Injection Molding Machine

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ARBURG’s injection molding machines are renowned for their well tried and tested modularity. When it comes to the ALLROUNDER ALLDRIVE (A) series, the principle of modularity also applies to the drives.

The ALLROUNDER A offers the choice of combining the electric main axes with either electric or hydraulic auxiliary axes, depending on which solution is best suited to any specific application. 
The first example of the electric ALLDRIVE series is the ALLROUNDER 420 A 800-400. It has an 800 kN clamping force, 420 x 420 mm distance between tie bars, 400 series injection unit, screw diameters of 35, 40 and 45 mm as well as electric main axes and also an electrically driven five-point toggle system to provide the highest degree of positional accuracy. 
Following the successful introduction of the first ALLDRIVE machine, the series was expanded through modular drive technology to include larger clamping forces. As a result, at Fakuma 2003, which is being held from October 14 to 18 in Friedrichshafen/ Germany, the ALLROUNDER 420 A will for the first time be accompanied by its big brother, the ALLROUNDER 520 A with a clamping force of 1,600 kN. 

plastic molding
plastic molding

The Good injection molding machine A concept

The main functions of the injection molding machine – opening and closing moulds, injection and dosing – have been designed with electric drives as the basic structure. The other movements such as ejection and moving the nozzle and mould functions can either be electric or hydraulic, depending on the operating requirements. 

The movement of the mould closing operation is initiated by rotation of the servomotor to the five-point toggle system via a threaded spindle. This has been specially configured to the dynamic behaviour of the electronic drive.

The injection and dosing movements are converted with high torque via a gear position and a threaded pinion. To operate the movements with optimised use of time and low maintenance, the spindles are equipped with a special cool lubrication system. This ensures a high level of efficiency with low service costs and the longest possible service life. 

The machine series are modular in design due to the choice of auxiliary axes with electric or hydraulic drive. In this way, for example, the eject function can be carried out electrically, extremely accurately and dynamically with a spindle, or it can be carried out conventionally (‘softly’) with a hydraulic cylinder.

The nozzle advance movement, which in essence has a contact force applying function for most applications, is mostly with hydraulics or it can also be carried out electrically.
In ARBURG’s view it is very important that core pulls and specific special movements on the plastic mold, which have previously been integrated hydraulically, continue to be optimally operated with hydraulics in the future. For this reason, a special energy-saving small-accumulator hydraulic system has been developed for the optional hydraulic auxiliary functions on the machine, which can be assembled and dismantled on a modular basis.

Regulation

The basic structure of the electric axes ensures that they are highly dynamic and location-and position-regulated. This produces a reproducible, pin-point procedural sequence. This is mainly used for application with absolute and relative positioning accuracy for the mould and ejection movements.

In this way, for example, stroke-dependent functions such as mould positions in connection with core pull, or final positions when unscrewing, can be achieved extremely accurately.

As all stroke positions are measured absolutely, it is not necessary to carry out a reference movement or set them to a reference point.

On the injection side, the positioning accuracy and the acceleration in conjunction with the position-regulated screw movement can lead to additional accuracy with the injection molded parts. During dosage, the effect of the electric drive can be seen in the accuracy and in the energy requirement. 

When viewed on an individual basis, the options and potential for the improvement described, in conjunction with the well-tried and tested SELOGICA control system, lead to added value in relation to parts production.

The opportunity to operate individual cycle stages simultaneously adds even more importance to the programming of the SELOGICA control system. The appropriate cycle symbols with their comprehensive logistic links are extremely clear and can be used to optimise the procedures.

The synergistic effects of the ALLROUNDER A

During the development of the ALLROUNDER 420 A a great deal of importance was placed on the synthesis between the most up-to-date drive technology and tried and tested injection moulding technology.

In this way the design of the clamping areas ensures continued use of existing moulds. Furthermore, the daily operational practice is taken into account owing to the modular nature and the option of connecting hydraulic core pulls onto the plastic molds.

Flexibility through modular construction

The concept of electrically driven main axes as the basis and the option of freely combinable electrically or hydraulically driven auxiliary axes integrates the advantages of both systems. 

The machines have sufficient hydraulic power at their disposal precisely where it is needed, and they have the highest level of electro-mechanical accuracy coupled with economic energy consumption wherever feasible for the production task.

This means that the ALLROUNDER A machines also represent extremely flexible production systems, which always allow the machines to be equipped within an optimum cost/benefit framework, while at the same time precisely adapting them to the prevailing production requirements.

Injection Molding Equipment

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Injection molding equipment is equipment that is very important for the operation of injection molding machines. Indeed, all injection molding machines utilize injection molding equipment that includes a power source, injection unit, mold assembly, and clamping unit to perform the four stages of the process cycle.

injection molding equipment
injection molding equipment

One of injection molding equipments is injection unit. This injection molding equipment is responsible for both heating and injecting the material into the mold. The first part of this unit is the hopper, a large container into which the raw plastic is poured. The hopper has an open bottom, which allows the material to feed into the barrel that contains the mechanism for heating and injecting the material into the mold.

