How to Operate the PVC Foam Board Production Line Accurately

Introduction

Running the PVC foam board production line accurately involves more than just hitting the “Start” button. There are numerous safety checks you have to undertake before operating the unit. Apart from donning the right safety gear, you have to ensure that every component of the equipment is in good working order. Operating the production line in the right manner means mitigating wear, corrosion, and other defects that might come up owing to reckless measures. Read on as we dissect every aspect of how to operate the PVC foam board production line.

Parts of the PVC Foam Board Production Line

Before diving into the details of operating a PVC foam board, it is crucial to understand the different parts involved:

Extruder Drive

It is the pat of the production line tasked with rotating the screw. The component provides the necessary torque required by the extruder’s screw shank. The extruder driver features; a hydraulic drive, DC motor drivers, and AC motor drivers.

Thrust Bearing

The component is crafted to resist any axial forces exerted on the screw as a result of die head pressure. It is linked to the drive’s output shank and the screw shank.

Feed Throat and Barrel

The feed throat and barrel components are crafted differently depending on the manufacturer. They might come connected or independent of each other. Ideally, the part in which the screw is enclosed is what we refer to as the barrel. On the other hand, the feed throat is the part through which materials enter the extrusion machine. FANLYPLAS extruders feature a feed throat design incorporating a water-based cooling system. The cooling system prevents any premature polymer melting that might occur around the feed entry. It also curbs material flow restrictions. 

Feed Hopper

Just like the feed throat, the feed hopper is also used to introduce material into the production line by the use of gravity force. To ensure continuous feeding of material into the machine, some units like the models made by FANLYPLAS come with a vacuum loader.

Extruder Screw

It is the heart of the PVC foam board production line. It features a screw crafted from a cylindrical rod with helical flights and varying diameters all around its surface. These features ensure smooth mixing, heating, and conveying of extrusion material. Carbon steel material is perfect for the long-lasting screw although other materials like nickel are also utilized.

Die Assembly

It is the second most precious part of the extrusion line. Most of the shaping and tuning of the final product happens in the component.

Breaker Plate

As the name suggests, the breaker plate stops the spiral movement of the melt material but instead changes the movement to a straight line. Consequently, the activity of the breaker plate eliminates any distortions that might impact the extrudate.

Screen Changers

The screen changer is tasked with filtering foreign material or contaminants from the melt. Moreover, it enhances the melt’s homogenization within the extruder. It can also be utilized in amplifying pressure in the die-head.

Heating systems

Coolers and heaters are used to regulate the extrusion temperature in the PVC foam board production line. Steam heating, fluid heating, and electric heating are mostly used in extrusion equipment. Our production lines feature the advanced infrared nano heating technology that is energy efficient and super effective.

Cooling system

Most of the heat in the extrusion comes from the rotation of the screw. When too much heat is generated from the interior of the unit the chances of excessive temperatures become critical. That is where cooling systems come in.

PVC Foam Board Extrusion Line Start-Up Procedures

Running the production machine recklessly without observing the correct startup formula can yield costly damage. . Here is a proper startup procedure:

• Turn the power off before running the unit
• Inspect the inside of the hopper and barrel for debris and dirt. Remove any available dirt or debris with the help of an air hose or a vacuum
• Take a look at pressure gauges. Ensure every transducer is in good working order by observing for the buildup of material around the diaphragm or bent shafts.
• Pick the right screw for the task at hand. Set it on the barrel’s front and insert it into the barrel’s chamber. For the screw to fit in place snugly, you need a brass hammer to gently knock it in place.
• Check the breaker plate and the die keenly ensuring they are in good working order and clean as well.
• Turn on the cooling system around the feed throat by allowing water to flow into the area.
• Turn on power in the heater band plugs, panel board, and main power.
• Allow the adapter zones, die, and barrel to attain a uniform temperature
• In the meantime, inspect the cutting table and hauling machine and ensure they are fully functional and adjusted to correct calibrations
• Load the hopper with the proper material for the extrusion process
• Hit the “START” button to get the extruder in motion but only allow it to run at a minimal speed. During this time, keep your eyes on the die pressure and amps while observing how the material moves through the equipment.

Let us break down every aspect of the extrusion machine operation you need to follow to avoid running into problems. Here are more detailed operation guidelines:

Ensure the heating system is okay

It is important to check if the heating system is working correctly and confirm that necessary heaters are fitted to the right instruments before kicking off production. Apart from that, you need to close off the feed gate if the hopper contains any thermoplastic material. In the same way, you have to turn off the drive motor or keep its speed as low as possible.

Next, confirm the cooling water is running with a correct flow rate. The water should seamlessly flow through the barrel cooling system and hopper throat. However, the screw should not have any cooling water. After that, proceed by turning on the heating system with temperature control adjusted to a low value of about 50 degrees Celsius. The temperature value of the temperature controllers ought to remain constant to heat the unit uniformly.

