Manufacturing Technologies: Shaping & Molding Processes
1. Manufacturing Technologies
Manufacturing technology is a set of transformation processes applied to a material during preparation. Requirements for piece manufacturing include:
- Prepared for assembly
- Faithful to the pre-established design
- Reasonable cost of materials and energy
- Reliable quality control
2. Shaping by Melting and Molding
A mold is a container with a cavity. Molten material is poured into the cavity, and solidifies in the shape of the cavity.
2.1 Mold Components
- Bottom: Main cavity or half of the piece’s contour.
- Top: The other half of the piece’s contour.
2.2 Mold Elements
- Casting Hole, Funnel, and Channel: Allow molten material to enter.
- Riser: Material reservoir.
- Core: Creates a hole in the molded part.
2.3 Mold Types
- Permanent: Reusable for multiple identical parts.
- Lost: Destroyed after the molding process.
2.4 The Molding Process
Once the material cools and solidifies, the mold is opened or destroyed to retrieve the piece. Processes are based on the mold material and the filling method.
3. Gravity Casting
Molten metal is poured into the mold, flowing downwards by gravity.
3.1 Sand Casting
Sand with high silica content is used in lost molds. The process involves model preparation, mold configuration, assembly, pouring, and piece retrieval.
3.2 Shell Molding
Four processes: preheating, pouring, metal solidification, and opening.
3.3 Lost Wax Casting
An older, expensive, and less common method. It involves model preparation, mold building, sand filling, mold removal, and piece extraction.
4. Pressure Casting
Molten metal is forced into a permanent mold.
4.1 Pressure Casting Techniques
- Centrifugal Casting: The mold rotates, forcing molten metal outwards.
- Injection Molding: Molten metal is injected using a plunger or compressed air.
5. Strain Shaping
Material is subjected to forces exceeding its elastic limit, causing permanent deformation.
5.1 Types of Strain
- Elastic: Material returns to its original shape.
- Plastic: Material does not return to its original shape.
5.2 Strain Processes
- Compression
- Traction
6. Forging
Hot deformation using large forces and pressures. Typical materials include pure metals (Al, Cu, Fe, Zn) and alloys (Al + Mg). Work types are finished pieces and machining parts.
Forging can be manual or mechanical, involving heating, forging operations, and cooling.
6.1 Heating
Manual forging uses portable or fixed forges.
6.2 Forging Process
Performed after the material reaches forging temperature. Tools include manual tools (hammers, pliers) and mechanical equipment (hammer). Operations include drawing, reducing, upsetting, punching, cutting, and bending.
7. Hot Stamping
Metal is placed between two molds and compressed. Phases include preparation, stamping, and finishing.
8. Extrusion
Metal is forced through shaped holes under pressure.
9. Rolling
Metal is passed between rotating rollers. Types include duo, trio, and double duo.
9.1 Rolling Process
Three phases: machining (removes irregularities), rolling (reduces section), and finishing.
10. Cold Stamping
Material is compressed on a die. Advantages over hot stamping include reduced costs and excellent finishes. Operations include coining, bending, and drawing.
11. Tensile Deformation
Ductile material is drawn through calibrated orifices (rows).
11.1 Tensile Deformation Techniques
- Drawing: Uses a drawing bench with a row and a movable cart.
- Wire Drawing: Uses a wire drawing bench with a row and a coil.