Logic Corp. Injection Molding Equipment. Consulting

***I.C.E. - Incremental Cavity Ejection***
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Paul E. Allen, President and Founder of The Logic Corporation, graduated from the University of Bridgeport with a Bachelor of Science in Mechanical Engineering and has been in business for 30 years.

With over 40 years experience in product design and injection molding processes, he is the holder of multiple patents on injection molding processes such as :

Logic Seals

Vac-U-Temps

Manifolds

Product Design

Mold Designs

Consulting by Paul E. Allen

Many of you know me as an inventor and injection molder. Others may know me as a person who presents interesting topics on injection molding at S.P.E. or S.P.I. meetings. I would prefer to be known as a pretty good mechanical engineer who, out of necessity, devised equipment and processes to resolve problems and save my sanity.

My thinking and actions over the years have always focused on achieving a goal that contained two equally important items:

Improving the molded part quality to the highest practical acceptable level.
Reducing the processing cycle to the shortest practical time frame.

In accomplishing these goals, I was forced to critically review every aspect. This would include the product design, mold design, injection machine controls and accessories, mold building practices, mold cooling, mold venting and mold material selections. Obviously, I have never been satisfied with the limitations of the "state of the art". Some problems must have new "Art" to solve them.

Please review an article that I authored in the June 1999 issue of Injection Molding Magazine. It appears on pages 76 and 77 and is new "Art". Running the front zone temperature with A.B.S. 100 degrees Fahrenheit lower to get higher quality and faster cycles is not in any book or taught in any class. Nor is it told to you by any material supplier, but it works and it works very, very well. The article is also available for your viewing on this consulting page.

My consulting service is done on the basis that:

You tell me, show me or explain your problem and if I accept the challenge and submit a quotation, I will resolve the problem to your satisfaction. If I am not able to resolve the problem to your satisfaction, my recommendations are free.

For additional information please call (800) 325-6442, Fax (203) 598-3401 or e-mail logic@logicseal.com

The following article appeared in the June 1999 issue of "Injection Molding Magazine". http://www.immnet.com

Reprinted with permission from Injection Molding Magazine;

COOLING THE BARREL:

Reduced temperature helps prevent leaking

Editor’s note: Paul Allen is the president of Logic Corporation and a veteran of injection molding for more than 40 years. More than 10 years ago he hatched the idea of cooling the end of the barrel as a way to reduce material degradation, prevent leakage, and reduce check ring and barrel wear. He has since updated the concept and presents the idea here

As molders know, to properly inject plastic into the mold, the tip of the screw must be sealed against the inside of the barrel to prevent molten material from slipping back during injection. This is done with the check ring, which allows melt to extrude in front of it, but shuts itself off in the opposite direction to build pressure during injection. Between the OD of the check ring and the ID of the barrel a clearance of .004 to .006 inch is typical on a 2-inch diameter barrel. But with metal-to-metal wear this dimension increases. When it does, melt can slip back through the clearance between the check ring and barrel wall. Available shot capacity is lost behind the check ring, and some material is reworked by the screw in subsequent shots.

Cooling is Key

Figure 1

Obviously, the best way to prevent such leaking is to seal the clearance between the check ring and the barrel. Logic Corp. has developed a system that does just that, cooling the front of the barrel to reduce the temperature and increase the viscosity of the resin between the barrel and the check ring (Figure 1). This higher-viscosity region acts as a seal and prevents material from slipping backward past the check ring. Because plastication occurs in the middle zone of the barrel, and because fresh melt is forced to the front zone in each cycle, the melt at the center of the barrel remains at the proper temperature for injection into the mold.

This system consists of cooling rings installed around the front of the barrel with steel or copper tubing wrapped around the barrel. Air moving through the tubing passes out of several small holes drilled into the side of the tubing that faces the barrel (Figure 2). Care must be taken to make sure the holes do not blow directly on the pyrometer that controls the front heat zone; this could produce false low readings and activate the heaters. Airflow should also be adjusted to prevent excessive cooling (i.e., the heaters stay on or come on too frequently). With a little more investment, a heat controller can be purchased to turn on the air only when needed.

The temperature at which viscosity increases such that a seal can be developed is an inexact science, dependent largely on material type, barrel size, shot size, and the cycle time. Trial and error may be required to help determine the best temperature for the machine and material.

Figure 2

An Example

The problem with even a little leakage-aside from pressure loss-is that material that gets reworked by the screw can degrade. Such was the case with a polycarbonate part molded with a small patch of highly degraded material near the gate. The hot tip was blamed and removed, but the problem persisted.

