Currently, many manufacturing industries are struggling with various issues – the inability to obtain essential raw materials or components to create their products, labor shortage issues, much longer delivery times, and more. Increasing costs are also driving a looming slowdown in many sectors. So, what can you do to maximize profits and save on expenses during a slowdown? Preventative maintenance is the key.
It would be best if you stayed on top of any potential issues that could slow or halt your production altogether. It is a good idea to perform regular maintenance based on the run-time of the machine and not by calendar date. Some machines run longer hours or run abrasive or corrosive resins and require more frequent inspections. If you prefer to go by calendar date, schedule your inspections quarterly, at a minimum. Even though regular preventative maintenance will cost you a bit of money and take a little time, improperly maintained equipment will cost you much more.
What should be checked regularly?
- The barrel
- The screw
- Control panel
- Gearbox
- All wiring
- Barrel fans
- Barrel heaters
- Breaker plates
- Valves and endcaps
- Sealing surfaces
- Feed throat channels
- All upstream and downstream equipment
Too many companies wait until their machines break down before repairing or replacing parts. Your company isn’t making money if your machines aren’t running. If you wait until a part has broken, you may find it difficult to replace or repair it as quickly as you need it.
How do you know there is a problem?
Some issues with your machines, particularly with the barrel and screw, can be challenging to detect. A few indicators that you have a problem include (but are not limited to):
- Gels start to become a problem
- Filter failures increase
- Higher temperatures in the barrel
- Process instabilities
- An increase in RPM rates with the same output levels
- And more
If you notice these types of issues, here are a few things you should check:
- Screw flights should maintain their squared edges
- Chromed surfaces should be free of flaking, peeling, or other wear
- If darkened in appearance, it should be uniform
- Flight should not have any visible cracking,
- There should be no scoring on the hub, screw, feed section, or throat
- Check for axial deflection
- Check the straightness of the screw and barrel
- And more
Wear
Closely inspect your screw, barrel, and valves for signs of wear. A worn but not yet broken part may still work but not as well as it should, resulting in slower cycle times and less finished product per work shift. Keeping a close on equipment wear allows you to plan for replacement parts before a broken or worn part negatively impacts your production. Excessive wear can cause issues such as instable throughput, increased melt temperatures, reduced plasticating rates, and more.
Some causes of excessive wear include (but are not limited to):
- Barrel straightness
- Barrel alignment to the gearbox
- Fillers in the polymer
- High head pressure
- The type of polymer being processed
- Screw flight to Barrel liner compatibility
- Screw or barrel concentricity
- Screw speed
- Screw straightness
- And more
Rebuild versus new
Even with regular maintenance, parts may still break. What do you do if you have a broken tip or drive? What if the screw has seized in the barrel? Many companies don’t know that often the parts can be rebuilt instead of having to be replaced. The broken tip can be extracted, the ID threads repaired, the drive repaired, seized screw pressed out of the barrel then repaired and polished, and more.
New parts are always great, but rebuilding can be a better choice for many problems. Particularly if you have a backup part, such as a backup alloy screw. The screw can be rebuilt and re-chromed to OEM standards at considerable savings when compared to the cost of a new screw. These repairs typically take a few days to a couple of weeks… just be sure to select a repair shop that is experienced with these parts and is reputable, such as Santa Fe Machine.
No matter what plasticating application (extrusion, injection molding, blow molding, twin screw extrusion, and more), you need your machines to work properly and hold critical tolerances. Preventative maintenance is key to keeping your production moving smoothly.
How can we help you?
For over 99 years, the doors have been open at Santa Fe Machine Works, Inc., and the past 45 years have been dedicated solely to the manufacture and supply of new & rebuilt injection & extrusion screws, as well as barrels & valves, to the plastics industry. We offer custom-tailored screw, barrel, and valve combos allowing our customer’s production goals to be met in the best, fastest, and most cost-effective ways possible. Our employees have over 200 years of combined experience in the plastics industry, be assured we can support your needs. Have a question, need assistance, or looking for a quote? Contact us today!
Causes of extrusion screw wear & how to minimize them
Extruder screws and barrels are exposed to different wear and corrosion environments as they operate. The first sign of wear is typically a maximum processing flow rate reduction. The screw is designed to rotate within the barrel and, as such, has a threaded flight lead diameter that is only slightly smaller than the barrel diameter so that it can rotate freely. During operation, the gap between the screw and barrel fills with molten polymer which acts as a lubricant. When processing non-abrasive polymers and maintaining proper screw and barrel alignment, you can expect many years of continuous operation with little to no wear. However, corrosive additives, abrasive polymers, and improper machine maintenance will cause wear issues, particularly on the screw.
Wear factors include:
All of these wear factors are caused by three things: abrasion, corrosion, and adhesion.
1.) Abrasion
Abrasion and abrasive wear is caused by hard additives or particles that have been added to the polymer being processed. These include particles such as calcium carbonate, flame retardants, glass fibers, and more. These particles slide against the screw at high temperatures and pressure as the polymer is extruded. The amount of abrasive wear depends heavily on the hardness, shape, and size of the particles in the polymer.
How can abrasion and abrasive wear be minimized?
Abrasion and abrasive wear can be minimized through surface hardening of the barrel and screw.
2.) Corrosion
Corrosion and corrosive wear is caused by additives in the polymer that are corrosive and cause degradation to the extruder components. This happens more frequently in the metering zone, where temperatures are higher, and the polymer remains for a longer period of time.
How can corrosion and corrosive wear be minimized?
Corrosion and corrosive wear can be minimized by using the correct barrel lining materials and the correct screw material.
3.) Adhesion
Adhesion and adhesive wear is caused by metal-to-metal contact between the barrel and the screw. This momentary contact between the screw’s flight and the barrel while the screw rotates causes galling in which the screw is immediately broken by the rotation.
How can adhesion and adhesive wear be minimized?
Adhesion and adhesive wear can be minimized by maintaining the correct alignment of the screw in the barrel and maintaining the proper straightness of the extrusion screw and barrel.
Warning Signs of Wear
No matter the cause of the wear, the first signs of wear problems will manifest in the flow rate of the processed material. The amount of wear present is directly proportional to the total output flow rate of the material. Meaning more wear = more material leakage. If ignored, the speed of the screw’s rotation will need to be increased in order to maintain the correct flow rate and discharge pressure.
Another warning sign of wear is an increase in polymer temperatures. This can cause thermal degradation of the polymers themselves if they reach a temperature too high for the specific polymer or if the polymer is left at high temperatures for too long. This can weaken or break macromolecule bonds and lead to the loss of mechanical or optical qualities of the extruded polymer.
How can we help you?
Since 1923, the doors have been open at Santa Fe Machine Works, Inc. For the past 45 years, we have been dedicated solely to manufacturing and supplying new & rebuilt injection & extrusion screws, barrels, and valves to the plastics industry. We offer custom-tailored screw, barrel, and valve combos allowing our customer’s production goals to be met in the best, fastest, and most cost-effective ways possible. Our employees have over 200 years of combined experience in the plastics industry, be assured we can support your needs. Have a question, need assistance, or looking for a quote? Contact us today!
How can your extrusion or injection shop maximize profits and save on expenses when business is slow?
Currently, many manufacturing industries are struggling with various issues – the inability to obtain essential raw materials or components to create their products, labor shortage issues, much longer delivery times, and more. Increasing costs are also driving a looming slowdown in many sectors. So, what can you do to maximize profits and save on expenses during a slowdown? Preventative maintenance is the key.
It would be best if you stayed on top of any potential issues that could slow or halt your production altogether. It is a good idea to perform regular maintenance based on the run-time of the machine and not by calendar date. Some machines run longer hours or run abrasive or corrosive resins and require more frequent inspections. If you prefer to go by calendar date, schedule your inspections quarterly, at a minimum. Even though regular preventative maintenance will cost you a bit of money and take a little time, improperly maintained equipment will cost you much more.
