Sand Casting Service

1. Kugadzira Patani

A pattern is a replica of the final part, slightly oversized to account for metal shrinkage during cooling.

It is usually made from wood, plastiki, kana simbi.

• Chinangwa: To create the mold cavity in the sand.
• Types: Split pattern (for complex parts), match-plate pattern, or cope-and-drag patterns.
• Shrinkage allowance: Typically 1–3% depending on the metal.

2. Mold kugadzira

The pattern is placed inside a molding box (Flask), uye sand mixed with a binder (like clay or resin) is packed around it.

The mold is made in two halves:

• Cope (top half) uye Drag (bottom half).
• The pattern is removed, leaving a cavity in the shape of the part.
• If required, cores are inserted into the mold to form internal features or hollow sections.

3. Core Kugadzira (If Applicable)

Cores are sand shapes inserted into the mold to form internal cavities in the casting.

• Made from core sand, which is more durable and heat-resistant.
• They must be accurately placed and often supported with chaplets (metal spacers).
• Cores are removed after casting, usually broken out and discarded.

4. Metal Melting and Pouring

Molten metal is prepared in a furnace and poured into the mold through a sprue uye runner system.

• The system includes magedhi (to direct flow), risers (to compensate for shrinkage), uye vents (to let gases escape).
• Metals used: simbi yakakandwa, aluminium, simbi, bronze, etc.
• Care is taken to avoid turbulence, gas entrapment, and inclusions during pouring.

5. Kutonhodza uye Solidification

After pouring, the metal is allowed to cool and solidify inside the mold.

• Cooling rates affect grain structure and mechanical properties.
• Proper riser design ensures that metal shrinkage is compensated to avoid internal voids.
• The solidification time depends on part thickness and metal type.

6. Shakeout and Mold Removal

Once the metal has cooled, the sand mold is broken apart to retrieve the solid casting.

• This step is called Shakeout.
• The sand can often be recycled after cooling and screening.
• The casting is rough at this point and may have residual sand or oxide layers.

7. Kuchenesa uye Kupedza

Excess material such as sprues, risers, and flash are removed by cutting or grinding.

• The surface may be kucheneswa by shot blasting, tumbling, or pickling.
• Machining is performed as needed to achieve final tolerances.
• Surface treatments or coatings (e.g., kupenda, kukwenenzvera) inogona kuiswa.

Sand casting supports a wide range of ferrous and non-ferrous metals. The choice depends on the desired mechanical properties, corrosion resistance, uremu, uye mutengo.

Ferrous Metals

These metals contain iron and are commonly used for high-strength and structural applications.

Non-Ferrous Metals

These are metals without significant iron content, typically used for corrosion resistance and weight savings.

• 1. Cost-Effective for Low to Medium Production
• 2. Wide Range of Material Compatibility
• 3. No Size Limitations
• 4. Complex Geometries Possible
• 5. Short Lead Time
• 6. Recyclable Materials
• 7. Suitable for a Variety of Surface Finishes