Final Object
  • Designing a mould (Solid work 3D design)

    The 3D model which i am going to design is an 3D dimensional object that i want to reproduce with the mould making and casting process.Actually from this 3D object i design mould and cast are made.One thing i need to point out here that how complicated the model is determines the kind of mould technique that must be used to successfully cast the object.In other words,if you look into a mould straight from above, you should be able to see the whole inner surface, with nothing hidden “behind a corner”. These overhangs could later cause the master model or final cast to become stuck in the mould.

    The first step is to design a 3D object.So i decided to used solid work for my 3D design since i used it before.I planned to 3D sketch of Piston.To decide this design my co-fab mate Tejeswini helped me .She shown me actual where we used this piston and told me application of in valve used in water flow design.So first i need to draw the sketch considering the dimension of mould.I brought my mould and measured it first and accordingly start sketching my 3D design.So lets see the screenshot which i have taken.

  • Outer Dimension
  • 70x30x80mm
  • Inner dimension
  • 60x30x80mm
  • Box Extrude-1
  • Cut extrude-1
  • Revolve2
  • Revolve3
  • Box-extrude2
  • Final sketch
  • Procedure to Mill wax on SRM-20

    After i design the 3D sketch in solid work now the second step is to mill the sketch.The procedure to milled the 3D sketch is such that first i need to configure the V-Pannel of SRM -20 i.e.Set the XY and Z origin.Then open the Modella software to create the rml file for SRM -20.In short this part is classified into two sections

  • Configure the V-Pannel of SRM-20
  • Create the rml file using Modella software
  • SRM-20 Compact Milling Machine Features

    The SRM-20 portable milling machine can mill a broad range of materials, including modeling wax, chemical wood, foam, acrylic, poly acetate, ABS and PC board. The following items are just some of the prototypes and applications made possible:>

  • Product inventions
  • Wax moulds for casting
  • Tools and machinery
  • Relief plaques and graphicsVehicle prototypes
  • Game and model parts
  • Art and design concepts
  • ...and much more!
  • The wax block is properly placed on sacrificial surface of SRM-20 milling machine with single sided tape underneath and used glue gun to tapped the wax to fixed the block.

  • Set the XY to origin
  • Set the Z to origin
  • Design steps in Modella

    As Modella software is used to generate the toolpath for the SRM -20 machine.I need to go through following three steps here

  • 1.Surfacing
  • 2.Roughing
  • 3.Finishing

  • Repeat the following steps for surfacing,roughing and finishing

  • Go to file -> Select the Roland SRM-20 machine
  • Go to file again -> Click on Open -> Select your Stl file -> Open
  • Go to Model -> Size and orientation -> Select the top surface as per your design ->Click OK
  • Model -> Size and orientation -> Go to origin
  • Select the origin according to your design
  • Go to modeling form -> Keep the default setting
  • Click on OK
  • For the first time Select the surfacing option
  • Then do next steps as follows->Click next
  • Click on NEXT
  • Choose the tool to used for cutting the process
  • I select the 3mm tool for cutting (it may be different for yours)
  • Click NEXT
  • Click NEXT
  • For surfacing options it automatically select the scan lines options
  • Click Next
  • Click Next
  • Click finish
  • After performing above steps roughing toolpath will generate
  • Click on cut menu
  • Click OK
  • Click on continue
  • Machine begin...........Repeat the above procedure for surfacing and finishing as well...........Finally successfully milled the wax
  • Carving the mould in wax

    In the following video you can see the two mould (side 1 and side 2) getting surfacing,roughing and finishing as well.

    #1.Video demonstration for surfacing the mould:

    #2.Video demonstration for roughing the mould:

    #3.Video demonstration for finishing the mould:

    roughing the mold

    Making the mould with silicone rubber

  • Step 1
  • Here is mouldsil 15 part A which i am going to used.

  • Step 2
  • This is Catalyst 16 part B which is being used as hardner.

  • Step 3
  • Then i put all necessary things on one platform like mould,silicon rubber,hardner,cups,water,pot etc.

  • Step 4
  • So first i put the water into the mould to understand how much total liquid material(mixture of silicon rubber and hardner) is enough to cover whole mould area.

  • Step 5
  • 61gm water ie required to fill the whole area.

  • Step 6
  • Then take 60% of 61gm mouldsil first into the glass.

  • Step 7
  • Immegiately take 40 % of 50 gm catalyst as herdner and put them into mouldsil and sturred it fast.

  • Step 8
  • Mixed hardner i.e.catalyst 16A into the mouldsil.

  • Step 9
  • Immediately filled whole mixture into the mould and then put it into the sterrer to remove the bubbles.

  • Step 10
  • After keeping it for few hours f inally i removed it from mould and and it is perfectly clear.

  • Step 11
  • As you can see i have made two rubber part.After pouring the materail this part need to be fixed over each other. To fixed the part properly i extrude the hole below the surface for first part and for the second one i extrude the hole above the surface which you can see in the image as well.


    Now time for casting the mould.To do casting we need to folow some steps as well.So i listed out what we need to do proper casting of mould?

  • Material:I have decided to used hydrostone powder
  • .

  • So I took hydrostone powder for casting
  • .

  • Since i get to know that hydrostone powder does not required hardner instead we can used water as well
  • So i mixed the water with hydrostone powder
  • After that i mixed hydrostone powder with water
  • .

