Lean Strategies For Injection Molding 3 Hour E Learning

Lean Strategies for
Injection Molders

1 - Lean

Questions
How do I know if the molder is giving the mold a chance to perform?
How do I know if the processor has the mold in the correct machine?

How do I know if this machine is even capable?

Why, when we adjust the tool steel to meet the dimensions, are they
not correct the next time they try it out?

We have modified this mold six times and it still is not correct!

They got good parts out of this mold at the other molder, why can’t
you?

It fits between the tie bars and you have enough shot size, so what is
the problem?

These are a small sampling of questions that cause process problems and cost
money. With increasing pressure from a global economy and local competition we
need to be more thorough in bringing the mold to production either as a new
production or a tool that has been transferred from another molder.

2 - Lean

Start-Up Companies
Domestic & Foreign Investment Groups
Your Company Your Competitors

 Your Building  Their Building
 Your Equipment  Their Equipment
 Your Employees  Their Employees
 Your Customers  Seeking Your Customers

What sets you apart from your competitors?
KNOWLEDGE!
And how you use it 3 - Lean

Systematic Molding Defined

Making operational decisions based on data and
analysis as opposed to only intuition, opinions and
politics to achieve optimal results.

Using monitoring, containment and control to
achieve a level of quality always exceeding the
customer’s expectation.

4 - Lean

“Progress Always Involves Risk.

You can’t steal second base and
keep your foot on first base.”
Frederick Wilcox

5 - Lean

Part Design

6 - Lean

Request for Quote

The part: AB Switch Housing
Material: Polypropylene MFI 4
Quantity: 100,000 annually
Cost: $$$$$$ per number of parts or per part
Time: Six weeks to production
Tooling Budget: $$$$$
Quality: First Article or PPAP
Gate Location: Cosmetic concerns

7 - Lean

Potential Problem Areas

 How can we fix this?
 How do we communicate this to the customer?
 Will the customer allow a design change?
9 - Lean

PART RELEASE
As plastic parts cool and shrink in the mold they:
 Pull away from the cavity
 Draw down tightly onto the core
Since the part must slide out of the mold without distortion, draft angles
parallel to. Part release are necessary on all draw surfaces.

The degree of draft required is a function of:
 Material shrinkage rate and abrasiveness
 Part surface requirements
 Uniformity of wall thickness
 Depth of draw
Any draft is better than none.
Specify the largest that the functional requirements of the part will
allow. 10 - Lean

Validating Draft for Part Release

If we cannot have draft our strategy must change to remove the
part from the mold (mechanically) and cavity pressures may
need to be kept low (process), therefore shrink rates go up.
11 - Lean

RADIUS

 In the design of the injection-molded parts, sharp corners should always be
avoided
 Inside corners on the molded parts are highly stressed and have historically
been the highest single cause of part failure
 Outside corners are difficult to fill and trap air and gas, which creates burn marks
 Generally desirable to be greater than 25% of the wall thickness

 Sufficient Radii
 Distribute stress
 Improve flow  It is rare when one size is best for all
 Promote uniform shrinkage corners
 Reduce sink, voids and  There may be locations (such as parting
warpage line) where radius is impractical
 Eliminate trapped air 12 - Lean

Adding Radius

What are some problems associated with lack of radius?
13 - Lean

Wall thickness
If the functional requirements of a part require a departure from
nominal wall, the designer must visualize how plastic flow and
shrinkage will interact with the design to affect properties.

 Wall thickness changes should be minimal and gradual
 As a general guideline, wall thickness changes should be less than
25% of the nominal. This is more important with semi-crystalline
plastics
 Lack of uniform nominal wall thickness is the single most troublesome
problem encountered relative to part design
14 - Lean

Constant Wall Thickness

15 - Lean

Additions & Subtractions
 Additions are part features that present a non-linear
extension of the wall
 Ribs
 Bosses
 Gussets
 Raised areas
 All have much in common from a design point of view
 The design issues relate to:
 Shape
 Spacing
 SHAPE
 The primary goal is to reduce the effect of modifying the
constant wall thickness by keeping the base as small as
possible
 Generally, around 1/2 the wall thickness (50% of the
wall thickness)
 Projections on parts are formed by depressions in the
mold
 Those depressed areas are difficult to fill and vent
 To minimize the effect, projections should be kept as
short as possible (generally less than three times the
wall thickness)
 Shrinkage of plastic between vertical projections can
cause stresses, particularly at the corners
 To minimize this effect, projections should not be placed
too close together (generally not closer than two times
the wall thickness)
16 - Lean

Modified Part Geometry for Wall
Thickness

17 - Lean

There is Still a Problem
 Depressions into the wall to create holes
 Through
 Blind
 Round
 Square
 Irregular
 Slots
 Grooves
 Threads (inside and outside)
 Square or irregular holes with sharp corners create stresses
which can cause cracks in parts as they shrink or during
ejection
 To minimize this effect, radius corners as much as the
functional requirements of the part will allow
 The part will be less stressed and progressively stronger as
radius is increased 18 - Lean

Cutaway of Another Addition to
the Wall

19 - Lean

A Hidden Thick Section

20 - Lean

Modified Part

21 - Lean

Gate and Location
 What type of gate would we use?
 Benefits
 Concerns
 Where would the gate be placed?
 What quality issues might we have?
 What if the budget for the mold was a concern or limited, what
options do we have?
 Should I be concerned with gate seal time at this time?
 What information do I need to make a decision on gate size?

 Where the knit line be?

22 - Lean

Developing a Setup Sheet
Prior to Cutting Steel
Measuring Risk of Producing this Product.

