Mold Validation Procedure Part-3

Option 4 Description:
This option does not evaluate the inherent material variation. It does investigate the differences attributed to molding the same part in a number of colorants along with the complication of using regrind. The Qualification study requires a representative virgin resin lot of the mean specification. In addition, it requires regrind and adequate amounts of all colorants which will run on the mold.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified injection molding machine operator.

Option 4 Procedure:




Shape of Sample Population for Qualification Study

• Two histograms (6 and 7 classes) indicate that the observations are likely follow a Normal Probability Distribution.
• The 9-class histogram fails the two-question test (see Histogram Construction on page 67) as the population appears to be slightly skewed toward the high end of the distribution.
• Assume that the parent population is indeed normally distributed (represent a more conservative estimate) and proceed with the Capability Analysis (next page).












4.6 Verification (30-Day Run)

Purpose:

The purpose of the Verification study is to determine if the process can sustain key part dimensions within specified tolerances. The Verification consists of monitoring 30 days of production. During this time product quality measures must be met; i.e., Cr, Tz & Cpk.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified blow molding machine operator.
Confirm quality through warehouse checks, trade surveys, and consumer comments.
If all criteria is met during a 30 day time span, the mold is validated.
Procedure:
4.6.1 Begin shipments to the trade, assuring individual component quality using established supplier/plant procedures.
4.6.2 Confirm quality through warehouse checks, trade surveys, and consumer comments.
4.6.3 If all criteria is met during a 30 day time span, the mold is validated.



5.2 CONTROL CHART INTERPRETATION

THREE BASIC RULES

C, P, R


C If any data points are outside the control limits, treat them as a special cause.
Caution: With 3 sigma limits, 3 out of 1000 times will not be a special cause,
but 997 times out of 1000 it will be!


P Since the data should be normally distributed about the mean, look for any non-normal patterns.
The easiest way to do this, is to divide the distance between the UCL and the mean or the LCL and the mean into 3 equal parts or zones.
- If about 68% of the data points fall within the first zone above and below the average, then there are no special causes.
- If there are more than 68% (say 90%) or less than 68% (say 45%) then there are special causes acting on the process.


R If there is a consecutive run of 7 points in a row above or below the mean,
treat the 7 or more points as a special cause, i.e., the process has "shifted".
Think of it as flipping a coin and getting 7 heads in a row.
A very unlikely event!! (Actually, only 8 chances out of 1000!)

5.3 HISTOGRAM CONSTRUCTION


Terms:
N - number of observations.
M - smallest unit of measure.
R - range= high - low.
K - number of classes (square root of N with K_12)
H - class width (R/K).

What:
Histograms are "snap-shot" pictures of a system's output over a defined period of time and shows central location (average), variability (spread), and distribution (shape).



Shape:
To determine if the shape of the histogram is Normal (bell shape curve) as a prerequisite to the capability analysis, answer the following two questions:

1. Does the highest bar of the histogram contain the mean of the sample population?
2. Do the bars on each side of the mean get equally smaller as you move away from the mean?

• If you answer "yes" to both questions, assume a Normal population.
• If you answer "no" to at least one question, determine how non-Normal the population may be, e.g., skewed or truncated. At this point, you may need a computer software capable of performing the capability analysis with a clearly non-Normal population.


5.4 CAPABILITY ANALYSIS COOKBOOK


1. MUST have determined that the Process is stable via Control Charts.
2. MUST have determined that the population is Normal via Histograms of observations.

Mold Vaildation Procedure Part -2

Mechanical Mold, Head Tooling and In-Mold Labeling Debug
Step 4.2.4:

Verify Process Operation

Purpose:

The purpose of the Verify Process Operation step is to ensure that the mold operates properly after the Mechanical Mold and Select Head Tooling steps have been completed. A slow molding cycle is established (the same rate used in the Parison Centering step) and mold movement should be inspected. At mold operating temperature, verify that the mold opens and closes easily without binding or galling on the leader pins or bushings. The mold ejection and detabing (where applicable) system components should operate smoothly without binding.

With the machine platens in the closed and locked position there should be no gap at the mold parting line. The center of the neck insert (ie, mold position on platen) for most symmetrical containers (without handles) should be aligned under the center line of the die(s). For more complex container designs and containers with handles mold positioning will depend on the blow mold design, type of blow molding process experience through trial and error.

Mold ejection system components should move freely, at normal mold operating temperature, without binding over the full motion range.



Wheel Process Procedure:



Mechanical Mold, Head Tooling and In-Mold Labeling Debug
Step 4.2.5 IML Setup

Purpose:

The IML system must be adjusted to accommodate the mold cavities, label size, and label position on the container. The adjustments must be done in relation to the molds, with the proper placer arm assembly, vacuum cup heads, and label magazines installed.


Procedure for Shuttle Process: (Avery Denison Labeling System)

A. Carriage and Placer Arm Assembly Setup

1. Adjust the carriage and placer arm assembly. Disconnect the actuator links from the front and back sides of the placer arm assembly at the drag links.
2. Check that the angle between actuator arms and the top of the carriage frame is 75 degrees.
3. On the cylinder side only, reconnect the actuator links to the drag link. Check to assure the actuator arm is still in contact with the latch link. Adjust the link as required so that the placer arms are flat against the placer arm bracket and the actuator arm is against the latch link. Adjust the opposite (non cylinder) side, similarly. It is important to ‘balance’ the force on both the front and back side of the actuator links, taking care not to put a
‘jacking force’ on the components.

