Patternmaking in Casting Technology
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Questions and Answers

What feature of the patternmaker's lathe allows for a greater number of spindle speeds?

  • Backgearing arrangement (correct)
  • Cross slide
  • Tool post
  • Sliding carriage

Which component of the woodworking lathe is responsible for carrying a dead centre?

  • Bed
  • Head stock
  • Tool rest
  • Tail stock (correct)

What is the primary purpose of using a woodworking lathe?

  • Drilling holes in wood
  • Turning jobs (correct)
  • Sharpening tools
  • Cutting straight wood pieces

How is the size of woodworking lathes typically specified?

<p>By swing and maximum distance between centres (D)</p> Signup and view all the answers

What material are the commonly used tools on woodworking lathes made from?

<p>High carbon steel (D)</p> Signup and view all the answers

What does equilibrium moisture content (EMC) primarily depend on?

<p>Temperature and relative humidity (D)</p> Signup and view all the answers

What is the result of moisture content in wood being below the fibre saturation point?

<p>Swelling and shrinkage (D)</p> Signup and view all the answers

What distinguishes the wood formed during spring growth from that of summer growth?

<p>Spring wood has thinner walls and a more open texture (D)</p> Signup and view all the answers

Which part of the tree trunk is known for being stronger and more durable?

<p>Heartwood (A)</p> Signup and view all the answers

What is the primary purpose of seasoning wood?

<p>To adjust the water content for stability (A)</p> Signup and view all the answers

What type of wood is found in the outer layer between the cambium and heartwood?

<p>Sapwood (A)</p> Signup and view all the answers

What are medullary rays primarily responsible for in wood structure?

<p>Reinforcing against lateral spreading (C)</p> Signup and view all the answers

What happens during the artificial seasoning method?

<p>Moisture content is adjusted rapidly (B)</p> Signup and view all the answers

What is one of the characteristics of sapwood?

<p>Fresh wood that is weaker (B)</p> Signup and view all the answers

What is one vital requirement that influences the quality of castings produced?

<p>The pattern material's design and construction (D)</p> Signup and view all the answers

When are expensive patterns justified in the casting process?

<p>When a large quantity of castings is required (B)</p> Signup and view all the answers

Which of the following is NOT one of the preparatory decisions that a patternmaker needs to make?

<p>Amount of metal required for casting (A)</p> Signup and view all the answers

What is the role of the patternmaker in casting production?

<p>To interpret engineering drawings and visualize objects in three dimensions (D)</p> Signup and view all the answers

Which pattern material is typically used for producing few castings?

<p>Loose patterns made from soft wood (A)</p> Signup and view all the answers

What does the layout drawn by the patternmaker serve as in the production process?

<p>The basis for production and later inspection of the pattern (B)</p> Signup and view all the answers

What technological skill is increasingly important for modern patternmakers?

<p>Use of computers for graphics, drawing, and design (C)</p> Signup and view all the answers

Which wood variety is best suited for pattern work due to its natural properties?

<p>Mahogany (C)</p> Signup and view all the answers

What is the primary advantage of compressed wood laminates?

<p>They are stronger and more stable than plain woods. (A)</p> Signup and view all the answers

Which wood type is known to be unaffected by fungus?

<p>Teak (A)</p> Signup and view all the answers

What is WPC an abbreviation for in the context of wood products?

<p>Wood Plastic Combination (A)</p> Signup and view all the answers

What is a unique feature of laminated wood impregnates?

<p>They involve the use of plastics or resins to enhance properties. (A)</p> Signup and view all the answers

Which of the following properties is improved in laminated wood impregnates?

<p>Strength and hardness (C)</p> Signup and view all the answers

What is the purpose of using nuclear radiation in the context of plastic wood?

<p>To achieve complete polymerization of plastic resin (A)</p> Signup and view all the answers

Which type of plywood is reinforced with a metal face for improved properties?

<p>Metal-faced plywood (B)</p> Signup and view all the answers

How are thin wooden laminates arranged in compressed laminates?

<p>With alternating grains in opposing directions (C)</p> Signup and view all the answers

What characteristic do laminated boards possess due to their construction method?

<p>Superior resistance to wear and abrasion (B)</p> Signup and view all the answers

What is one of the primary reasons epoxy resin patterns have gained popularity over metallic patterns?

<p>They offer a higher strength-to-weight ratio. (D)</p> Signup and view all the answers

What characterizes the gel coat or surface coat resin in the epoxy resin system?

