Marine grade 316 stainless steel ball bearings for shafts from 3mm to 50mm diameter
See product table below for dimensions and technical drawings
316 grade stainless steel, known as marine grade stainless steel, is an austenitic stainless steel which means it has very good corrosion resistance. Unlike 440 grade martensitic stainless steel, 316 grade is not hardenable by heat treatment. As a result, 316 stainless steel has a much lower load capacity than the standard 440 grade stainless steel most commonly used for bearings. This softer grade of steel is more difficult to grind to very close tolerances than chrome steel or 440 stainless steel so, like plastic bearings, marine grade 316 bearings are semi-precision. 316 stainless steel bearings are slightly magnetic unlike the strongly magnetic 440 grade stainless steel bearings so it is possible to tell the two types apart with a magnet. Corrosion resistant bearings can also be supplied in synthetic materials or zirconia or silicon nitride. For more information on bearings for harsh environments, see our informative guide. Most of our range of marine grade bearings are supplied from stock in the UK.
The 316 grade bearings, shown in the table below, are highly resistant to seawater, salt spray and many aggressive chemicals. The standard range is supplied with polyethylene (PE) cages and seals but alternative cage and seal materials such as PEEK or PTFE can be offered. 316 stainless steel bearings are used in low load and low speed applications in the marine industry when used above the waterline or where the bearings can be washed down after temporary submersion in seawater. They can be immersed in seawater for longer periods if there is a regular flow of water over the bearings as oxygen helps to regenerate the steel. These bearings are found in the food and beverage industry, in bakeries and fish or meat processing plant as well as in the dyeing industry, the textile industry, the pharmaceutical industry and the paper industry.
316 stainless steel has a very wide temperature range. The cage and seals will limit the temperatures at which these bearings can be used but open, full complement 316 grade bearings can withstand temperatures as low as -200°C and as high as 500°C although the load capacity is reduced at more extreme temperatures. Full complement 316 grade bearings and those with PTFE cages and seals are suitable for use in cryogenic applications as PTFE has good low temperature performance down to -190°C. The standard PE cage and seals are not recommended for temperatures below -40°C or above 80°C. If a bearing with a cage and seals is required for high temperature applications, PEEK or PTFE can be used up to 250°C.
Click on INFO in the rows below to display technical drawings of the bearings with load and speed data. Please note that the maximum loads and speeds are used in theoretical life calculations. It is recommended to use bearings at significantly less than the maximum load and speed ratings to ensure reasonable bearing life.