B. Centering the Placer Arm Assemblies Horizontally Between the Molds

1. Assure adequate daylight opening between mold halves exist on both side A and side B. Back-off the deployment roller (move towards the mold).
2. Move the placer arm assembly between the mold halves to the full in position and set the carriage lock.
3. Loosen the (4) screws that bolt the slide base to the upper frame.
4. Measure the distance from the inside face of the placer arm to the front face of the mold. Repeat the procedure on back face of the mold. If the measurement is not the same turn the adjustment screw located on the upper frame and below the slide base. The placer arm assembly is centered when this distance is the same on both the front and back halves of the mold.
5. Retighten the (4) screws on the slide base.

C. Centering the Vacuum Heads Vertically in the Cavity

1. Back off the deployment roller on the lift-up cam.
2. Move the inserter carriage between the mold halves to the full in position and set the carriage lock.
3. Slightly loosen the (4) screws on the back of the lower frame.
4. Turn the adjustment jackscrew: clockwise to raise, counterclockwise to lower.
5. Check to assure the vacuum cup head is approximately centered vertically in the cavity.
6. Retighten (4) screws.
7. Release the carriage lock and move the carriage out and in by hand to insure that no part of the placer arm interferes with the mold cavities or platen tie rod as it is lifted up into position. Readjust as required, then reset carriage lock to continue.


D. Setting the Tow Bar Length

1. With the placer arm ‘in molds’ and carriage lock engaged, loosen tow bar jam nuts (R.H. and L.H. nuts).
2. While manually extending placer arms, turn the tow bar until vacuum cups are located in the mold cavities as required, usually centered in the label panel area.
3. Tighten the jam nuts.

E. Adjusting the Deployment Roller

1. Assure the carriage lock is engaged.
2. Loosen the lock screw on front of the deployment roller housing.
3. Turn the adjustment screw: clockwise to extend vacuum cups deeper (moves roller away from molds); counterclockwise to retract arms (moves roller towards molds).
4. Check vacuum cup centering, readjust as required.
5. Retighten the lock screw. Placer arm extension should allow for only slight flattening of the vacuum cups against the walls of the mold. Over extension and excessive force may cause excessive wear and premature failure of the placer arm assembly components.

F. Adjusting the Label Magazines

1. Unlock and open the door of the magazine guard.
2. Pull back the pusher plate while holding the remaining stack upright.
3. Load new labels in until desired amount is reached.
4. While releasing pressure on the pusher plate shuffle stack down into and even stack.
5. Close and lock the magazine guard door. Label stacks should be ‘riffled’ several times to eliminate ‘edge welding’ due to die cutting and to allow some air to become entrapped between labels.
6. Set the label stops to allow the labels to be picked easily without double picking or moving the next label out of position. The overlap of the stops onto the label may be different from side to side or top to bottom. The overlap should be about 1/16” initially.
7. Adjust the magazine position (amount of contact force) between the label stack and the vacuum cup heads by moving the magazines in and out. Loosen the lock-down collars and release the lock-down clamp that holds the magazine in place.
8. With the blow molding machine and IML system in ‘Manual’ mode, press the ‘Step/Home’ button to move the first pair of placer arms to the first label pick position. Note how the vacuum cups contact the end label on the stack in the magazine.
9. Adjust the label magazine in or out as required to achieve proper contact. Secure lock-down collars after proper magazine position is achieved.

G. Pick Cylinder Speed

1. Ensure that adequate plant air pressure is available.. Adjust the regulator located on the pneumatic control assembly to 80 psi.
2. Adjust extension speed of the placer arms on valve connected to rod end of cylinder, turn stem: clockwise to slow; counterclockwise to speed up.
3. To adjust retraction speed of the placer arms turn valve connected to other end of cylinder do likewise.

H. Pick and Mold Vacuum

1. The IML system vacuum pumps require 80 psi for optimum performance. Adjust the pick vacuum with the regulator located on the pneumatic control assembly. Settings lower than 60 psi may result in missed picks.
2. Adjust mold vacuum with the regulator located on the pneumatic control assembly. Mold vacuum requirements will vary depending on the number of vacuum ports in the mold, label materials, container shape, etc.

I. Adjusting Label Position on Container

1. The adjustments are side to side, height, and skew (rotation). Adjust the label position by loosening the appropriate clamps and moving the adjustments in direct relation to the container. Retighten clamps to prevent changes in settings due to vibration.

J. Setting Up and Modifying Programs

1. Refer to the IML operating instructions manual for specific program modifications. The number of picks and the position of label picking are normally modified whenever the number of cavities or cavity spacing is changed. No other program modifications are normally required.

4.3 Design of Experiments

A statistical design of experiments, or DOX, is the preferred method to determine an optimum blow molding process and processing window. Initial mold/process evaluations should be completed on a small prototype mold when possible. The mold is normally shipped from the tool builder to the molder's development laboratory. The molder's development laboratory should have the time and resources available to evaluate the molding process for that mold and to perform any initial Design of Experiments.


The objective of a design of experiments is to not only identify an optimum process and processing window, but also to identify the main effects from process variables, interactions between them, and possible curvature effects. Initial experiments are run to determine which combination of process control parameters yields the lowest dimensional variability. Once this is determined, the tool steel can be adjusted to meet the molded container dimensional specifications. It is important NOT to choose process control parameters solely based on the part specifications. If your tool builder constructs the mold using a "Steel Safe" approach, you will be able to easily cut and ‘adjust’ the steel for the most stable and efficient process.

