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The three items shown below are manufactured from plastic materials - Leaving Cert Engineering - Question 5 - 2015
Question 5
The three items shown below are manufactured from plastic materials. Ice cube tray Sports bottle Toothbrush (a) (i) Identify a manufacturing process used in the pr... show full transcript
Worked Solution & Example Answer:The three items shown below are manufactured from plastic materials - Leaving Cert Engineering - Question 5 - 2015
Step 1
Identify a manufacturing process used in the production of each of the items shown above.
Answer
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Ice Cube Tray: Vacuum forming is the manufacturing process used for producing ice cube trays. This involves heating a thermoplastic sheet and forming it over a mold using a vacuum.
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Sports Bottle: Blow molding is the appropriate process for manufacturing sports bottles. A preform is heated and air is blown into the mold to shape it into the desired form.
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Toothbrush: Injection molding is the method used for toothbrush production. Plastic is melted and injected into a mold to create the toothbrush shape.
Step 2
Describe with the aid of a diagram, one of the manufacturing processes named in 5(a)(i).
Answer
Vacuum Forming
Process Description: Vacuum forming is extensively used in creating products from thermoplastic sheets. The process includes the following steps:
- A thermoplastic sheet is clamped in place.
- The sheet is heated until it becomes soft and pliable.
- A mold is placed underneath the sheet, and a vacuum is applied, pulling the sheet down to take the shape of the mold.
- After the sheet cools and hardens, the vacuum is released, and the shaped part is removed from the mold.
Figure: Process of Vacuum Forming.
Step 3
State two safety precautions to be observed when machining acrylic.
Answer
- Ensure that the correct cutting speed and feeds are selected when turning on a center lathe to prevent chipping or fracturing the acrylic.
- When drilling, support the acrylic sheet underneath to reduce the likelihood of breakage and help the drill cut through successfully.
Step 4
Explain any three of the following terms associated with plastic technology: (i) Thermoplastic, (ii) Fibreglass, (iii) Thermoforming.
Answer
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Thermoplastic: Thermoplastics are materials that become soft and moldable upon heating. They can be repeatedly softened and remolded without significant chemical change, making them versatile for various applications.
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Fibreglass: Fibreglass consists of a plastic matrix reinforced with glass fibers, making it strong and resilient. The glass fibers are woven into a mat to provide additional strength, and the composite is commonly used in construction and automotive parts.
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Thermoforming: Thermoforming is a manufacturing process where a plastic sheet is heated until pliable and then formed into a specific shape using molds. After cooling, the formed plastic retains its shape.
Step 5
Describe a procedure used to produce a highly finished edge on an acrylic sheet.
Answer
To achieve a highly finished edge on an acrylic sheet, the following procedure is usually followed:
- Draw File Edge: Use a file to remove any sharp edges or irregularities from the acrylic edge.
- Use Wet and Dry Emery Paper: Sand the edge with wet and dry emery paper to further smooth the surface. Start with a coarser grit and progressively use finer grits for a polished finish.
- Finish with Plastic Polish: Finally, apply a plastic polish to enhance clarity and shine on the edge, resulting in a smooth and aesthetically pleasing finish.