23 - Lean

Solid Model
Key Information from Solid Model
Cubic inch volume of the solid model is 5.09
Sprue / Runner volume is 2.73 cubic inches
Square inches at the parting line is 7.99

Key Information from Flow Analysis
Fill Time is .95 seconds
Pressure near gate is 12,000 ppsi
Pressure at end of part 2,600 ppsi
Average pressure in the mold to produce a good
part is 7300ppsi
Tons per square inch is 3.65
Cooling Time 16 seconds
Pack/Hold Time 7 seconds
Pack/Hold Pressure 14,370ppsi
Set up Sheet
We can establish a shot size, transfer position and cushion from the volume.
We can establish the clamp force needed based on the square inches and the
average cavity pressure.
24 - Lean

Measuring Risk of Potential
Problem Areas

 Square corners equals risk of 5
 Additions to walls equals risk of 5
 Change in wall thickness equals risk of 5 if
gate location is on opposing end of part
25 - Lean

Modified Part

High Risk Part Design Low Risk Part Design

Square corners equals risk of 5
Square corners equals risk of 2
Additions to walls equals risk of 5
Additions to walls equals risk of 5
Change in wall thickness equals risk of 5 if
gate location is on opposing end of part Change in wall thickness equals risk of 3

26 - Lean

Selected Number of Cavities

Risk
Runner layout: a risk of 2
Gate location: a risk of 5
Gate Type: a risk of 3
Balance of Fill 3
Risk of cold slug well/puller design 5 27 - Lean

Flow Analysis

Risk of Balance 5

28 - Lean

Our Potential Molding Machine

 220 ton clamp force
 1.77 in diameter screw
 2600 psi hydraulic pump
 12.2:1 Intensification Ratio
 Maximum Plastic pressure generated is 31,720 ppsi
 General Purpose Screw with a compression ration of 2.0
 L/D of 20:1
 Square pitch flight pattern of 10/5/5
 12 inch linear shot capability
 Maximum Injection Speed 10.2

29 - Lean

Decoupled II Pre Process
Setup Sheet

Plastic Flow Rate

Shot Size 10.668 inches Transfer Position 1.454 inches Cushion .969 inches Decompress .312 inches

Fill Time .95 seconds Injection Speed 9.7 inches per second Fill Only Part Weight 72.07 grams

Clamp Force
Clamp Force 136 Tons

30 - Lean

Decoupled II Pre Process Setup Sheet
Plastic Flow Rate



Clamp Force

Plastic Temperature
Melt Temperature 412.5 degrees Back Pressure 61.5psi RPM 75
Nozzle 412.5 degrees Front Zone 412.5 degrees Middle Zone 412.5 degrees Rear Zone 412.5 degrees

Plastic Pressure
Pack/Hold Time 7 seconds Pack/Hold Pressure 14,370 ppsi Full Part Weight 75.87 grams
Gate Seal Yes

Plastic Cooling

Cooling Timer 16 seconds Mold Temperature 120 degrees

32 - Lean

Measuring the Risk of the Setup
Plastic Flow Rate

Shot Size 10.668 inches5 Transfer Position 1.454 inches1 Cushion .969 inches1 Decompress .312inches1

Fill Time .95 seconds5 Injection Speed 9.7 inches per second5 Fill Only Part Weight 72.07 grams1

Clamp Force
Clamp Force 136 Tons3

Plastic Temperature
Melt Temperature 412.5 degrees2 Back Pressure 61.5ps1 RPM 751
Nozzle 412.5 degrees1 Front Zone 412.5 degrees1 Middle Zone 412.5 degrees1 Rear Zone 412.5 degrees1

Plastic Pressure
Pack/Hold Time 7 seconds1 Pack/Hold Pressure 14,370 ppsi1 Full Part Weight 75.87 grams1
Gate Seal Yes

Plastic Cooling

Cooling Timer 16 seconds1 Mold Temperature 120 degrees1

33 - Lean

The Risk
The Process
Shot Size 10.668 inches5 Transfer Position 1.454 inches1 Cushion .969 inches1 Decompress .312inches1


Clamp Force 136 Tons3 Back Pressure 61.5ps1 RPM 751
Melt Temperature 412.5 degrees2
Nozzle 412.5 degrees1 Front Zone 412.5 degrees1 Middle Zone 412.5 degrees1 Rear Zone 412.5 degrees1

Gate Seal 1 Cooling Timer 16 seconds1 Mold Temperature 120 degrees1

The Part
Square corners equals risk of 5 Additions to walls equals risk of 5 Change in wall thickness equals risk of 5

Cavity Layout
Runner layout: a risk of 5 Gate location: a risk of 5 Gate Type: a risk of 3 Balance of Fill 5
Risk of cold slug well/puller design 5

Potential Total Risk of 29 topics at a Our Risk of Producing this Product is 74 which is a
severe rating of 5 equals very average part to produce

145 74
34 - Lean

Systematic Tool Transfers Defined

Systematic Tool Transfer uses information from
all available sources and data from sensors to
establish a normalized setup which can be
recreated with a high degree of certainty on other
correct and capable machines.

35 - Lean

Reasons for tool transfers
 New Tool Launch with tryout at tool builders facility
 Intra company tool transfers
 Reorganization
 Reduction (manpower, Building usage, Consolidation)

 Outside Tool Transfer (Some may be Hostile)
 Lack of Profits
 Poor repeatable quality from production
 Poor tool quality
 Better Logistics

In this seminar will focus on Intra and Outside Tool Transfers.

36 - Lean

Tool Transfer Methodology
Step 1: Risk Analysis Step 2: Risk Mitigation (Transfer Strategy) Step 3: Implementation

Traditional Start Over
Transfer Build New Process

Transfer Process
Paper Setup Sheet
(Med-High Risk)
Re-Build Process

Tool Transfer Machine
Strategy Normalized
Transfer Process
Graphical Machine Data
(Med-Low Risk)
Re-Build Process

Transfer Process
Cavity
Pressure
Re-Build Process

37 - Lean

Step 1: Risk Analysis
 Properly size mold to machine (on sending and
receiving side)
 Max shot capacity and % of shot capacity actually used
 Maximum injection pressure capacity and max injection
pressure setting used (Ri) – must accommodate 20%
viscosity shift
 Maximum injection speed capacity and injection speed
used
 Tie bar spacing and actual size of the mold
 Clamp tonnage capacity and actual clamp tonnage used
 Clamp design (toggle vs.. hydraulic)
 Thermolator flow and temperature capability
 Drier throughput
 Screw type
38 - Lean

Step 1: Risk Analysis Cont.

