Resistant materials (3)
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1.
A student is designing a lightweight chair for a school classroom. The chair needs to be strong enough to support a student's weight and durable enough to withstand daily use. Discuss the suitability of three different materials – wood, aluminium, and plastic – for this application. Consider their properties, advantages, and disadvantages in relation to the design requirements. Include specific examples of grades or types of each material that might be appropriate.
When selecting materials for a school chair, several factors must be considered, including strength, weight, durability, cost, and aesthetics. Here's an analysis of wood, aluminium, and plastic:
Wood
- Properties: Wood is a natural composite material, known for its strength-to-weight ratio, particularly hardwoods like oak or ash. It's also relatively easy to work with.
- Advantages: Wood is aesthetically pleasing, can be easily shaped and finished, and is relatively inexpensive compared to some other materials. It's also renewable.
- Disadvantages: Wood can be susceptible to moisture damage, warping, and rot if not properly treated. It's also generally heavier than aluminium or plastic. The strength can vary depending on the grade of wood.
- Suitable Grades/Types: Hardwoods like oak, beech, or ash would be suitable due to their strength. Laminated wood (e.g., plywood) could be used for structural components to enhance strength and reduce weight.
Aluminium
- Properties: Aluminium is lightweight, strong, and corrosion-resistant. It's a metal alloy.
- Advantages: Aluminium is significantly lighter than wood, making the chair easier to move. It's also highly resistant to corrosion, which is beneficial in a classroom environment. It can be easily shaped and manufactured.
- Disadvantages: Aluminium is generally more expensive than wood or plastic. It requires specialized tools and processes for fabrication.
- Suitable Grades/Types: 6061-T6 aluminium is a common alloy known for its strength and weldability. Extruded aluminium profiles could be used for the frame.
Plastic
- Properties: Plastics offer a wide range of properties depending on the type. They are generally lightweight and can be molded into complex shapes.
- Advantages: Plastics are relatively inexpensive, can be easily coloured, and are resistant to moisture. They can be molded into ergonomic shapes for comfort.
- Disadvantages: Some plastics are less strong than wood or aluminium. They can be brittle and may not be as durable over time. Environmental concerns regarding plastic waste are also a consideration.
- Suitable Grades/Types: Polypropylene (PP) or Polyethylene (PE) are commonly used plastics. Reinforced plastics (e.g., with glass fibres) could be used to improve strength. Consider recycled plastics for sustainability.
In conclusion, the best material depends on the specific priorities. For a balance of strength, cost, and aesthetics, a combination of wood and aluminium might be a good solution. However, the final decision should be based on a detailed analysis of the design requirements and the trade-offs between the different materials.
2.
A designer is considering using different materials for the construction of a mobile phone case. The case needs to protect the phone from damage (e.g., scratches, drops), be lightweight, and have a good grip. Compare and contrast the suitability of three different materials for this application, considering their properties and advantages/disadvantages.
Selecting the right material for a mobile phone case involves balancing protection, weight, grip, and aesthetics. Here's a comparison of three materials:
| Material | Properties | Advantages | Disadvantages |
| Thermoplastic Polyurethane (TPU) | Flexible, impact-resistant, good abrasion resistance. | Excellent drop protection, lightweight, good grip. | Can be prone to yellowing over time, less rigid than other options. |
| Polycarbonate (PC) | Very strong, impact-resistant, transparent. | High level of protection, can be transparent for aesthetic purposes. | Less flexible than TPU, can be prone to cracking under extreme impact. |
| Silicone | Flexible, shock-absorbing, good grip. | Excellent shock absorption, comfortable to hold, good grip. | Can be prone to scratches, may not offer the same level of impact protection as TPU or PC. |
TPU is often favoured for its balance of protection and flexibility. PC provides superior impact resistance, while silicone prioritizes grip and shock absorption. The best choice depends on the user's priorities.
3.
A company is considering using a combination of automated and manual processes in the manufacturing of a new electronic device. Identify and explain three different types of automation that could be implemented in the manufacturing process. For each type, discuss the potential benefits and drawbacks in terms of efficiency, quality, and cost.
Here are three types of automation that could be used in electronic device manufacturing, along with their benefits and drawbacks:
| 1. Robotic Assembly: Robots can be used for repetitive tasks like component placement, soldering, and testing. |
| Benefits: Increased speed and accuracy, reduced labour costs, consistent quality. Drawbacks: High initial investment, requires skilled programmers and maintenance, limited flexibility for complex or changing designs. |
| 2. Automated Testing Equipment: Specialized machines can perform functional testing of the electronic device, identifying faults and defects. |
| Benefits: High speed and reliability of testing, consistent results, reduced human error. Drawbacks: High initial cost, requires specialized training for operation and maintenance, may not detect all types of faults. |
| 3. Automated Material Handling Systems: Conveyor belts, automated guided vehicles (AGVs), and robotic arms can be used to move components and finished products throughout the manufacturing facility. |
| Benefits: Improved efficiency and reduced handling time, safer working environment, reduced risk of damage to products. Drawbacks: High initial investment, requires careful planning of the layout, potential for breakdowns and disruptions. |
The selection of automation methods will depend on the specific tasks involved in the manufacturing process, the volume of production, and the desired level of quality and efficiency. A combination of different automation techniques is often used to optimize the overall manufacturing process.