MAS.863.10 Masoud Akbarzadeh MArch | SMArchs | Computation
How to Make almost everything MIT department of Architecture
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molding and casting |  

THe exercise for this wee was to make a mold and cast into that. I decided to make a mold for part of my final project proposal.



This is the model for the 4 Axis robotic arm which I would like to finish by the end of the semester. For this week I made the model and took the last portion of the arm for manufacturing experience.



In order to make the assembly of the whole arm feasable, I divided each member into two segments; a male and a female. The male has some tabs which interlocks with the female for assembly process.


Each member is divided into two segments and each segment would be divided into exterior and interior.  

Making the mold for a halow mamber is a little bit tricky. in order to design the mold, it is important to seperate the whole exterior surface of the model from the interior. Later there should be a mold for exterior and the one for interior.



The whole surface looked very clean except some parts which were hit by the plastic sheild of the vacume around the mill. Later I had to take off the plastic sheild for cleaner cuts.



Later I used CNC machine to make the mold for the molds. I used 1/4" end mill (ball end) for Horizontal roughing with 50% step over, and 1/8" end mill (Ball) for the Horizontal Finishing with 10% step over.



Using a large amount of material might fill the some small parts of the mold and change the accuracy of the mold.



Before pouring the polyurethane into the molds, the surface of the mold should be covered with a thin layer of Geso. You should be very patiant to use very little material for covering.



The next step is mixing the polyurethane in a separate dish.


1/8" diameter Aluminum bars.    

In order to think ahead about the casting part, I need to use some ventilation pipes in the mold itself. I use Aluminum rods for this objective.


Th rods are coming out of the liquid.    

The molds after pouring polyurethane.



16 hours later the polyurethane cured and flexible



The process of detaching from the foam and Al. rods



Two molds for one part on top of eachother


It is better to put two layer of stiff materials around the molds not let the rubber bands to cut the flexible mold    

Now, it is time to cast the Smooth Cast Plastic into the molds. I used syringe to inject the cast into the molds.



Final Step opening the mold and detaching the part from the mold. there are some problems regarding this part. the Male part didn't have a very good tabs to go inside the female. I guess this needs more experience in how to desig the tabs in a more efficient way. (further investigation of course!!)


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