TZERO®

The Next Level of Systematic Molding: The Influence of Plastic Behavior on Part Design

Doug EspinozaRJG, Inc. TZERO® Manager

616-889-5684Doug.espinoza@rjginc.com

Doug Espinoza is a TZER0® Manager at the corporate office of RJG, Inc. His varied career includes service in the United States Marine Corps, engineering, management, business, development, and strategic planning. Doug has spent more than 21 years in the plastics industry, practicing the RJG methods of scientific molding and implementation while working for injection molding companies.

Doug holds a Bachelor of Science in Plastics Engineering Technology from Ferris State University and a Master of Business Administration degree with an emphasis in International Business from Loyola University Chicago.

Doug is a regular contributor to professional organizations committed to the ongoing development of the plastics industry.

Where Does the Influence of Plastic Behavior on Part Design Start?

A Story…2. Dimensions Specified

QC: “Airflow” out of spec.

Molder’s tool shut down for a year for a spec. not given!

3. Part Concept

4. Part Design

5. Economics: # Cavities, etc.

6. Tool Concept

7. Detailed Tool Design

8. Tool Construction

9. First Article

10. Molding Process Developed

11. Parts to Specification

12. Designed Experiment and Validation

13. Production

14. Fix Problems During Production:

1. Performance Spec.

+ PANIC

Source: 2016 NORTH AMERICAN PLASTICS INDUSTRY STUDY Plante Moran

What Drives Profitable Growth?

Efficient Program Launches

Successful companies know that launches can become money pits if not managed with formal processes and effective teams.

Source: 2016 NORTH AMERICAN PLASTICS INDUSTRY STUDY Plante Moran

RJG Global OfficesRJG USA Traverse City, MI(RJG, Inc. Headquarters)

Woodstock, GA(Regional Training Center)

Gibsonville, NC(Regional Training Center)

RJG MexicoChihuahua, Mexico

RJG FranceArinthod, France

RJG GermanyKarlstein, Germany

RJG Ireland / UKCo Tipperary, Ireland

RJG Italy Next Innovation SrlMilano, Italy

RJG (S.E.A.) PTE LTDRepublic of Singapore

RJG ChinaChengdu, China

RJG KoreaCAEProSeoul, Korea

Helping Molders and Their Customers Succeed- RJG’s Mission & Core Competence

Think Like Plastic!

Heat

Flow

Pressure

Cooling

Title of chapter will be displayed here/Contents

Part Design• Design affects processing.

Material• All materials do not flow or pack the

same way.• Additives change the way material flows

and packs, including color.

Mold Design & Construction• Fill balance from PPV• Changing waterline locations can

change how a mold processes.

The Process• Two identical machines may perform

differently.• Converting pellets into parts using a

systematic approach yields success.

Successful DFM is based on an understanding of the entire process - from design to the end user

Cardinal Rule

• Nominal Wall Thickness• Effects Mold Design and Construction• Influences 3 of 4 Plastic Variables

• Plastic Flow Rate• Plastic Pressure Gradient• Plastic Cooling Rate & Time

Wall Thickness Change 4 mm to 3 mm

Pressure also depends on ____________________Wall Thickness

5,455 psi @97% full

4 mm Nominal Wall 3 mm Nominal Wall, same flow rate

8,950 psi @97% full

Wall Thickness and Cooling

Fountain Flow

Wall Thickness and Cooling - Continued

Wall Thickness and Cooling - Continued

Another Example

Temp. 52 sec.

316 °F

200 °F

88 °F

Freeze293 °F

Wall Thickness and Packing

Cavity metal

Flow: Thin section stretches and freezes molecules in alignment

“Living” hinge

Blue = Frozen:no flow => no pack

Frozen about .4 seconds after left edge fills

Wall Thickness and Packing - Continued

What if the wall gets so stiff that it can’t bend

inward and sink?

Plastic Cooling Behavior at Rib Junctions

Filling the Mold: Pressure and Flow

High Pressure

Pressure to push plastic into a part depends on…

LowerPressure

? ____________________Distance (Length of Flow)

High Pressure Lower

Pressure

? __________________Width (of flow front)

The tighter the radius, the higher the stress and BTU content due to shear. This will add risk to your part design.

What About Corners?

Cooling Time & Part Design

Poor Design Better Design

Can be further improved

Material

How Will the Material be Used?

Thermoplastic Morphology

Material Viscosity (“thickness”) Varies Over Time

78000

79000

80000

81000

82000

83000

84000

85000

86000

18000

18200

18400

18600

18800

19000

19200

19400

19600

Material viscosityincreasing over time

(new lot?)

Material gets thicker => harder to pack so end of

cavity pressure drops

Change in Material Viscosity => Change in Plastic Pressure

Ineos Lustran 248 ABSDay 1 Lot

(D1 = 7309)

Ineos Lustran 248 ABSDay 2 Lot

(D1 = 12,742)

13,300

15,800

4,120 Pack

3,170 Pack

Mold

Volumetric ShrinkageGating Thick to Thin

Source: “Moldflow Design Guide” from Hanser

Mold Cooling Evaluation

Heat Flow Restriction in Narrow Core

Temperature at ejection over 170 °F

max eject Temp.

