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As the K 2016 exhibition is approaching, I hope the excellent extruder sales staff will tell us to buy quickly before then, because the delivery time will be longer after that.

This may be true, but it does not mean that you need another line. However, this may be a good time to see if you do.

If you want more capacity, or want to replace old machines, in addition to buying a new production line, there are many options:

Can you sell it? You need to know how much you expect to squeeze out in the next few years. It is difficult to predict, but this is the purpose of the sales meeting. 

After completing these tasks, you will most likely decide that you don’t need another line at all. However, if you do want more equipment, make sure it meets your needs. Based on the material, check the motor power and know the number of lb/HP you can expect. In addition, deal with thrust carrying capacity (you need to know the expected head pressure) and speed range: Many lines do not allow full horsepower at lower speeds because this may cause too much torque to the system (torsion shaft). In any case, don't trust anyone how much you can get per hour unless they know some ideas about the exact type of resin, mold resistance, and mixing quality.

Remember, faster screw speed does not necessarily mean more output/hour, because higher frictional heat generation may make it undesirable. It may also cost more, so remember that what matters is the cost per unit of good output.

Regarding screw design, this mainly refers to the size of the screw, especially the depth of the channel. Who decides and on what basis? There are some computer programs that can tell you the melt pressure at the tip of the screw, the melt temperature (not at the tip of the screw, but deeper-dual meters are misleading, especially for temperature), motor current (amperes), and several Output at screw speed. On a large production line that may cost $1 million or more, it is certainly worth running a few computers before cutting the metal.

Don't forget to choose the right material for the screw thread tip and barrel lining. Consider drilling the screw for internal cooling later (this helps mixing and prevents sticking at the screw root, with minimal cooling effect).

If you need to preheat, the production line must send the hot resin directly into the hopper as much as possible to avoid backflow of moisture.

Auxiliary tools: understand the options in the filter (continuous, semi-, manual) and the screen size you want to run. Do you need or want a static mixer? what type? Get the pressure drop data of your material at the appropriate temperature. The same goes for gear pumps: if you want one, you need the expected pressure data before and after the pump.

Controls and sensors: Today, simple readings (big numbers) and easy reference to stored data are essential, but people with the necessary time and ability need to read the content there and take action.

The extruder certainly needs downstream equipment. The scope discussed here is too large, but attention must be paid to take-off speed, size, online measurement/feedback, and other key characteristics related to the final product.

Don't forget the cost of delivery and installation. Can you save money by doing these things at home? For example, when transporting or loading and unloading equipment, make sure that there is no gap in insurance.

For used machines, try to check their operation—or at least plug them into a power source—to ensure that the controls and other electrical components are working properly. And get as many original documents as possible. My rough rule is to find out the cost of a similar new machine: pay one-third of the amount for the machine; allow the other third to be used for repairs, missing parts, etc.; There are benefits of being here now. Any cheaper one may be too old (with exceptions, such as distress auctions), and any more expensive one should be the latest model being sold, for example, due to the failure of the owner company.

Last but not least, be fair and cautious when setting payment terms (how much now; how much when completed; how much when delivered and/or launched; any penalty for late shipment, and vice versa). Get quotes from multiple suppliers to determine current practices, or learn this from your own experience.

Allan Griff is a senior extrusion engineer. He initially provided technical services for a major resin supplier. Now he has been working independently for many years as a consultant and an expert witness in legal cases, especially as an educator and public and public educator through webinars and seminars. internal. As early as the 1960s, he wrote the first practical extrusion book and the plastic extrusion operation manual updated almost every year, and it is available in Spanish, French and English. Learn more on his website www.griffex.com or send an email to [email protected].

In the fall, Griff will host a one-day hands-on seminar "Introduction to Squeeze" in Chicago, Los Angeles and Houston. Topics include ten (11) key principles of extrusion, plastic chemistry for non-chemists, review of extrusion hardware, productivity limitations, raw material quality control, simplified rheology, startup and shutdown procedures, and troubleshooting common extrusion issues. Email him to the address listed above for more information.

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