1. Metal Casting and Forming
ALL manufacturing starts here!

2. What is Metal Casting?
When liquid metal is poured into a mold, then solidifies and takes the form of the mold.
Iron, steel, aluminum, brass, bronze, magnesium, and zinc are all metals that can be casted.

3. Patterns Part to be made Allow for shrinkage (1-2%)
Cast iron 1/8” per foot
Steel 1/4” per foot
Aluminum 5/32” per foot
Metal, plastics, or wood
Single or multiple pieces
Pattern removed from mold

4. Patterns cont. Draft to allow removal from the mold (2-3*)
Commonly oversized for machinability
Ice cube trays have draft angles.

5. Castings Castings: Parts made using casting process
Molds or Patterns used to make castings can be made of one or more pieces.

6. Foundry A factory specializing in metal casting.
Dirty, hot, loud hard but rewarding work
Modern Foundry Video

7. Different Casting Processes
1. Green Sand Casting 2. Permanent & Die Casting 3. Investment (Wax & Foam) 4. Continuous 5. Centrifugal

8. Sand Casting Pattern is formed into a sand cast.
Liquid metal is poured into the sand cast.
A sand cast is a ONE time use casting
Mold is destroyed to remove casting/part

9. Sand Casting Produce castings of virtually any size and weight.
Common for prototyping & low volume production. 

10. Sand Mold
Section view of mold showing spru, runner and gating system, risers (feeders), cores and pattern draft.

11. Permanent Mold Casting
Mold is made of iron or steel
Molds are good for multiple uses
Used when poring large quantities of identical parts

12. Permanent Mold Casting
Advantages: Consistent, Precise, tighter tolerances Disadvantages: very expensive to produce molds

13. Permanent Die Casting
Similar to permanent mold casting except that the metal is forced into the mold under pressure
Large quantity production.

14. Investment Casting (Lost Wax)
Over 1,000 year old technology
Pattern is made of wax.
A ceramic shell is built around the wax pattern.
Wax pattern is melted out of the shell.
Molten metal is poured into the shell.
Investment Casting Video
Investment Casting Video 2

15. Investment Casting (Lost Foam)
Styrofoam pattern is coated with a refractory material and dry sand is compacted around pattern.
Metal is poured onto the foam & instantly vaporized.
No draft required

16. Continuous Casting
Used to make large steel fixtures (iron plates, beams)
Metal is melted in hopper & gravity fed
Metal taken as needed
Unused metal recycled into hopper

17. Centrifugal Casting
Used to produce objects with large holes such as cast iron drain pipe
Mold is spun ~ 1000 RPM
Impurities gravitate to the inside surface
Impurities machined off

18. Modern Foundry Processes
Engineering
Mold Making
Melting
Checking Gas Levels
Pouring
Shakeout
Degating
Heat Treating
Surface Cleaning
Finishing
Secondary Machining
Quality Control

19. Engineering The best castings start with precise engineering
CAD software: concept to prototyping
Maximize production, minimize production cost
Maximize efficiency, consistency
Minimize waste
Design Engineering Video

20. Producing the Mold Fine sand is compressed tightly around pattern
Course sand used as fill

21. Producing the Mold

22. Melting Metal Solid metal is placed into crucible (melting pot)
Ceramic bowl that that withstands extreme temps.
Crucible is placed in furnace
Slowly heated until metal is liquefied
Poured into mold.

23. Melting Temperatures LEAD 700*F ALUMINUM 1200*F BRASS 1500*F
COPPER *F
STEEL *F
Aluminum is typically poured at 1350*F

24. Checking Gas Levels High gas levels Low gas levels Low viscosity
Gas levels: specific to alloy & pattern complexity
Quality Control: sample is taken and density is measured
Porosity: Air pockets formed in metal
High gas levels
Low gas levels
Low viscosity
More porosity
Weaker casting
More viscous
Less porosity
Stronger casting

25. Altering Gas Levels Argon or nitrogen is bubbled into metal
Too High
Too Low
Argon or nitrogen is bubbled into metal
Introduced at the bottom
Bubbles rise and catch hydrogen
Bubbles rise to top
Potatoes are added
Adds gas to metal
New sample taken

26. Pouring Metal is poured into mold to solidify
Some molds require 4-5 pours
1-2% shrinkage common

27. Automatic Die Casting Machine
Computerized casting machine that prevents fluctuations in metal
Mold is rolled into machine
Metal is casted beneath via low pressure
Provides consistency for difficult molds

28. Shakeout
Solidified metal component is then removed from its mold via shaking or tumbling
Frees the casting from the sand
Runners and gates are still attached
Allows sand to be reclaimed and reused
Lowers foundry production cost
Old days sand went to landfill!

