John Altman jaltman@mdplastics.com

We are pleased to announce the addition of John Altman to our sales staff effective October 31, 2011.  John will take the position of Regional Sales Manager and is responsible for promoting Md Plastics Inc. value added processing assistance as well as Plasticating Unit components such as Screws (Posi-Melt^TM) for Injection, Blow and Extrusion machines, Screw Tips (MDP ^TM performance), Barrels, Nozzles (Shutoff and Regular), Nozzle tips (Mini-Shut ^TM ) and Endcaps.

Prior to accepting this position, John held key management positions with New Castle Industries (XALOY), Imperial Systems Inc., McShane Welding Co., Inc., and National Specialty Alloys.

“John brings over 30 years of experience and a proven track record of success in the plastics industry, and understands the importance of exceptional engineering and customer service”.

John can be reached; E-mail: jaltman@mdplastics.com

Compactness, durability, and low cost—everything that has been missing in many typical shutoff nozzles—are delivered by the new Mini-Shut nozzle, according to Md Plastics Inc., Columbiana, Ohio (mdplastics.com). Injection molders have used melt decompression to avoid stringing and drooling. But according to Michael Durina, head of Md Plastics, melt decompression can be the cause of other problems, like splay and inconsistent shot size. The answer, he says, is a shutoff nozzle that eliminates the need for melt decompression—as well as stringing and drool—and also allows simultaneous operation of the screw and clamp for faster cycles.

The Mini-Shut is a spring-loaded device designed to fit on almost all nozzle bodies, both American and European. It is short—1.5 to 2 in., vs. 6 to 24 in. for other shutoff nozzles—as well as long-lasting, low-maintenance, and low-cost—$225 to $300, vs. $1500 to $9000 for competing models, Durina says. He adds that it withstands up to 750 F, provides low shear and pressure drop, and can be easily cleaned by standard purging methods. The Mini-Shut is also distributed by DME Molding Supplies.

http://www.ptonline.com/products/injection-molding-everything-you-always-wanted-in-a-shutoff-nozzle

That’s the question, and succinct answer, that MD Plastics Inc. (Columbiana, OH), has for injection molders who normally have to control their resin melt via decompression to eliminate stringing and drooling. MD Plastics President Michael F. Durina says his company’s Mini-Shut provides an inexpensive, automatic, miniature nozzle shut-off tip that not only eliminates stringing and drooling, but also the need for melt decompression itself.

The Mini-Shut, for which a U.S. patent is being sought, was engineered to ensure repeatable part weight distribution, while also reducing surface imperfections. Designed to fit on the majority of nozzle bodies, MD Plastics says the Easy Nozzle is easy to install and remove and can run reliably at temperatures above 750F. In addition to ensuring low pressure drop and shear, the Mini-Shut also allows for the simultaneous operation of the clamp and the screw to boost productivity and can be cleaned using conventional purging methods.

Durina told PlasticsToday that the miniaturization of the device, as well as its cost ($225-$300), make it very unique from anything else that has been invented. Durina noted that melt decompression has been used since the invention of the reciprocating screw as a method to minimize drooling and stringing, but that it is decompression that can create other issues such as splay, melt cushion and shot inconsistency, as well as shifting of the solids bed along the screw axis, which can create screw slippage, bubbles/voids in the melt pool, and shear when the screw is called to rotate during the next phase of the cycle.

“My challenge is to provoke processors to critically look at what they have been doing and offer them a solution to a problem that most of them don’t know they have,” Durina said. “Up until now, the solution has been a shutoff nozzle that costs between $1500 and $9000 and has been plagued with maintenance problems, excessive length, and a short life span so most processors don’t think of using a shutoff nozzle.”

Md Plastics distributes the product in the U.S. through its own offices, as well as through DME Molding Supplies, SE System Engineering AG (Däniken, Switzerland) is its exclusive distributor throughout Continental Europe, while Cooper Technology (Bangor, Northerin Ireland) distributes Mini-Shut in both the U.K. and Ireland

Read Article from Plastics Today here: http://www.plasticstoday.com/imm/articles/why-control-melt-decompression-just-shut-it0908201101

Columbiana, OH—Effective control over the melt-phase of plastic materials in the injection molding process depends upon a number of key factors, not the least of which is the pressing need to eliminate stringing and drooling through effective control over melt decompression. However,  Mini-Shut™ —an inexpensive, automatic, miniature nozzle shut-off tip that now is exclusively available in the USA from Md Plastics Incorporated, (Columbiana, OH; www.mdplastics.com)—not only eliminates stringing and drooling, but also eliminates the need for melt decompression itself.

In addition, Mini-Shut™ is engineered to ensure repeatable part weight distribution, while also significantly reducing any chance of surface imperfections ever appearing on molded parts.

