Silicon Mold Design – Lessons Learned

Soft Robots

The previous week, I learned to convert some PVC pipe, a 3D printed inner core into a mold to cast silicon in. We made an inflatable silicon actuator by adding fabric cut in the right places inside the cast.

After that, I wanted to cast my own actuator, and this time try to do a sleeker, longer version of the one last week. I decided to use paper instead of fabric, and use straws of different thicknesses to create a hollow tube, rigid in some places and inflatable in others.

My mold was made using a large milkshake straw, a thinner plastic straw, a metal stick to hold the straws in place, a base made of cardboard and paper.

Upon casting, I learned that pouring silicon into such a tiny space was impossible — at that stage I believe I wanted a funnel attached to the mouth of the larger straw.

The next morning:

After the cast has cured over night, I learned that despite using ample amount of demolding spray, it was impossible to pull it out from the tight space between the straws.

I then learned that mine was a deconstruct-able mold. I cut through the bigger straw to find out that air bubbles had formed all over the cast, and realised that instead of a funnel, to achieve this kind of shape I must have a mechanism to pour (and demold) longitudinally. Two half molds for the outer shell would have solved the problem of air bubbles.

Soft Robotics — Inspiration From Nature

Soft Robots

The skin of humans is a very important organ, the largest in fact. It is the largest organ of the integumentary system. Because it interfaces with the environment, skin plays an important immunity role in protecting the body against pathogens and excessive water loss.

Sweat glands are used to regulate temperature and remove waste by secreting water, salts, and nitrogenous waste (such as urea) onto the skin surface.

They are almost invisible pores that can also be used for lubrication. 



Soft robots

–can incorporate this phenomena in to lower temperatures and increase mobility by reducing friction. Robots that are biomimetic and humanoid can also be made more realistic.