 Press Performance (sending and
receiving)
 Pressure response
 Optional:
 Injection Speed Linearity
 Pressure Response
 Load Sensitivity
 Check-ring Study
 Maximum Plastic Pressure

39 - Lean


 Part Design
 Uniform wall
 Radiusing
 Part Thickness
Better Candidate for a transfer.
 Pressure loss or study
(can get from flow
analysis)
 Solid Model Information
 Part Draft
 Weld Line Concerns

Transferring a poorly designed part will not fix it.
40 - Lean


 Runner Layout
 Naturally Balanced vs..
Imbalanced
 Measurement of actual
balance
 Hot vs. Cold Runner
 Pressure losses (actual
measurements)
 Family Tool?

 Gate and Gate Type
 Gate Type
 Gate Location
 Weld Line Concerns

41 - Lean


 Material
 Viscosity (amount and
consistency)
 Injection Grade vs.. Extrusion
Grade
 Wide Spec Material
 Uncontrolled Regrind
 Screw design appropriate?
 Material Delivery System
 Dryer Capability
 Validation of Material Conditions

42 - Lean

Decoupled II, 2-Stage Molding
Process Sheet

 Setup Sheet from Mold #: Trim RH Footwell Template Name: Cycle Time: Under 90 sec

Material Information

Current Process Resin Type: Solvay 2420 TPO

Nozzle Type: Straight Inject
Color: Dk Gray
Dk Taupe
Color %:
Blowing Agent: n/a

B/A %: n/a

Dryer Temp: 100 °F GAS psi: n/a Nozzle Tip Size: record for us

 Material Processing Plastic Temperature

Guide 30/30: 440 Charge Time: 2 to 4 seconds

Plastic Flow Rate
BP (ppsi): 800-1000 plastic pressure

Fill Time: 3.5 seconds Part(s) weight: 2.16 lbs Inject Delay: n/a

Peak Plastic Pressure/Mold: 10,381 ppsi Air: record this for us

Plastic Pressure

Pack/Hold Time: 15.5 seconds Inject Timer: Toshiba setting n/a
F&P Part(s) weight: 2.275 lbs
Hold Time: 15.5 seconds Hold Plastic psi: 6229 ppsi
Gate Seal: yes Final part weight: 2.275 lbs

Plasitc Cooling

Cooling timer: 60 seconds
Coolant:
A Temp(in) 80 °F Temp(out) +/- 5 °F Flow:
B Temp(in) 80 °F Temp(out) +/- 5 °F
Clamp

Force: 1052 tons Gate 1 open: n/a Gate 2 open: n/a
Type: record this Gate 1 closed: n/a Gate 2 closed: n/a
toggle/hydr
Gate 3 open: n/a Gate 4 open: n/a
Gate 3 closed: n/a Gate 4 closed: n/a

43 - Lean


 Does Mold Currently Make Good Parts
Consistently?
 Tool Condition
 Is it in the Correct Machine Now?
 Any Deviations
 First Article or PPAP

44 - Lean


 Graphical Process Data
 eDART™
 Cavity Pressure Curves

 Temperature Sensors

 Delta Pressure for cooling

 Appropriate Machine Signals/Triggers

45 - Lean

Step 1: Risk Analysis Step 2: Risk Mitigation (Transfer Strategy) Step 3: Implementation

Traditional Start Over

Transfer Process
Paper Setup Sheet
(Med-High Risk)
Re-Build Process

Strategy Normalized
Transfer Process
(Med-Low Risk)
Re-Build Process

Transfer Process
Cavity
Pressure
Re-Build Process

46 - Lean

Step 2: Risk Mitigation
Runner Layout (Transfer Strategy)
Naturally Balanced vs. Graphical Process Data
Imbalanced eDART™
Measurement of actual Cavity Pressure Curves
balance Part Design Temperature Sensors
Hot vs. Cold Runner Uniform wall Delta Pressure for cooling
Pressure losses (actual Radiusing Appropriate Machine
measurements) Part Thickness Signals/Triggers
Family Tool? Pressure loss or study (can get from
Gate and Gate Type flow analysis)
Press Performance (sending and
Gate Type Solid Model Information
receiving)
Gate Location Part Draft
Pressure response
Weld Line Concerns Weld Line Concerns
Optional:
Injection Speed
Properly size mold to machine (on sending and receiving side)
Linearity
Max shot capacity and % of shot capacity actually used
Pressure
Maximum injection pressure capacity and max injection
Response
pressure setting used (Ri) – must accommodate 20% viscosity
Load Sensitivity
shift
Check-ring Study
Maximum injection speed capacity and injection speed used
Maximum Plastic
Tie bar spacing and actual size of the mold
Pressure
Clamp tonnage capacity and actual clamp tonnage used Setup Sheet from Current Process
Clamp design (toggle vs. hydraulic) Material Processing Guide
Thermolator flow and temperature capability
Drier throughput
Material Does Mold Currently Make Good Parts
Screw type
Viscosity (amount and Consistently?
consistency) Tool Condition
Injection Grade vs.. Is it in the Correct Machine Now?
Extrusion Grade Any Deviations
Wide Spec Material First Article or PPAP
Uncontrolled Regrind
Screw design appropriate?
Material Delivery System
Dryer Capability
Validation of Material
Conditions

The more information missing, the higher the RISK 47 - Lean

Three types of Tool Transfers

 High Risk
 Tool Shows up with no parts, prints and no setup sheet

 Middle Risk
 Mold shows up with a prints, a part and setup sheet from
prior process