Easy to install and remove, and designed to fit on the majority of all nozzle bodies, Mini-Shut™ provides repeatable operation, even at temperatures exceeding 750°F. And, in addition to ensuring low pressure drop and low shear, Mini-Shut™ also allows for the simultaneous operation of the clamp and the screw to boost productivity. What’s more, Mini-Shut™ can easily be cleaned using conventional purging methods.

“Our miniature automatic shut-off nozzle fills an existing void in the industry by supplying an inexpensive, low maintenance, easily installed and removed solution that prevents drooling and minimizes excessive melt decompression,” says Michael F. Durina, President of MD Plastics Incorporated.

“I honestly believe that a Mini-Shut™ should be installed on every molding machine in the world, since the benefits that it offers to the molding process are so easy to understand. However, until now, an inexpensive, easy-to-use, miniature device that provides such benefits simply didn’t exist.”

Md Plastics, which has applied for a U.S. patent on the Mini-Shut™ for injection molding, distributes the product in the USA through its own offices, as well as through DME Molding Supplies (www.dme.net/moldingsupplies). SE System Engineering AG,  (Däniken, Switzerland; www.se-ag.com) is its exclusive distributor throughout Continental Europe, while Cooper Technology (Bangor, County Down, N. Ireland; www.coopertech.com) distributes Mini-Shut™ in both the UK and Ireland

Mini-Shut™ is now in stock and available Stateside, off-the-shelf, for all machine sizes and molding applications.

Fig. 1: Engineered for installation on most nozzle bodies, the new Mini-Shut™ nozzle shut-off tip shuts off drooling and stringing, while ensuring repeatable part weight distribution, shot after shot.

MD Plastics Incorporated is a leader in the design, engineering, manufacturing, and marketing of plasticating components that add value to the science of Melt Preparation Technology. Since 1999 the company has emerged as a leader in the design, engineering, manufacturing and marketing of screws, screw tips, barrels, nozzles, end caps, nozzle adapters, and heater-bands. Its globally sourced products and processing expertise help its customers cost-effectively improve both product quality and productivity.

For More Information, Contact::  Michael F. Durina

Phone: 330-482-5100

E-mail: mdplastic@msn.com

Web: www.mdplastics.com

Advantages of the SE shut-off nozzle

Single hole technology

The melt is led central by the nozzle needle

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  Minimal pressure drop
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  Optimised heat transport
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  Minimal shearing of melt

Easy construction

From few parts manufactured the SE shut-off nozzle offer substantial advantages in the handling

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  Easy assembling
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  Quick and easy cleaning
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  Trouble free production

Shut-off in the nozzle tip

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  No sprue, no drooling
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  Controlled, clean shut-off of the melt stream
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  Reduced cycle times

Intelligent design

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  Compact
• 
  Solid

Modular system

Specific adapter for any client. The nozzle is always the same and is available from stock. This means short delivery time

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  Quick change of nozzle
• 
  Shortest delivery time
• 
  Most economic solution

Flexible system

For a fast changeover to various tools and machines there are available different tip lengths from stock

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  Different penetration
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  Same nozzle tip

The principals at Md Plastics Incorporated have been focusing on these plasticating unit components for over 27 years with the quest for perfecting the perfect NRV.  Our philosophy has been to develop a quantum change in the function of the design while considering the constraints that are prevalent on all Injection machines.  Afterall, the sliding ring, ball check and poppet designs have been tweaked and redesigned over and over again during this period with only minimal improvement.  Not unlike many inventions, it takes numerous tries and endless hours of development before an idea is proven and worthy of the test that the market will bring; our latest “MDP” performance design is such a design and worthy of the continued discussion.

A very accomplished custom Midwest Injection Molding Company sought to find a solution to poor part quality, frequent NRV changes that were application specific and a longer lasting component.  They have been using a Industry Standard “Three Piece Sliding Ring” Free Flow design for a majority of their standard processes and a QSO poppet design for gas assist processes.  A series of tests were conducted on a 90mm diameter “MDP” performance sliding ring design for a Mitsubishi Molding Machine for the evaluation.

The first test was conducted with a 20% Glass filled 12 MI PP material, the results are as follows;

The data proves that our design shut off quicker than the Three Piece Sliding Ring design, was more precise and worked very well without the use of melt decompression.

The second test was with a 20% Glass Filled Polycarbonate with an in-mold Gas Assist application.  The process requires that the screw bottom out each shot so a proper distribution of gas disperses throughout the part.  The results are as follows;

It is important to note that the Poppet Valve was run first with a 145mm stroke, when the “MDP” valve was installed the part weight immediately increased to 1012.4 grams which proves that the “MDP” valve shut off quicker than the Poppet Valve.  Since the process dictates that that the screw needs to bottom out, the stroke had to be reduced to 140mm. If a volumetric evaluation is made using 1.2g/cm^ 3 for density of the polymer, the part weight would be 1069.9 grams, proving that the “MDP” valve shuts off quickly and stays shut through the full stroke.  The data also supports a more precise operating component.

