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.

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Click here for the full MDP Valve Performance Evaluation

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 better performance compared to an 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 shut off 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.  The variation in part weights over 40 consecutive shots was 1.2 grams on a 505 gram part!

FEATURES:

- SIMPLE TWO OR THREE PIECE SLIDING RING DESIGN

- HIGH FLOW; LOWEST PRESSURE DROP IN THE INDUSTRY

- GOOD FOR ALL RESIN GROUPS

- EXTREMELY ACCURATE WITH OR WITHOUT DECOMPRESSION

- MULTIPLE CONSTRUCTION OPTIONS INCLUDING WC BUSHINGS AND PINS

- REPLACEABLE “MDP” BUSHING ASSEMBLY

- METAL TO METAL WEAR IS TRANSFERRED TO THE BUSHING ASSEMBLY

BENEFITS:

- EASY INSTALLATION AND REMOVAL

- COMPETITIVE PRICING

- HIGH THROUGHPUT

- QUICK AND PRECISE SHUTOFF, LOWEST PART WEIGHT DISTRIBUTION IN THE INDUSTRY

- MULTI-PURPOSE USUAGE

- PROVEN MATERIAL SAVINGS

- LONG WEAR LIFE

- QUICK MATERIAL AND COLOR CHANGES

Mini-Shut Installation Guide

Precision Injection Molding: Mini-Shut™ Nozzle Tip

The Mini-Shut™ Automatic Shutoff Nozzle Tip

Melt Temperature Sensor Technology Presentation

The MeltTempPress© System;

Enables you to Measure the Melt Temperature, Density and total Energy expended within the melt stream and  the mold cavity!  The resultant MeltTempPress© readout is used to monitor and or control your process.

The Thermal Energy Curve below can be obtained by simply Installing the Sensor into a Nozzle Adapter

Thermal Energy Curve

The Melt Temp Press © System Includes:

•4s-Temp Unit video recorder-indicator, bench mount with handle

•115 V supply with 10’ cord •Ethernet or USB Communication

•Five Sensors (4 active & 1 spare) with 10’ extensions, male mini connectors

•One Nozzle Compression Fitting •One Nozzle Adapter

Conclusion:

•The Plasticating screw, non-return valve and nozzle design is the Heart of a molding machine

•The greatest area for improvement in producing quality Injection Molded Parts relates to Melt Preparation Technology, the Science of preparing the Polymer Melt.

a). Plasticating Screw design

b). Non-return valve design

c). Nozzle Tip design

•In order to prepare the Melt properly one needs to know what the effects of machine controls have on the Polymer.  The MeltTempPress© System is the first and only system for Evaluating machine control effects on the Polymer!

Click Here for a MeltTempPress Video

Features of the Posi-melt™

• Meter depths designed for maximum throughput with no raised register.
• Average of 45% more exposure to the barrel wall for more efficient melting.
• Stepped design adds a high degree of mixing to the melt stream.
• SMQI of at least four times better than the Industry Standard GP design.
• Increased leads add a velocity change to the melt stream for added melting and mixing.

Benefits of the Posi-melt™

The revolutionary Multi-Purpose™ Posi-Melt™ screw is the Ultimate Multi-Purpose screw for tough injection molding applications. The “EXL”™ design adds a high degree of additional melting and mixing to the polymer making this design one of the most advanced designs in the world. Repeatability and melt homogeneity are the basis for high productivity from an injection unit. From a process engineering perspective, the control variables that help us determine the correct injection screw design are: Resin type, Residence time, Swept volume, Plasticating rate, Screw torque, Cycle time, Melt temperature and Melt homogeneity. When the application demands precise color match with residence times lower than 90 seconds only an advanced design such as the “EXL” will be able to deliver a quality molded part

“EXL” MIXING SECTION

- Channel volume controlled by previous channel meter depths for low pressure loss.

- Disruption of melt stream with extensional strain, relaxation and cross flow for distributive mixing.

- SMQI of at least 6.0 times better than a GP design.

POSI-MELT™ METERING SECTION

- Meter depths designed for maximum throughput.

- Average of 45% more exposure to the barrel wall for more efficient melting.

- Stepped design adds a high degree of mixing to the melt stream.

TRANSITION SECTION

- Extended melting lengths compared to a standard GP design.

- More thorough melting while using a low compression design.

- Large leading and trailing flight radii for pressurized flight channels and no material contamination.

- Positive feeding pressure, designed to feed even the “hard to feed materials”.

- Low RMS value for better solids conveying.

- Consistent recovery times on all screw sizes.

- Feed lengths based on resin type and application.

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