If you’ve ever stood in a manufacturing plant, grain storage facility, or pharmaceutical processing line watching raw materials move from point A to point B, chances are that a tubular screw conveyor was doing most of the heavy lifting. For decades, these systems have been the workhorse of bulk material handling: they’re relatively low-cost, easy to install, and versatile enough to move everything from flour and wood chips to chemicals and small grains. As a screw conveyor supplier who’s been working in this space for more than 15 years, I’ve seen them work flawlessly for thousands of applications—and I’ve also seen them grind to a halt, leak, or wear out far earlier than they should, all because of common problems that are easy to miss if you don’t know what to look for. Screw Conveyor
Today, I want to pull back the curtain on the most frequent issues we help clients troubleshoot, explain why they happen, and what you can do to avoid them. I’m not here to sell you a brand new conveyor unless that’s the right fix for your operation; half the jobs we take are retrofits or repairs for conveyors that another supplier installed incorrectly, or that were sized wrong from the start. Let’s start with the problems that show up first, usually within the first few months of operation, and work our way to the ones that sneak up on you after years of use.
The first and most ubiquitous issue we see is misalignment of the screw shaft. It sounds simple: a screw has to spin straight inside the tubular housing, right? But when a conveyor is assembled on-site, even small off-center gaps or twists in the shaft during installation can turn into big problems. I remember a client last year who installed a 40-foot tubular screw to move plastic pellets for injection molding. Their crew aligned the shaft by eye, which they thought was good enough—after a week, the screw was scraping the inner wall of the tube, wearing holes in both the flighting and the housing, and generating so much friction that their motor was burning out every two weeks. When we pulled the conveyor apart, we found that the shaft was off by just 3/16 of an inch at the center bearing, enough to create constant contact with the tube. Misalignment doesn’t just cause wear; it also messes with the efficiency of the system. When the screw isn’t centered, it can’t move material evenly, leading to clogging, uneven flow, and inconsistent throughput. The fix isn’t always a full replacement, either—often, it’s a minor realignment, replacing worn flighting sections, and adjusting the bearing mounts to keep the shaft straight.
Next up: clogging and backflow. This is probably the most frustrating problem for operators, because it doesn’t just shut down production; it’s a mess to clean up, especially if you’re handling fine powders or sticky materials. Clogging happens for a handful of reasons, but the biggest one we see is oversizing the conveyor or running it at a speed that’s too slow. Wait, you might ask—wouldn’t a bigger conveyor move more material, faster? Not if the material is too dense or too cohesive. For example, moving wet grain mash with a tubular screw that’s sized for dry corn is a recipe for backup. The dense mash can’t flow through the gaps between the screw flights, so it builds up at the inlet, forcing material to back up into the feeding hopper. Another common cause of clogging is poor inlet and outlet design. If your inlet is too small, or located in a spot where material can’t feed evenly into the screw, you’ll get gaps of empty space along the shaft, and when material finally builds up, it clogs. We had a pharmaceutical client a few years back who was moving lactose powder; their inlet was a straight pipe dropped into the top of the tubular housing, so all the powder would pile up on one side of the screw. We added a small "feeder wing" to the inlet to distribute material evenly, and cut their clog rate by 90% overnight. Backflow is usually a subset of this problem, too—if the outlet is too low, or not sealed properly, material will spill back into the conveyor instead of exiting at the end.
Wear and tear on the screw flights and housing is another big one, and it’s usually a slow bleed that doesn’t show up until it’s too late. Tubular screws are designed to move material, not grind it, but when the flights are worn down, they start to crush or abrade material instead of conveying it. How does this happen? Abrasive materials like sand, metal shavings, or grain with high silica content will eat away at the steel flighting over time, especially if the screw is misaligned. I’ve seen a conveyor handling frac sand go from new to worn through in less than a year, because the operator didn’t replace the flights when they first noticed uneven wear. Corrosive materials are another culprit: if you’re moving fertilizer, salt, or certain chemicals, they can eat away at the inner lining of the tube, leading to holes that leak material. The mistake here is often using a one-size-fits-all conveyor. A standard carbon steel screw is fine for dry grains, but if you’re handling abrasive or corrosive material, you need a hardened steel flighting or a coated tubular housing. We once supplied a set of replaceable flighting sections for a client moving wood chips; instead of replacing the entire conveyor every two years, they just swap out the flights, cutting their maintenance costs in half.
