Product Comparison
Cast Iron vs Malleable Iron Taper Bushings: Material Properties and When to Use Each
Product Comparison
Material names matter because they describe how a bushing may respond to machining, clamping and shock, but they should not be treated as a shortcut for application design. A cast-iron bushing in a correctly selected, steady drive can be entirely appropriate; a high-impact or corrosive duty may justify another material only after the complete connection is reviewed.
The XT stock-bore table is especially useful because it marks selected bore entries with an asterisk and states that those marked bushings are malleable iron while the other entries are cast iron. The mark applies to the listed stock-bore entries, not automatically to every bushing in a model family.
Cast iron in taper bushing service
Gray cast iron is common in industrial hubs and bushings because it machines well, is dimensionally stable and suits many steady mechanical loads. Its limitation is lower ductility than steel or malleable iron, so impact, abuse during installation and severe stress concentration deserve attention. The material choice should be paired with correct shaft fit and hub geometry.
Malleable iron and the XT asterisk notation
Malleable iron is produced through heat treatment that changes the microstructure and gives greater ductility than ordinary gray cast iron. In the XT stock-bore table, an asterisk identifies the entries specified as malleable iron. If material is important to a replacement, quote the exact EP-XTB model and stock bore rather than asking for “malleable XT” generically.
Material comparison for selection
| Decision factor | Cast iron | Malleable iron |
|---|---|---|
| Typical role | General industrial bushing/hub construction where the catalogue specifies it. | Selected stock-bore XT entries where the catalogue marks malleable iron. |
| Ductility | Lower; avoid impact damage and stress concentration. | Higher than gray cast iron, useful where additional toughness is specified. |
| Machining/fit | Good machinability; final fit still depends on bore/keyway tolerances. | Machinable, but replacement must match the specified material and dimensions. |
| Selection rule | Use when the exact model/configuration calls for cast iron. | Use when the exact model/bore is marked or a custom specification requires it. |
Shock, corrosion and special materials
Do not infer that malleable iron alone makes a connection suitable for mining, agriculture or reversing shock. Shaft condition, keyway, hub thickness, fasteners and duty all matter. For corrosion or hygiene-sensitive service, the relevant discussion may shift to steel, stainless steel, coating or a custom component rather than simply switching iron grade.
How to specify material in an RFQ
State the product family, model, bore and keyway first, then add the required material or environment. If you are replacing an existing bushing, include a photo of the marking and any material documentation available from the machine. For custom stainless or steel requests, a drawing is preferable to a material name alone.
Frequently asked questions
Are all EP-XTB15 to EP-XTB35 bushings malleable iron?
No. The XT stock-bore table marks selected entries with an asterisk; those marked entries are identified as malleable iron, while the other entries are cast iron.
Should I automatically choose malleable iron for shock loads?
Treat material as one part of the duty review. Confirm the exact bushing configuration, shaft/hub condition and load before changing material.
Related products and resources
Need help with a real application?
Send the model, shaft diameter, keyway or drawing so the enquiry can be checked against the correct bushing family.