{"id":3536,"date":"2026-10-08T20:22:07","date_gmt":"2026-10-08T12:22:07","guid":{"rendered":"http:\/\/www.mozaik-people.com\/blog\/?p=3536"},"modified":"2026-10-08T20:22:07","modified_gmt":"2026-10-08T12:22:07","slug":"what-is-the-porosity-of-a-bearing-bush-4ee9-f192f4","status":"publish","type":"post","link":"http:\/\/www.mozaik-people.com\/blog\/2026\/10\/08\/what-is-the-porosity-of-a-bearing-bush-4ee9-f192f4\/","title":{"rendered":"What is the porosity of a bearing bush?"},"content":{"rendered":"

Hey there, if you\u2019ve ever dug into how bearing bushes actually work (like, beyond just the \u201cthey make machines spin easier\u201d surface level), you\u2019ve probably stumbled on the term \u201cporosity\u201d and thought\u2014wait, what does that even mean here, and why should I, someone buying or using these parts, care? Let\u2019s break this down like we\u2019re chatting over a coffee (or a work lunch, no judgment if it\u2019s a quick snack on the factory floor) because I get that technical jargon can feel like a foreign language, especially when you\u2019re just trying to keep your assembly line or machine running smooth. Bearing Bush<\/a><\/p>\n

<\/p>\n

First off, full disclosure: I\u2019ve been in the bearing bush game for over a decade now, selling these bad boys to all kinds of folks\u2014from small machine shops in the Midwest to big manufacturing plants that pump out everything from farm equipment to HVAC units. Porosity is one of the most common questions I get from customers, right up there with \u201chow long do these last?\u201d and \u201ccan you rush my order?\u201d So let\u2019s start with the basics: what is<\/em> porosity in a bearing bush, not just in science class.<\/p>\n

At its core, a bearing bush is a sleeve that sits between two moving parts\u2014say, a shaft and a housing\u2014to reduce friction, handle loads, and stop metal from grinding on metal. Now, these bushes are usually made from materials like bronze, leaded bronze, cast iron, or even self-lubricating composites that mix metal with polymers. When we talk about porosity here, we\u2019re not talking about tiny holes like the ones in a sponge (well, kinda, but purpose-built). Porosity is basically the presence of tiny, intentional (or sometimes accidental) voids or pores throughout the material of the bush. Most of the time, when we reference porosity for bearing bushes, we\u2019re talking about controlled porosity<\/em>\u2014the kind we actually make on purpose, not a flaw from bad manufacturing.<\/p>\n

Wait, hold on\u2014wait, why would anyone want tiny holes in a part that\u2019s supposed to be strong? That\u2019s the million-dollar question, honestly. Let me give you a real example that I\u2019ve seen play out time and time again. Last year, a customer who makes small electric motors hit a snag: their motors would overheat and burn out because the bearing was seizing up within six months. They were using non-porous bronze bushes from another supplier, and when they sent a bad one back for me to look at, we cut it open under a microscope (I\u2019ve got a portable one in my office for these exact calls, no big deal) and saw zero pores. The problem? They needed a place to hold lubricant\u2014oil or grease\u2014so when the shaft rubs against the bush, that oil seeps out of the tiny pores, creating a consistent lubrication layer that cuts friction, reduces heat, and stops wear. Controlled porosity is like building a tiny, built-in oil reservoir right into the bearing material.<\/p>\n

But not all porosity is created equal, and that\u2019s the part where a lot of suppliers cut corners, if I\u2019m being honest. Porosity is measured in percentages, right? Like, a bearing bush might have a porosity level of 10% or 15%. That percentage is the total volume of all those tiny pores compared to the total volume of the whole bush. The key here is balance\u2014too little porosity, and you don\u2019t have enough space for lubricant, so it runs dry way too fast, leading to wear and tear. Too much porosity, and you\u2019re weakening the material; those holes make the bush more likely to crack under heavy loads, or the lubricant will leak out too quick, and you\u2019re back to the same seizing problem.<\/p>\n

