I have design my mold of ‘WAZIR’ (Queen) in solid works. This software is very user friendly for me so I have used this software for designing mold. While designing the mold I have face many problems. First I was unknown about how to design the queen in the box. Then first I have select the top plane and have drawn the rectangle with 70 X 80 mm dimension and have extruded it with 30mm thickness. These are the dimensions of rectangular box of machinable wax. Always we have to consider the dimensions of the wax we are going to use for mold preparation. It is important while designing the mold in any designing software.

In my design I have shown the ‘registration marks’ and ‘air vent’. We have to design two mold designs in first design I have ‘Extruded’ the registration marks by 5mm thickness and in second half I have cut that holes by 5mm depth. This is because when we prepare negative molds out of it, by using flexible molding material like silicon rubber with hardener we have to fit these two molds with each other. There these registration marks help us to fix the molds with each other. And second thing that I have consider in my design is the position of air vent. When we poor the casting material in to the mold we should make sure that the air should not any presence of air otherwise it will create air pockets in the casting material when it gets solidify. Also I have made the position of air vent with some angle so that minimum material will get inside the cavity while preparing the casting product.

Open ‘ Modela player 4’ we see the following window on the screen.

To start milling operation we have to go to file menu on the menu-bar and select ‘Machine selection’ option from drop down menu. Check the following settings like machine name – ‘SRM-20’, spindle unit - standard, printer name – ‘Roland SRM-20’.

Click on ‘open’ option and select the .stl file from the location we have save the file.

In the above image we see 4 options we have to use for ‘Operating player 4’. Select First option ‘Mold’ and select following options length in X, Y and Z direction. When we select the file for milling in the ‘Modela player 4’ , the software takes the dimensions automatically.

Next we have to check the orientation of the object we are going to print. This is the important step because generation of tool path and in which direction the tool will travel is depend upon how we set the orientation of the object and then press ‘Ok’.

Then click on ‘Origin’ and select the position of origin. Once we select the origin in the window the tool will always take the same path from the origin while starts its operation. Here I have selected front left position of the origin so that my tool will always take the path from the same point. As shown in the following image.

Then go to ‘New process creation’. In this we have to select the operation which the tool will perform on the object (Machinable wax). At the beginning we have to perform surfacing operation to cline the surface of the wax. In this operation the tool will remove 3mm layer of the wax from the surface. Then press on next button.

Here we have selected the surfacing operation therefore the software will take the type of tool path as ‘Scan line’ and we can see in which manner the tool will travel to the right hand side in the window.

Now click on ‘Molding form’ and click on ‘manual’. By selecting this option we can change the dimension manually. Next we have to check the depth of tool that is at which depth the tool will go inside the wax.

Again press on next and check whether ‘Top [+Z]’ option is selected, again press next. Now select the diameter of the tool which we are using for the operation.

Normally at the first when we perform the surfacing and roughing operation, we select ‘Flat end tool’ and we have the ‘flat end tool’ with 3.17mm diameter. But in the drop down window we don’t have the specific diameter of the tool hence I have selected 3mm diameter of the tool and press next.

Press on next and set the area and depth of surface levelling. Next set the cutting parameters and check tool diameter be 3mm. Here we are performing surfacing operation Z-speed is 10 mm/sec the speed is same for roughing. XY speed is 24 mm/sec and it will remain same for surfacing and roughing.

After performing all the steps mentioned above, tool path is created as shown in the image below. The blue line shows the generated tool path and it will also shows the direction in which the tool will travel on the path.

The blue area in the window shows the mold we will get after removing the wax by tool. Also we can see the list of operations that we have selected, in the model tree on the left hand side of the window.

When we are performing next operation suppose roughing operation we have to delete the previous operation let us consider the previous operation as surfacing.

This is important because, in each operation the different toolpath is get generated, it may be possible that the machine will follow the path that we have replaces by another path. It is also easy to visualise the on-going operation on the machine for the person who is operating the machine if only that operations are selected in the list which will perform by the machine.