29. Shakeout Machine

30. Degating Spru, runners, gates, and risers are removed
Torches, bandsaws, ceramic cutoff blades, sledge hammers
Specialized knockoff machinery used if design permits
Gating system (sprue, runner, gate) may equal 50% of a poor.
Gating components must be remelted as salvage.
Important economic consideration

31. Heat Treating
Part baked in large oven at a controlled temperature and time interval
Changes molecular grain for more strength
Heat Treated part is then quenched in bath
Adds strength to casting
Not all parts are
heat treated

32. Surface Cleaning Casting is blasted with tiny steel bb’s
Removes any sand or debris
May be used to achieve a particular rough finish

33. Finishing
The final step in the process usually involves grinding and sanding
Achieve dimensional accuracies, shape & finish.
These steps are done prior to any final machining.

34. Quality Control CNC equipment for precision gauging
Parts are x-rayed for imperfections
(Internal cracks, Porosity)
X-Ray Photograph
X-Ray Machine

35. Secondary Machining Parts are machined using precise CNC equipment.
Some foundries machine parts in house & some sub-contract machine shops
Secondary Machining Video

36. Tooling Up Flask Molding Board Bottom Board Rammer Riddle Trowel Slick
Sprue Pin
Riser Pin

37. Lance Pyrometer Tool used to identify molten metal temperature.
Different types of metal poor better at different temperatures.
Aluminum – 1450*F

38. Ingots
Ingot: a solid piece of metal that has been formed into a particular shape (such as a brick) so that it is easy to handle or stored

39. Flask & Boards Flask Cope - top Drag – bottom Boards
Molding Board – used on drag when being rammed
Bottom Board – placed on top of drag when flipping the mold, supports the bottom of the mold.

40. Sand Charactoristics Sand grit is determined just like sand paper
Fine sand will give a smooth finish
Rough sand will give a rough finish
Sand is 6% moisture – don’t let it dry out
Shovel – Used to mix & move sand
Riddle find sand around mold!
Sand allows gas to escape to

41. Slick, Sprue Pin, Riser Pin
Slick – Another tool used to flatten face of the mold.
Sprue Pin – Tapered wood or metal pin used to form sprue hole
Riser Pin – Wood or metal pin used to form overflow

42. Vent Wire, Molder’s Bellow, Bulb Sponge
Vent Wire - Small holes in mold to allow for gas escape.
Bellow - Tool used to blow excess sand from the mold cavity
Bulb Sponge – Smoothens the edges of the pattern to prevent loose sand from entering mold.

43. Sprue, Riser, & Gate Cutters
Same purpose as pins but used after the sand has been rammed/packed.
Tapered shank allows us to cut & extrude.

44. Parting Compound Sprinkled around pattern for easy mold extraction
Baby powder or fine gritt sand may be used

45. Hot Tips Finish molding before you starting the furnace!
Safety & Attention to detail
Keep sand covered or in a sealed container when not in use!
Avoid melting aluminum cans!
Cans are coated with vinyl for protection
Best results are obtained from clean metal
DO NOT stir molten metal, this adds gas!
Always skim slag before pouring!

46. Safety PPE: GLASSES, FACE SHIELD, SPATS, COAT, GLOVES!
ALWAYS PRE-HEAT METAL !
NEVER ADD LIQUID OR MOISTURE!
PLACE HOT CASTINGS IN A SAFE PLACE!
NEVER SET CRUCIABLE ON CONCRETE!
NEVER LOOK DIRECTLY OVER MELTING POT!
KEEP AREA CLEAN!
DON’T RUSH!
ALWAYS POUR WITH A PARTNER!
AVOID MOLDING NEAR EDGES OF FLASK!
NEVER LEAVE THE ROOM!
INSTRUCTOR MUST BE PRESENT!

47. A look at Local Foundries
Eck Industries
Wisconsin Aluminum Foundry
Bremer Manufacturing