These are bearings with tapped threads on the outer diameter.
We received an inquiry from overseas regarding the use of plastic bearings for a new development project. Since the parts would be exposed to or submerged in salt water, metal bearings could not be used. The surrounding components also seemed to be designed using plastic for the same environmental reasons.
The reason for tapping the outer diameter was that the customer wanted to bond and fix the bearing to the plastic housing. In general, plastic is non-adhesive, so most materials (except for some, like phenolic resin) cannot be bonded effectively. (Strictly speaking, bonding is not entirely impossible — the surfaces may stick, but applying force or sliding them will cause them to peel off easily.)
In this case, the peripheral speed was high, making phenolic resin bearings unsuitable, so we proposed using PEEK.
As mentioned above, since PEEK cannot be bonded, we decided to machine an M36 thread on the outer diameter as a fixation method.
The customer specified the bearing size as φ40×φ20×30L — a non-standard and relatively long dimension — but we proposed a one-piece integrated design, which led to this final shape.
Although this example features tapping on the outer diameter, we can also perform internal thread tapping.
For more details, please refer to the following article:
Plastic Bearings with Inner Stud (Threaded Hole) Specification
There are various fixation methods, but if you are looking for an easy screw-based solution, please consider this option.
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