Die Casting Parts Review
Pinless tag clip- zinc die casting parts
- Zinc: ZA-8
- Weight: 0.35 oz
- Miniature zinc
- 100,000 parts in 4 weeks
Power conditioning module chases – aluminum die casting parts
- Aluminum: 380
- Weight: 2..3lbs
- ̴12”ꭗ12” (30ꭗ30 cm)
- Die built in 8 weeks
- Replace machined component
- Significant cost savings
Steering knuckles
Performance
- Passed 1.4g cornering load at 130,000 min and 280,000 cycle’s max (4 to 8ꭗ req.)
- UTS > 2ꭗ customer requirements in all tests
- Lower control arm test: unbreakable (fixture failure)
- Outperformed all previous AI knuckles
- 10% weight reduction
- 5% cost reduction
Thrust rods
Performance
- ̴50% weight reduction
- Ribs allowed stiffness needed
- Three parts consolidated into one
- Replaced stamped steel parts
Engine base bracket
Performance
- 43.6% weight reduction over stamped steel fabrication
- Met strength and ductility requirements
- 16 parts to 1
- 4 different brackets now one common bracket
- Cost reduction confidential per customer
- Up to 1M per year
Engine subframe
Performance
- Welded to hydro/bulge formed and squeeze cast parts
- 46% weld length reduction ̴40% lighter
- Down to 16 parts from 48 (66% less)
- Cost reduction realized, but confidential
Shock tower
Performance
- 40% weight savings
- Eliminated 5 part steel assembly
- Exceeded requirements
- Elongation allowed self-piercing riveting
- Allowed thin wall heat treatment
Porosity – background
- Common in many die castings
- Common in metal casting
- All defects are characteristics of the process
- Considered a defect when porosity level exceed requirements
Outline
- Sources of casting defects
- Process control of defects
- Design control of defects
- Measuring defects
The cause of defects
Background
- Two sources of porosity
- Solidification
- Gas (various sources)
- Smooth pores formed at high liquid fractions
- Jagged pores formed at a lower liquid fraction
- Many aluminum alloys shrink ̴6%
- Common casting pore fraction < 3%
Shrinkage porosity – summary
- Shrinkage can account for all the porosity
- To reduce shrinkage porosity
- Feeding, feeding, feeding
- Bigger gates
- High pressure
- Etc
- Alloy design
- Interacts with gas porosity
Dissolved gas porosity
Three major causes of gas
- Hydrogen gas
- Entrained air
- Evaporation of lubes, water, etc…
cannot be separated from shrinkage easily
gas will fill shrinkage pores
Hydrogen porosity
hydrogen solubility
- high in liquid
- low in solid
during solidification
- hydrogen gas rejection
- forms porosity
typically
- microspores
- combine with larger pores
Entrained air porosity
air caught during filling
- in short sleeve
- during injection
- poor venting
difficult to predict quantitatively
process variables and design affects air entrainment
The vacuum can be effective
Other gas porosity
typical other sources of porosity include:
- die lube
- plunger tip lube
- water
- hydraulic oil/heating oil leaks
color of porosity can help identify sources
- dark = lubes
- light/shiny = water
Reduce leaking
- impregnation
- reduce porosity
- avoid removing skin
- avoid soldering
- move knit lines
practically
- process control
- gating
- design