Let me back that up with another story\u2014this one about a farm equipment client I had a few years back. They were plowing fields in Illinois, super rough work, and their original bearing bushes had 20% porosity. The supplier told them it was \u201chigh-performance,\u201d but after a month, half their bearings were splitting right down the middle. Turns out, that 20% porosity was way too high for the heavy, shock loads plowing puts on the parts. We swapped them out for our bushes with a controlled 12% porosity\u2014enough to hold plenty of grease, but not so many holes that the material couldn\u2019t handle the stress\u2014and those bushes lasted the entire planting season, no issues. Moral of that story: porosity isn\u2019t a one-size-fits-all number; it depends entirely on what the bush is going to be used for.<\/p>\n

Now, how do we actually create<\/em> that controlled porosity? Because like I said, it\u2019s not a flaw, it\u2019s a feature. The main methods I use (and most reputable bearing bush suppliers use) are powder metallurgy, which is the most common for porous metal bushes. Here\u2019s how that works: you take metal powders (bronze, iron, whatever the material is), mix them with a small amount of a fugitive material\u2014something that burns away or dissolves when you heat the part\u2014and then press the powder mix into the shape of the bush, then bake it in a furnace. The fugitive material leaves tiny, uniform pores behind when it vaporizes or melts out, and we can control how big those pores are and how many there are by adjusting the amount of fugitive material, the pressure we use to press the powder, and the temperature of the furnace. Some suppliers might use other methods, like casting, but powder metallurgy is way more consistent for getting that exact, controlled porosity you need for a bearing bush.<\/p>\n

Wait, but what if porosity is too high or<\/em> too low for the application? Let\u2019s break down common scenarios so you can tell if your current bearing bushes are right or if you need to switch. If your application is something low-load, low-speed\u2014like a small desk fan, or a toy wheel, maybe\u2014you don\u2019t need super high porosity. Those don\u2019t put much stress on the bush, so even a 5-8% porosity bush will hold just enough lubricant to last a long time without risk of it leaking or the bush being too weak. On the flip side, if you\u2019re dealing with high-load, high-speed, or heavy-shock applications\u2014like construction equipment, farm plows, or industrial pumps\u2014you need that medium-to-high porosity, usually 10-15%, to hold enough lubricant to keep up with the friction and heat, but not so high that the material fails under pressure.<\/p>\n

Another thing I get asked all the time: do porous bearing bushes need more maintenance? It\u2019s actually the opposite, for the most part. Because those pores hold lubricant, you don\u2019t have to regrease them as often. A non-porous bush, you have to grease it every few weeks or months, depending on use, but a good porous one can go for years with just the initial lubrication, because the oil seeps out slowly as the shaft moves, and the pores actually pull more lubricant in if you do a top-up later\u2014they work like a sponge, basically. The only time you might need extra maintenance is if the pores get clogged with dirt or debris, which is why it\u2019s important to keep the surrounding housing clean, but that\u2019s pretty standard for any bearing.<\/p>\n

Let me also touch on a common misconception here: a lot of people think porosity is only for metal bushes, but no, self-lubricating composite bushes (the ones that have a metal back with a polymer liner) can also have controlled porosity in the polymer or the interface layer. Same idea\u2014tiny pores that hold solid lubricants like PTFE, so you don\u2019t need any oil or grease at all for things like food processing equipment, where lubricants can contaminate the product. That\u2019s a big one for the food and beverage industry\u2014they need bearings that are clean, no messy oil, and porous composite bushes check that box because the lubricant is built right into the pores, not sitting on the surface where it can drip.<\/p>\n

