Fab Lab Rwanda · Group work
Molding and Casting
Our group method starts with the exact materials and their safety information, then compares small test casts and the effect of printed and milled molds. Mixing and curing instructions must come from the products actually used.
Material selection and safe handling
We will identify each product, component and supplier and read its current Safety Data Sheet (SDS) and technical instructions. The SDS covers hazards and controls; the technical sheet supplies the mixing basis, working time, cure conditions and compatibility information.
Ventilation, gloves, eye protection, release agents and waste handling must suit those exact materials and the lab procedure. No single mixing ratio, respirator recommendation or disposal rule can be applied to every silicone or resin.
A controlled small-cast workflow
- Prepare a labelled mold and check its release and cure compatibility with the selected product.
- Measure components using the manufacturer's stated mass or volume basis. A ratio by volume must not be substituted for a ratio by mass.
- Mix using the product procedure; record batch quantities, temperature and elapsed time.
- Pour and use only the specified bubble-removal procedure and equipment.
- Demold after the stated conditions are met and compare the result with the original geometry.
For a mass ratio A:B, a total batch mass M can be divided as mA = M × A/(A+B) and mB = M × B/(A+B). The values of A and B must come from the actual product instructions.
Comparing test casts
| Comparison | What we will keep consistent | What we will observe |
|---|---|---|
| Different casting materials | Comparable cavity geometry and documented cure conditions | Surface detail, bubbles, flexibility, damage and dimensional change |
| Printed versus milled molds | Same intended cavity and casting material where compatible | Layer/tool marks, release, surface finish and detail transfer |
| Process changes | Change one variable and label each sample | Whether the change solves a specific defect |
Photographs should show sample labels and close views of the same feature. The comparison should explain tradeoffs observed in the actual casts rather than rank materials from generic descriptions.
Digital design and process records
The mold design should include draft, access, parting and registration features where the geometry needs them. For a printed mold we will retain the editable model and slicer profile; for a milled mold, the model, CAM setup, tool and toolpaths.
Our group comparison will connect those files to the actual sample, product sheets and casting record. This makes a visible defect traceable to a material or process choice.