Center for
Die Casting
Computational Tools for Short Run Insert
Production and Improved Yield
Ohio State University/NADCA
R. Allen Miller
AMC
Castings for Improved Readiness
1
Status
Center for
Die Casting

AMC Castings for Improved Readiness
(CIR) project
 Officially started June 2006
2
Project Objective

Center for
Die Casting
The problem
 DLA needs cast parts rapidly and in low volumes
 Die casting is a high volume process with long
tooling lead times

The objective
 Optimize the insert and die to meet quality
specifications while using modular components to
shorten lead times and reduce break-even point
 Optimize shot yield by managing runner system
design

The technology will
 Match modular die components with parts and inserts
reducing the number of die components that must be
fabricated
 Optimize runner design so modular tooling does not
impose a quality or yield penalty
 Aid in configuring die to improve/optimize shot yield
Ejector die built with
a unit die base
3
Needs and Benefits

Center for
Die Casting
DoD / Supply Centers
 Die castings feasible for short-run production (100 – 200 +)
 Increase size of the supplier base
 Shorter design / production lead times for die castings
 Lower cost castings due to


Lower tooling cost
Higher yield and lower melting costs
4
Needs and Benefits

Center for
Die Casting
Metalcasting Industry
 Break even at lower total production quantities for die
castings
 Lower
tooling cost with reusable modular components
 Minimization process degradation typical with modular components
 Less on-machine process debugging associated with modular
tooling
 Significantly reduced tooling lead time when combined with
rapid tooling
 Higher shot yields
 Lower
unit material and melting costs
5
Tasks
1.
Center for
Die Casting
Yield Improvement (current work)
 Visualization approach – yield feedback provided for user
 Optimization – suggestions for yield improvement
2.
Short-run Holder Block Selection (scheduled to
start mid 2008)
 Group technology/database approach
 Match insert to base depending on part features
6
Project Progress – Yr 1

Center for
Die Casting
Completed review of part quality/die design
constraints
 Map of design variables and defects/quality constraints
 Map sets constraints for layout and yield
 Map also provides constraints for modular tooling work that
will start next year

Started visualization software for shot yield
determination. Features include:
 Configure die
 Layout runner system
 Quantify shot yield versus part requirements
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Yield Improvement
Center for
Die Casting


Yield = Casting Wt / Shot Wt
Shot Wt = Casting Wt + Biscuit/Sprue +
Runner + Overflow + Flash
 Casting Wt = Finished Part Wt +
Machining Allowance
 Machining allowances & flash not
considered in this work

Yield improvement largely means
optimizing biscuit, runners and overflows
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Technical Problem

Center for
Die Casting
Provide software to help determine the
part/die configuration that results in the
highest yield subject to the gating constraints
and machine availability
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Yield Approach
Center for
Die Casting
Visualization (low difficulty)
1.
•
•
Adjustments are input interactively and yield, flow
distance, and fill time are fed back
User makes changes interactively
Optimization (high difficulty)
2.
•
•
Algorithm makes translations and rotations in 3space seeking higher yield, shorter fill distances, and
minimum number of gates
Depends on feasibility of some type of ejectability
analysis
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Progress

Part Geom.
Yield
PQ2
Runner
Layout
Insert
Layout
Quality vs. Yield
 PQ2 is the best available way to
relate quality requirements to
die/process design (fill time, gate
velocity, static pressure).
 Fill time and gate velocity largely
control surface finish and porosity
 Biscuit volume and runner layout
determine yield
 Die configuration and gate area
controls the runner layout
Quality
Spec’s
Fill Time
& Gate Vel
Center for
Die Casting

Plunger selection and runner
layout are the primary levers to
control yield
Die Base
11
Injection System & Quality
Relationships





Metal pressure and metal flow rate
control surface finish, porosity,
casting integrity – i.e. control quality
Machine determines power available
Plunger size and machine control
flow rate and also pressure on metal
Gate area and machine operating
point control metal speed thru gate
Plunger size determines biscuit size
that contributes to yield
PQ2 Diagram Relating Machine, Die and Gating
Major Constraints/Limits
Center for
Die Casting

Machine availability
 Sleeve availability
 Fill requirements (control fill
defects)
 Surface finish
 Consistency across cavities
 Possibly solidification pattern
13
Key Factors

Center for
Die Casting
Biscuit
 Sleeve selection controls diameter


2.5” sleeve vs. 2.0  56% larger volume for same length
Sleeve should be optimized based on requirements
 Process control controls biscuit length

Runner System
 Depends on die layout
 Fill zone requirements control number of gates
 Gate dimensions and location plus layout control runner
layout
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Summary
Runner System and Quality



Center for
Die Casting
Runner big factor in yield
Runner must connect gate to part
Gate locations and size determined by fill pattern
requirements that impact trapped gas porosity and
surface finish
 More gates means more runner volume and lower yield
 More gates often used to reduce distance metal must flow to fill cavity
(reduce chance of premature solidification and fill defects)

Total gate size determined by machine and metal gate
speed requirements
 Match machine power to part requirements (see figure on previous
slide)

Opportunity is to improve part layout in die to improve
the runner system to improve both yield and performance
15
Runner Layout for Visualization



Center for
Die Casting
Quadratic spline
techniques implemented
to aid runner system
layout
Fast and easy generation
of alternatives
Immediate yield feed
back while meeting gate
area (quality)
constraints
16
Example – What should happen




Part should be rotated 180 degrees
Kicker gates removed eliminating the outside runners
Main gates increased in size to accommodate the other changes
Depending on machine, biscuit could be moved closer to the part to
shorten runner
Short Term Plans

Center for
Die Casting
Visualization work for yield will be
completed.
 Testing “before and after” yield and quality
results for at least 3 dies
18
Short term Plans Con’t

Center for
Die Casting
Existing qualitative ejectability analysis
algorithms will be implemented
 Die layout affects ejectability as well as yield
 Visual and quantitative feedback of the
ejection force distribution on the part will be
provided
 User of the software will be able evaluate
yield/ejection tradeoffs
19
Mid Term

Center for
Die Casting
Explore optimization/design guidance
for yield and quality
20
Longer Term

Center for
Die Casting
Holder block matching and selection
21
Acknowledgements

Center for
Die Casting
AMC’s PRO-ACT program is sponsored by
the Defense Supply Center Philadelphia,
Philadelphia, PA, Defense Logistics Agency, Ft.
Belvoir, VA
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