Assignment Brief:

As a group review the safety data sheets (SDS) for each molding and casting material, make and compare test casts, and compare different mold-making processes.
Design a mold for your chosen process, produce it with a smooth surface finish hiding toolpaths, and use it for casting parts.
Extra credit: create a mold with more than two parts.

Materials & Manufacturing

This week's assignment focused on learning different methods of molding and casting.
With this assignment, I intended to explore and understand the following key processes and techniques:

I started with learning how various materials, especially metals and plastics, are processed using molding, casting, machining, 3D printing, and welding — each method selected based on the material’s properties and the final product's requirements.

Metals Processing:

Casting — Molten metal is poured into molds to create complex and heavy parts such as engine blocks, tools, and machinery components.
Sheet Metal Forming — Thin metal sheets are bent, stamped, or drawn into products like automotive panels, enclosures, and appliances.
Forging — Metals are deformed under high pressure to manufacture strong components like shafts, gears, and aerospace parts.
Machining — Precision cutting and shaping of metals using lathes, mills, drills, and CNC machines to create engine components and custom metal parts.
3D Printing (Metals) — Building complex and precise metal parts using selective laser melting and electron beam melting, typically used for aerospace and medical applications.
Welding — Joining metal parts by fusing them using processes like MIG, TIG, arc, and spot welding, commonly used in pipelines, structures, and vehicles.

Plastics Processing:

Injection Molding — Forming complex plastic shapes (like toys and automotive parts) by injecting molten plastic into a mold.
Blow Molding — Producing hollow plastic objects such as bottles, containers, and fuel tanks by inflating heated plastic into a mold.
Rotational Molding — Creating large hollow products like tanks and playground equipment by rotating and heating plastic inside molds.
Extrusion — Forming continuous plastic products like pipes, sheets, and films by pushing melted plastic through a die.
Thermoforming — Heating plastic sheets until pliable and molding them over a form to create trays, packaging, and disposable items.
3D Printing (Plastics) — Fabricating plastic parts layer-by-layer for prototypes, customized designs, and intricate geometries.

Test Moulding and casting

To start with, I came across 2 new terminologies, 1) Master Mold (also called Master Model) and 2) Mother Mold Master Mold/Model- The original object you want to copy. Can be made by any material (3D print, clay, wax). This is to create the first mold. Mother Mold- The rigid shell that supports a soft mold. Can be made by plaster, fiberglass, resin and this made is to prevent deformation during casting

For my molding and casting project, I began by testing different types of mold-making techniques to better understand material behavior and mold quality. My initial goal was to create a sphere mold as a test object, because a sphere has continuous curves and can reveal imperfections clearly during casting.

To start, I designed and fabricated two different Master molds using two different methods: Bamboo Labs 3D Printing and Wax Milling.

Design Process

A sphere mold as a test object, because a sphere has continuous curves and can reveal imperfections clearly during casting. Later, over having a converstaion with my Lab instructor I learnt that having an egg shaped mould will help test impurities better. As the oval shapes helps give a direct link to the exact eroor in the design or the part of fault unlike a perfect sphere would give. This would also help us dig into learning on casting over more complex shapes

Create an elipse + a centre line> Use trim tool to Trim half of the elipse to get a semicircular elipse.

Finish sketch> Use revolve tool to revolve the semi circle elipse around the centre line.

From the centre plan pf the oval, create a rectangle around the Oval sphere and extrude in symmetry.

Change the opacity of the rectangle around the oval sphere to see thought the rectangle body, by right-clicking over the body and chnaging opacity controls.

Here comes the interesting part of creating the Master Mold of our egg shell. Select the combine tool> Target body- outer cuboid> Tool body- centre egg.

As you do this, most importantly in the operation- select operation of cut through, And the Egg cut off the cuboid at its perfect location.

Learning: From the above process we made a cuboidal casing for our silicon mother mould and we split the overall mould into two halves are we desired. Now in the further process was a learning. In the next stage of the process, I created a trail body that connects the edge of the cuboid to the oval shape. This step is crucial as it will form a hollow path in the master mold (or silicone mold), which will serve as the channel for pouring the casting material. The hollow path ensures that the material flows smoothly into all sections of the mold. At the same time, the trail body also creates a pouring tube in the mother mold (or resin mold), which will be used to pour the resin or casting material into the mold.

I created a trail body that starts connects the edge of the cuboid to the oval shape.

Also, a key learning was to taper the pouring section as we come to the the oval as clearing of the pouring layer from the casting is very simpler.

Now Select both the bodies> Split tool> Use centre plane as the splitting tool.

This gives us a two Separate moulds.

Note: Use the middle plane as the slitting tool only when you hav designed with reference to the origin.

Learning 2: From the aobe model hide the half side of the total modl and for the remaining half extrude cut the overall block height to 20mm from the egg body and give a rectangular closure to the top surface. Finally we get the Master mould for our Sphere.

I designed and fabricated the above master mould using two different methods:

Bamboo Labs 3D Printing: I created the first mold by 3D printing a sphere model using a Bamboo Labs 3D printer. This method allowed for precise detail and complex geometry, but I was also aware that the layered texture typical of FDM 3D prints might affect the surface finish of the cast.
Wax Milling: For the second mold, I milled a sphere out of wax using a CNC milling machine. Wax milling provided a smoother finish and more accurate curves compared to 3D printing, but it was a more time-consuming process requiring careful toolpath planning and milling setup.