What should be checked regularly?
Too many companies wait until their machines break down before repairing or replacing parts. Your company isn’t making money if your machines aren’t running. If you wait until a part has broken, you may find it difficult to replace or repair it as quickly as you need it.
How do you know there is a problem?
Some issues with your machines, particularly with the barrel and screw, can be challenging to detect. A few indicators that you have a problem include (but are not limited to):
If you notice these types of issues, here are a few things you should check:
Wear
Closely inspect your screw, barrel, and valves for signs of wear. A worn but not yet broken part may still work but not as well as it should, resulting in slower cycle times and less finished product per work shift. Keeping a close on equipment wear allows you to plan for replacement parts before a broken or worn part negatively impacts your production. Excessive wear can cause issues such as instable throughput, increased melt temperatures, reduced plasticating rates, and more.
Some causes of excessive wear include (but are not limited to):
Rebuild versus new
Even with regular maintenance, parts may still break. What do you do if you have a broken tip or drive? What if the screw has seized in the barrel? Many companies don’t know that often the parts can be rebuilt instead of having to be replaced. The broken tip can be extracted, the ID threads repaired, the drive repaired, seized screw pressed out of the barrel then repaired and polished, and more.
New parts are always great, but rebuilding can be a better choice for many problems. Particularly if you have a backup part, such as a backup alloy screw. The screw can be rebuilt and re-chromed to OEM standards at considerable savings when compared to the cost of a new screw. These repairs typically take a few days to a couple of weeks… just be sure to select a repair shop that is experienced with these parts and is reputable, such as Santa Fe Machine.
No matter what plasticating application (extrusion, injection molding, blow molding, twin screw extrusion, and more), you need your machines to work properly and hold critical tolerances. Preventative maintenance is key to keeping your production moving smoothly.
How can we help you?
For over 99 years, the doors have been open at Santa Fe Machine Works, Inc., and the past 45 years have been dedicated solely to the manufacture and supply of new & rebuilt injection & extrusion screws, as well as barrels & valves, to the plastics industry. We offer custom-tailored screw, barrel, and valve combos allowing our customer’s production goals to be met in the best, fastest, and most cost-effective ways possible. Our employees have over 200 years of combined experience in the plastics industry, be assured we can support your needs. Have a question, need assistance, or looking for a quote? Contact us today!
Why Custom Screws Are The Right Choice
Choosing the right screw for injection molding can significantly impact the throughput of your machine. In addition, it can also determine how successful your project will be. The screw choice can ensure that there is no material degradation and the material is properly melted.
The end results are a more efficiently molded product reducing scrap and maintaining the proper size and weight of the part. The right screw will help keep manufacturing costs down and reduce wear and tear on your machine.
The basic design of any injection molding screw has three zones along the length:
The feed section conveys the solid plastic pellets to the transition section where they are compressed by a change in screw geometry (the channel depth). This compression forces the pellets to melt through the action of pushing up against each other, which is called shear. The metering section then conveys the melt to the front of the screw, ready for injection into the mold cavity.
The right screw for your material.
If you are running polypropylene (PP) or polyethylene (PE) with no additives, a general purpose injection screw will work great.
When you try to run polycarbonate (PC) on a general purpose screw, the material will burn in the compression section of the screw. This is because it forces too much material into the compression section and causes too much shear heat and burns the material. Santa Fe Machine can solve that by making a custom screw to fit your exact process. Having a screw that fits the polymer your running will increase your throughput since you won’t need to make as many adjustments to your pressure and heat that could increase your cycle time. In addition the screw material can be modified to increase screw life based upon the polymers you may be running.
Consulting a feed screw design specialist such as Santa Fe Machine will help you maximize your output and reduce downtime.