Automotive Brake Drum ME 324 Project Group 9 12/5/05 Jon RichardsonJared Chezik Kelly McGeoughBryan Johnsen Matt Creswick

Outline Problem Statement Common materials CGI Machining of CGI Manufacturing Process Safety Cost References Questions

Problem Statement Analyze the current processes involved with manufacturing an automotive brake drum Develop a manufacturing process based on our research and other acquired knowledge

Common Materials Cast iron  Inexpensive  Widely used  Easily machined Aluminum  Lightweight  Easily warped Cast Iron Drum Aluminum Drums

Our Material of Choice Compacted Graphite Iron, CGI  High casting productivity  Special machining considerations  Nearly 2x stronger than grey iron due to its structure Parts can be made lighter  High heat transfer rate Cast iron microstructures

Machining of CGI Machining considerations  Requires 30% more power than grey iron  Requires more rigid tooling than grey iron Requires a specialized rotary insert cutting tool  Cost is justified by a high machining speed (1000m/min) Rotary Insert Cutting Tool

Manufacturing Process  1) A sand mold is made from a pattern that represents the final casting  2) Molten iron is poured into the mold cavity  3) The cooled casting is cleaned by mechanical methods  4) Casting is painted  5) Casting is turned to final dimensions using a lathe  6) The bolt circle is then drilled into the drum  7) Drum is balanced to eliminate vibrational forces  8) Drum is ready for shipment

Casting A sand/chemical compound forms the pattern Molten iron is poured into the hardened cope/drag mold combo Results in a rough brake drum casting

Bead blasting Removes sand and flash from rough casting  Tiny abrasive particles impact drum surface at high velocity  Propelled by compressed air Can’t remove large imperfections or large amounts of flash  Must be ground off with abrasive wheel

Painting Powder Coating  Durable coating  Professional finish  Little waste Dipping  Dip-and-spin  Barrel enameling Industrial Spray Painting

Machining The friction surface is machined on a lathe  Tolerances not good enough Final dimensions and surface finish is reached in a secondary operation  Friction surface is honed Vertical Brake Drum Lathe

Machining cont. Bolt pattern varies greatly between applications  Typically 4 to 8 bolt holes  Varying bolt circle pattern  Varying bolt hole diameters Holes bored and measured with aid of a computer to ensure accuracy Bolt pattern showing bolt circle

Safety Casting Safety  Various protective equipment when casting the drums High-temp resistant gloves Sand floor Protective leathers Helmet with face shield Foot protectors Respiratory protection (if needed) Heat resistant suit or jacket Safety glasses

Safety cont. Machining Safety  Eye protection  Hand protection  Proper clothing Painting Safety  Eye and skin protection  Respiratory protection

Cost Material choice greatly affects all costs  More expensive material cost compared to grey iron  More expensive machine tools  High speed machining justifies cost Use of CGI not recommend for small scale production  Large scale production is needed to dampen material cost burden

Cost (cont.) Actual production cost per unit  Dependent on production application Size, Quantity produced, etc. Predicted future of CGI  Reduced cost with increased production usage More brake drum manufacturers using CGI Ford beginning to use CGI for engine blocks

References Neil Shroff – DuraBrake Co

QUESTIONS?