This set of Foundry Multiple Choice Questions & Answers (MCQs) focuses on “Pattern Materials”.
1. _____________ is used as a pattern material for the easy handling of the equipment.
Explanation: In all the pattern materials, wood is a material which is widely used. The properties of the wood being easy availability and low weight make it sustainable for the longer run. Hence, it is used as a pattern material for easy handling of the equipment.
2. Which of the following is the most pattern materials are corrosion prone?
a) Grey Cast Iron
Explanation: The Grey cast iron is a ferrous component hence it is corrosion prone. Even though the steel is an alloy of Iron, it is heterogeneous component and is less prone to corrosion than Grey cast Iron.
3. Wooden patterns have a high maintenance cost.
Explanation: The wooden patterns can be shaped easily and are relatively cheap. But the main disadvantage of wood is its absorption of moisture as a result of which distortions and dimensional changes occur. A good construction may be able to reduce the war page to some extent. Hence, proper seasoning and upkeep of wood is a pre-requisite for large scale use of wood as a pattern material.
4. Which of the following types of wood are used to make patterns?
Explanation: All of the above mentioned types of wood are used to make pattern due to the wide availability and the property of the wood to sustain for a long duration and yields dimensional accuracy.
5. Plywood boards are used for making patterns requiring high impact strength.
Explanation: The plywood boards of veneer type as well as the particle boards are also used for making patterns. Because of their availability in various thickness, their higher strengths and no need for seasoning are the reasons for their usage. However, they can be used only in patterns which are the flat type (Pattern plates) and no three-dimensional contours.
6. The ____________ is used for making additional patterns with minimal double shrinkages.
b) White Metal
d) Grey Cast Iron
Explanation: The white metal is light, can be easily worked and is corrosion resistant. Since white metal has very small shrinkage, the white metal pattern can be made use of for making additional patterns without worrying about the double shrinkage allowances.
7. _________ patterns are useful for large castings in the foundry.
b) Lead alloys
c) Aluminium alloys
Explanation: The quantity of wood required for the large castings’ pattern is high. The manufacturing of large casting requires high dimensional accuracy as several parts of the casting cannot be machined. Hence wood is the only practical pattern material.
8. Which of the following plastic is used for making patterns?
a) Epoxy resins
c) Thermosetting plastics
d) Polyvinyl chloride
Explanation: The making of a plastic pattern can be done by sand clay moulds or moulds made of plaster of Paris. Hence, the cold setting epoxy resins with suitable fillers are used. With a proper combination, it is possible to obtain a no shrink plastic material and as such double shrinkage allowances may not be required.
9. The plastic patterns give the highest dimensional accuracy.
Explanation: Plastics are used as pattern materials because of their low weight, easier formability, smooth surfaces and durability. They do not absorb moisture and are therefore, dimensionally stable and can be cleaned easily.
10. The metal pattern is more useful over wood patterns.
Explanation: Molding sand is made up of highly abrasive particles for the large scale production and metal pattern provide higher resistance to abrasion over the wood patterns. Hence, where ever possible, metal patterns are preferred over the wood patterns.
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