The third and final test was with a 30% Glass Filled PA 6/6 material.  The results are as follows;

The Three Piece Free Flow Sliding Ring design experienced numerous short shots and flashed parts with 15mm decompression and two short shots with 10mm decompression.

Since its inception, the “MDP” performance NRV has proven that it is the most precise sliding ring NRV in the industry virtue of its unique geometry and low pressure drop in applications from 16mm through 215mm in diameter while covering the gamut of resin Viscosity and Injection Velocity.

One of our customers, a large sophisticated Midwest Injection Molding Manufacturer recently reported some very interesting performance numbers to us while using our “MDP” performance  three piece sliding ring screw tip (NRV) on a 90mm diameter 500 ton Mitsubishi Injection Machine.  The customer was looking for some better performance compared to a Industry Standard Three Piece Sliding Ring screw tip so they put our “MDP” design under some scrutiny.  The performance was outstanding; it exhibited a quicker shutoff 12.2-15.2mm cushion compared to 1.6-12.6mm, more consistent with less variation and the “MDP” worked very well with zero decompression whereas the “Three Piece” design simply did not work.  When the weigh scale was working properly, the variation in part weights over 40 consecutive shots was 1.2 grams on a 505 gram part!

We can supply a screw tip that shuts off quickly, is extremely accurate, cost competitive, versatile with all resin groups and can be used without decompression.  If you are interested in seeing the data generated from the test view our “Case Studies” section on our web site or contact us to see what we can do to improve your operation.

Equipment Specification:
150t Injection Moulding Machine
Foboha 4 Cavity Closure Mould Tool
Husky Valve Gate System
Material PP Moplen HP501L
Cooper Technology Posimelt Screw + MDP Screw Tip
35mm Screw
8.2 second Cycle Time

Initial Test Results:

Visual equivalence achieved
Cycle time achieved
Material saving per 24 hour shift 3.4 kg

I think that John is over-simplifying the science involved in getting a valve to shutoff and specifically shutoff in a short period of time without leaking through the full axial movement of the screw, especially considering that the viscosity of the polymer fluids that the average molder uses everyday can vary by a factor of ten with varying injection speeds.  There is only one similarity between the engine valve which he describes and the sliding ring NRV used in the plastics industry and that is that it is a SEAT.  In our industry there are many more variables to be concerned with such as;
1. The viscosity of Thermo Plastics is 10,000 1,000,000 times more than that of water…let alone air.
2. The pressure within the plastic fluid changes which is dependent upon the viscosity which is influenced by the heat that is being applied via the heater bands on a cyclic nature and shear heat from the screw which can change due to slippage between the polymer and the screw as well as the residence time.
3. The pressure within the plastic fluid that is measured across the valve which is dependent upon the design itself and the factors mentioned above.
4. The relative speed of the screw during injection forward.
5. Fillers that are part of many of the polymers that we use today.  The type of filler will determine if it will deter complete shutoff because they are solids and do not change shape unless they are exposed to compressive forces that are greater than they can resist.

I believe that the seat is important but if there is a poor hydraulic design no matter what type of seat is employed, complete and quick shutoff will not occur.  I am a believer that the best designs are ones that have a minimal pressure drop across the shutoff mechanism which is the ring on a sliding ring design and a poppet or ball on one of those namesake designs.  If there is a lower pressure differential across the shutoff mechanism then when the screw moves forward on a ring valve for example, the displacement of the fluid between the faces of the ring and rear seat will take place quicker and therefore less material will traverse upstream along the flight channel.  In this case, the theoretical displacement of the polymer fluid and the actual will be closer.  When the two faces touch, then and only then can pressure be built and complete shutoff occur, this is where the seat design comes in.  I think that the best way to assure a shutoff between two components is to assure alignment between them.  A screw and ring that sits within a barrel does not assure a rigid alignment because of tolerances and eventually greater differentials because of wear, therefore I believe and have tested that a flat seat is the best way to assure a seal.  After all, the caps on the milk container that John mentions in his article are all flat surfaces.

Our “MDP” performance sliding ring valve (Patented US #7,527,493) has the lowest pressure drop in the industry because the front seat and rear seat see virtually identical surface areas as opposed to most valves that have flutes that retain the ring’s forward movement.  We have had rave reviews from our customers regarding shutoff performance…and no bridging issues. In addition, we design an Automatic version of the “MDP” design and we sell a “Spring” loaded poppet valve as well.  Overall, I am pleased with our offerings and can make a recommendation for your company and will guarantee performance.  In fact if you record shutoff performance now I would love to get data from you after using one of our designs.

Michael F. Durina