How the Plastic EBM Process Works

Bottle-making companies are busier now more than ever. The goal is to provide the various industries they serve with quality products. To accomplish that, they use different processes. One of these is extrusion blow molding.

The Steps for Using an Extrusion Blow Molding Machine

Not only do bottle-making companies work with higher quality plastics, but they also have a broader range of options. In addition, they can work with a reputable supplier that sells products from a leading extrusion blow molding machine manufacturer. For one thing, that streamlines the extrusion process. For another, it bolsters the customer’s level of satisfaction.

The extrusion process begins with a properly-formed parison. The same machine produces this hollow tube of plastic but through a different method. There are two options for an extrusion blow molding machine – single and double-sided. The difference has to do with the number of cavities a machine has, which dictates the level of production.

Below are the steps involved in the extrusion blow molding process.

Carriage Systems

As part of the machine’s design is a carriage system. At the beginning of the process, the carriage moves the clamping system beneath the extrusion head. The machine has two types of carriages: incline and horizontal.

An extrusion blow molding machine manufacturer makes both types of carriage/clamping systems. A single machine has just one, while a double-sided machine has both. The double-sized machine is the most common. Not only does it make the process more cost-effective, but it also increases productivity.

• Incline Carriage – The incline carriage moves at an upward angle as it goes from the blowing station to the parison. As the clamp closes, a knife cuts the parison. This separates each parison while going through the extrusion process. From there, the incline carriage moves at a downward angle as it makes its way back to the starting position. Remember, an EBM machine works continuously. Due to the angle that the incline carriage travels back to the home station, extruder bobbing isn’t required.
• Horizontal Carriage – As the name implies, the horizontal carriage moves horizontally as it goes from the blowing station to the parison. However, to lift the extruder head, it needs a bobbing platform. This gives the carriage clearance to get past the parison before it lowers down again.

Cutting the Parisons

Several options exist for this step of the extrusion blow molding process.

• Spear Knife – Some bottle-making companies opt for the spear knife system. While a beveled-edged blade cuts the center of the parison quickly, there are some drawbacks. For instance, this only works on open parisons, as well as those of smaller sizes.
• Pre-pinch Cold Cut Knives – In this case, overlapping blades perform the cut. This system mounts below pinch bars cooled by water. After cutting, these bars squeeze the following parison at the bottom to create a tight seal. Then forced air from the extrusion head inflates the hollow plastic.
• Pre-pinch Linear Knives – The difference between this system and pre-pinched cold knives is that the beveled blades move through the parison linearly. This pushes the parison toward the neck. For that reason, this works well to create an offset neck on the parison’s opening.
• Hot Knives – With this, an extrusion blow molding machine features an electrical metal strip that heats the blade. Rather than cut a parison, it burns through it. This is a good alternative to the cold blade system, which doesn’t work on PET, LDPE, and PP plastics.

Calibration

The calibration system is another key feature of the extrusion blow molding machine. With the mold closed, cutting done, and carriage back at the starting position, it’s time to inflate the parison. For this, the machine’s calibration system forces compressed air inside the hollow plastic.

Typically, the machine uses a blow pin that inserts at the top of the mold. Although this involves using high-force air, this step is carefully controlled. As the parison inflates, the top flash gets trimmed.

Compared to using the blown neck process to finish a parison, this creates better thread definition and controlled ID. This station either strips the parison from the blow pin or holds it for demolding.

Automated Features

Remember, every extrusion blow molding machine manufacturer operates a little differently. So, as you work with a supplier, you’ll discover varying features. However, here are some of those in the most demand.

• Blow and Drop Machine – Depending on your operations, you might benefit from this additional machine. It works in coordination with an extrusion blow molding machine by allowing it to drop products onto a conveyor. At the end of the conveyor, flash products get separated while finished products go into the appropriate packaging.
• Machine Trimming/Finishing – Automated trimming and finishing are other options. With this, a handover tool finishes the product before placing it on a conveyor. The benefit is that everything gets done in an oriented way.

We Offer Superior Products at a Competitive Price

For advanced solutions from a leading extrusion blow molding machine manufacturer, turn to PET All Manufacturing, Inc. Give us a call, and we’ll answer all your questions and help you through the selection process.

Understanding the Extrusion Blow Molding Process

For extrusion blow molding, manufacturers first create a parison. This hollow tube of plastic will eventually become a bottle or container. From there, the machine’s carriage system moves the parison toward the blowing station.

An extrusion blow molding machine can have one of two types of carriage systems. The incline carriage moves at an upward angle toward the blow station and then returns to the starting position. The horizontal carriage moves horizontally. It, too, goes to the blow station before going back to the starting position.

An extrusion blow molding even comes with different types of cutting systems. These separate one parison from another as they move through the machine. These include spear knives, pre-pinch cold cut knives, pre-pinch linear knives, and hot knives.

The extrusion blow molding machine also inflates the parison. For this, a calibration system forces compressed air inside the hollow plastic.

To add cutting-edge machinery to your operations, contact us at PET All Manufacturing, Inc. As a reputable extrusion blow molding machine manufacturer, we’ll help you select the right equipment.