Now, as someone who sells these, I\u2019ll be straight with you: not all suppliers get porosity right. I\u2019ve had customers come to me with bushes that are labeled \u201cporous\u201d but when we test them, they\u2019ve got random, big pores (not uniform controlled ones) or way too little porosity because the supplier cut corners on the powder metallurgy process. Those will fail fast, like that 20% porosity farm bush I mentioned earlier. The key is to work with a supplier that actually understands how porosity works for different applications, not just churning out parts with a random number stamped on them. For example, if you send me your specs\u2014what machine the bush is going in, load, speed, operating environment\u2014I can tell you exactly what porosity level you need, no guesswork.<\/p>\n

Wait, let\u2019s circle back to that electric motor customer I had last year, just to make it relatable. They came to me super frustrated because their line was down for three days replacing burnt-out motors. We swapped their bushes for our 10% porosity bronze ones, added a light coating of grease, and they\u2019ve been running for almost two years without a single bearing issue. They ended up ordering 10,000 more units, so that\u2019s a big win for both of us, but it all came down to getting the porosity right for their specific motor\u2019s speed and load.<\/p>\n

So to wrap this up, let\u2019s make sure we hit all the key points in plain English:<\/p>\n

    \n
  1. Porosity in a bearing bush is intentional, uniform tiny pores for holding lubricant, not a flaw.<\/li>\n
  2. The right porosity (usually 5-15% depending on your application) is a balance between enough lubricant storage and enough material strength.<\/li>\n
  3. It\u2019s made with powder metallurgy, not random casting, so consistency is key.<\/li>\n
  4. Using the wrong porosity leads to seizing, wear, or part failure.<\/li>\n
  5. It cuts down on maintenance and works for all kinds of applications, from tiny fans to heavy farm equipment.<\/li>\n<\/ol>\n

    <\/p>\n

    If you\u2019re reading this and you\u2019re not sure if your current bearing bushes have the right porosity, or if you\u2019re looking to switch to a supplier that actually knows their stuff, feel free to reach out. I don\u2019t do generic, one-size-fits-all parts\u2014when you give me your application details, I\u2019ll hook you up with bushes that have the exact porosity you need to keep your machines running smooth, no downtime, no headaches.<\/p>\n

    Steam Turbine Components<\/a> References:<\/p>\n

      \n
    1. Kennedy, F. E. (2000). Principles of Lubrication and Bearing Design. CRC Press.<\/li>\n
    2. ASTM B438-19, Standard Specification for Sintered Metal Bearing Materials. American Society for Testing and Materials.<\/li>\n
    3. Czichos, H. (2013). Tribology: Systems and Materials, 3rd Edition. Springer.<\/li>\n
    4. Powder Metallurgy Design Guide. Metal Powder Industries Federation, 2018.<\/li>\n<\/ol>\n
      \n

      Hebei Guoyuan Electric Co., Ltd.<\/a>
      With abundant experience, we are one of the most professional bearing bush manufacturers in China. We warmly welcome you to buy discount bearing bush for sale here and get pricelist from our factory. Quality products and low price are available.
      Address: No. 18 Tianshan Science and Technology Industrial Park, No. 319 Xiangjiang Road, Shijiazhuang High-tech Zone, Hebei Province, China
      E-mail: turbine@goineep.com
      WebSite:       https:\/\/www.goineep.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

      Hey there, if you\u2019ve ever dug into how bearing bushes actually work (like, beyond just the … What is the porosity of a bearing bush?<\/span>Read more<\/a><\/p>\n","protected":false},"author":51,"featured_media":3536,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3499],"class_list":["post-3536","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-bearing-bush-48b1-f1d3c8"],"_links":{"self":[{"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/posts\/3536","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/users\/51"}],"replies":[{"embeddable":true,"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/comments?post=3536"}],"version-history":[{"count":0,"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/posts\/3536\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/posts\/3536"}],"wp:attachment":[{"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/media?parent=3536"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/categories?post=3536"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.mozaik-people.com\/blog\/wp-json\/wp\/v2\/tags?post=3536"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}