P, Q, R and S are masks made of wood, rubber, plastic and metal, respectively. Which of the following statements is/are TRUE?
Show Hint
When analyzing manufacturing processes, consider both the material properties (rigid vs. flexible) and the object's geometry. Undercuts are key constraints for rigid moulding but can often be overcome with flexible materials or single-use moulds (like in sand casting).
Step 1: Understanding the Concept:
This question assesses understanding of manufacturing processes and the geometric constraints of moulding and carving different materials. We need to evaluate the feasibility of mass-producing each mask based on its shape and material. A "one-piece mould" is a simple mould without moving parts; an object can be made in it only if it can be removed without being destroyed, which means it cannot have undercuts (unless the material is flexible).
Step 2: Detailed Explanation:
A. Q is mass producible with one-piece mould: Mask Q is made of rubber, which is a flexible material. The mask has significant undercuts, especially inside the open mouth. For a rigid material, a one-piece mould would be impossible. However, because rubber is highly elastic, the finished mask can be stretched and deformed to be pulled out of a one-piece mould. Therefore, this statement is TRUE.
B. R requires one-piece mould to mass produce: Mask R is made of plastic, which is typically rigid. It is a full-head mask with a complex 3D shape that fully encloses the front and sides. To remove a rigid object like this from a mould, the mould must be able to open up. This requires a multi-part mould (e.g., a two-piece "clamshell" mould). A one-piece mould would trap the object. Therefore, this statement is FALSE.
C. S can be achieved with one-piece mould: Mask S is made of metal and has intricate surface details and undercuts. While it cannot be made with a simple one-piece permanent mould, certain casting processes like sand casting or lost-wax casting utilize a mould that is effectively one piece (in terms of the final cavity) but is destroyed after a single use. Such processes allow for complex shapes. Thus, it 'can be achieved'. This statement is TRUE.
D. P is a unique mask and cannot be mass produced: Mask P is made of wood. The appearance of the grain and the carving style suggest it is hand-carved. Wood carving is a craft process, not an industrial mass-production technique like moulding. Each hand-carved piece is inherently unique due to variations in the wood grain and the craftsperson's work. Therefore, this statement is TRUE.
Step 3: Final Answer:
Based on the analysis of materials and manufacturing processes, statements A, C, and D are true.