  • Remember while doing so don't sturred in reverse direction.
  • Finally i need to pour the mixture (hydrostone + water) into the rubber mould which i made and shown above as well.Pouring should be smooth and put it into rubber mould and wait for few hours
  • After pouring the mixture into both rubber parts i joined both of them onto each other and wait for few hours
  • Problem faced: In the first attempt i removed material in just 1hr and what i found is that cast wont get come up properly and got borken once again i repeat the abobe procedure and wait for sufficient amount of time
  • After waiting for around 6-7 hours the time is come to see how the cast is done
  • Then i took off the thing and finally i made my cast which i wanted
  • Hero shot:

  • Happy to see my cast design after taking huge efforts starting from design mould and finally cast as well
  • Learning outcomes

  • First i design the 3D object of my mould
  • Then i milled the 3D object using SRM -20 and uderstand design steps for how to used the modella software
  • Then i made rubber mould using MOLDSIL 16A and understand the procedure of it
  • Here i also get to know proper concentartion of material during rubber mold and casting is more important
  • Understand how to used hydrostone powder for casting the objects
  • Finally understand how to make physical structure of 3D object using moling and casting method
  • Group assignment

    On Thusday morning, our week mentor give us brief idea about this week.During this discussion she actually introduce us about different material ,What is moulding and casting,Design,installation procedure and the process as well.After this brainstrorming she asked to do our group assignment work for that i need to read the datasheet of silicone rubber and thentry to explain others mates as well.So i start reading the things about silicone rubber which i mentioned below.

    What is silicone rubber?: Silicon rubber is a thrmoset process that actually combine two compound together and later you need to heat cured in the mould using different catalyst options which i mentioned below.After doing all this exersize it will result into liquid silicone rubber.Now to undestand in detaled about the silicone rubber i finally go through the data sheet mouldsil-15 PLUS i.e.High Performance Silicone Rubber for Long Lasting Flexible moulds )

    mouldsil-15 PLUS(High Performance Silicone Rubber for Long Lasting Flexible moulds )

    Introduction:mouldsil-15 PLUS is a premium grade condensation curing type Silicone RTV, recommended for mould making applications. This is a flowable grade, having high mechanical strength and cures with various catalyst options (depending on the application requirements) at room temperature to a flexible elastomer, well suited for detailed and exact reproduction of artifacts, figures, architectural items and similar objects. mouldsil-15 PLUS will reproduce the finest detail of the master and is suitable for a variety of art related and industrial applications such as mould making for reproducing prototypes, furniture, architectural items and sculptures.

  • Datasheet of moldsil - 15A
  • Features:

  • Flowable type high strength silicone rubber curing at room temperature – Excellent detail reproduction.
  • • Good mechanical properties - leading to long service Life.
  • • Highly elastic and excellent release properties – for easy de-moulding.
  • • Excellent chemical resistance – compatible with most moulding materials with long service life.
  • • Vertical surface replication with the use of a thixotropic additive Thixopol-88.
  • CATALYST OPTIONS:There are three types of catalyst options.

  • CAT-24 : Slow catalyst: Catalyst with long work life for slow demoulding (useful in pouring application). Takes about 24 hours at room temperature for complete curing.
  • CAT-16 : Medium speed Catalyst : Catalyst with moderate work life for fast demoulding. Takes about 16 hours at room temperature for complete curing.
  • CAT-04 : Rapid Catalyst : demoulding catalyst with short work life for high speed mould making.(useful for brushing). The use of this catalyst results in durometers 5-10 points higher than CAT-16. Takes about 4 hours at room temperature for complete curing.

  • Surface Preparation:
  • Mixing of Components:
  • De-aeration :
  • This system is sensitive to temperature and humidity
  • Pouring the Mix and Curing:
  • How to mix silicone rubber?

    HANDLING PRECAUTIONS AND SAFETY:mouldsil-15 PLUS contains constituents that have been found to be safe. Hence special handing precautions except general industrial hygiene need to be followed. Catalysts (CAT-24, CAT-16 and CAT-04) contain organo-tin compounds and are flammable and might cause irritation upon contact with eyes and skin. Adequate protective measures are recommended. Refer to Material Safety Data Sheet (MSDS) for safe use of the product

    Procedure to used mouldsil and catalyst

  • Step 1
  • Here is mouldsil 15 part A which i am going to used.

  • Step 2
  • This is Catalyst 16 part B which is being used as hardner.

  • Step 3
  • Then i put all necessary things on one platform like mould,silicon rubber,hardner,cups,water,pot etc.

  • Step 4
  • So first i put water into the mould and measure it as well which is 50gm(100%)

  • Step 5
  • Then take 60% of 50gm mouldsil first into the glass.

  • Step 6
  • Immegiately take 40 % of 50 gm catalyst as herdner and put them into mouldsil and sturred it fast.

  • Step 7
  • Apply the mixture first into corners

  • Step 8
  • And finally put all into required area of mould.

  • Step 9
  • Removing few bubbles using sterrer.

    For more details click on group assignments page Group assignment

    Learning outcomes:

  • Understand how to used SRM 20 for making the 3D design mould
  • Understand procedure for surfacing,roughing and finising the mould using Modella software.
  • Understand how to used silicon rubber to create a longlasting mould.
  • Understand how to used hydrostone powder for casting the applications.