Week Task
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
individual assignment: design a mold 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
Introduction
Pattern is the principal tool during the casting process. It may be defined as a model of anything, so constructed that it may be
used for forming an impression called mould in damp sand or other suitable material. When this mould is filled with molten metal, and the metal is allowed to solidify, it forms
a reproduction of the pattern and is known as casting. The process of making a pattern is known as pattern making.
The casting have five stages: (1)pattern making (2) moulding and coremaking (3) melting and casting (4) fettling and (5) testing and inspection.
Pattern Material
Following are the some basic pattern material available in market
1. Wood
2. Metal (CI, Brass, Al, White metal )
3.Plastics
4. Rubbers
5. Plasters
6. Waxes
Types of Patterns
Following are the some basic pattern material available in market
1. Single-piece Patteran
2. Split Pattern
3. Match plate Pattern
4. Cope and drag Pattern
5. Gated Pattern
6. Loose-piece Pattern
7. Sweep Pattern
8. Skeleton Pattern
9. Segmental Pattern
10. Shell Pattern
11. Built-up Pattern
12. Boxed-up Pattern
13. Lagged-up Pattern
14. Left and right hand pattern

Pattern Making Allowances
Pattern are not made the exact same size as the desired casting for several reasons. Such a pattern would produce castings which are undersize, allowance must therefore be allowed for shrinkage, draft, finish, distortion and rapping.
Following are the allowance need to consider during patterna making
1. Shrinkage Allowance

2. Draft Allowance

3. Distortion or camber Allowance

4. Rapping Allowance
Difference between 3D printing and molding
3D printing is an additive process. It manufactures objects by building them up layer by layer. We can watch this build process as it happens, which is useful when we’re testing a new design.

Injection molding makes use of molds. First, an object’s inverse is carved out of a material that is safe to handle the molten build material (the material the finished object is made of. Then, the molten build material is poured into the mold.
Once the material has cooled in the mold, the finished object is ready.

Another difference in them is the way of material is put into the machines, in injection moulding small piece of plastic called “Pellets” are used while in 3D printing “filament” is used.
Individual Assignment
The task for the week is to design a mold , mill it and use it to cast parts. So I am decided to crate the design our project i.e. smart kitchen chimeny and paste this casted part on the body of chimeny.
I am using FreeCAD software for the design. Basically in Fab Academy, split pattern are used to create the cast. So that why we need to split item in two parts, one is female part and second is male part. Then assemble is to create the cast.
Here is my design of male and female part.



Creating a Mold from the Machinable Wax
After design. I started to prepare the design for milling on SRM-20 Milling machine. Now this design is exported as a .stl file from the design software.This type we are used during 3D printing.

There are the three process during milling 1. Surfacing 2. Roughing 3. Finishing. For to create toolpath for miiling we have used Modella 4 software.let us see the stepwise procedure.
Firslty open the software>open the file (saved in .stl formatt)


Open the model option (on right top corner)>select the size and orientation and origin of the model>then select the material for milling (here we are using Modeling Wax)


Then click on Modeling Form option and check the parameter

Now click on New Process Creation> select the process we required>firstly we are going for surfacing so surfacing is selected> create the process

Select the cutting surface>then click on next

Select the tool > here we are using 3 mm diameter tool

Then set the area and depth for surface leveling

Then select the type of toolpath to create> here I am selecting X-direction

The set the cutting parameter> here only we have to check it and click on "Next"

Now enter the name of the process and when to create it

In the same way I am creating the three process> the software shows you the cuttting path on the material. Now set the X, Y and Z point for the tool on the material using SRM-20 V pannel.
Before this I have to paste the wax block on the bed of the machine and attach the drill bit. The first image shows the available wax for milling, second shown drill bit specification i.e. 1/8 inch Ti-Namite Coated End Mill is used.
and third image shown the hows the wax is pasted on bed so for pasting I am using extra glue, it has pasted with help of glue gun.



Now X,Y and Z axis of the tool is set on this material for milling using below SRM-20 V pannel

Now back to our Modella software>select the process>click on cut option> Following image shows the path for surfacing

The next image shows the path for Roughing operation.

The last image is shows the path for finishing operation

Now starting milling, one by one I am giving the operation as stated above

Around 8 hour I have required for milling and the wax after milling is here

Ohh..but there is two issue in male pattern. one is in air vent, the machine make the slot there and second one is the at the extruded circle, the material will not get properly remove, because the space available for drill bit is less than its diameter so it will not travel at there.

But the time required is too much so I decided to solve this here without new part milling. So I have mold some wax and fill it into the slot at air vent and for second issue I have the hot tool and remove the extra material from there. Now the pattern is ready
Fab Academy Course on Digital Fabrication by Nikhilkumar More is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Based on a work at http://fabacademy.org/2020/labs/vigyanashram/students/nikhilkumar-more/.
Permissions beyond the scope of this license may be available at http://fabacademy.org/2020/labs/vigyanashram/students/nikhilkumar-more//contact.html