It is recommended that the Design of Experiments be performed on the blow molding machine on which the mold will run on during production or sampling. Only a skilled molding company can accurately translate the process control parameters from one blow molding machine to another. Even if the machines are similar, there are always differences that will affect the attributes of the molded part. The amount of wear on the extruder, the mold clamp system design, hydraulic valves, screw, barrel and timers can differ and can have large effects on process control parameter adjustments. In addition, the molder’s development laboratory often utilizes a different (mold) cooling system than the system used in a manufacturing area. Differences in development laboratory (individual mold temperature control systems) and manufacturing plant (central) coolant system performance can be significant. Careful attention must be given to the actual cooling (heat transfer) variables in the mold.

The following steps are part of the Design of Experiments section:

Step 43.1: Establish Initial Cycle Time

Step 4.3.2: Container Performance Optimization

Step 4.3.3: Commissioning (Multi-Cavity Analysis)

Step 4.3.4: Design of Experiments






Designed Experiments
Step 4.3.1: Establish Initial Cycle Time

Purpose:

The purpose of the Establish Initial Cycle Time step is to begin molding containers for initial dimension measurements, to complete ‘fine’ parison centering adjustments and to increase the rate of extrusion, and the process,
to a typical production level. Extrusion of the parison should be synchronized with the mold shuttle movement or wheel speed (RPM) so that proper pinch-off occurs and the parison is held (using pre-blow or support air as required) in position by the closed mold before blowing. For shuttle blow molding machines the hot knife should cut the parison ‘clean’ without tearing or deforming the parison in the neck area.

Blow molded containers must eject, without sticking in the mold and drop from the mold(s) or strip from the blow pin(s) without ‘hanging-up’.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified blow molding machine operator.
Procedure:



Designed Experiments
Step 4.3.2: Container Performance Optimization

Purpose:

The Container Performance Optimization step is used to establish an initial parsion profile and then to provide a method for adjusting the profile, head tooling ovalization and mold dimensions. Container performance is optimized using an iterative procedure. Optimum container performance is determined by measuring the top load, drop impact, bulge and overflow properties of the containers. As the parison profile and head tooling modifications are developed, molded containers are collected, labeled and conditioned for subsequent dimension measurements and mechanical testing. Sample containers are collected at each parison profile selection and head tooling configuration. All process parameters, head tooling dimensions and container mechanical property data are recorded.
The optimization procedure requires that both mechanical performance data and container dimension data be interpreted before modifying the parison profile and head tooling configuration. Several evaluation iterations are often required to optimize the container performance.

The flowchart on page 39 illustrates the Container Performance Optimization procedure.

Considerations:
Conditioning of the sample containers is recommended (step 4.3.2.9) before performing mechanical tests and measuring dimensions on the containers. However, time constraints on the blow molding machine often need to be considered. When time on the blow molding machine is limited the sample containers are quenched in water immediately after molding and then tested and measured to develop the necessary data for the optimization procedure.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified blow molding machine operator.

Procedure:





Container Performance Optimization





Designed Experiments
Step 4.3.3: Commissioning (Multi-Cavity Analysis)

Purpose:

The purpose of the Commissioning step is to ensure that all mold cavities deliver the same quality, i.e., there is no significant difference of critical cavity dimensions between mold cavities. The time required to perform this analysis is a function of the number of mold cavities and number of critical cavity dimensions. The time on the blow molding machine is minimal compared with the time required to measure the molded containers. However, by performing this analysis the number of containers required to test and measure for future experiments will be reduced significantly.
A solid understanding of creating and interpreting statistical control charts is necessary to perform the multi-cavity analysis.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified blow molding machine operator.
Procedure:


A typical "multi-cavity analysis" curve for the inside diameter of HDPE detergent bottles is shown in Figure 6.

1. The range chart is in control (pass C, P, R1): The variation (range) within any cavity is not significantly different than the mold average-range of 0.0027" (.0068 cm).
2. The average chart fails C (cavities 2, 9, 13): Cavity 2 produces caps that are consistently larger than the rest of the mold cavities while cavities 9 and 13 produce caps that are consistently smaller than the rest of the mold cavities. All other cavities are not significantly different than the average inside diameter of 2.1728" (5.52 cm).

The cause for the "out-of-control" cavities should be investigated and identified. Root causes may be measurement errors, different steel dimensions, unbalanced runner system, small/large gates, different probe tip temperatures, different cooling conditions, etc.


The "multi-cavity analysis" control charts for the injection molded preform of a 32oz.(.946L) bottle is shown
in Figure 7.

1. The range chart is in control (pass C, P, R): The variation (range) in weight within any cavity is not significantly different than the mold average-range of 0.121 grams.
2. The average chart is also in control (pass C, P, R): All weights are not significantly different than the average preform weight of 29.024 grams, i.e., any one cavity is representative of the quality (weight) of the 16 cavity mold.

Since there is no significant weight difference between cavities, on-going monitoring of the weight (as an overall process stability indicator) can be achieved by sampling ONLY one cavity randomly from the 16 cavities in the mold. Remember to spread the observations within samples to capture the "true" process variation.



Designed Experiments
Step 4.3.4: Design of Experiments

Purpose:

The purpose of the Design of Experiments (DOX) is to identify optimum process variables (process control parameters) and the mold(s) processing window. A solid statistical understanding of design of experiments is necessary. There are many different types of software that can be used to assist you in performing design of experiments. Use the design of experiment software that you are most comfortable with.

