design for manufacturing - class 6 - die casting
TRANSCRIPT
DRAGON INNOVATION, INC. !
DESIGN FOR MANUFACTURING !
COURSE 6: DIE CASTING !!!!!!!
SCOTT N. MILLER | CEO | @DRAGONINNOVATE | WWW.DRAGONINNOVATION.COM
•Overview •Die Casting Process •Part Design •Materials
AGENDA
Overview
Recommended References
www.matweb.com
Typical Engineering Die Cast Parts (Examples)
• Housings / Brackets
• Gears
• Joints
Die Casting Advantages
• Ability to create complex geometry • Thin walls vs. other casting processes • Excellent dimensional stability • Excellent mechanical strength • Good surface finish • Suitable for high volume production
Die Casting Disadvantages
• High tooling costs and long lead-times
• Difficult to make changes
• Large undercuts are difficult. Cannot use internal slides.
• Limited Alloys
• Cannot produce very large parts as a single piece.
Die Casting Process
Die Casting Shop
Die Casting Process
Hot vs. Cold Chamber
Secondary Ops
Inspection
Die Cast Part Design
Design Guidelines
• Similar to Injection Molding. Consider die casting when injected part does not have sufficient strength.
• Wall Thickness function of alloy (typ 1.0 - 3mm). Can go up to 10mm (will be porous - strength not proportional to wall)
• Ribs 80% wall thickness. Shrinkage less of an issue. • Cooling time proportional to wall thickness (injection is
t^2), so can have faster cycle times and thicker walls. • Draft depends on alloy. Assume >1.0 deg, esp. on
cavity side. • Tolerance is a function of the alloy, part geometry and
die construction. • Zinc Alloy Linear: +/- 0.025mm across up to
50mm • Zinc Alloy Hole: +/- 0.015mm up to 25 mm
diameter. • Need overflow wells and secondary ops -> $$ • No internal slides or snap fits.Reference: Product Design for Manufacture and Assembly. Geoffrey Boothroyd,, Peter Dewhurst and Winston Knight.
Materials
Common Alloys
Alloy / Resin Young’s (MN/m2)
Yield (MN/m2)
Spc Gravity (g/cm3)
Cost ($/kg)
Die Life (cycles)
Pressure (psi)
Wall Thickness (mm)
Melting Temp (C)
Zinc 70,000 250 6.6 1.80 500,000 3,000 1.0 – 1.5 420
Zinc-‐AL 80,000 330 5.8 1.90 500,000 5,100 2.0 – 2.3 430
Aluminum 125,000 150 2.7 1.70 100,000 7,000 2.0 – 2.3 660
Magnesium 45,000 150 1.8 2.93 180,000 7,000 2.0 – 2.3 650
Copper 100,000 215 8.4 6.60 15,000 5,800 2.0 – 3.0 950
GF Nylon 28,000 70 1.13 4.00 300,000 16,000 2.0 – 3.0 130
Reference: Product Design for Manufacture and Assembly. Geoffrey Boothroyd,, Peter Dewhurst and Winston Knight.
Finishes
Finishing Process Cost per 50 cm2 (cents)
Sealant Impregnation 1.8Cu / N / Cr Plating 4.5
Polish 1.3
Anodize 1.6
Prime Coat 2.1
Finish Paint Coat 2.4
Reference: Product Design for Manufacture and Assembly. Geoffrey Boothroyd,, Peter Dewhurst and Winston Knight.
Questions?