<p>It creates the outer layer which is harder and stronger. (A)</p> Signup and view all the answers

Which feature of epoxy resin patterns makes them resistant to moisture action?

<p>Their complete immunity from moisture. (D)</p> Signup and view all the answers

What is the role of laminating resin in the epoxy resin system?

<p>To apply layers of glass wool for added strength. (B)</p> Signup and view all the answers

Which type of resin combination is essential for filling the voids and forming the complete solid shape of the pattern?

<p>Casting Resin (C)</p> Signup and view all the answers

What additional materials can be added to casting resin to enhance its properties?

<p>Filler materials like talc and chalk powder (B)</p> Signup and view all the answers

What is the primary characteristic of silicone rubbers mentioned in relation to their application?

<p>They are utilized for making dies in special cases. (D)</p> Signup and view all the answers

Why might a manufacturer prefer epoxy resin patterns over aluminum ones in terms of cost?

<p>There are no costs associated with casting and machining for epoxy. (B)</p> Signup and view all the answers

What is one disadvantage of using epoxy resin patterns compared to metallic options?

<p>Longer time needed to set. (C)</p> Signup and view all the answers

How does the strength-to-weight ratio of epoxy resin compare to that of cast iron?

<p>It is significantly higher than that of cast iron. (A)</p> Signup and view all the answers

Flashcards

Pattern

The primary tool in the casting process, its quality directly influences the quality of the final casting.

Pattern Material

The material used to construct the pattern, impacting its durability, cost, and suitability for different production needs.

Quantity of Castings

The number of identical castings required. This determines the cost and complexity of the pattern.

Service Requirement

The purpose for which the casting is intended. This dictates the required material properties and casting process.

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Loose Pattern

A pattern made from a soft wood, suitable for producing only a few castings.

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Metal or Epoxy Patterns

Patterns made from metal or epoxy resin, mounted on plates for use on specialized moulding machines, suitable for mass production.

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Pattern Construction

The process of designing and constructing the pattern, including details like core prints, loose pieces, and gating systems.

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Equilibrium Moisture Content (EMC)

The moisture content of wood at which it reaches a stable equilibrium with the surrounding atmosphere.

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Fibre Saturation Point (FSP)

The point at which wood can no longer absorb more water, even when immersed.

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Seasoning

The process of drying wood to reduce its moisture content and stabilize its dimensions.

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Annual Rings

The growth rings in wood that are formed by the difference in density and cell structure between springwood and summerwood.

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Heartwood

The harder, darker, inner wood of a tree that is more resistant to decay.

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Sapwood

The lighter, outer wood of a tree that is more porous and susceptible to decay.

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Medullary Rays

Cells that radiate from the center of the tree, forming vertical channels.

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Cambium

The layer of living cells under the bark that produces new wood and bark.

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Secondary Growth

The process by which a tree increases in diameter by adding new layers of wood under the bark.

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Patternmaker's Lathe

A type of lathe specifically designed for creating wooden patterns for casting, featuring robust construction and precise control for accurate pattern making.

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Height-of-Centre

The distance from the center of the lathe spindle to the upper surface of the bed, determining the maximum height of workpieces the lathe can handle.

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Swing

Double the value of the height-of-centre, indicating the maximum diameter of workpieces that can be turned on a lathe.

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Compound Slide

A device that allows precise adjustments in the tool's movement along both the work axis and perpendicular to it, ensuring accuracy in pattern making.

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Woodturning Tools

Steel tools used in woodworking lathes, containing a high percentage of carbon for strength and durability.

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Mahogany

A type of wood ideal for pattern work due to its fine polish, stainability, and excellent gluing properties, making it suitable for high-volume production.

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Teak

A hard and strong wood resistant to fungus and readily available, making it a durable option for pattern work.

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Deodar

A softer wood, slightly harder than pine, easily machinable, and polishes well, suitable for pattern work where strength is not a primary concern.

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Compressed Wood Laminates

Wood products made by gluing and pressing thin layers of wood together, resulting in stronger, denser, and more dimensionally stable material compared to plain wood.

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Metal-faced Plywood

A type of compressed wood laminate with facing material like mild steel, stainless steel, or brass, enhancing its mechanical properties, wear resistance, and dimensional stability.

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Laminated Wood Impregnates

Wood varieties that are impregnated with resins to enhance their properties like strength, density, hardness, and wear resistance, overcoming limitations of natural wood.