Design of experiments can require a large amount of time to perform depending on the number of process variables selected to evaluate. In some cases a properly conducted DOX can require 3-4 days to perform, as well as additional time to measure molded container attributes. It is best to perform an extensive design of experiments on a
pre-production mold, i.e., a unit tool, that replicates the production mold(s). This approach normally yields good, reliable results and adequately represents key process variables that effect critical attributes of the molded container.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified blow molding machine operator.

Procedure:





4.4 Qualification (Process Capability Study)

Purpose:

The purpose of the Qualification study is to determine if the process can meet the specified key part tolerance ranges. The first mold being manufactured to produce a molded part might be made “metal safe”. In this case, the Qualification step will determine how much metal needs to be modified in the mold. Resin and colorant properties also need to be evaluated so that process capability may be determined.

Once a process has been selected from performing the DOX, the Qualification study needs to be performed to determine the amount of variation of each key dimension (via control charts). This variation is compared with specified key part tolerances to estimate percent out of specification and product quality measures (Cr, Tz & Cpk). A solid understanding on creating and interpreting statistical control charts is necessary to perform the process capability study.

It is recommended that the Qualification study be performed on the injection molding machine on which the mold will run during production or sampling. Only a skilled molding company can accurately translate the learnings from one injection molding press to another. Even if the machines are similar there are always differences that will affect the attributes of the molded part. The amount of wear to the injection unit, clamping unit, hydraulic valves, screw, barrel and timers can differ and have large effects. In most circumstances the development lab of the molder utilizes a different cooling system than that of a manufacturing area. This is difficult to take into consideration.


Material and Colorant Variation

Resin differences and the addition of colorants effect molded part performance. The rate of the shrinkage changes depending on the resin properties and type of colorant used. This will effect molded part dimensions and mechanical performance. In many cases, there is variation from one resin lot to the next, i.e., lot to lot variation. This lot to lot variation in resin properties is inherent. The resin variation must be evaluated to determine if the material specification range will drive the molded part to be out of the specification. In addition, the Qualification study must properly evaluate each colorant, while including the lot to lot variation in the base resin. Understanding the effects of different colorants is imperative since the same part must be produced in multiple colors from the same mold. The information obtained from the Qualification study results can be used to properly modify the mold.

To quantify base resin, and resin to colorant blend properties, a reliable test method must be selected. Equipment such as the gel permeation chromatograph (GPC), differential scanning calorimeter (DSC) and capillary rheometer are reliable tools for quantifying the lot to lot range. However, it is sometimes difficult to obtain the data from these tools. Material suppliers in all regions generally provide data from the melt flow index (MFI) apparatus. The disadvantage of using the MFI unit is it only provides one data point on the shear rate versus viscosity curve. And, more importantly for qualification purposes, the accuracy of the test is poor. When data from the GPC, DSC or capillary rheometer is not available, regress to the MFI data as a means to quantify the upper, lower, and mean specification of the base resin.

While the mold is being designed, a lot to lot variation representing the maximum expected variation in the resin should be requested from the material supplier. Three lots of the base resin representing the upper, lower and mean specifications from the supplier will deliver an accurate indication of the capability ratio achievable in a production environment. Couple this together with an investigation of all colorants and the percent regrind to capture the remaining sources of inherent variation. Multiple options of the procedure for the Qualification study were created to allow for a variety of different circumstances. A description of when to use each option is provided with the procedure. Review these descriptions to find an option which best meets the needs of your Qualification study.


Option 1 Description:
This is the best option to study the inherent material and colorant variation. It requires representative virgin resin lots of the upper, lower and mean specifications. In addition, it requires adequate amounts of all colorants which will run on the mold.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified injection molding machine operator.






Option 2 Description:
This option does not evaluate the inherent material variation. It does investigate the differences attributed to molding the same part in a number of colorants. It requires a representative virgin resin lot of the mean specification. In addition, it requires adequate amounts of all colorants which will run on the mold.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified injection molding machine operator.

Option 2 Procedure:




Option 3 Description:
This option evaluates the inherent material variation along with the complication of using regrind. This Qualification study investigates the variation attributed to molding the same part in a number of colorants. It requires a representative virgin resin lot of the mean specification. In addition, it requires adequate amounts of all colorants which will run on the mold and regrind.

All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified injection molding machine operator.

Option 3 Procedure:






Continue In Next Post...Thanks

Mold Validation Procedure Part-1

Yes Mold validation is very Important to avoid any Future Quality & production Related problem, But as actual we always Noticed that due to short period of time you can say customer want mold As early as possible, There always many parameter you will face problem so Question is that Is all the molds need to be verified I will say Yes, There is Many scientific way to validate the Injection, Blow molds Simple way to analysis the process parameter which is required to get the desired Quality. perform the MCA (Multicavity analysis) PCA (Process capability Analysis)activity to validate any molds

OK Lets Go Through procedure:
Scope/Purpose:
1.1 The purpose of the Validation Procedure for Blow Molds is to identify a capable mold and process that will achieve key part dimensions, attributes and weight. It is also the purpose of the Validation Procedure for Blow Molds to establish a processing-window for the blow molds. This document provides a detailed description of the steps that will deliver the types of results a qualification process is designed for.

