Molding and Casting

This week, we focused intensively on the topic of Molding and Casting. We explored various materials and processes for both positive and negative molds. For the positive object, it was particularly important to ensure that the manufacturing process would not be visible in the final cast.

To create the positive mold, we examined the following processes and materials: - FDM printing (Material: PLA) - SLA printing (Material: Resin) - CNC milling (Materials: Wood, Styrodur)

We compared them based on their material properties and the required post-processing.

For the negative mold, we used silicone casting – both food-safe and non-food-safe variants. We paid close attention to the respective advantages and disadvantages of the materials as well as the release agents required, such as mold release oil or rapeseed oil, to enable clean demolding.

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Table 1: Positive Mold – Processes and Materials

Process	Material	Material Properties	Post-processing
FDM Printing	PLA	Stable, inexpensive, visible layer lines	Sanding, filling, smoothing (e.g. with spray filler)
SLA Printing	Resin	Very smooth, detailed, brittle	UV curing, light sanding if necessary
CNC Milling	Wood	Stable, natural, easy to work with	Sanding, sealing, chisels and hand plane)
CNC Milling	Styrodur	Lightweight, soft, sensitive to heat and pressure	Sealing (e.g. with acrylic or lacquer)

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Table 2: Negative Mold – Silicone Casting

Material	Advantages	Disadvantages	Possible Release Agents	Curing time
food-safe Silicone (e.g. RTV)	Flexible, detailed, durable, good for food production	Relatively expensive, curing time	rapeseed oil	360 hours
Non-food Silicone (e.g. RTV)	Flexible, detailed, durable	Relatively expensive, curing time	Mold release oil	hours

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Table 3: Endproduct – Casting

Material	Advantages	Disadvantages	Possible Release Agents	Curing Time
Food Creme Ganache	Perfect for pastry, nice finish look	Simple shapes, fragile when removing	Fine flour	24 hours