Warming up the machine while empty

First, you have to turn on the main power switch. Thereafter, adjust heat input settings to a correct value to prevent melt temperature override or an overshoot. You need to do this while warming up the machine over a short period. It is advisable to set the temperatures between 20 and 30 degrees Celsius under the operating settings during the first stage of barrel warm-up. Before heating the machine to a desired operating temperature, it is vital to ensure it stabilizes at preliminary temperature settings.

Uniform heating comes in handy when processing materials like PVC are prone to degrading. Degradation is triggered by a temperature overshoot and can be problematic when starting the extrusion unit. When the equipment attains the preferred operating temperature, allow it to equilibrate before adding materials into the barrel. Equilibration must be done within a short duration. If not, residual materials within the screw flight might start burning to compromise the process. 

Warming up the machine while loaded

The procedure of heating an empty machine and the procedure of heating a production line loaded with polymers are different. Polymers decompose if the heating process is not done according to the book. Decomposing polymers emit toxic gases that can trigger accidents if they interact with hot material from the die. That is why the ideal heating temperature must be adjusted to be under the melting point of the material loaded in the machine.

After that, allow the machine to equilibrate and attain the right temperature. When that is done, work on raising the die temperature to be higher than the resin melting temperature. Go on and raise the heat in the rear and front zone to a value higher than the melting temperature of the material. When the rear and front zones are hot enough, proceed by raising temperatures within the remaining zones. Give the machine time to equilibrate once more to the changing heat value before purging. Only move on to the next step when the purged material looks perfect. It must be uniformly melted yet not too hot. 

Set proper barrel temperatures

Every extrusion unit comes with specific temperature control instrument settings necessary for attaining the correct melt temperature. A lot of heat input necessary for extrusion is provided in the course of operating the equipment within the drive system and screw component. Heaters only come in handy when warming up the equipment and streamlining system operation. Barrel temperature specifications do not matter. Focus mostly on the melt temperature. If you are processing some material grade for the first time, it is advisable to adjust the barrel temperature settings to the lowest value. It is also important to note that the melt temperature is ever higher than the optimal set barrel temperature value.

Equilibrate the machine

When the ideal temperature values have been adjusted, the machine should be allowed up to 20 minutes to effect equilibration. That must be done before introducing materials into the barrel chamber. In the course of the equilibration, it would be prudent to confirm the quality and cleanliness of the die. Additionally, utilize this time to check if all other components of the extrusion line are functional. Other than that, take time to ensure everything from the materials to the tools is available for a seamless production process. Ancillary equipment such as the cutting machine should be clean and in good working order too.

Initiate the purging process

Before the purging process, make sure to utilize the right screw type to suit the extrusion process. Moreover, it is imperative to ensure the screw is installed correctly besides running without a hitch. When the equilibration process is over, it would be to power the screw and run it in slow rotations. Thereafter, introduce materials into the hopper by hand. While filling the screw, avoid loading it to the throat. If that is done, the extruded material will fail to melt uniformly or completely.

As a consequence, un-melted granules within the material could block off the die. The granules may also mess up pressure transducers within the barrel and die. Once everything is in order, gradually increase the input of material into the screw. After that, feed more material into the hopper as well. Moving on, use a melt probe to check the melt temperature. The general outlook of the melt should be okay in terms of texture and uniformity. To move on to the next stage, check for correct motor amperage, accurate temperature adjustments, and a satisfactory material appearance.

Final touches

Just before finally powering the machine, use a piece of string to thread it through the haul-off and the cooling system. The operator carrying out the exercise should use a pair of protective gloves. Other than that, the machine ought to have clear indicators showing the movement path of the extrudate along with the direction of the roll rotation. Onward, run the extruder at a slow speed after removing the haul off to a more convenient position.

Safety measures during machine start-up

The startup procedure carries a significant amount of risks. One of the biggest dangers is include spit production from the die along with the decomposition of material during machine heating. On the same note, the operators are at more risk of injury as they come into close contact with the machine. Therefore, it is paramount to utilize excellent protective gear in the form of helmets, heat-resistant gloves, or work boots to avoid preventable accidents. Together with that, the hopper lid ought to be secured in place. Still, no one should be in the way of the nozzle or die when starting the production equipment. Finally, any unauthorized persons should not be within the processing space.

Process-Based Monitoring

The goal of the process and product-based monitoring is to improve product quality. Process-oriented monitoring focuses on production process variables such as pressure, temperature, and melt. Contrarily, product-based monitoring is all about the properties of the final product like color, thickness, or clarity. Here is a deeper analysis of all the metrics involved in process monitoring:

Pressure measurement

To measure pressure changes in the extrusion machine, use a pressure sensor or transducer. The strain gauge pressure transducer is the most commonly utilized tool owing to its repeatability, unbeatable accuracy, and string nature. The option also has a universal touch with unmatched ease of use. It is the pressure within the barrel and pressure in the extrusion line that matters. Pressure change measurements are usually taken along the length of the barrel.

