Rapid Prototyping & Alternative Manufacturing Techniques

or how to get it done differently than we told you yesterday

Outline

• Welding• Waterjet• EDM• Stereolithography & 3-D printing• Casting• Forming• Injection Molding• Thermoforming

Outline

• Welding• Waterjet• EDM• Stereolithography & 3-D printing• Casting• Forming• Injection Molding• Thermoforming

Welding

• Fabrication method that joins metal by melting the base materials & adding a filler

• Needs protective clothing, masks, special equipment

• STRONG welds take practice and experience, otherwise get a professional to do it

weld

Heat affected zone

Base material

Waterjet

• Cut material using high-pressure water and an abrasive powder

• No Heat-Affected Zone

• Can cut almost anything– No tempered glass, some

ceramics

Waterjet - DFM

• Planar geometry

• Kurf – part won’t have straight edges

EDM – Electrical Discharge Machining

• Must be conductive material

• Great for cutting very hard material easily

• Expensive & hard to find shops that do it

• Intricate detail

• Non-contact machining

Stereolithography & 3-D Printing

• Go straight from CAD to part

• Material is often brittle, although new polymers are being developed

• Can have undercuts, long holes, high depth-width ratios

Stereolithography & 3-D Printing

Sand Casting

• Interesting part geometries• Can be pretty cheap• Not good surface finish• Not good accuracy• Need to make pattern• Need draft angles• Shrinks on cooling (not predictable)• Local (Burlington, MA)

Forming

• Can bend or punch sheet metal

• Cheap, fast, easy

• Not very accurate

Injection Molding

• Melt plastic pellets and presses melted plastic into molds

• Molds have to be machined, expensive, time-intensive

• Good for high-rate production

Thermoforming

• Thermoplastic heated to a rubbery consistency and then stretched over a mold and allowed to cool

• Not high precision or accuracy

• Good for moderately complex geometry