Length

Width, thickness

Thermal resistance

(1/conductivity)

ThicknessWidthResistance ThermalLengthFlow HeatTemp

×××

∝∆

ΔT

Collaborate FEASIBLE Design Scenarios

Lifters in MoldMax

Both Halves in MoldMax

Cavity and inserts are cut in half to save calculation time.

Core Half in MoldMax + baffles

Mold TemperatureLifters in MoldMax Core Half in

MoldMax + baffles

Both Halves in MoldMax

“Close the Loop”- Validate!

Machine

Machine Performance

Machine A can fill the part in 1 sec Machine B can only fill the part in 3 sec

Requirement is Specified to your Process Windows and Quality RequirementsReal example: Fill speed

Systematic Molding From “the plastic’s point of view”

The Process

Title of chapter will be displayed here/

• What are common processmistakes made as a result of lack of knowledge?

• Is there one technique that can be used by everyone?

Systematic Molding

Need Mold PressureSensors

Non-Scientific

Decoupled II

Decoupled III

Typical Process Variation

Viscosity on Process Settings

Trended stability over time

Forecasting a Process SheetRisk the Process BEFORE Cutting Steel

UNIVERSAL PROCESS SHEETDecoupled II

Press# IMM-10 (Nissei PNX40)Part Number Puzzle Piece Part Description Puzzle Piece

Mold Number 1809 Cavities 4Material Toyolac 100 322

Hot Runner:Zone1 Zone2 Zone3 Zone4 Zone5 Zone6 Zone7 Zone8N/A N/A N/A N/A N/A N/A N/A N/A

Zone 9 Zone 10 Zone 11 Zone 12 Zone 13 Zone 14 Zone 15 Zone 16N/A N/A N/A N/A N/A N/A N/A N/A

Man1 Man2 Man3 Man4 Man5 Man6 Man7 Man8N/A N/A N/A N/A N/A N/A N/A N/A

Plastic TemperatureCharge

Delay 0.5 sec

Screw Rec 6 secBack 350 ppsiPart

Volume 0.65 cu.inch

Nozzle Zone 1 Zone 2 Zone 3 Zone4 Melt:

Setpoints: 410 410 410 410 410 °F 405 °F

Profile: Flat Screw Type: General Purpose RPM: 50

Plastic Flow

Fill TimeFill Only

Part WeightPeak ppsi in

Mold Peak ppsi in Air0.31 sec 11.1 grms 10016 ppsi 9967 ppsi

Plastic Pressure

Hold TimeHold

PressureFinal Part Shot

Weight Gate Sealed? 17.5 sec 5655 ppsi 12.34 Grams

1Plastic Cooling

Cooling Time 12 sec 24.5 secPRESSURE

MTCU Supply Return Flow Supply Return Delta Δ1 113 113 ºF 1 GPM2 113 113 ºF 1.5 GPM3 ºF GPM4 ºF GPM

Clamp

Clamp Type Hydraulic Tonnage Used 20 tons

Part Out 4.2 sec

FORECASTING THE PROCESSBEFORE CUTTING STEEL

Consider the following:• Press performance• Least Capable Machine Information

• Screw Diameter• Volumetric Flow rate• Max Tonnage• Max Screw Recovery at

recommended back pressure• Nozzle Pressure Loss• Mold open and close time on a

“like Part”• Sample Press Information (Listed Above)• Part Volume• Material Data

• Recommended Melt• Max Shear Rate • Data for Simulated Molding

Software• Part Characteristic's/ Concerns

• Defect Concerns• Dimensional

Cycle Time

Half the Battle is Knowing What is Happening in the Mold

DFM Analysis of Complete Product Assembly

Each Part and Mold Design is Reviewed

Odor filterHousing

Front CoverRear Cover

RJG Now Offers a “Part Design” Class After Successful Launch with Brand Owners

• Private Workshops• Simulation Services• TZER0® end-to-end

RJG, Inc. Classes# of Days Online Public In-House

Injection Molding Essentials 2 x x x

Math for Molders 1 x x

Systematic Molding 3 x x

Successful Strategies for Tool Launch 3 x x

Master Molder I 10 x

Master Molder II 10 x

Advanced eDART® Training 3 x x

Part Design for Injection Molding 3 x x

DECOUPLED MOLDING® Workshop 3 x x

Systematic Molding for LSR (Liquid Silicone Rubber) 3 x x

Mold Design for Injection Molding 3 x x

Template Match (Process Match & Troubleshooting) 3 x

Alarms Setting Workshop (eDART® / Optional) 1 x

DOE for Injection Molding Workshop 3 x

Summary The Next Level of Systematic Molding:

Influence of Plastic Behavior on Part Design• Collaboration with key parties (OEM, material, hot runners…etc )

at early product development phase• Education for enhanced collaboration

TZERO®

The Next Level of Systematic Molding: The Influence of Plastic Behavior on Part Design

Doug EspinozaRJG, Inc. TZERO® Manager

616-889-5684Doug.espinoza@rjginc.com

For more information on RJG’s TZERO® services, visit the RJG, Inc. web pagehttps://www.rjginc.com/consulting/tzero