FAQs about Sintered Metal Filters
If you’re reading this, you likely already know a thing or two about sintered metal filters, though you may not know exactly what you need for your unique application. Here at Fluid Conditioning Products (FCP), our goal is to assist customers in procuring precisely the right porous metal filter for their larger-scale manufacturing or other custom projects that require at least 100 units.
We work directly with sintered filter producers and can customize and adapt filters for a wide variety of applications. Need a housing for your filter, as well, to assure optimal performance? We can create one for you!
Still have questions about sintered metal filters? We designed this helpful FAQ to address some of our customers’ most common questions.
Q: What sizes of sintered metal filters are available?
A: Sintered filters can be made as small as the head of a pin, and maximum size is only limited by the size of the equipment the manufacturer has available. Generally, that maximum size is about the dimensions of a 5-gallon bucket. Though, it is possible to create sintered filters as large as a 55-gallon drum. Sintered material is not limited to cylindrical forms, either. It can be produced in sheets of various thicknesses that can be cut and shaped, too.
Q: Can I buy a standard sintered metal filter off the shelf?
A: Unfortunately, no. Sintered filters are usually made to order with a custom die to create the exact size and shape you specify. In rare cases, a sintered filter manufacturer may have something in a size and shape you need, but it is unlikely.
Q: Can I order just one or two sintered filters?
A: Sorry, but no. The minimum quantity is 100. We realize that many prospective customers are disappointed when they learn that most sintered filter manufacturers require a minimum order of 100 pieces, especially with smaller size filters. Unfortunately, it’s just not economical to produce sintered filters in small quantities. With custom die setup costs, manufacturers have to charge a premium to then only create a handful of filters. Of course, if that premium cost does not bother you, a manufacturer might be willing to accommodate your request.
Note that in low volume situations, customers may want to look into woven wire mesh filter elements instead of sintered metal. Wire mesh filters can provide filtration down to 5 microns and can be easily formed to fit most configurations.
Q: What are the setup fee involved with creating sintered metal filters?
A: Custom die setup usually starts at $600-$900 and goes up from there. The reason setup costs are what they are has to do with the complexity of manufacturing filters from sintered material. The process requires significant pressure and precise heat applied by specialized machinery and utilizing sometimes quite valuable metals.
To manufacture a sintered filter, metal powder is pressed in the custom-made die at sufficient pressure to make the powder particles adhere at their contact points with adequate strength for the formed part to be handled after ejection from the die. The unsintered, “green” strength of the part depends on the metal powder characteristics (composition, particle size, shape, purity, etc.) and the forming pressure. After forming, the “green” parts are then heated, or sintered, in a carefully controlled atmosphere at a temperature below the melting point of the metal but still sufficient to bond the particles together, which markedly increases the part’s strength. Note that the manufacturer must allow for some shrinkage during the sintering process, so the original die is made oversized in a precise way.
Q: What are the material choices for sintered filters?
A: Bronze, stainless steel, and various alloys are common. (Need something specific? Just contact us!) Bronze is the most popular and lowest cost alloy metal used for sintered filters. Reasons you may need to choose another metal type or alloy may be for higher strength, better corrosion resistance, or higher temperature applications. Stainless steel, another popular material, provides excellent heat and corrosion resistance – 316L stainless steel gives the best result.
For even more extreme environments, a nickel alloy may be desirable. Choices include Monel, Hastelloy, and Inconel. It’s true that these alloys each carry a premium cost, which is due to them being harder to work with and their basic makeup of more expensive metals.
Q: What are some of the design considerations for sintered metal filters?
A: Consider desired particle retention, the flow rate through the filter, operating fluid, and more when choosing sintered metal filters. Our previous blog post about filter design consideration focuses on specific uses, such as fuel filters and hydraulic fluid filters in industries like aerospace, defense, and marine. When thinking about sintered metal filters more specifically, you’ll want to the following additional points:
- Pore size – Also known as the micron rating, pore size defines what size particles you want to keep out. If a filter is rated for 5 micron “absolute,” this means that 99% of all particles over 5 microns in size will be blocked. If you specify a 5 micron “nominal” rating, you are allowing a larger percentage of 5-micron particles to pass through, perhaps as high as 60%.
- Pressure drop – This refers to the loss of pressure that occurs as liquids or gasses flow through the filter. You will have to determine what your specific application can allow and specify this to the filter manufacturer.
- Temperature range – How hot or cold is the operating environment where your filter will be working. The metal alloy you choose for your filter must be able to tolerate it.
- Strength – Sintered filters are an excellent choice where high strength is a requirement. Another advantage is that they provide the same level of strength in forward or reverse flow.
Q: What information will I need to provide to the manufacturer to place an order?
A: See the previous question about design considerations. You will need to understand your application thoroughly before you can order sintered metal filters. The following questions need to be answered before a die can be created to manufacture your sintered filters:
- What is the application? (Examples are: filtration, fluidization, gas dispersion in a liquid, silencing, oil or other liquid extraction from a gas, )
- What will pass through the filter?
- What are the corrosion problems?
- What special operating conditions, such as temperature or pressure, are involved?
- What contaminants might be encountered?
- What dimensions, shape, and tolerance are required?
- How many units are needed?
- How is the filter to be mounted or supported?
- What are the desirable rate of flow and the allowable pressure drop across the filter unit?
- What is overall the system pressure?
Q: I still have questions, how can I get in touch with FCP?
A: All of our contact details are on this page.