 Low Risk
 We have Prints, short shots, full shot and setup sheet
 We have their machine evaluations
 We have all graphical data from the process with cavity
curves

48 - Lean


Traditional High Risk Start Over

Middle Risk Transfer Process
Paper Setup Sheet
(Med-High Risk)
Re-Build Process

Strategy Normalized
Transfer Process
(Med-Low Risk)
Re-Build Process

Low Risk
Transfer Process
Cavity
Pressure
Re-Build Process

49 - Lean

What is a High Risk Tool Transfer


Paper Setup Sheet
(Med-High Risk)
Re-Build Process

Strategy Normalized
Transfer Process
(Med-Low Risk)
Re-Build Process

Low Risk
Transfer Process
Cavity
Pressure
Re-Build Process

50 - Lean

Items Transferred
 Mold
 How was the water lines installed during production?
 Was the clamp forced optimized or set at maximum?
 Traditional Setup Sheet (maybe)
 Could the machine actually go that many inches per second?
 What screw diameter did they use?
 How full was the part at transfer or was it a pressure limited process?
 How do I convert these pressures, not knowing the intensification ratio?
 Parts (maybe)
 Are these the parts that they ran before sending the mold or are these when
the mold was new?
 For the Receiving Machine this is a Mystery Tool

There is no plan for success with this (lack of)
information.
51 - Lean


Paper Setup Sheet
(Med-High Risk)
Re-Build Process

Strategy Normalized
Transfer Process
(Med-Low Risk)
Re-Build Process

Low Risk
Transfer Process
Cavity
Pressure
Re-Build Process

52 - Lean

Middle Risk
 With setup sheet (higher risk than using data acquisition)
 Transfer a GOOD PROCESS (based on risk assessment)
 Sprue Orifice Diameter
 Clamp Force (may depend on tie bar spacing due to platen deflection)
 Fill Time (must be consistent measurement – includes decomp or
not?)
 Fill Only Part Weight (consistent fill only part measurement strategy)
 Hold Pressure (plastic)
 Hold Time
 Screw Run Time
 Back Pressure (plastic)
 Mold Clamped Time (ideally)
 Cycle Time
 Temperature Map (understanding challenges) – including temp in/out
 Better: Water Temp in/out and volumetric water flow
 Melt Temperature: 30/30
 Better: Thin wire temperature probe
 Cushion: 5-10% of shot size (not ¼” everywhere)
 Decompression: Just over check ring throw
 Have all process testing information
 Have all machine testing information
 Have Graphical Data for Machine Injection and Screw Run
53 - Lean

Middle Risk Cont.

 Transfer a MOLD with a POOR PROCESS
(re-establish process)
 Have most of process/machine tests
 We can’t run to that speed because our machine is out
of tune.
 Our machine has never been squared and leveled.
 Our screw is worn out.
 Check-ring leaks bad so we use a large cushion.
 Have no way of validating the material moisture.
 We use Maximum clamp force because we always
have.
 The shot size is only 14% of the barrel capacity.
54 - Lean


Paper Setup Sheet
(Med-High Risk)
Re-Build Process

Strategy Normalized
Transfer Process
(Med-Low Risk)
Re-Build Process

Low Risk
Transfer Process
Cavity
Pressure
Re-Build Process

55 - Lean

Low Risk

 Transfer a MOLD with a POOR
PROCESS and Graphical Data (re-
establish process)
 Shot size less than 20% or more than
80%
 Clamp force set less than 50%
 Mold covers less than 60% of the platens.
 Wrong screw design

56 - Lean

Low Risk Cont.
With eDART™ (volume and plastic injection pressure data) – lower
risk than just normalized setup sheet
 Transfer a GOOD PROCESS (based on risk assessment)
 Sprue Orifice Diameter and length known
 Clamp Force (may depend on tie bar spacing due to platen deflection)
 Fill Time (volumetric flow rate)
 Fill Only Part Weight (maybe match relative shape of injection volume curve)
 Hold Pressure (plastic)
 Hold Time
 Screw Run Time
 Back Pressure (plastic)
 Mold Clamped Time (ideally)
 Cycle Time
 Temperature Map (understanding challenges) – including temp in/out
 Better: Water Temp in/out and volumetric water flow
 Melt Temperature: 30/30
 Better: Thin wire temperature probe
 Cushion: 5-10% of shot size (not ¼” everywhere)
 Decompression: Just over check ring throw
 Possibly a Decoupled III process

Process Match has high potential success.
57 - Lean

Lowest Risk

 Low Risk (With Cavity Pressure, and ideally Cavity
Temperature)
 Ideally (but not mandatory) have information about
processing window (rheology curve, flow
simulation, solid model, etc)
 For some applications (e.g. thick walled crystalline
parts), cavity temperature may be more important
than cavity pressure
 MATCH 4 PLASTICS VARIABLES

This process has the best opportunity for a match.

58 - Lean

Implementation for Success
Tool Transfers

Now we start building the recipe for success!

59 - Lean

The Five Core Phases

60 - Lean

Process control involves reduction of
normal variation of all primary variables
during all phases of the cycle

 Drying the plastic
 Melting the plastic
 Filling the mold
 Packing
 Holding
 Cooling rate and time
 Releasing the part

61 - Lean

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62 - Lean

Understanding the Risk
of Producing this Product

63 - Lean

First Scenario

 Non-Instrumented Tool Transfer
 No eDART™ Graphical Data

64 - Lean

A Tool Transfer is Information from many
Sources

Inputs
Flow Analysis Outputs
Fill only short shot
Machine Sizing
Current Setup Sheet
Machine Performance Evaluations
Part Prints or Solid Model
Full shot (parts and runner) Transfer Mold To
Material Processing Guide
Machine Performance Evaluations
Quality Inspections and Deviations
Graphical Cycle Data from Sensored Mold with Cavity Pressure

As more information is missing, the RISK of the transfer rises.
65 - Lean

Robust Molds
“Poor tool maintenance - easily tolerated in the old
batch system - repeatedly stopped the whole cell.”

