6. Technological process of riveting

On principle, the following sequence of operations is necessary for a riveted connection:

6.1. Clamping/drilling:

All plates to be riveted must be clamped with one another as tightly as possible and be drilled together.

With separately drilled parts, attention has to be paid that misaligned holes are reamed by a structural reamer.

Figure 23 - Reaming of misaligned bore holes

Rivet holes have to be drilled a little larger the diameter of the rivet shank:

For rivets thicker than indicated in the table, the bore holes are made by 1 mm larger than the diameter of the rivet shank.

Recommended values
D	DB
1	1.1
2	2.2
3	3.2
4	4.3
5	5.3
6	6.4
8	8.4

D = diameter of the rivet shank
D_B = diameter of the bore hole

6.2. Deburring/countersinking;

Rivet holes are always debarred with the help of a countersinking cutter; for countersunk-head rivets, countersinking must be made by the 75° countersinking cutter. For this, the recommended values are to be found in the marginal table:

Figure 24 - Deburring/countersinking

Recommended values
D	DS
1	1.8
2	3.5
3	5.2
4	7
5	8.8
6	10.3
8	14

D = diameter of the rivet shank
D_S = countersinking diameter

6.3. Inserting/setting

The rivet is inserted into the bore hole, the workpieces are placed on the riveting support in such a way that the set head is underneath. By hammer blows on the rivet setter, the plates are pressed together and the set head draws itself to the workpiece.

Figure 25 - Inserting/setting

6.4. Upsetting

By a couple of hammer blows accurately in the direction of the longitudinal axis, the rivet is upset - until it fills up the bore hole completely.

Figure 26 - Upsetting

6.5. Preforming/heading

By even and steady blows around the rivet head, the rivet head is preformed, if a button head riveting shall be made.

Figure 27 - Preforming

With countersunk-head rivetings, the rivet head can be driven into the countersinking immediately.

Figure 28 - Heading

6.6. Finish-forming of the button closing head

If the closing head has been preformed sufficiently, the head is finish-formed by the rivet header.

Figure 29 - Finish-forming

Note:

- Riveting by hand can be carried out in cold condition of the steel rivet up to approximately 8 mm diameter - thicker rivets must be worked in red-hot condition.

- Non-ferrous metal rivets are worked in cold condition after having them annealed before.

With every cold working of steel or non-ferrous metal, the material becomes hard and brittle, especially if it is formed by many hammer blows. In order to keep the material as tough and elastic as possible, the rivet should be shaped by a few, well-aimed blows.

Peculiarities of the technological process

- If no prefabricated button head rivets or countersunk-head rivets are at disposal, steel or non-ferrous metal wires may also be used as rivet bolts.

In this case, the rivet bolt has to be clamped in clamping jaws for round material with a set head to be preformed.

If no clamping jaws for round material are at hand. the rivet bolt must be preheaded in the rivet hole, the set head is formed, then the workpiece is turned and the closing head is shaped.

Figure 30 - Sequence of operations for a double-strap countersunk-head riveting with rivet bolt

- If hollow rivets shall be used, an allowance has to be calculated as it is done with countersunk-head rivets; the rivet -after having been inserted - is to be expanded by a centre punch and to be upset by two short blows.

Figure 31 - Hollow rivet expanded by a centre punch

What individual steps are required for making a button head riveting?
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What is to be done, if individually drilled parts - when being put together - show misaligned holes?
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What hole must be drilled for a 4 mm thick rivet?
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What countersink do you use to prepare countersunk-head riveted joints?
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How must the countersinking diameter be for a 4 mm countersunk-head rivet?
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