It should be recognized that training in design of experiments and statistics, e.g., interpretation of control charts, is needed and that terminology in the blow molding industry varies throughout different regions of the world. Please make use of the glossary at the end of the document to better define terms. Examples are provided for each step of the mold qualification process to assist in understanding the procedure and qualifying the mold.

1.2 The extrusion blow molding cycle is broken up into the following segments:

Parison Extrusion -> Mold Close -> Parison Blow -> Cool -> Mold Open -> Part Ejection

The blow molding process is a complex process that is controlled by four categories of processing variables: Temperature, Flow Rate, Cooling Rate, and Pressure.

Temperature Flow Rate Cooling Rate Pressure
Melt Temperature Extrusion Rate Mold Temp Blow Pressure
Coolant Temperature Coolant Water Rate Coolant Temp Melt Pressure

Some combination of settings for these process variables will provide an optimum molding process capable of producing molded containers to within container specifications. In addition, the molds will have a window of process variable settings that will provide parts within specification.

The objective of the Validation Procedure for Blow Molds is to determine molding process conditions that provide production personnel maximized process capability and process adjustment range while maintaining a capable, controlled process. Applying statistical methods to evaluate the molds and the process should help identify key process variables for evaluation. The Validation Procedure for Blow Molds will also serve as a standard for process optimization so that terms, specific procedures and result data formats are defined. The document may be used as a reference resource after the methods have been successfully implemented. One of the goals of the Validation Procedure for Blow Molds is to develop a common platform for mold and process evaluation and to maintain efficient communication practices.

Procedures

The following steps are required in validating a blow mold with the overall process shown in figure 1:
4.1 Mold Certification (page 7)
4.2 Mechanical Mold, Head Tooling and In-Mold Labeling Debug (page 10)
4.3 Design of Experiments (page 31)
4.4 Qualification (Process Capability Study) (page 48)
4.5 Mold/Neck/Push-up Steel Adjustments (Process Centering) (page 62)
4.6 Verification (30 Day Run) (page 64)

5.0 Attachments
5.1 Table of Constants and Formulae for Control Charts (page 65)
5.2 Control Chart Interpretation: Three Basic Rules -> C, P, R (page 66)
5.3 Histogram Construction (page 67)
5.4 Capability Analysis Cookbook (page 68)
5.5 Standard Normal Distribution Table (page 69)
5.6 Product Quality Measures (page 70)
5.7 Example of DOX worksheet for process conditions and variables (page 71)
5.8 Safety Precautions For Blow Molding (page 72)
5.9 Glossary of Blow Molding Terms (page 73)


Blow Mold Validation Flow Chart

Flow Chart

Figure-1



Figure-2


Figure-3

Mold Certification

The purpose of Mold Certification step is to verify cavity and mold base dimensions and materials of mold construction. Cavity and neck insert dimensions, mold cooling channel diameter dimensions, cooling line connector diameter dimensions, mold backing plate mounting hole pattern, mounting bolt hole diameter dimension and mounting bolt hole thread type should be verified with the mold and blow molding machine platen prints. Dimensions for the mold mounting bolt holes and the bolt hole pattern in the mold backing plates are verified to help avoid machine scheduling delays during mold installation, initial start-up and process optimization procedures.

The Mold Certification procedure should be performed at the mold builder to expedite any required mold modifications and to help avoid delays during mold installation, process start-up and process optimization procedures. Mold Certification documentation must be provided by the mold builder for review before the molds are shipped to the production blow molding plant.

Use of the specified materials in mold construction help to ensure the required level of mold mechanical integrity necessary to meet production run requirements. The specified materials of mold construction also provide the required level of heat transfer characteristics in the neck insert, cavity and pinch-off areas during production.

Mold cooling channel and cooling line connector dimensions should be verified so that heat transfer in the mold is optimized and so that cooling control may be maintained during production.

Cavity and neck insert dimensions should be verified to establish the mold dimension ‘base line’ before process optimization procedures are initiated. The ‘base line’ dimension data may be used later in the process optimization procedures and for process centering purposes. Table 1 may be used to tabulate the mold certification data. Refer to figure 3 for neck finish nomenclature and dimensions.

Table 1: Mold Certification Data








4.2 Mechanical Mold, Head Tooling and In-Mold Labeling Debug

The purpose of the Mechanical Mold, Head Tooling and In-Mold Labeling Debug is to test the mechanical operation of the mold, mechanical and electrical operation of the extrusion die head and the mechanical and electrical operation of the in-mold labeling mechanism to reveal any gross design, construction or operational problems.

The Mechanical Mold Debug should be performed at the tool builder to ‘dry cycle’ the mold. Inspect the mold(s) and verify leader pin and bushing alignment, mold shut height, cavity parting line match, ejection system component function and expedite any required mold adjustment evident from the debug. If completed off site, a tool builder representative must be present to make necessary adjustments as required. The mold must run without flash and must meet cosmetic quality requirements, e.g., no drag lines or poor surface finish, no parting line mismatch, etc. Upon request, the tool builder should be able to provide verification of all critical steel tolerances and that these were made "Steel Safe".

The Head Tooling Debug should be performed at the plant site on the production blow molding machine. The operation of the moveable, mandrel or the die should be tested for full range motion at operating temperature. Movement and position of the mandrel or die should be calibrated with the parison program controller and verified for repeatability. A specified, operational tolerance ‘fit’ between the mandrel outside diameter and the guide bushing inside diameter should be verified. If excessive wear is evident, the mandrel and/or guide bushing should be replaced before the process optimization procedure is initiated. The melt flow surfaces on the mandrel should be inspected for any physical damage or excessive wear and repaired or replaced as required.

Range of centering adjustment for the die (bushing) and the die adjustment bolts should be verified for operation. The die and adjustment bolts should be free of any degraded material and must be adjustable at normal operating temperatures. The melt flow surfaces on the die should be inspected for any physical damage or excessive wear and repaired or replaced as required.

When die ovalization is required, verify that the melt flow surface contour dimensions agree with the die design print. Ensure that the die is installed in the proper position (orientation) relative to the mold parting line. Scribe a reference line on the outside surface of the die so that the die(s) may be assembled in the proper position after cleaning or repairs.

The In-Mold Labeling Debug should be performed at the plant site on the production blow molding system. IML (In-Mold Labeling) system designs are developed specifically for shuttle or wheel blow molding machines and require different set-up and operation procedures, respectively.

IML system components are adjustable and can support a range of label, mold cavity and container design configurations. Primary components in the IML system for the shuttle blow molding process include the following:

• Placer Arm Assembly - Consists of the vacuum cup heads and the mechanism to operate them to pick labels from the magazines and places them into the mold cavities.

• Tow Bar Assembly - Connects to the inserter to the mold platens and defines the position of the Placer Arm Assembly relative to the mold cavities and maintains that position.

• Magazine Adjustment Assembly - Holds the label magazines and allows them to be repositioned to change the label location on the container.

IML systems for shuttle blow molding machines have 3 basic areas that require adjustment for label positioning:

• Inserter Position Relative to the Mold Cavities
• Magazine Adjustments
• Label Pick Program

Label positioning can be optimized with trial adjustments. Section 4.2.5 IML Setup provides system adjustment procedures for label positioning with the shuttle process.

The following steps are part of the Mechanical Mold, Head Tooling and In-Mold Labeling Debug:

Step 4.2.1: Select Head Tooling

Step 4.2.2: Parison Centering

Step 4.2.3: Manifold Balance

Step 4.2.4: Verify Process Operation

Step 4.2.5: IML Setup
Mechanical Mold, Head Tooling and In-Mold Labeling Debug
Step 4.2.1: Select Head Tooling

Purpose:

The purpose of the Select Head Tooling step is to provide a guide for determining the correct mandrel and die bushing size for the blow molding machine head tooling assembly. Mandrel and die dimensions are estimated based on container dimensional data, container symmetry, blow-up ratio, targeted container weight, neck finish requirements and the type of material (degree of parison swell) that will be used to produce the container.

An initial blow-up ratio must be calculated using the container design dimensions and the required parison diameter.
The required parison diameter will depend on the relative size of the container, the container design (handle or no handle) and the container neck finish requirements. Initial blow-up ratios may be calculated using the following equation.

Blow up ratio = Bd / Nd

where: Bd = Bottle diameter, in
Nd = Minimum neck diameter, in

The blow-up ratio is compared with the maximum recommended blow-up ratio of the selected material.
Figure 2 shows a typical blow molded container with dimension and design nomenclature for reference.

Blow up ratios of 2 or 3 to 1 are considered normal when molding commodity resins such as polyethylene. A blow-up ratio as high as 4:1 is a practical upper limit. The blow up ratio for large containers with a small neck, is generally extended to 7:1 so that the parison fits within the neck and so that there is no mold parting line mark on the neck finish. Blow up ratios for a containers with a handles are generally in the 3 or 5 to 1 range as the die diameter must be larger to allow the handle to be blown.

In order to properly estimate and ‘size’ mandrel and die geometry for the blow mold(s), and to effectively control the process, a thorough understanding of parison swell and draw down phenomena is required. Parison swell is a combination of diameter swell and weight swell. It is a difficult blow molding property to estimate and to control. The parison diameter swell is a complex function of the weight swell, the rate of swell, and the melt strength.

Parison swell behavior varies significantly depending on material type, material processing conditions, machine processing parameters, basic die design (diverging vs. converging), container geometry (required parison diameter), container weight (shuttle process) and type of blow molding process. Some of the wheel type blow molding processes clamp (pinch off) and hold the parison at both ends during the blowing sequence in the process. The parison swell effects are normally more readily controlled on the wheel process compared with the shuttle process.

Parison swell data for a given material is often not available for mandrel and die calculations. The alternative is to proceed in a stepwise approximation towards the desired mandrel and die dimensions, and through trial and error, towards the targeted container weight with the aid of an interchangeable set of dies.

Internal die design dimensions including approach angles and land lengths vary significantly with blow molding machine capabilities and machinery manufacturers experience. Calculations for these dimensions are beyond the scope of this document and will not be discussed here.

However, as a rule of thumb, when blow molding commodity materials (PE, PP), a die land length of at least 8 times the annulus gap (die gap) is typical.
Blow Molded Bottle Nomenclature



A simplified approach for calculating and estimating mandrel and die dimensions is presented here to serve as a general guide. The following equations may be applied in cases where the container geometry is symmetrical and there is no handle on the container.

Case A

When the neck size of a container or the smallest diameter of the container is the controlling feature (as when the parison must be contained within the smallest diameter) , the following approximations may be used to calculate the dimensions of the mandrel and die. Use of these equations assume a free-falling parison and they can be used with most PE blow molding materials.

