"FOUNDRIES IN NORTHERN CALIFORNIA??" An Overview of Your Neighborhood Aluminum, Brass, Iron, and Steel Foundries (and Why We’re Here).
Why? • What keeps these foundries here? • Local Designers • Local Start-ups • Local OEM’s Specialized in their Niche Products and Services. • Medical Capital Equipment • Semi-conductor Capital Equipment • Networking Enclosures & Equipment • Heavy Trucking Components • Oil Exploration Equipment • Indoor & Outdoor Lighting • Why are there only a small number remaining in Northern CA? • There were approximately 125 Foundries in 1940’s • Consumer items after WWII • Less than 20 in 2007 • Foundries have moved Outside of California • Closed Global Competition
Who? • Aluminum • California Casting - Richmond • California State University - Chico • Castco - San Leandro • East Bay Brass Foundry - Richmond (Brass, Bronze, Lead, Copper) • Exper Cast Foundry - Santa Clara • General Foundry Service - San Leandro • Kearney Pattern Works & Foundry – San Jose • Production Pattern & Foundry Ridge Cast Metals Carson City, NV • Terminal Brass/Aluminum Foundry – South San Francisco • Iron • McWane Inc - AB&I Foundry – Oakland • Ridge Foundry – San Leandro • Lodi Iron Works - Lodi • U S Pipe & Foundry - Union City • Steel • California Electric Steel – Angels Camp • Grass Valley Steel Cast - Grass Valley • Pacific Steel – Berkeley • Tusco Casting – Lodi • Specialty Services • Rapid Mold (Digitized Molding) – Most Alloys Poured • St. John Associates
Bonded Sand Casting Green Sand Chemically Bonded Sand Vacuum Casting Shell Sand Casting Permanent Mold Casting Rubber Plaster Mold (RPM) Casting Investment Casting Centrifugal Casting True Centrifugal Centrifugal Processes
Bonded Sand Processes Green Sand Chemically Bonded Sand – “No Bake”
Green Sand Components • Sand • Clay • Water • Additives • Carbons • Cellulose • Cereals
Steel ice cleat cast in green sand replaced a forging Green Sand Advantages • Cost effective • Not “hazardous” waste in landfills • Minimal VOC’s emitted during pouring • Versatile; By far, most widely used • Applicable to all alloys except Ti & Zr • Adaptable to both low and high volume • Forgiving of minor tooling flaws Ductile iron air scoop replaced weldment at 40% cost reduction
8 Lost Foam When Would Green Sand Be Used?
No Bake Advantages • Also called Air-Set or Self-Setting • Used to make cores & molds • Easy sand mix compared to green sand • Good sand flowability • Uniform strength in cores & molds • Good dimensional control • Dry; No Moisture in mold = Steam • Longer “shelf life” than Greensand • Can make any size mold or core Strut Fan Cowl Support Beam for Boeing—Aluminum no-bake mold; holds engine to wing
8 Lost Foam When Would No-Bake (Air-Set) Be Used?
Shell Sand Advantages • Holds tight tolerances • Less draft required • Very thin walled sections possible • Small cored holes easily cast • Excellent surface finish • Excellent dimensional capability • Excellent dimensional stability
Shell Sand Drawbacks • Special pattern equipment required • Capital outlay for machinery • Size limits - small to medium sized molds & cores • Resin level is slightly higher than other chemically bonded sands • High casting volume needed for cost efficiency
8 Lost Foam When Would Shell Molds/Cores Be Used?
Permanent Molding Permanent Mold Semi-Permanent Mold Low-Pressure Die Casting
Permanent Mold Low Pressure Permanent Mold Die Casting Gravity Die Casting Low Pressure Die Casting High Pressure Die Casting Interchangeable Terms Confused Yet?
Types of Permanent Mold Casting • Static Pouring • similar to sand casting • Tilt Pouring • metal is poured into a basin while mold is horizontal and flows into the mold cavity as the mold is gradually tilted to a vertical position • Low Pressure or Vacuum • metal is drawn from below the mold up into the mold (counter gravity ) via a vacuum or pressure
Permanent Mold Advantages Oscar-Copper-based alloy • Good dimensional accuracy • Consistent quality • Metal fill can be controlled (tilt-pour) • Suitable for fairly complex castings • Multiple alloys castable • Expendable cores can be used • Process is then called Semi-Permanent mold Corvette Brake Pedal-converted from steel to aluminum
Permanent Mold Drawbacks • High cost of tooling • Limited casting size
8 Lost Foam When Would Permanent Molds Be Used?
Plaster Molding Process • Mold is made from a mixture of plaster, talc, other refractory materials and water • Slurry is poured or piped into a flask containing the pattern • Mold is dried in a circulating air oven until no moisture is present
Plaster Mold Casting • Rubber Plaster Mold process • Commonly replaces plastic injection molding with aluminum casting • Natural EMI RF Shielding • Tolerances: +/- 0.010” first 8 inches. • 20 days from CAD files to delivery (inc. machining)
Plaster Advantages • High casting yield • no gas or steam produced when metal is poured • Fine detail & intricate thin sections possible • Very little cleaning, if any, needed
Plaster Drawbacks • Drying time can take hours and can cause warpage or shrinkage of the mold • Low to medium volume production capabilities • Limited alloys - usually nonferrous
8 Lost Foam What Is a Common Use for Plaster Molds?
Investment Casting Advantages • Extremely accurate & flexible design parameters • Useful for casting difficult to machine alloys • Superior casting finish • Suitable for large or small quantities • Wide range of alloys cast Cast in Stainless or Chrome-Moly Steel for Integrity, Cast-In Features and Aesthetics; All Ruger Castings Are Visible
Investment Casting Drawbacks • Casting size is limited • Costly process • Equipment • Patterns • Process components very important • Additional quality checks required
8 Lost Foam When Would Investment Casting Be Used?
“True” Centrifugal Casting • Casting is spun on its own axis • No risers are required • No center core is needed
Pipe Casting MachineIron Flowing into the Mold at ~2340°F. • Plant produces about 4 miles of pipe/day. Pipe are approximately 85-90% recycled materials.
Centrifuged Casting • Mold impressions are grouped around a central down-gate • Centrifugal force is used as a mold filling device
Centrifugal Casting Advantages • Improved homogeneity • Improved accuracy in special circumstances
Centrifugal Casting Drawback Limitations on casting shape
8 Lost Foam What Questions Remain About Processes?