Chapter 2 Introduction

1
Chapter 2 Introduction

• Why would a product designer choose a die casting
  over a component manufactured by another
  competing process?
• What are the capabilities of a product made with
  a die casting?

2
Chapter 2 Objectives

• List the advantages of using die castings
• Identify die casting applications
• List the characteristics of the optimum die
  casting configuration
• Identify the components of the die casting shot

3
New Terms

• Die casting shot
• EMI
• Overflows
• Runner
• Sprue

4
Die Casting Advantage

• Produces components at high speed
• Uses a range of durable metal alloys
• Faithfully captures the most intricate design
  details
• So, its the choice for
• High volume production components
• Lower-volume production as well

5
Die Casting Applications

• Agricultural machinery
• Automotive vehicles
• Building hardware
• Electrical and electronic equipment
• Hand tools
• Home appliances
• Industrial products

• Instrumentation
• Lawn and garden equipment
• Office furniture
• Office machines
• Portable power tools
• Recreational equipment

6
Optimum Configuration

• Fill completely with metal
• Solidify quickly without defects
• Eject readily from the die

7
Principle 1

• Wall thickness should be as consistent as
  possible
• No hard and fast rules
• Wall section possesses a dense fine-grained skin
• Defects likely in material in between walls
• Wall sections should be as uniform as possible.
• Thinner walls contribute a lesser heat load than
  heavier walls and will have a longer die life

8
Principle 2

• Intersections of walls, ribs and gussets should
  blend with transitions and generous radii
• Generous radii and transitions promote metal flow
  and internal integrity
• Radii and fillets enhance structural integrity
• Fillets reduce heat concentration in both the die
  and castings

9
Principle 3

• Specify standard draft
• Draft is highly desirable on surfaces parallel to
  the direction of die draw
• Recommended draft is determined by
• The alloy
• The length of the dimension parallel to the die
  draw
• If the dimension is an inside or outside wall

10
Principles 4 and 5

• Eliminate or minimize sharp corners
• Accommodate them at parting lines and at the
  junctions of die components
• Break them with radii or chamfers
• Avoid undercuts
• May require machining operations or additional
  die components, such as retractable core slides

11
Principle 6

• Dimensions with critical tolerances should relate
  to only one die member
• Precision is greatest when related features are
  in same piece of cavity steel
• Precision is reduced for relationships across the
  parting line or to moving components
• Judicious use of ribbing can aid die filling and
  strengthen the component

12
The Shot

• The result of injecting metal into the die,
  i.e., making a shot (verb), is also called a
  shot (noun)
• Shot elements
• Runner
• Biscuit
• Overflows (not pictured)
• Casting

13
Overflow

• A reservoir for the first metal to flow through
  the cavity
• Vents inside provide a path for air to get out of
  the die
• A strategically placed overflow can be used to
  add heat in a cold area of the die
• May help eject the casting from the die

14
Summary

• Many reasons to choose die casting over a
  competing process
• Many product lines made from die castings
• 6 principles must be followed to ensure optimum
  design