Thrust Washers.

What are Thrust Washers?

Thrust washers are the flat, ring-shaped bearings that take load along a shaft rather than around it. Wherever a rotating part pushes lengthwise against a fixed one, a gear against a gearbox wall, a hub against a housing, a spindle against its end stop, the washer sits between the two faces and lets them slide instead of grind. It carries that axial (end) load on a low-friction surface, so the expensive parts either side of it stay unworn. Two shapes cover most jobs:

• Plain thrust washers (HITW): a symmetrical flat ring washer that seats between the rotating and fixed faces and simply does the sliding.
• With-hole thrust washers (HITWH): the same washer with mounting holes on a pitch circle, so it can be bolted to one face and stay put in service.

A thrust washer is not a flat fastening washer, which only spreads a bolt's clamping load, nor a rolling-element thrust bearing with balls or races. It’s a plain bearing in its own right. Accu's are moulded from self-lubricating iglidur polymer, so they run completely dry with no oil or grease to apply, top up or clean away.

How Plastic Thrust Washers Work

A plastic thrust washer works by sliding. Solid lubricants are built into the iglidur polymer, so as the loaded face rotates against the washer, a thin transfer film forms and keeps friction low without any added grease. The washer sits between the rotating and stationary faces and absorbs the axial thrust, so wear happens on the cheap, replaceable washer rather than on the shaft or housing. Because there are no rolling elements, the part is thin, light and quiet. It also tolerates dirt and washdown better than a lubricated metal bearing.

That makes plastic thrust washers a fit for gearboxes, rotary tables, pivots, castors, pumps and actuators across automotive, agricultural machinery, packaging, material handling, medical and food processing. The right grade depends on the duty: how much axial pressure the washer carries, how hot the assembly runs and how chemically aggressive the surroundings are.

Materials Plastic Thrust Washers Are Made From

Accu thrust washers are made from self-lubricating, tribologically optimised iglidur polymers, offered in three grades so the material can be matched to the load, the temperature and the working environment rather than forced to suit them all.

• iglidur G: All-round general-purpose grade. A polyamide-based compound with a Shore-D hardness of 81, it carries up to 80 MPa of surface pressure, runs from -40°C to +130°C with short peaks to +220°C and holds a coefficient of friction between 0.08 and 0.15. It balances wear resistance, strength and cost across the widest spread of duties.
• iglidur J: Low-friction, low-wear grade for lighter, slower or more delicate work. Softer at Shore-D 74, it offers friction as low as 0.06 for smooth, quiet running against soft shafts, works from -50°C to +90°C and suits duties up to 35 MPa.
• iglidur X: High-performance grade for the hardest environments. At Shore-D 85 it carries up to 150 MPa and holds up from -100°C to +250°C with short peaks to +315°C, standing up to heat and aggressive media.

Every washer is supplied in its natural, unpigmented finish, with the iglidur material itself providing the running surface rather than any applied coating.

Sizes and Types of Thrust Washers Available

The range runs to 87 sizes across the three grades, all metric, organised around the two shapes and the grade that suits the duty. Plain washers (HITW) cover the straightforward job of sitting between two faces, while with-hole washers (HITWH) add pitch-circle mounting holes for assemblies where the washer needs to stay located on one face.

• Inside diameter: starts at 4 mm held to a 0 +0.25 mm tolerance.
• Outside diameter: up to 188 mm depending on grade, to 0 -0.25 mm tolerance.
• Thickness: 0.5 to 2 mm, to 0 -0.05 mm tolerance. 

Where a design needs to carry load around the shaft rather than along it, Accu's plain slide bearings and plate bearings cover radial and flat sliding duty, and the wider bearings range covers rolling types. A thrust washer should not be confused with the flat washers and spacers used under fasteners, which do a different job. 

FAQs

Q: What is the difference between a thrust washer and a thrust bearing?

A: A thrust washer is a flat annular sliding surface that carries axial load directly, whereas a thrust bearing usually adds rolling elements or races: the plain iglidur washer does the same job with no moving parts and no lubrication.

Q: What are plastic thrust washers made from?

A: Accu plastic thrust washers are moulded from self-lubricating iglidur polymers: general-purpose iglidur G, low-friction iglidur J and high-temperature high-load iglidur X.

Q: Do plastic thrust washers need lubrication?

A: No: iglidur polymer thrust washers are self-lubricating and run dry, with solid lubricants built into the material so they need no oil or grease and stay clean in service.

Q: What is the difference between a thrust washer and a flat washer?

A: A flat washer is a fastening component: it spreads the clamping load under a bolt or nut and helps stop it pulling through or working loose. A thrust washer is a bearing component: it is engineered to slide against a rotating face and carry a continuous axial load with low friction and low wear. They can look similar, but a flat washer is meant to stay still while a thrust washer is meant to be run against, so the two are not interchangeable.

Q: Which way round does a thrust washer fit?

A: A plain iglidur thrust washer is symmetrical and seats flat between the rotating and stationary faces, so it has no wrong way round. Fit it square in its recess and be sure to check the axial clearance.

Q: Do plastic thrust washers wear out?

A: Yes, gradually, though that is the point of them. A thrust washer is the deliberate sacrificial part in the assembly, wearing in place of the shaft or housing it protects, as replacing an inexpensive washer is far cheaper than repairing the components either side of it. How long it lasts depends on the load, speed and temperature, so choosing a higher-performance grade such as iglidur X will noticeably extend service life in demanding duty.

Bespoke Thrust Washers Manufacture.

High precision, bespoke manufacture of Thrust Washers to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.