There are no toxic plastics. None of them. This will be my intro to everything I do that allows it. If you don’t believe me, you are in the majority, and that’s the problem. Find out the truth and try to convince others. You’ll find out how a missionary feels in a hostile land.
Now, to extrusion. Our machines may have a lot of information on them, or none at all. Get it into your hard drives while you can, before it disappears or you can’t read it reliably any more, as you may need it, maybe now, maybe later. This is what you may find.
Extruder ID plate
There should be a plate on the body of the extruder, which identifies the maker, size, model designation, serial number and sometimes sales order and date of manufacture. This will help identification if long-distance service is needed. Today’s communication possibilities make service easier, provided you can get the right person on the other end of the line.
Somewhere on this plate (or another) may be the gearbox reduction ratio, the amount and type of lubricant needed, and also the thrust bearing capacity or an estimated bearing life at standard conditions, typically 5000 psi and 100 rpm. From either the capacity or standard life, you can calculate your own projected bearing life based on expected rpm and pressure. The numbers may be very high—20 to 200 years, for example—as it is easy and relatively cheap to overdesign a bearing, so that its failure is usually a result of lubrication failure and/or misalignment. When you can’t find a number, or there is reason to believe the original bearing has been replaced, find out who made the bearing and get an estimate of its capacity, using photos of the bearing, if needed, to identify the maker or to help them get the right numbers.
Some extruders show information about the electrical heating (power, voltage), which will be useful to the person who installs the line or moves it later. Heater data are also needed for separate heaters on the head zone and, especially, for large dies, which lose a lot of heat by radiation during operation and need to be preheated before startup. I’m less worried about the cost of heat loss (calculate it before you worry too much), more so about requiring long startup times, especially with resin in the system that can cook and degrade while waiting for the head and die to get hot enough long enough.
Don’t forget the heads, accessories (screen changers, gear pumps) and the dies. They may not have information visible on them, but it’s still important to know the basics, such as makers, model numbers, dimensions and heater capacities.
This plate will show the maker, type of motor and other identifiers that you’ll need to get service and replacement parts. Look for serial numbers (common) and dates of manufacture (rare but may be coded into the serial number). Find the four key numbers:
- Power, in HP (horsepower) or kW (kilowatts). One horsepower is 746 watts or 0.746 kW, so 4 HP equals 3 kW, close enough for