“Our tools had deteriorated to a shocking extent without
the management ever realizing what was happening.”
Tool audits and maintenance
are a Key Part of Lean.

66 - Lean

Robust Machines
 Always reliable and ready to produce on demand
 Robust Preventive maintenance is essential

67 - Lean

High Risk

Mold is delivered with a part print only.
With only this information, I can only establish what my tie bar
spacing should be. (mold is 14in x 14in)

I will have to guess at shot size, transfer, cushion, injection
speed, rpm, back pressure and many more attributes to the
process.

Which means potentially I will not duplicate the same shear rates
in the cavity so the part will not be the same. This effects the
following:
 Pressure distribution in the cavity.

 Temperature distribution across the mold and part.

 Shrink rates across the part.
68 - Lean

220 ton clamp force 250 Ton clamp force 200 Ton clamp force
 1.77 in diameter screw  2.0in diameter screw  1.625 diameter screw
 2600 psi hydraulic pump  2150 psi pump  1800 psi pump
 12.2:1 Intensification Ratio  11.2 Intensification Ratio  10.2 Intensification Ratio
 Maximum Plastic pressure 31,720  Maximum Plastic Pressure 24,080  Maximum Plastic Pressure
ppsi ppsi 18,360 ppsi
 General Purpose Screw  General purpose screw  General Purpose Screw
 12 inch linear shot capability  12.5 in linear shot capability  11.1 linear shot capacity
 Maximum Injection Speed 10.2  Maximum injection speed 8.6  Maximum injection speed
in/sec in/sec 10.5 in/sec
 Utilization is at 85%  Utilization is at 46%  Utilization is at 67%
 Tie Bar Spacing is 17in x 17in  Tie bar spacing is 20in x 20in  Tie bar spacing is 15in x
15in

Based on our High Risk Tool Transfer, What Molding
Machine would you chose?

69 - Lean

Normalization of Machines
Make all machines interchangeable from
The Plastic’s Point of View

Starts with an Audit 70 - Lean

We will be guessing on what is going on with
our tool transfer especially if the wrong
machine is chosen.

We were told this mold made great parts, what’s the
problem?!?!? 71 - Lean

Middle Risk

 Mold is delivered with Part
prints
 Received setup sheets from
different machines. (none like
ours)
 Received a set of parts
(hopefully the last shot)

Four of these, no runner

Would we still choose the same machine?
72 - Lean

Setup Sheet from Old Process
Plastic Flow Rate If we don’t know screw diameter
we can not calculate any of these.



Clamp Force If we don’t know the Intensification Ratio
Without knowing the machines Clamp Force 250 Tons We can not convert the back pressure
Clamp force we don’t know if Or Pack/Hold Settings.
optimized or set at max.
Plastic Temperature

Melt Temperature 412.5 degrees Back Pressure 66.45 psi RPM 60
Nozzle 450.5 degrees Front Zone 420 degrees Middle Zone 425 degrees Rear Zone 430 degrees
Don’t know if this is a general purpose screw
or High compression for Polypro, so we can not
Plastic Pressure trust these settings.
Pack/Hold Time 8 seconds Pack/Hold Pressure 1500 psi Full Part Weight 82.57 grams
Gate Seal Yes
How do I know that the part is
Plastic Cooling not over-packed?

Cooling Timer 18 seconds This sheet does not tell us how the mold was Mold Temperature 120 degrees
plumbed nor how well it was performing.

Without any information from the prior molding machine we can not do much with
this information to create a new setup for our new process. 73 - Lean

Low Risk

 Mold arrives with the following:

 Part prints, solid model,
flow analysis
 Quality inspections
including any deviations
 Setup sheets

 Short shot at transfer

 Full shot including the
runner
 Fully sensored mold with
graphical data for cavity
pressure.
 Machine evaluations
74 - Lean

Do you practice a need for Absolutely
Capable Process?

 IQ - Installation Qualification: quot;Did you
put the thing together right?quot;

 OQ - Operational Qualification: Create a
good process and define the process
limits

 PQ - Performance Qualification: Make
sure good parts can be made over time
using an extended run

75 - Lean

IQ - Installation Qualification:
 IQ has nothing to do with your intelligence (or lack
thereof). Instead, IQ asks one basic question: quot;Did you put the
thing together rightquot;. In the case of an injection molding process,
that can refer to the machine, the mold, or the auxiliaries. Did the
steel get cut right? Are the water lines hooked up correctly? Is
the mold sized correctly for the machine it is in? Is the
equipment properly calibrated? The list can get pretty long, but
the point is doing your home work up front so you don't overlook
something simple.

The Items Needed:
 Solid Model
 Flow Analysis
 Machine sizing information (coming from and going to)
 Performance information of both machines

76 - Lean

Actual Machine Evaluation
Testing Data

Machine Testing:
 Injection Speed Linearity
 Load Sensitivity
 Pressure Response
 Check Ring Study
 Repeatability

77 - Lean

Injection Speed Linearity
Stroke (include decompression): 270.97 mm 10.67
1st-2nd Position Transfer: 36.83 mm 1.45
MAX MACHINE VELOCITY IN/SEC 10.2 in/sec
Actual
MACHINE SET Machine Set Machine Expected Fill
VELOCITY % Velocity IN/SEC Fill Time Velocity Time % Difference
99 10.00 1.45 6.36 0.92 -57.3%
89 9.00 1.49 6.19 1.02 -45.5%
79 8.00 1.73 5.33 1.15 -50.1%
69 7.00 1.89 4.88 1.32 -43.5%
59 6.00 1.98 4.66 1.54 -28.9%
49 5.00 2.15 4.29 1.84 -16.6%
39 4.00 2.50 3.69 2.30 -8.5%
29 3.00 3.15 2.93 3.07 -2.5%
19 2.00 5.75 1.60 4.61 -24.8%
9 1.00 12.44 0.74 9.22 -35.0%

Average % Difference:
-31%

This machine can not achieve the desired fill time the flow analysis
suggested, therefore it will be impossible to achieve the desired
shear rates. This would get a high risk of 5 for this test.