The part, which had a highly polished surface, had been molded for 18 years without this problem. It wasn’t until the customer asked for a light texture on the polished surface that the tint appeared. Parts in stock that were produced with the polished surface were pulled and found to have the same blemish visible in the right light. It didn’t become obvious until the texture was applied.

The answer: Some material was being trapped between the check ring and the barrel wall. When injection forward stopped that material was not reworked into good material, but flowed into the injection stream and was later mixed by the sprue, runner, and gate. This degraded polycarbonate appeared in the part in the form of the discolored spot. Cooling the barrel and increasing the viscosity of the polycarbonate along the barrel wall would have eliminated the leakage and discoloration.

There are other benefits of cooling the front of the barrel. By reducing leakage the screw maintains a consistent pressure on pack and hold, the screw does not bottom out, and part surface texture is enhanced. This is particularly evident in clear parts, especially engineering resins such as polycarbonate. Heat-sensitive resins also show appearance improvement.

Increased Capacity

If cooling the barrel reduces material slippage, more material is left in the shot, effectively increasing shot capacity. But even in a robust system with a new check ring and minimal slippage, cooling the barrel can increase shot size.

A mold that produced 14-oz parts was run in a machine with a maximum shot capacity of 14-oz. Not only was the shot size too small to pack out the part, but many parts were shorted. A cooling system was installed, enabling the part to be adequately packed out with a cushion to spare.

Why did this occur? On the original system, before barrel cooling was introduced, even though capacity was maximized it was difficult to build all 14 oz required because the check ring floated freely in the barrel and was not immediately and fully seated against the screw. When the screw did move forward, the check ring tended to move with it.

By cooling the barrel, the higher-viscosity material that develops holds the check ring in a relatively centered and straight position in the barrel. When the screw moves forward on injection the check ring is held by the friction of the material. The screw then effectively moves through the check ring before it seals itself against the seat. The consistency and stability of the check ring’s orientation produces repeatable processing conditions, shortens the shut off distance, and eliminates variations in shot size that caused the shorts in the earlier test.

This system has been successfully applied many times in molding programs. Molders are encouraged to test this system and report their findings. This process is not licensed.

INCREMENTAL CAVITY EJECTION Patent# 5,932,164

WHAT YOU SHOULD KNOW ABOUT ICE

These are the parts referred to in the May 2005 issue of Plastics Technology article �Injection Molding � How to demold
parts faster, with less stress and fewer surface defects.� On page 45 regarding Prototype & Plastic Mold.

I.C.E.Process

Almost perfectly flat

No sinks

No parting line *

No ejection distortion

No polishing *

No drag lines

Tool cost = $X

Process

Not flat at all

Sinks

Parting line *

Ejection distortion

Polished for release *

Drag line to de- mold

Cost = $X + 30- 50%

* CHANGES TOOL COST
Both parts are Polysulfune and have less than .15� draft angle. The I.C.E. part shown was sampled with
machine problem unrelated to the I.C.E. process (inject forward did not stop and holding pressure was
not controllable)

The part on the right may not represent the best looking part that could be molded with the regular
process, but the defects shown appeared to different degrees on every part ever molded. A lower
quality standard was accepted but even then there was a high reject rate and continuous adjustment to
the machine to lessen the rate along with high tool upkeep, material loss and the uses of mold release.
With I.C.E. being used, all of the machine cycle settings are wide open as compared to a regular
molding cycle. Also molded in stresses from ejecting the part almost disappear and the stress from the
flow to fill and pack out become very very low so annealing may be able to be eliminated.

Paul E. Allen - President

Logic Corporation 80 Turnpike Dr. STE 3 Middlebury, CT 06762-1830
E-mail: logic@logicseal.com 800-325-6442 www.logicseal.com

Redefine Moldability, Mold Faster with less stress & Defects

Paul E. Allen, president of Logic Corp., is the holder of many design, equipment and process patents. His company is a manufacturer and supplier of cluster valves, manifolds and mold temperature controls. Paul's most well known invention is the LogicSeal�. It was the first negative pressure cooling system in the world that was designed to stop water leaks and to vent and cool long thin cores. The newest process is called Incremental Cavity Ejection or I.C.E. (Pat. No. 5,932,164) The system removes many limitations associated with conventional methods, and allows part, mold designers and molders to redefine the concept of �moldability�, particularly for parts that would otherwise be unmoldable without high tool cost and cosmetic defects.