Dd = 0.5 N d (Equation 1.1)

Pd = ( D d2 - 2Bdt + 2t2)1/2 (Equation 1.2)

where: Dd = Diameter of die bushing, in
Nd = Minimum neck diameter, in
Pd = Mandrel diameter, in
Bd = Bottle diameter, in
t = Bottle thickness at Bd, in

Case B

When the container weight is specified instead of the wall thickness for a process using inside-the-neck blowing, the following equations may be applied:

(The equation may be applied for a free-falling parison, and is applicable to most irregularly shaped containers.)

Pd = (Dd 2 - 2 (W/T2) Ld)1/2 (Equation 1.3)

where: Pd = Mandrel diameter, in
Dd = Diameter of die bushing, in
W = Weight of container, g
L = Length of container, in
d = Density of material, g/cc
T = Wall thickness, in

Case C

When a parison is partially controlled by tension, i.e., the rotary wheel blow molding process, the following relationships may be used. The assumption here is that the parison is not free-falling.

Dd * 0.9 N d (Equation 1.4)

Pd * ( Dd 2 - 3.6 Bd t + 3.6 t 2)1/2 (Equation 1.5)

Pd * ( Dd 2 - 3.6 ( W / T 2 ) Ld) 1 / 2 (Equation 1.6)


where: Pd = Mandrel diameter, in
Nd = Minimum neck diameter, in
Dd = Diameter of die bushing, in
W = Weight of container, g
L = Length of container, in
d = Density of material, g/cc
T = Wall thickness, in
Bd = Bottle diameter, in
t = Bottle thickness at Bd, in

Case D

Estimating head tooling dimensions for containers with handles requires an empirical method based on container size and geometry. When the container has a molded handle use the following equations to determine the estimated dimensions for the head tooling die and mandrel.

The die diameter can be estimated using equation 1.7 and the container dimension data.

D = ( 0.8 Z ) / 3 Equation 1.7

Where: Z = Maximum container width or diameter
D = Diameter of die bushing, in.

The die diameter, D, is then substituted in equation 1.3, equation 1.5 or equation 1.6 depending on available container data and the blow molding process that will be used.


All the steps during the procedure that involve intimate contact with the blow molding machine are to be done by a qualified blow molding machine operator.

Procedure:


Mechanical Mold, Head Tooling and In-Mold Labeling Debug
Step 4.2.2: Parison Centering
Purpose:

The purpose of the Parison Centering step is to establish a preliminary die position adjustment to achieve stable parison extrusion and uniform, circumferential parison wall thickness distribution. The ‘fine’ adjustments of the die will be completed later in the Container Performance Optimization step 4.3.2 (page 35) of this document.

Die bolts should be free of any degraded material and turn freely over the adjustment range at normal operating temperature for the die bushing. Appropriate repairs should be made for damaged threads on either the die bolt(s) or the die bushing.

Procedure outlines for the shuttle and wheel blow molding processes follow, respectively:

Shuttle Process Procedure:




Wheel Process Procedure:






Mechanical Mold, Head Tooling and In-Mold Labeling Debug
Step 4.2.3: Manifold Balance

Purpose:

The purpose of the Manifold Balance step is to evaluate the thermal and melt flow balance of the head tooling manifold distribution system and to establish uniform melt flow to each die on multi-head blow molding systems. The melt flow control (normally a choker valve) must adjust freely at normal operating temperature. The valve design must be capable of adjusting material flow to each die head so that the melt flow is stable over a range of extrusion rates.

Both the parison weight and length differences are an indicator of the degree of melt balance control and the quality of the manifold system design. A typical, well balanced manifold will be balanced to within 5%. It is critical to have the flows balanced to each die or the part-to-part variation may be large and process capability may not be achievable.

Initial manifold control valve balance adjustments should be made during the Parison Centering step to optimize the manifold system flow balance. The Manifold Balance step may have to be repeated at higher extrusion rates, i.e. production rate, as melt flow pressure gradients change with melt flow rate and can affect the manifold melt flow balance.

Proceed to the Verify Mold Operation step if the blow molding machine is a single die head system.

All the steps during the procedure that involve intimate contact with the bow molding machine are to be done by a qualified blow molding machine operator.

Shuttle Process Procedure:






Figure 4 depicts typical results for a manifold which is not properly balanced, i.e., parison 9, 10, and 12 are not within 5% of the weight of the control parison #7. Further balance adjustments must be made in order to bring the manifold system into balance.
Table 2: Manifold Balance Test Results





Please check My next Post to in continuation........ thanks

Plastic Recycling Code & Meaning

There are many types of plastic in common use. Plastic must be sorted by type for recycling since each type melts at a different temperature and displays different properties. The plastics industry has developed identification codes to label different types of plastic. The identification system divides plastic into seven distinct types and uses a number code generally found on the bottom of containers. The following table explains the seven code system.

Plastic #1: Polyethylene Terephthalate (PETE)
Common uses: 2 liter soda bottles, cooking oil bottles, peanut butter jars. This is the most widely recycled plastic and often has redemption value under the "Bottle Bill."

Plastic #2: High Density Polyethylene (HDPE)
Common uses: detergent bottles, milk jugs.

Plastic #3: Polyvinyl Chloride (PVC)
Common uses: plastic pipes, outdoor furniture, shrink wrap, water bottles, salad dressing and liquid detergent containers. Please note that plastic bags are not accepted for recycling curbside. However, stop and shop and Big Y Supermarkets accept plastic bags for recycling. Please remove food waste and receipts.