78 - Lean

Load Sensitivity

Choose Type of Pressure

Fill Time (mold) 1.45 sec
X Fill Time (air) 1.03 sec
Peak Pressure (mold) 15,256 PSI
Peak Pressure (air) 5,245 PSI

*Fill in highlighted Areas*

Actual Test %
2.89%

Acceptable Range: 3%

This machine is not sensitive to a load change therefore receiving a
risk of 2.

79 - Lean

Pressure Response

X

Time 1 1.5600 sec
Pressure 1 15256.00 ppsi
Time 2 1.7600 sec
Pressure 2 14370.00 ppsi

Actual Response Time: 2.257336343

Acceptable Response Time: <0.2 sec/1000 psi

Pressure Response is somewhat challenged with a risk of 4.
80 - Lean

Measuring the Risk of
Potential Problem Areas

 Square corners equals risk of 5
 Additions to walls equals risk of 5
 Change in wall thickness equals risk of 5 if gate location is on
opposing end of part

We have either blue prints and/or solid model
81 - Lean
information

Information from Solid Model and Flow Analysis

Key Information from Solid Model
Cubic inch volume of the solid model is 5.09
Sprue / Runner volume is 2.73 cubic inches
Square inches at the parting line is 7.99

Key Information from Flow Analysis
Fill Time is .95 seconds
Pressure near gate is 12,000 ppsi
Pressure at end of part 2,600 ppsi
Average pressure in the mold to produce a good
part is 7300ppsi
Tons per square inch is 3.65
Cooling Time 16 seconds
Pack/Hold Time 7 seconds
Development of Set up Sheet Pack/Hold Pressure 14,370ppsi

We can establish a shot size, transfer position and cushion from the
volume based on screw diameter.
We can establish the clamp force needed based on the square inches
and the average cavity pressure. 82 - Lean

Decoupled II Pre Process
Setup Sheet
Plastic Flow Rate

Shot Size 10.7 inches Transfer Position 1.5 inches Cushion 1 inch Decompress .31inches


Clamp Force

These can be calculated based on
our transfer machine information.

From the flow analysis
Weighing parts or flow
analysis can give us this
information.

Reduce the amount of guessing during the startup of
your transfer tool.
83 - Lean

Selected Number of Cavities

Risk
Runner layout: a risk of 2
Gate location: a risk of 5
Gate Type: a risk of 3
Balance of Fill 3
84 - Lean

If we have the short shot, we can
see potential problems.

Risk of Balance 5

Flow Analysis can also give us a snapshot of this problem.

85 - Lean

Material Processing Guide

86 - Lean

Cycle from the
Plastics’ Point of View

Heat it up Flow it Pressurize it Cool it
The rest are details:

The devil’s in those details!

87 - Lean

A Strategy Based on the
4 Plastics’ Variables
“Helps Injection Molders Succeed”

 Temperature

 Flow Rate

 Pressure

 Cooling
88 - Lean

Decoupled II Pre Process Setup Sheet for
the 220 Ton Machine
Plastic Flow Rate
Shot Size 10.7 inches Transfer Position 1.5 inches Cushion 1 inch Decompress .3 inches


Clamp Force
Information From material
Clamp Force 136 Tons processing guide
Plastic Temperature
Melt Temperature 412 degrees Back Pressure 61psi RPM 75
Nozzle 412 degrees Front Zone 412 degrees Middle Zone 412 degrees Rear Zone 412 degrees

Plastic Pressure
Gate Seal Yes Peak at Transfer 15,256ppsi

Plastic Cooling


This information could be gathered from Could weigh the parts you
a former setup sheet or flow analysis. received with your mold or ask
89 - Lean
the flow analysis

Only Choice

15in

This machine would fail due
From our selection of machines, this This machine would fail due
to lack of Max. Plastic
is the only machine that is capable to lack of injection speed
of making the same part. capability, I could not Pressure, it would become
pressure limited when the
duplicate the same shear
viscosity changed.
rates.

90 - Lean

Setup Sheet from Old Process for the
250 Ton Molding Machine
Plastic Flow Rate


Fill Time will be impossible to meet Clamp Force
Injection Speed is maxed OUT

Only using 54% of Clamp Force
Plastic Temperature

Plastic Pressure
Gate Seal Yes

Plastic Cooling

Putting the Mold in this Machine Would be Extremely High Risk as
we can not achieve the Shear rates due to the fact it will need to be
slowed down. 91 - Lean

Setup Sheet from Old Process for the
200 Ton Molding Machine
Max Linear Shot for this Machine is 11.1
We can not achieve the volume Plastic Flow Rate
Shot Size 12.5 inches Transfer Position 1.66 inches Cushion 1.1 inches Decompress .250 inches


Clamp Force
Max Injection Speed is only 10.5 in/sec
Fill time can not be Reached Clamp Force 136 Tons
We can not achieve the Shear Rates for the Plastic

Plastic Temperature

Plastic Pressure
Gate Seal Yes

Plastic Cooling

Putting the Mold in this Machine Would be a Disaster as we can
not achieve the Shear rates nor do we have enough volume of
92 - Lean
plastic in our shot.

OQ - Operational Qualification:

 OQ is quot;the heart of validationquot;. This is
where the process is created. Bottom line is, make
sure the process is a good one. Here is where we can
really help molders. Make sure the melt temperature
is at the manufacturer's midrange. Set a fill speed
based on your rheology curve. Transfer when the part
is 95-98% full. Sound familiar?

93 - Lean

RIGOROUS MOLD Transfer
(Rigorous: Severe; Logical; Uncompromising)
OBJECTIVES:
Challenge a mold early and hard so that it’s weaknesses can be quickly defined
and corrected before it must produce parts in a production environment.

