Buyers new to the fastener equipment market often assume that one assembly machine can produce any expansion bolt. In practice, internal and external expansion bolts have different structures, and the machines that assemble them are built around different feeding and insertion principles. Choosing the wrong type means lower output, unstable feeding and expensive modification later.
The difference in the product. An external expansion bolt uses a sleeve that expands outward when the bolt is tightened. The nut sits on the outside of the bolt body, and the sleeve surrounds the bolt. An internal expansion bolt uses a bolt body with an expanding element inside, usually driven by a cone or an internal wedge. The parts look similar at a glance but are assembled in a different order and with different orientation requirements.
The difference in the machine. On an external expansion bolt machine, the sleeve is usually placed over the bolt first, then the washer and nut are assembled onto the exposed thread. On an internal expansion bolt machine, the internal expanding element must be inserted into the bolt body before the bolt end is closed or formed, which requires a different insertion station and often a different discharge mechanism.
Tooling and changeover. Both machine types are configured for a specific bolt size and family. Changing from M6 to M10 normally requires changing bowl tooling, tracks, insertion jaws and sometimes the pressing module. Buyers should ask suppliers how long a size changeover takes and how many mechanical parts need to be replaced, because this directly affects how flexibly the machine can be used for multiple orders.
Which one to buy. If your product range is mostly external expansion bolts and metal anchors for construction fixings, an external expansion bolt assembly machine is the standard choice, with models available in different generations offering different output levels. If you also produce internal expansion bolts, you will generally need a separate machine rather than trying to convert one type into the other.
Double-sleeve and double-nut variants. Some buyers need mechanical anchors with two sleeves or two nuts. These require additional stations, a longer machine frame and more complex feeding, so they are normally quoted as a distinct model rather than a machine option.
Foshan Zhio Equipment Co., Ltd. manufactures automatic assembly machines for internal expansion bolts, external expansion bolts, metal anchors and double-sleeve mechanical anchors. Buyers are encouraged to send drawings or physical samples so the correct machine type and tooling configuration can be confirmed before quotation.