Your OEM customer reorders the same nylon bearings bushings drawing they have run for three years, the new batch lands, and the first machine jams on assembly - the bushing won't slide onto the shaft, or it fits cold and seizes an hour later. Same drawing, different grade, different result. Nylon is a material family, not a spec; the grade, the filler, and the fit decide whether a nylon bearings bushings order works in the field or fails on the bench. This guide covers the nylon bearings bushings lines you have to pin down before the order - grade, fit, expansion, and the drawing details - in the order they cause returns.
PA6, PA66, or MC Nylon - the Grade Names the Duty
Standard nylon is PA6 and PA66, and the difference shows up in duty. PA6 machines well and absorbs moisture a bit more; PA66 runs hotter, wears harder, and holds its stiffness better - the usual choice for moving parts. PA46 and cast (MC) nylon step up again: PA46 for sustained high temperature, MC nylon for big, thick bushings machined from cast blanks where load and impact matter more than tight tolerances. Then the fillers change the game - MoS₂ or oil-filled grades run dry with less wear, glass-filled grades add stiffness at the cost of surface finish, and aramid-filled grades resist heavy impact. Most nylon bearings bushings quotes fail here first: the buyer writes "nylon" and lets the factory pick. Name the grade and the filler on the RFQ; "nylon" alone is not a specification.
The Fit - Press In, Slip In, and the Expansion Problem
The bushing has two fits to manage, not one, and most nylon bearings bushings failures trace back to the fit, not the material. The outer diameter presses into the housing with an interference fit, and the inner diameter runs on the shaft with running clearance. Both change after machining, because nylon moves: it expands when it absorbs moisture and when it heats up, at rates far above steel. A nylon bearings bushings order that ignores the expansion allowance shows up as a jammed shaft in humid climates or after an hour of running. Ask the factory for the fitted bore diameter at the working temperature and humidity, not just the machined size.
Temperature, Moisture, and the PV Limit
Nylon has a working envelope. Standard grades run comfortably to about 80°C continuous; beyond that the load rating drops and the wear rises. The PV limit - pressure times surface velocity - is the number that tells you whether the nylon bearings bushings survive their duty cycle; exceed it and the surface overheats and smears. Moisture is the quiet killer: nylon absorbs up to several percent by weight, swelling the part and softening it, so a bushing sized for a dry workshop can bind in a humid plant. Give the factory the actual temperature, the sliding speed, and the humidity, and let them size the nylon bearings bushings against the PV curve instead of the catalog.
Machined, Molded, or Machined-from-Stock
The production route sets the tolerance and the price. Injection molding makes sense at high volumes but locks the tooling cost and the draft angles into the part. CNC machining from bar or plate handles small batches, tight tolerances, and features like oil grooves and slots that molding struggles with. Machined-from-stock, using cast nylon blanks, is the route for large, thick bushings where the material's cast structure carries the load. Ask which route the quote assumes - the same nylon bearings bushings drawing can cost three different prices depending on whether it is molded, machined, or machined from cast stock.
The Drawing Lines That Decide the Price
Most returns trace back to a drawing that left too much to the supplier. Put the grade and filler on the drawing. State the outer diameter and its interference range, the bore and its running clearance, the wall thickness, and the length. Call out the surface roughness on the bore, the chamfer on both ends - sharp edges tear nylon on assembly - and any oil groove, slot, or flange. Then lock the batch: nylon grade substitutions and regrind content change the part without changing the print, so ask for the material certificate and keep samples from the approved lot. A nylon bearings bushings order that names every line is an order that fits the first time.
FAQ
PA6 or PA66? PA66 for moving parts that run hotter and wear harder; PA6 where machinability and cost matter more. Step to PA46 or MC nylon for sustained high temperature or heavy impact.
Press or slip fit? Press the outer diameter into the housing; keep running clearance on the bore. Account for moisture and thermal expansion in both.
How much expansion allowance? It depends on grade, climate, and running temperature - the factory should size the fitted bore from your operating conditions, not a fixed rule.
How hot can nylon run? Standard nylon bearings bushings run to about 80°C continuous; beyond that switch grades and re-check the PV rating.
Molded or machined? Mold for high volumes, machine for small batches and tight tolerances, and machine from cast stock for large, thick bushings.
Name the five lines - grade and filler, both fits, the working temperature and humidity, the production route, and the drawing details - and the nylon bearings bushings order stops coming back. Our PEEK ball bearings guide covers the high-temperature plastic option when nylon hits its limit, our custom ball bearings guide walks through the metal alternative for higher load, and our inquiry page is where you send the shaft size, the duty cycle, and the environment for a sized recommendation. A bushing specified like a bearing is a bushing your assembly line never stops for.