“NEVER AGAIN PUT A BAD TRANSFER MOLD INTO PRODUCTION”

Develop, refine and center machine independent process conditions for optimum
product quality.
 During successive tryouts, parts made under the same plastic processing conditions can
be compared to evaluate mold rework

Establish alarm limits for ongoing process monitoring and automatic suspect part
containment.
 Production launch can be machine independent with predictable results

94 - Lean

But OQ goes one step further.
 In addition to building and documenting a good process, OQ requires that the
molder quot;define the key processing parameters and their associated rangesquot;. Or,
in simple terms, what press settings have an impact on part quality? How much
can the operator adjust these settings and still make a good part? For example,
the target fill speed might be 5 inches per second, but how much faster or slower
is acceptable? The example below shows the target with the max and min
settings.
Press Setting Min Target Max
Fill Speed 4.5 in/s 5 in/s 5.5 in/s

This is OK, but is useless if the mold is transferred to another press. The
mold would have to be validated every time the mold is moved to a different
machine! A better approach is to document the process settings and ranges
in quot;Machine Independentquot; terms based on the 4 Plastics Variables. Instead
of fill speed, the FILL TIME should be used. Here's an example of the same
process setting from above:

Press Setting Min Target Max
Fill Time 0.55 sec 0.6 sec 0.7 sec

Using a Machine Independent Process Setup Sheet, the OQ stage can usually be avoided
(or at least greatly reduced), saving the molder lots of time and money.
95 - Lean

Using Data to Verify Process
Parameter
Plastic Effective
Shot Fill Time 1/t
Pressure Viscosity
30000
1 0.20 8720 5.0 1,744
10
27000 2 0.22 8160 4.55 1,795
3 0.30 5440 3.33 1,632
24000
4 0.62 4640 1.61 2,877
9
21000 5 1.47 2969 .68 4,364
6 1.52 2960 .65 4,499
18000
8 7 1.92 6260 .52 12,019
15000 8 2.13 8160 .47 17,381
9 2.52 8560 .40 21,571
12000 7
10 3.31 8360 .30 27,672
9000

6000
6
5
4
3000
3 2 1
4.0
.50

4.5
2.0

2.5
1.5

3.0
1.0

3.5

5.0

96 - Lean

Cavity Balance Study

Fast inj Speed Med Inj Speed Slow Inj Speed
1. 72.1g weight 66.9 49.6
2. 71.5 66.1 43.4
3. 71.9 65.4 41.2
4. 70.9 64.0 42.3
Balance
1.94% 4.33% 16.94%

97 - Lean

Part of process control involves knowing if and when gate
seal occurs on all cavities for all molds.

Without Instrumentation
we use part weight study

With instrumentation we use post
gate psi curve including hold time

Gate Seal = Best Dimensional Control

Allowing discharge or backflow out of the gate after a set period of time:
 Can reduce compressive stresses near the gate
 Can affect pressure gradient caused warpage
98 - Lean

Pressure Loss Study

15,256 ppsi

9,628 ppsi

8,343 ppsi

What happens if the
viscosity changes?
5,245ppsi
99 - Lean

How do we know how much RISK we
are taking to mold these products?
Example: The shot size for this process is 10.668 linear inches.

 The molding machine’s maximum stroke is 12 inches.
You are using 88.9% of the barrel capacity, 80% is the
maximum usage which gives us a rating of 5.

NOTE:
 1 is a low risk condition

 3 is an average amount of risk

 5 is high risk and could result in process challenges
100 - Lean

The Risk including the Machine Performance

The Process
Shot Size 10.7 inches5 Transfer Position 1.5 inches1 Cushion 1 inch1 Decompress .3 inches1

Clamp Force 136 Tons3 Back Pressure 62 ps1 RPM 751 Melt Temperature 412 degrees2
Nozzle 412 degrees1 Front Zone 412 degrees1 Middle Zone 412 degrees1 Rear Zone 412 degrees1
Gate Seal 1 Cooling Timer 16 seconds1 Mold Temperature 120 degrees1

The Part
Square corners equals risk of 5 Additions to walls equals risk of 5 Change in wall thickness equals risk of 5

Cavity Layout
Runner layout: a risk of 5 Gate location: a risk of 5 Gate Type: a risk of 3 Balance of Fill 5

Machine Performance
Injection Speed Linearity 5 Pressure Response 4 Load Sensitivity 2

Potential Total Risk of 32 topics at a Our Risk of Producing this Product is 85
severe rating of 5 equals which is a very average part to produce
160 85
101 - Lean

Only Choice

15in

This machine would fail due
From our selection of machines, this This machine would fail due
to lack of Max. Plastic
is the only machine that is capable to lack of injection speed
of making the same part. capability, I could not Pressure, it would become
pressure limited when the
duplicate the same shear
viscosity changed.
rates.

102 - Lean

Other Items to Consider

Viscosity shift should also be
considered.

Our average maximum pressure at the parting line without flashing is:

Clamp force in pounds (440,000) divided by the total square inches of (32.96 sq/in) equals
a pressure of 13,349ppsi in the cavity.

A good part requires an average pressure of 7,300ppsi (from flow analysis) which provides
a nice process window.

If 20% viscosity shift or regrind is used our good part may require 7,300 times 1.2 (1 = part,
.2 = viscosity shift) which equates to a new average pressure for a good part of 8,760ppsi
in the cavity. Many times looking at the risk of utilizing regrind is never considered and
could cause a pressure limit condition be default. Another risk factor that could be
considered. 103 - Lean

Does the Molding Machine Have enough
Performance when Viscosity Changes?