As I mentioned above we have take a reference of ‘User manual’ of ‘SPM-20’ for operating the function of mold making. In this manual it is mention that while we set the origin using ‘v-panel’ we have to select ‘machine co-ordinate system’. But when I have select this option, tool was not following the path. The tool was only moves in the Z direction and it travels the downward path and suddenly it falls on the sacrificial layer, it also damages the tool tip. At worst case the tool will breaks.

But when I have selected ‘User co-ordinate system’ option, the tool was follow the path which we have generated for the operation.

Befor going for the final stage of machining. Check the selected operation is surfacing and cutting position setup in X,Y and Z direction.

At last select ‘Cut’ option which is at bottom left position of the window and set the cutting position of the tool with machinable wax and press ‘Ok’.

Following window get open showing the machine name and status of the machine to be ready. Press ‘Ok’. Now output in progress window gets open which shows our ongoing process. Press ok and the machine get start to move the tool for surfacing operation.

After surfacing operation, follow the same steps for Roughing and Finishing operations.

For surfacing and roughing I have used Flat end milling bit and for finishing operation I have used Ball end milling bit with 2mm tip diameter.

Ball end mill is having ball like round shape at its end it helps to remove the material from the small gaps in the milling object to get perfect finished object and also a smooth finish on the surface of object.

Fixed the tool one by one for performing the surfacing, roughing, and finishing opertion. Then give the file to SRM-20 milling machine.

The below images are showing the output of the given file on ‘SRM-20’. The first image shows the object before finishing operation. And in second image we can see the finished object.

In the finish cut we should not have to change the settings in the Modela player 4. We just need to adjust the cut depth by adjusting the depth of the milling tool (Ball-end-mill). Here in the finished object we can see a perticular texture on it. I like this texture on the mold of queen. Because I like this texture it gives some different look to my object. So I have used a single finish cut.

This is the Positive mold of the Wazier. The first level of preparing the positive mold is done.

Room temperature cure.

Low viscosity - which provide easy flow and excellent detail reproduction.

Excellent Mechanical properties - which make it sutaible for deep undercut molding.

Good Chemical resistance - compatible with various casting materials.

Compatible with various master materials.

Color - White

Item part number - 15 PLUS

Primary material - Silicone

Capacity of the box - 1 kg

Material in the box - Moldmaking Silicone RTV (Room Temperature Vulcanizing silicone)

Manufacturer - Performance Polymers

We need the correct measurement of the volume so, first I have measure the wight of empty vessel/ measuring beaker. on the digital weighing balance.

It should not add the weight of beaker in our calculated weight, so first we need to balance the weight of empty vessel to ' 0 '

Then take a glass of water and start adding water in the empty beaker slowly.

For that first I have measure the volume of the mold by puring the water in the positive wax mold. I have found that the volume of my mold is equal to 130gm.

For prepairing the negative mold we have to mix the silicone rubber with hardner with fixed proportion.

Here the mixing proportion is 1:10(i.e. if we take 100gm of silicone then take 10gm of hardner)

That is the total volume of silicone I have require to made a mold is equal to 130gm.

Hence, now we have to add 13gm of hardner in the silicone. As we have lock-down in our area we have limited stock of hardner in our lab. Hence I get 12.12gm of hardner and stir it properly in on direction for properly mixing it and to remove the air bubbles.

As I have mentioned above; we add hardner(the catalyst) in the solution to increase the rate of reaction. In this case to increase the rate of curing. As I have get the less hardner than I require. It will just increase the time for curing the mold.

Then pour the solution in the positive mold and allow it to get settle to form a flexible rubber like structure.

For forming the negative mold I have required the period of 6 days for curing process to for a complete negative mold.

Here is my negative mold of silicone rubber.

We know for forming a solid object from the moltan material like silicone rubber solution, we need a hardner.

But, in case of hydrostone, we does not need any external hardner. We just need to add the specifice amount of water into the powder of hydrostone.

It was writen on the box of hydrostone gypsum cement that we need to take if we take 100gm of hydrostone then take 65gm of water.

So I have done some calculations.