for the group work we needed to review different material available in the lab. at the time we have two kinds the smooth cast and the ecoflex. the main difference between the two is the flexibility and depending on your application you can choose from them.
upon reviewing the datasheet for these materials we noticed that along with mechanical properties the curing time is also different in both materials. sof the ecoflex it takes 3-4 hours to cure where as for the smooth cast it takes 5- 10 minuites. booth material advices to wear gloves and protect your eyes and skin and to seek medical attention. for the smooth cast it can get very hot too.
for the molding we have a range of molding material one is the food safe grade and other is high resistance can used for etal casting and the normal one for plastic casting.
for all of them they advice to use it in ventilated room. and the curing time it takes 24 hours in proper tempreture
Designing the Mold
i want to make something memorable so i decided to cast my son's hand. since we needed to make a mold i tryied to 3d scan his hand but it was difficult to get him still. hence i used Smoothie 3D.
the process is simple. you select around a uniform area and the software makes it 3d. you have to fix the thikness of that 3d and position. once i got the final 3d part object i saved it as STL file.
Then i used solidworks to work aroung the stl file. i uloded it as solid body instead of the defualt graphic body which you cant work around.
then i tried to close the open holes and discounected bodies by extruding material into them.
then add the molding block. according to the one provided in the lab. and i made pins to help in aligning the two parts for casting and sprue to pour the casting material inside the mold.
then i didn't have the design of the hand from behind so i just used the same profile of the designed hand and cut it into half and then attched it to the molding block. i want to try to do two parts mold.
then i saved the file as STL to take it to SPR player the cam software for milling with roland.
Preparing for Molding
i used srp play and its pretty striaght forward you just have to go through the options. in the first tab i just checked the dimentions of my piece. then in the second tap i chose the cutting options to be fast as i did not want it to waist time on that. then in toopath tab before creating the toolpath i chose to edit the bit for both operations and one important step here is to make sure that the margines are set to zero you can find them in one of the optiones under the roughing and finishing methods.
i got this error massage saying that uncreated process pending. after many trials i understood that the problem is with the cordinate system. the z was differnet in solidworks then the one i wanted. so i fixed that in solidworks in very simple steps and it worked.
Milling the Mold
so this process is operated from the same software the srp player. in the forth tab you can see the preview of the cutting and in the fifth tab its just a mater of sending it to the milling machine. i used the Roland MDX-50 with the proper tools. just make sure you align the top surface of the designwith the wax. from the machine i centered the origin in the middle of the wax.
Then the process started and it took almost 3 hours to finish.
preparing the plastic mold
this step is fun but you need to be carefull with the mix. its not safe and any mistake in proporthins wll ruin the mix. we used the mold max 60 which have 100 to 90 ratio we calculated the weight for each substance and mixed them then pored them in the mold. the next day we got the plastic mold ready.
casting
here the the only issue is the time of the plastic curing is so fast that i had to do it agin and agin. it takes 5 miniuts from the moment of mixing them. i used a syrange to feed the mix inside the silicone mold. and the final result is the hand of my son in plastic.