The measurement comes in handy when assessing the efficiency of screw design and functionality. Excessive pressure is not good for the extrusion machine as it may bring up material flow restrictions. Another great spot for pressure measurement is around the die. It is vital in curbing material waste and stabilizing output. Pressure measurement at the outlet or inlet of the gear pump helps to sustain a continuous melt flow for elevated pump safety and performance. Generally, pressure measurement improves machine efficiency and output.

Temperature measurement

There are different kinds of temperatures that can be used to ascertain the amount of hotness in the extrusion machine or melt material. Uniformity in temperature means better plasticization and enhanced product quality. Infrared line scanning thermometers along with the thermocouple are the most utilized tools for this purpose.

 Speed measurement

It is essential to know the speed of the extrusion process. That can be deduced from the screw speed. The rotational speed of the screw component is estimated using the number of revolutions per minute. It indicates the quantity of material that is pumped at every given time. Moreover, speed measurement has something to do with melt temperature changes, shear history, and material mixture. The extrusion machine needs to maintain a constant speed. Otherwise, a change in the processing speed may indicate screw wear. Excellent extrusion lines come with inbuilt speed measurement features.

Width or size measurement

Width measurement is vital in ascertaining the standard of extrusion products. Fortunately, production lines made by FANLYPLAS come with integrated applications that will easily take the measurements.

Product standard recording

Recording the condition of production every time you run the extrusion machine is important. It will help you to keep tabs on the mechanical well-being of your equipment as well as the quality of the output. Other than that, you get to understand the production rate and the efficiency of the production line. Of course, production units by FANLYPLAS incorporate microprocessor controls that seamlessly keep accurate records of machine functionality.

Shut Down Procedures

A solid shutdown procedure a go a long way in saving you a great deal of repair money and time. For example, you will not have to undertake a lot of reheating or purging if the resin does not burn. Therefore, you get to save a lot on the cost of cleaning the machine or the expense of a total machine power down.

If you have been extruding a thermally stable material, there are several measures to undertake before stopping the machine:

Shut down procedure after extruding heat-stable materials

• Close or lock the slide located at the feed hopper’s base
• Shut down heaters on the cylinder but allow die heaters to keep running
• Pump the screw dry to allow complete purging of the barrel
• When the die section is empty, maximize the barrel cooling settings
• Thereafter, bring the screw to a full stop
• Finally, turn off the machine once it gets cool enough

Shut down procedure after extruding heat-sensitive materials

It is essential to initiate a thorough cleanout and a complete shutdown of the extrusion machine after processing working on a heat-sensitive material. Thermally sensitive materials tend to decompose negatively impacting the quality of the final product. Additionally, the final product may experience unfavorable color changes if the polymer within the extruder barrel happens to burn. The best way to avoid decomposition or impurities from processing thermally sensitive resin is to purge the machine before shutting it down.

It is advisable to purge with another thermally stable polymer. In this manner, the heat-stable polymer will not decompose in the course of reheating. Onward, if the oxidation problem persists, it would be prudent to avoid pumping everything out of the screw but instead leave the cylinder full. The cooling water should continue flowing to the feed throat. That should happen till the first zone temperature falls under the polymer’s melting point.

Shut down procedure after high-temperature processing

Undertaking high-temperature extrusion comes with a high risk of resin decomposition. Hence the shutdown procedure ought to consider that:

• Do not turn off the die heater but rather turn off heaters on the cylinder
• Adjust the cooling system to the maximum value
• Pump resin into the extruder periodically while cooling at the same time. Keep the barrel temperature higher than the resin’s melting point.
• Lock-off the slide at the feed hopper’s base
• Pump resin out of the screw till it dries then purge the barrel to keep it clean
• Only when the die is empty and the extruder machine is cool enough can you turn off the machine and prepare it for reheating

FAQS About Operating a PVC Foam Board Production Line

How do you start an extrusion machine?

Every unit is designed differently according to the manufacturer. Thus, the user manual could be unique depending on where you sourced your unit from. FANLYPLAS produces fully automated production lines that can be started with a single button. However, there are precautionary measures you ought to take before and after starting the machine as discussed previously.

What do PVC foam board extrusion machines do?

These units melt and process thermoplastic resin to form a continuous profile in high volumes.

What safety measures should I consider when operating the extrusion machine?

First, you should keep off loose clothing like dangling ties, lab coats, and shirt sleeves. Such clothing could get stuck in the moving part of the unit. The same applies to jewelry. Together with that, take time to inspect for defects in electrical equipment and inspection tools. Here are more protective measures:

• To protect your hands, use Kevlar sleeves and hot mill gloves when processing the die.
• Never place metal probes or fingers inside the feed throat. The best way to clear the throat is using a plastic probe.
• It is not advisable to directly stand in front of the extruder whether it is shutting down, running, or starting up.
• Clean the unit with an air hose or a vacuum cleaner.
• The floor around the PVC extruder ought to be free of water or compound to eliminate electrical shock hazards and slipping.
• Always monitor the extruder pressure keenly

Conclusion

Adopting the tips and guidelines outlined above in the day-to-day running of your PVC foam board production line will minimize downtimes and save you from regular repair expenses. It will also create a safe working environment for your staff and improve the efficiency of your production line.