Plastic #4: Low Density Polyethylene (LDPE)
Common uses: dry cleaning bags, produce bags, trash can liners, food storage containers. Safeway Stores and Lucky Food Centers accept HDPE (#2) and LDPE (#4) plastic bags for recycling.

Plastic #5: Polypropylene (PP)
Common uses: bottle caps, drinking straws. Recycling centers almost never take #5 plastic.

Plastic #6: Polystyrene (PS)
Common uses: packaging pellets or "Styrofoam peanuts," cups, plastic tableware, meat trays, to-go "clam shell" containers. Many shipping/packaging stores will accept polystyrene peanuts and other packaging materials for reuse. Cups, meat trays, and other containers that have come in contact with food are more difficult to recycle.

Plastic #7: Other
Common uses: certain kinds of food containers and Tupperware. This plastic category, as its name of "other" implies, is any plastic other than the named #1-#6 plastic types. These containers can be any of the several different types of plastic polymers. Recycling centers cannot recycle plastic #7. Look for alternatives.

Assembly and Disassembly Mold

The following is a good checklist for dis-assembly and assembly of a plastic injection mold.

the picture at the top show disassembly various parts of mold
Disassembly:
• The mold must be placed on two rails on a clean table with sufficient space. Tools used must be in good condition and should include allen wrenches, aluminum prybars, rubber mallet, duct tape, and some containers.
• Separate mold at parting line carefully and look for any visible damage. If mold is damaged, report it at once. Check for rust in core and cavity and report it at once if found.
• Have containers to put all the parts in and identify it with the proper job number.
• Check for core pins in Ejector Housing (at the bottom clamp plate) and remove the core pins first.
• Remove all necessary screws in the Ejector Housing and remove it.
• Remove screws from the Ejector Plate and remove it.
• Check if all pins are marked, if not mark as necessary.
• Check if lift cores are marked, if not mark as necessary.
• Remove all pins and parts from Ejector Housing. Protect all fragile parts and critical areas with duct tape.
• Remove all water line jiffy-plugs
• Remove all slides assemblies and protect all critical areas with tape or carefully store in container.
• Remove the Sprue bushing, hot sprue, or any hot runner system.
• Remove all screws from cavity and core inserts and install two or four longer screws in cavity and core. Then knock out cavity and core inserts from mold base by hitting screws with a rubber, aluminum, or copper mallet. BE CAREFUL NOT to knock insert out onto the bench or floor and damage it. If you can't bump the insert out into your own hand GET HELP.
• Once the primary inserts are removed, remove all sub-inserts, gate inserts, core pins, etc. and protect all critical edges with tape or carefully store in container.
• Carefully clean all details with a clean, mild solvent and clean towels being careful NOT to damage sharp edges, parting surfaces, shutoffs, or the cavity finish.
• Finally, store all inserts in such a way that the molding surfaces are protected and cannot be accidentally damaged.


Assembly:
• Have all the mold plates, inserts, and components in one place ready for assembly. Have a clean table and two rails to slide plates on. Tools used must be in good condition and should include allen wrenches, aluminum prybars, rubber/copper/aluminum mallets.
• Cleanliness is critical in mold assembly. Make sure all plates, inserts, and components are clean and free from grit, debris, and chips. After you have carefully cleaned all details with a clean, mild solvent and clean towels THEN wipe everything again with your clean, bare hand to remove small grit (Careful NOT to damage sharp edges, parting surfaces, shutoffs, or the cavity finish)
• Install all sub-inserts, gate inserts, core pins, etc. into the primary inserts. Check that all inserts and pins are marked and that they are installed in the correct location and position.
• Mount the B-Plate to the Support Plate
• Install the B-Half insert set, any slide assemblies, and any other B-plate components. Check that all parts are marked and that they are installed in the correct location and position.
• Insert and grease all ejector pins, ejector sleeves, and ejector blades through the pin retainer plate, support plate, and core inserts. Install all return pins and springs. Install and grease any Lifter mechanisms. Bolt on the Ejector plate.
• Assemble the ejector housing, with support pillars, guided ejection pins, etc. Guide this assembly through the ejector & other plates and bolt it to the support plate. Insert any core pins that mount in the bottom clamp plate and fasten their backup plates. Lubricate the entire assembly.
• Verify that the Slide assembly moves freely, is greased, and that the slide retainer is functioning properly.
• Move the Ejector assembly forward and check if all pins, sleeves, lift cores and all other moving components spin freely. Wiggle to verify correct clearance and that all components move freely
• Check that ejector plate can use the full length of travel. Check if runner & part will clear the core when ejected.
• Mount the A-Plate to the top clamp plate
• Install A-Half insert set, heel blocks, angle pins, and any other A-plate components. Check that all parts are marked and that they are installed in the correct location and position.
• Install the locating ring & sprue bushing, check that sprue radius, and oriface are the correct size and verify that the sprue bushing is rotation locked and retained
• If the mold features 3-plate or hot runner system install them at this stage.
• For Three-Plate molds, verify that all latches function properly, that they latch and release in assembly, and that plate separation is sufficient to let both the part AND the runner drop through. Also check that all latch dowel pins are secured so as not to come loose during operation. Lubricate the whole assembly and verify that it moves freely.
• For Hot Runner molds check that all wiring is in a channel, free from damage, and free from possible "pinches" during assembly. Check continuity all all circuits
• Install all jiffy-connectors with teflon tape or suitable thread sealant and water test.
• Check all limit switches
• Spray with WD-40 and close the assembly
• Verify that the mold has a mold strap and that it is fastened correctly