Another injection molding equipment is clamping unit. Prior to the injection of the molten plastic into the plastic mold, the two halves of the mold must first be securely closed by the clamping unit. The hydraulically powered clamping motor actuates clamping bars that push the moveable platen towards the stationary platen and exert sufficient force to keep the mold securely closed while the material is injected and subsequently cools. After the required cooling time, the mold is then opened by the clamping motor.

There are also molds, typically made of steel or aluminum, as the plastic injection mould and molding equipment. The mold has many components, but can be split into two halves. Each half is attached inside the injection molding machine and the rear half is allowed to slide so that the mold can be opened and closed along the mould’s parting line. The two main components of the mold are the mold core and the mold cavity.

When this injection molding equipment is closed, the space between the mold core and the mold cavity forms the part cavity that will be filled with molten plastic to create the desired part. Multiple-cavity molds are sometimes used, in which the two mold halves form several identical part cavities.

Mold base also includes injection molding equipment that is a place where the plastic mold core and cavity are each mounted. Then, the mold base is fixed to the platens inside the injection molding machine. The front half of the mold base includes a support plate, to which the mold cavity is attached, the sprue bushing, into which the material will flow from the nozzle, and a locating ring, in order to align the mold base with the nozzle.

The rear half of the mold base includes the ejection system, to which the mold core is attached, and a support plate. When the clamping unit separates the mold halves, the ejector bar actuates the ejection system. Meanwhile, mold channels are one of injection molding equipment types that is usually integrated into the mold design in order for the molten plastic to flow into the mold cavities.

First, the molten plastic enters the mold through the sprue. Additional channels, called runners, carry the molten plastic from the sprue to all of the cavities that must be filled. At the end of each runner, the molten plastic enters the cavity through a gate which directs the flow. The molten plastic that solidifies inside these runners is attached to the part and must be separated after the part has been ejected from the mold.

Besides using several types of injection molding equipment, there are many types of materials that may be used in the injection molding process. Most polymers may be used, including all thermoplastics, some thermosets, and some elastomers. When these materials are used in the Thermoplastic Injection Molding Process, their raw form is usually small pellets or a fine powder. Also, colourants may be added in the process to control the colour of the final part.

Plastic Food Package

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The Safety of Plastic Food Wraps

  • Plastic food Package Containers are used safely by millions of people every day to help protect foods against spoilage and contamination.
  • Some food wraps contain adipates, a kind of plastic softener that allows plastic wrap to cling to bowls to help keep food fresh and safe.
  • One of these adipates, called DEHA, has been the subject of inaccurate media reports recently. These stories ignored decades of safety studies showing that DEHA is safe in food wrap.
  • The U.S Food and Drug Administration, which ensures the safety of food packaging, carefully reviews studies on all substances before allowing their use in food packaging. Based on extensive research, the Food and Drug Administration permits the use of DEHA in packaging for all types of food.
  • Based on U.S. Department of Agriculture figures for average consumption, the exposure to DEHA is below levels of concern. A Consumer’s Union study alleged high exposures, but even assuming that the analysis was accurate, a 150-pound adult would need to eat more than 1,000 pounds of cheese in a single day to reach the observable effect level found in lab animal testing.
  • On its Internet website, Georgetown University’s Center for Food and Nutrition Policy (CFNP) recently wrote, “We at CFNP view the benefits of using plastic wrap to protect food safety and quality on the shelf to far outweigh the imagined risks ….” 

Plastics in the Microwave

Over the years, consumers have come to appreciate the important role plastics play in keeping food safe and healthful. In the home, plastic wraps, storage containers and sealable bags help keep your family safe and your food fresh and free of contamination.

What may be less clear is how appropriate these containers are for use in your microwave oven. Dr. Charles Breder, an expert on food packaging and former supervisory chemist at the U.S. Food and Drug Administration (FDA), offers these guidelines:

  • Cook or reheat foods in containers intended for microwave use. These containers are designed to withstand the high temperatures that are possible when the foods you’re heating contain fat or sugar.
  • Plastic Molding company can make plastic food package box and other type of plastic mold base on customer requirement
  • Remove food from store wrap before thawing or reheating in a microwave oven unless the manufacturer has indicated that it’s meant for microwave use. Some plastic trays, wraps or containers can melt or warp when the food gets hot, possibly causing spills and burns.
  • Most cold-food packages – such as margarine tubs, cottage cheese containers and foam meat trays – are not intended for microwave use.
  • Plastic wraps, placed loosely over bowls or dishes during rewarming, can help keep moisture in and provide even cooking. If the wrap touches the food, the wrap could get overly hot and possibly melt. Yet, as Dr. Breder notes, if you were to accidentally eat food containing melted plastic, you’ll likely have an unpleasant eating experience – but you won’t be harmed.