Then there’s bearing and seal failure, which is the bane of conveyor operators everywhere. The bearings that support the screw shaft at the ends (and sometimes in the middle of long conveyors) are under constant stress from the weight of the shaft and the friction of moving material. If the bearings are poorly lubricated, or if the seals that keep material out of the bearing housing fail, you’ll be replacing them every few months. The biggest mistake we see here is using the wrong type of seal for the material. For example, if you’re handling fine powder, a standard rubber seal won’t keep dust and fines out of the bearing—they’ll seep in, cause the bearing to seize up, and before you know it, your screw is stuck and your motor is making a horrible noise. Last year, a client in the food processing industry had to shut down their entire line three times in a month because of bearing failure; when we inspected, we found they were using a generic seal meant for dry material, but they were moving fine sugar powder. We swapped in food-grade labyrinth seals that prevent fines from entering the bearing, and they haven’t had a bearing issue since. Middle bearings are even trickier, too—they’re often the weak spot in long conveyors, because they have to support the middle of the shaft, and if they’re not installed correctly, they can cause alignment issues and more wear.
Motor and drive overloading is another common problem, and it’s often a symptom of the other issues I mentioned, but sometimes it’s a sizing mistake. If you size a motor for the maximum theoretical load of the conveyor, but your actual material is denser, or the conveyor is clogged, the motor will work way harder than it should, leading to overheating and burnout. I’ve seen clients try to save money by buying a smaller motor than they need, only to have it fail within six months, and then have to pay more for a replacement plus lose production time. The fix here is simple: work with a supplier who will test your material’s properties before sizing the conveyor. We always ask clients to send a sample of the material, test its bulk density, angle of repose, and abrasiveness, so we can size the motor, screw diameter, and speed correctly. If you’re already dealing with a motor that’s overloading, check first for clogs or misalignment—9 times out of 10, that’s the root cause, not the motor itself.
Wait, let’s not forget about environmental factors that people overlook. If your conveyor is installed outdoors, exposed to rain, snow, or extreme temperatures, the tubular housing can rust, and the screw shaft can warp, leading to alignment issues. I worked with a farm client in the Midwest a few years back who had an outdoor conveyor for moving corn; after a harsh winter, the steel tube rusted through at the mounting points, and the shaft warped from the cold, so the screw was scraping the housing. The solution here was to add a weatherproof housing with a galvanized coating, and install temperature-resistant bearings that can handle extreme cold. Even indoor conveyors can have issues with humidity; if you’re moving materials that absorb moisture, like flour or grain, the conveyor can develop mold or clumps, which clog the system.
Now, I want to be clear: none of these problems are inevitable. Most of the time, they’re avoidable with proper installation, regular maintenance, and working with a supplier who understands your specific application. A lot of clients come to us thinking that all tubular screw conveyors are the same, but that couldn’t be further from the truth. The conveyor that works for moving flour won’t work for moving corrosive chemicals, and the one that works indoors won’t hold up outdoors.
If you’re currently dealing with any of these issues—constant clogs, wear, bearing failures, or overloaded motors—we can help. We don’t just sell conveyors; we audit your current system, troubleshoot the root cause of the problem, and offer cost-effective solutions, whether that’s a simple repair, a retrofit, or a new custom conveyor sized for your exact needs. No matter what industry you’re in—grain, food processing, pharmaceuticals, mining, or manufacturing—we have the expertise to get your conveyor working efficiently, with minimal downtime.
Don’t let a faulty tubular screw conveyor slow down your operation any longer. Reach out to us today to discuss your needs, and we’ll help you find the right solution for your bulk material handling challenges.
Centrifugal Fan References
- Bulk Material Handling: Design and Application of Screw Conveyors, 4th Edition, Conveyor Equipment Manufacturers Association (CEMA), 2020.
- Handbook of Conveying Systems and Material Handling, CRC Press, 2018.
- “Common Failure Modes of Tubular Screw Conveyors in Industrial Applications,” Journal of Material Handling Engineering, Vol. 12, No. 3, 2021, pp. 45-52.
ZXMC Environmental Protection Machinery Co., Ltd.
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