The benefits from I.C.E. take many forms:

Molded parts that have been scraping and scuffing stop doing that.
Textured or parts with undercuts, can be molded with far less mold draft and zero is possible.
Air can replace more forceful methods of ejection, such as the use of knock out pins and plates.
I.C.E.- processed parts exhibit extremely low levels of residual stress.
Sink marks can be lessened or eliminated because higher packing pressures can be used.
Tool cost is almost always less and this system produces the highest quality surface appearance.

All of these benefits, and more, are obtainable with decreased cycle time.

These are the parts referred to in the May 2005 issue of Plastics Technology article �Injection Molding � How to demold parts faster, with less stress and fewer surface defects.� On page 45 regarding Prototype & Plastic Mold.

Question: Which one would your customers prefer?

Traditional practice is to keep the mold closed until the molded part shrinks on to the core and then wait while the part cools enough for the mold to be opened with the molded part secure on the core. The molded part is then ejected off the core with an ejection system.

Almost all materials shrink as they cool. Although most of us do not think about it this way, as injection is taking place cooling is also. More of us consider pack out as cooling time and we all agree it�s cooling between gate freeze and ejection. O.K. it�s been cooling and trying to shrink, but it can only shrink (change dimension) across its wall thickness. The inside dimensions are unable to shrink and change dimension because the core is in the way!

Questions:
With part dimensions 3 1/8" x 6 1/4" x 6 3/4" deep, .100" thick with a draft of .15˚ max. shrinkage across it's wall thickness = .005 in./in. x .100" = .0005 max. at room temperature.

Will your press be able to open with the part on the core?
If so, what will the outside of the part look like?
Is machine ejector force high enough?
Will the force on the part damage it?
Will shape and dimensions change over it's life?

By contrast, in the I.C.E. system, the mold opens sooner, as it does the ejectors move forward holding the return pins against the stationary half and the part in the cavity, as the core (having some taper) is pulled out. The part remains in contact with the cavity and the core as the previously restrained shrinkage force relieves itself by shrinking (changing dimension) across the part diameter radially away from the cavity, thus reducing any further restrained shrinkage. The PART ON THE LEFT was molded with the I.C.E. process and can shrink itself away from its cavity surfaces up to 50 times faster and more than with the traditional injection molding process. When a molded part is completely free from its cavity, ejection forward stops as the mold continues to open, with the molded part holding on to its core.

The part can then be ejected from the core during the rest of the press opening or at the end of the clamp open. Either way, the force from the ejector system to remove the molded part from the core will be very low, close to zero. The reduced ejection force results in reduced residual stresses in the final parts.

The I.C.E. �Incremental Cavity Ejection� concept/system does just what the words say: For a distance the cavity helps eject the part from the mold. Mr. Allen states that the injection molding industry should have been thinking this way for the last 40 years. He freely admits that he should have been. I.C.E. is surprisingly simple; forces holding the part in the cavity are in one direction and those on the core in the opposite direction. The I.C.E. process has these two forces cancel each other out, leaving far less force needed by the ejection system.

Once the part is molded and before the mold opens the plastic part on it's outside surfaces is in contact with
the mold cavity surfaces that are located on the stationary half of the injection molding machine. Also the inside surfaces of the molded part are in contact with the core which is on the movable half of the injection molding machine. When the mold opens there is a reaction across the plastic part thickness, which is usually a small dimension in the range of .020 to .150 inches. This reaction extends throughout the entire surface area of the side walls of the molded part. Therefore the stress in the plastic part is low and self contained; however, the force can be high because the area is large.

One I.C.E. Box is reasonably priced, includes the license and can be moved from press to press. It turns air off and on the ejector system and air to cavity and core. The only electrical connection with the machine is a dry switch that interrupts the signal going to the ejection forward solenoid.

Logic Corp. offers these capabilities, through licensing, to injection molding machine manufacturers. Their machines must have true �EJECTION ON THE FLY� and can also eject at or before the parting line opens.
There is nothing extra on the clamp end.

Please contact Logic Corporation for additional information regarding this patented new exciting system that
can consistently mold higher quality parts at a lower cost.

Contact Information
Logic Corporation
80 Turnpike Drive STE 3
Middlebury, CT 06762
800-325-6442
www.logicseal.com

Paul E. Allen - President

Logic Corporation 80 Turnpike Dr. STE 3 Middlebury, CT 06762-1830 E-mail: logic@logicseal.com 800-325-6442 www.logicseal.com

Logic Corporation 80 Turnpike Dr. STE 3 Middlebury, CT 06762-1830
E-mail: logic@logicseal.com 800-325-6442 www.logicseal.com