On a Tuesday morning in July 2024, the HPGR slip alarm on our clinker grinding line started chirping. I remember looking at the screen and thinking: we replaced those tires six months ago. That thought was wrong. And that wrong thought cost us 18 days of production.
I'm a maintenance planner at a cement plant. I have been handling wear-part orders for mining and cement equipment for nine years, and I've personally made and documented 13 significant procurement mistakes. Altogether, those mistakes totaled roughly $174,000 in wasted budget. This HPGR tire replacement was the biggest one.
We commissioned our FLSmidth HPGR in 2021 to pre-grind clinker before the ball mill. For our site, it felt like the dawn of a new millennium. Nothing about our grinding circuit had changed that dramatically in decades. The FLSmidth HPGR quickly became the workhorse of the department. It pushed more tonnage than we had expected, and the operators loved it. The only problem was wear on the tires, which is normal for an HPGR.
The tires on an HPGR are not like truck tires. They are thick, studded wear rings that sit on the rolls and transfer the grinding pressure through the material bed. When they wear past the OEM limit, you have to replace them. In July 2024, the inspection report came back clear: both tires needed to go.
I'll be straight with you. The FLSmidth quote came first. The official price for the pair was about $76,000, with a six-week lead time. Then the aftermarket supplier quoted $42,000 and promised delivery in three weeks. I did what a lot of people in my position do. I thought I was being efficient.
I wrote a justification for the plant manager. Same function, lower price, faster delivery. The buyer in me felt smart. The maintenance engineer in me had a small voice saying: check the tolerance spec. I ignored it. That was mistake number one.
The conventional wisdom in procurement is that if you buy from a lower-cost supplier, you save money and the equipment doesn't know the difference. My experience with this FLSmidth HPGR suggested otherwise. The tires are not a commodity. They are machined against a load-bearing contact pattern that has to match the roll geometry and the operator's feed conditions. But I didn't want to believe that. I wanted the budget win.
The aftermarket tires actually arrived on time. That made me feel vindicated. We installed them during a routine maintenance window in September, and for the first two weeks the HPGR ran fine. I was already patting myself on the back.
Then an operator spotted a hairline crack near the edge of the drive-side tire. We stopped the unit and measured runout. The new tire was sitting at 0.17 mm of runout. The OEM specification in the FLSmidth manual called for a maximum of 0.05 mm. Or rather, called for 0.05 mm on a properly seated tire. We were more than three times over the limit.
I sent photos to the aftermarket supplier. They told me it was likely caused by feed moisture and general operating conditions. Then they stopped returning my emails. The cracks expanded fast. By the time we made the call to stop production, the drive-side tire had a visible fracture line running across about a third of the contact face.
We were looking at an unplanned shutdown right before our busiest order month. It was the kind of situation where two days of waiting for a critical part feels like a millennium.
At that point I had no pride left. I called the FLSmidth service line and explained the situation. The service desk routed me to a senior engineer from the FLSmidth Mariager team. He asked one question before anything else: What tires are on the rolls now?
I said they were aftermarket replacements. There was a pause. Then he said, that explains the crack pattern.
He asked for photos, operating data, and the measurements we had taken. We sent everything. The diagnosis was painful but clear. The aftermarket tires had the wrong contact profile. Instead of distributing the grinding load evenly across the roll, the profile concentrated pressure near the edges. That caused edge cracking, and worse, it had started to fret the roll body underneath.
That's when the real cost of the mistake hit me. We didn't just need new tires. We needed roll surface repair too.
A few weeks later, with the new FLSmidth tires sitting in our warehouse, I had the chance to compare the two designs side by side. I finally understood what I had missed. The OEM tire had a subtle crown profile and a hardness range that matched the roll geometry. The aftermarket tire was flat and slightly harder at the surface. Outwardly they looked the same, but they were not the same problem.
People assume expensive OEM parts cost more because of the brand. Actually, they cost more because someone already spent the engineering hours figuring out what fails in the field. The brand is not the markup. The brand is the solution to failure modes you haven't seen yet. I didn't see that until I measured the destruction it caused.
The FLSmidth Mariager engineer walked us through the repair sequence step by step. We repaired the roll body, mounted the OEM tires, and re-tensioned everything according to the manual. The final runout came in at 0.03 mm, well inside spec. The HPGR has been running for about 1,200 operating hours since the repair. No cracks. No slip alarms.
The total financial damage was roughly $91,000 in direct costs. That was split between the wasted aftermarket order, extra labor, roll repair, and expedited freight. It did not include the lost production from the 18-day shutdown. That was significantly worse.
I now have a checklist that I force every procurement request through. It's not complicated, but it would have caught this specific disaster:
We also changed our CMMS to automatically open a service request when predicted tire wear falls below 90 days. That gives us time to do this the right way instead of the rushed way. So far, the checklist has caught eleven potential mistakes in the past ten months. I don't get excited about that number anymore. I just wish I had it before I bought those tires.
When a part is a load-bearing wear component in a machine as precise as an HPGR, close enough is not close at all.
If you have a FLSmidth HPGR and you're thinking about saving a few dollars on replacement tires, take it from someone who learned the hard way. Call the FLSmidth Mariager team first. Ask them what can go wrong. Then decide if you really want to gamble on a part that holds up your entire production line.
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