Peak pressure at transfer
was 15,256ppsi (from Flow
Analysis).
220 ton clamp force
1.77 in diameter screw If viscosity goes up 20%
2600 psi hydraulic pump
12.2:1 Intensification Ratio
our new peak pressure at
Maximum Plastic pressure 31,720 ppsi transfer would be
General Purpose Screw
12 inch linear shot capability
18,307ppsi
Maximum Injection Speed 10.2 in/sec
Utilization is at 85%
Tie Bar Spacing is 17in x 17in
This would be Low Risk
104 - Lean

How much will your dimensions
change over time?
Note: The longer a flow Post Gate control
transducer @
front has to travel the
12,000 psi
more pressure loss that
will exist.
Pressure Loss 10,000psi

.500 post detail
with a tolerance of
± .002 EOC monitor
transducer @
2000 psi

Calculation for Dimensional Change Using Actual Data
 Peak End of Cavity Pressure  Peak End of Cavity Pressure Low  
 x Compressib ility  x Dimension  % of dimension change
 1000psi 
*amorphous .005

.5% = .005 amorphous per 1000 psi
.75% = .0025 low crystalline per 1000 psi
.1% = .01 high crystalline per 1000 psi
105 - Lean

PQ - Performance Qualification:
The objective of PQ is to show that good parts can be made
over time. In PQ, the process is run for an extended period
(24 hours is not uncommon) and parts are monitored
carefully to make sure they are acceptable. Parts are
inspected regularly, and some parts will usually be sent off
for functional testing (putting the parts into a final assembly
to make sure they actually work!)

During PQ, the process is often quot;challengedquot; by throwing in
common sources of variation to make sure that parts still
come out good. For example, the fill speed might be
adjusted from the high to the low range settings (using our
example from above). The point is to try to catch problems
that might not be caught in a short term run. Note that
practices here vary. Some customers quot;challengequot; the
process during PQ, some during OQ

106 - Lean

Changes in Dimensions?

 Why do part dimensions vary???
 Over time?
 Shot to shot?
 During startups?
107 - Lean

2nd Scenario
 A Fully Instrumented Mold Transfer
 Using eDART™ Graphical Data

108 - Lean

Data Analysis

A.

B.

A. Summary Screen: Displays summary data values in a
running bar chart for analyzing trends over time.

B. Cycle Graph Screen: Displays each cycle versus time as a
graphical waveform. 109 - Lean

Typical Cycle Graph

10,000 Plastic
Injection Shot Volume
PRESSURE (PSI)

Pressure

Gate End
Mold Pressure

End of Cavity
Mold Pressure

0 TIME 16
(SECONDS)
110 - Lean

End of Cavity Pressure

20,000  Most Variable
 Best For Monitoring
PRESSURE (PSIP)

 Contain Short Shots!!

Peak PSI

Cooling Rate
No Dynamic PSI
Part is Full
Pack Rate

0 TIME (SECONDS) 15
111 - Lean

Gate End Pressure
20,000
 Best For Control
 Fill Dynamics
PRESSURE (PSIP)

 Gate Seal

Peak
PSI
Pack
Rate

Sudden Pressure
Reduction due to
Cooling Discharge
Rate
Full Packed

0 Cavity
Fill Time TIME (SECONDS)
112 - Lean

Cavity Pressure Integrals
The most useful data for process monitoring is the end-of-cavity pressure.

The area under this curve represents the packing of the mold to a peak
pressure and then this time delay of pressure during cooling.

Changes to the rate and degree of packing, or the rate of cooling affect the
end-of-cavity cycle integral.
PRESSURE (PSI)

Pack & Hold

End of Cavity
Mold Pressure

0 Start Mold TIME (SECONDS) 16
Fill Time
113 - Lean

Cavity Pressure
Gate End Showing Discharge
This is best detected by monitoring the integral
Fill Pack Hold  A chart with two seconds less
2nd stage time is shown where
plastic is allowed to run back
out of the cavity, at point F
D
 This is called discharge or
backflow
PRESSURE (PSI)

 Discharge is not always
undesirable in molding
 Many center gated parts,
E especially ones where flatness
is desirable, must be allowed to
F discharge for correct part
characteristics
B
C
Gate End
A Mold Pressure

0 Start Mold TIME (SECONDS) 15
Fill Time
114 - Lean

Historical Data for Steady State

108 second stop

8 cycles

Start of process

Small Steel Mold 115 - Lean

Before the Mold is Prepared for Transfer a
Graphical Snap Shot of the Process is Taken

116 - Lean

Problem

Post Gate

End of Cavity

The original process traces are saved as dotted lines to become our template. It is
imperative to match what goes on inside the cavity (Post Gate and End of Cavity).
117 - Lean

Mold temperature was fluctuating
About 10 degrees

Thermal stability is challenged and will affect part quality.
118 - Lean

Cushion

Screw Trace

Shot Size
Transfer Position

Decompress

119 - Lean

the 220 Ton Machine
Plastic Flow Rate


Clamp Force
This information can be found Clamp Force 136 Tons
on the Screw Trace
Plastic Temperature


Plastic Pressure

Plastic Cooling


120 - Lean

Peak Pressure at
Transfer

Injection Speed Pack and Hold Pressure

Fill Time In Cavity Pack Time

121 - Lean

the 220 Ton Machine
Plastic Flow Rate


Clamp Force From the Screw Trace
From Graphical Data
Clamp Force 136 Tons Turn Pack and Hold Off
To Verify
Plastic Temperature


Plastic Pressure
Gate Seal Yes Peak at Transfer 15,256ppsi From the Machine Pressure
Trace
Plastic Cooling


122 - Lean

Temperature Information from
Inside the Cavity

Screw Run Information

Back Pressure

Pack and Hold Time

123 - Lean

Decoupled II Pre Process Setup Sheet for the
220 Ton Machine
Plastic Flow Rate


Clamp Force
From the Temperature Trace From the Screw Trace
Inside the Cavity Clamp Force 136 Tons
From the Machine Pressure
Plastic Temperature Trace


Plastic Pressure

From the Machine Pressure Trace Plastic Cooling

124 - Lean

Lean Strategies For Injection Molding 3 Hour E Learning

Lean Strategies For Injection Molding 3 Hour E Learning

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