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WPC (Wood Plastic Combination)

A specific example of a laminated wood impregnate, often used as a cost-effective alternative to aluminum patterns in automotive casting.

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Wood Impregnation

A process used to strengthen wood by filling cell cavities with resins, sometimes enhanced by using nuclear radiation to ensure complete resin hardening.

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Resin Applied in Laminated Wood

Resins used to impregnate and strengthen laminated wood, often in the form of sheets of varying thickness.

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Polymerisation of Plastic Resin

A method used to ensure complete hardening of plastic resins in laminated wood, sometimes involving nuclear radiation for faster and efficient hardening.

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Epoxy Resin

A type of plastic resin that is used in the creation of patterns for casting. It's known for its easy castability, high strength-to-weight ratio, and good resistance to wear and abrasion.

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Gel Coat Resin

A type of epoxy resin used to create the outermost layer of a pattern. It's designed to be harder and stronger than the inner layers.

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Laminating Resin

A type of epoxy resin used to build up layers on the back of the gel coat. It's mixed with glass wool to enhance strength, toughness, and flexibility in the pattern.

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Casting Resin

A type of epoxy resin used to fill the bulk of the pattern, providing the necessary shape and backing.

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Fillers

Materials that can be added to casting resin to enhance its strength, rigidity, and hardness. Common examples include talc, chalk powder, and fine sand.

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Mould Preparation

This technique is used to create patterns, often in metal, plaster, or epoxy resin itself. It involves creating a mold from a master pattern.

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Release Agent

A substance applied to the mould to prevent the pattern from sticking to it during the casting process.

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Polyester Resin

A type of resin that is used to create patterns for casting. It is popular due to its relatively low cost and easy processing.

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Polystyrene Resin

A type of resin that is used to create patterns for casting. It's often used in mass production due to its ease of use and low cost.

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Silicone Rubber

A rubber-like material that has been used to create dies for casting. It is more specialized and often used for unique applications.

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Study Notes

Technology of Patternmaking - Requirements

  • Patterns are the primary tools in the casting process.
  • Casting quality is heavily influenced by pattern material, design, and construction.
  • Expensive patterns are justified for large quantities of castings.
  • Simple, loose patterns made of wood are sufficient for small numbers.
  • Metal or epoxy resin patterns are used for repeated production of large quantities.
  • Pattern preparation involves crucial decisions about materials, moulding methods, core boxes, allowances, gating, and feeding.
  • Separate drawings are prepared for patterns and core boxes.
  • Patternmakers play a vital role in the casting process: determining the first tangible form, interpreting engineering drawings, and creating detailed layouts for the casting.

Pattern Materials

  • Selection depends on service needs (quantity, quality), potential for design changes, production type, and repeat order possibilities.
  • Suitable materials are easily worked and joined, light, strong, and durable (high strength-to-weight ratio), resistant to wear, abrasion, corrosion, and chemical action, dimensionally stable, readily available, and affordable.
  • Wood and wood products are the most common, but are susceptible to moisture.
  • Wood consists of cells with cellulose and lignin.
  • Wooden cells absorb moisture causing dimensional instability and swelling/shrinking.
  • Wood seasoning is crucial for reducing shrinkage/swelling to ensure stability, strength, and durability.
  • Various seasoning methods (natural or artificial) are used.
  • Metal alloys are used for large quantity production.
  • Common metallic alloys are cast iron, steel, aluminium, and brass/bronze.
  • Selecting the appropriate metal alloy depends on availability, castability, machinability, surface finish, tendency to oxidation, weight, brittleness, cost, and modification potential.
  • Wood is used frequently due to ease in shaping and cost-effectiveness.

Patternmaking Machines and Tools

  • Woodworking lathes are frequently used for cylindrical work.
  • Circular saws are used for cutting.
  • Band saws are best for curved irregular cuts.
  • Jig saws are suited for intricate details.
  • Jointers are helpful for planing straight surfaces.
  • Planers are for planing large sized work.
  • Shapers are helpful to produce shapes with a cutter head.
  • Pattern Milling machines are valuable for complex tasks, such as drilling, milling, slotting, grooving, and shapes.

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Technology of Patternmaking PDF

Description

Explore the essential requirements and materials involved in the technology of patternmaking for casting processes. Learn about the impact of pattern design, construction, and material selection on the quality of castings. This quiz covers the roles and responsibilities of patternmakers, as well as the decisions involved in pattern preparation.

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