Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course


5.2 Mechanical joining

In mechanical joints, various methods are used which clamp or fasten the parts of the assembly together (e.g. nails, screws, bolts, rivets and circlips). Mechanical joints find innumerable applications from cheap plastic toys to aircraft bodies. They are versatile, easy to use, allow dismantling of the product and permit different materials to be joined with ease. Fountain pens and gearboxes are typical examples; many pens screw together in two sections so that the ink cartridge can be replaced, and gearboxes can be dismantled for maintenance. Mechanical joining also allows movement of components relative to one another, for example, by the use of hinges and bearings.

Mechanical joints do have disadvantages – the fasteners join at discrete points and do not, by themselves, seal the joint against the passage of liquids and gases. Gaskets (such as rubber ones that seal washing machine doors), and the silicone bead around the bath or shower tray, are typical methods of sealing joints, but almost all the other joining methods that are examined in this section form a continuous connection between surfaces and therefore seal the joint without the need for these additional materials. The hole that the fastener goes through in a mechanical joint is a potential weak spot and failure often occurs at these sections (remember that stress = force ÷ area, so by reducing the load-bearing area the stress is increased). If account is not made for this during the design stage then problems may arise during service. In a Boeing 747 (Figure 47) there are 6 million parts, of which 3 million are fasteners of some kind and about half of these fasteners are rivets – that is a lot of joining!

Figure 47
Figure 47 A typical wide-bodied aircraft can contain several million fasteners

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, we offer two gentle introductory routes to our qualifications find out Where to take your learning next? You could either choose to start with an Access courses or an open box module which allows you to count your previous learning towards an Open University qualification.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus