Plastics Technology

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Structural Foam Goes All-Electric

What may be the first all-electric structural- foam molding machine was recently built by Milacron’s Elektron Technologies unit in Batavia, Ohio, in cooperation with structural-foam specialist Uniloy Milacron in Manchester, Mich. This development occurred because a major foam molder wanted a large all-electric machine for the sake of energy savings, oil-free operation, and noise reduction. Uniloy’s Springfield Div. always uses two-stage injection for its structural-foam machines, so Milacron adapted its Sidewinder two-stage electric injection unit to this process. This being the first foam application of a two-stage electric machine, Milacron says, Uniloy developed a new screw design, a barrel-cooling system, and gas- injection metering hardware for the Sidewinder. 

The result was a 550-ton Powerline machine that reportedly provides highly consistent foam melt with both gas injection and chemical blowing agents, as well as a wide range of shot sizes. The separate shooting pot allows use of any shot size from 100% down to 3% of machine capacity. The machine molded an electrical housing (see photo) of GE’s Noryl PPO/PS alloy with nitrogen gas. The part weighs 83 oz and has a 15% weight reduction with a typical foam/skin structure. The Sidewinder unit can be converted to standard high- pressure injection molding with a simple screw change. 

Cooling Screw Cranks Up Foam Output

A new screw design for foam extrusion is believed to be the first to use cross-flight melt channels to increase cooling and foam output. The channels perforating the curved flights scoop hot polymer off the screw root and brings it into contact with the cooled barrel. In the single-screw cooling extruder of a tandem foam line, it reportedly increases output by 25-40%. Developed and patented by Plastic Engineering Associates Inc., Boca Raton, Fla., The Turbo-Cool screw was publicly discussed for the first time at the SPE ANTEC meeting in Dallas in May, though it is already used commercially by several large producers of PS-foam sheet for clamshells and board for construction. 

Integrated Stretch-Blow Machine Is All-Electric

The upcoming K 2001 show in Dusseldorf, Germany, will see the debut of the first all-electric integrated PET injection stretch-blow molder from Automa of Italy (represented here by Automa Machine & Tool Inc., Maple Grove, Minn.). The servo-driven NSB100 system is designed to run at three times the production rate of conventional ISBM machines. For example, it reportedly can mold 16-oz bottles at 5000/hr. NSB100 will have a 5:1 ratio of injection to blowing cavities (up to 20 and four, respectively). 

Automotive TPO Goes Antistatic

Two versions of Sequel 1514, a new mar-resistant TPO from Solvay Engineered Polymers, Auburn Hills, Mich., are being used in the tailgate liner and protective moldings atop the tailgate and side rails surrounding the cargo box on the Ford Explorer Sport Trac vehicle. The liner compound is the first static-dissipative TPO to be used in an automotive role. The parts are molded by Ventra Plastics in Russellville, Ky. 

Although Ford initially specified ionomer for the moldings, Ventra foresaw processing advantages in TPOs that could cut costs. Tests by Ford and Ventra confirmed that durability of Sequel 1514 matched that of ionomer, but the TPO’s improved flow permitted downgauging from 3.5 to 3 mm, and the ionomer required longer cycles to prevent sticking in the plastic mold.

Colorants for Packaging Offer Light Protection

A new line of color concentrates for packaging of light-sensitive retort products has been developed by Ferro Corp.’s Plastics Colorants Div., Stryker, Ohio. The new Light Blocker Concentrates are said to be heat stable and to meet FDA standards for direct food contact at retort temperatures. Five light pastel shades are said to provide both uv and visible-light protection for nutrients in milk-based products. 

These concentrates are intended for use in LDPE, LLDPE, HDPE, PP injection molding, and PS bottles, injection molded containers, and thermoformed sheet. Letdown ratios are 10:1 to 50:1, depending on layer thickness and shelf life. These customizeable concentrates reportedly offer cost- saving opportunities. For example, they can permit downgauging an outer white layer over the light barrier, using a monolayer structure, or eliminating foil.

Plastic Injection Molds

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Plastic Injection Molds

If you demand long-life plastic injection molds, it is insufficient if you only requires good mould from mold supplier; the life of the mold have great relationship with normal operation and maintenance, so a mature molding company usually have plastic mold engineer, who will responsible for mould repairing and maintenance; of course, plastic molds disassembly is a basic work in mold maintenance.

Do you know how to disassemble plastic molds? And what you should pay attention in moulds disassembly? When you disassemble theplastic moulds, you need to pay attention to following matters.

It is necessary to print the mould assembly drawings, clear up each of the parts in the plastic molds and the principle of operation as well as the assembly relationships.

According to the parts list on the assembly drawing, preparing the necessary disassembly tools.

Analysis the plastic injection moulds, learn the injection type, such as normal hot runner, valve gate or cold runner, and check the parting line and ejector system. Make a disassembly order list before do it.

When you disassemble the plastic mold, placing the mould on rubber mat or low hardness plane workbench. Parting surface to be parallel with the table; that means guide pin should perpendicular to the workbench. It can protect the mould parts, such as ejector pin, if the mould is not in correct direction, small pin will be easy to be bend.

Usually, you need to separated the cavity and core, and disassemble plastic injection moulds from back side, it means start disassembling from the ejection and injection systems.

If you don’t know about the mould well, you need to mark all the removed parts, and put in sequential, it will be convenient for installation and it can avoid mistake when you assembling the mould.

Tools to be used correctly make the force balance when you rotating or beating, don’t forcibly disassemble the undetectable parts.

If the tool needs to reach to cavity or core surface, be sure to use less hardness tool than the core cavity, usually, we suggest copper.

If you don’t have any mould engineer in your company, it is not rational to do plastic molds disassembly without any technical support. We suggest you send injection molding molds to local mould workshop, or do the plastic molds disassembly under guidance of mould manufacture.