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close this bookThreaded Joints - Course: Techniques of fitting and assembling component parts to produce simple units. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 25 p.)
View the document(introduction...)
View the documentPreliminary Remarks
View the documentHints on Labour Safety
View the document1. Purpose of Threaded Joints
View the document2. Selected Types of Bolts and Screws
View the document3. Selected Types of Nuts
View the document4. Selected Types of Locking Devices for Bolts and Screws
View the document5. Selected Types of Washers
View the document6. Types of Threaded Joints
View the document7. Stresses in Threaded Joint
View the document8. Tools
View the document9. The Technological Steps of Making Threaded Joints
View the document10. Undoing Threaded Joints

2. Selected Types of Bolts and Screws

Bolts and screws made of steel are used in machines, steel structures, vehicles and ships because of their strength and toughness. They may be electrically plated with cadmium, zinc, copper or brass.

Bolts and screws made of copper, brass or light metal are used in electrical equipment because they conduct electricity and do not corrode easily.

Hexagon head screws

Used mainly for iron and steel work and in machines generally. There are hexagon head screws of different sizes and lengths of thread in accordance with ISO metric coarse and fine threads.

Typical designation:

Hexagon Head Screw M6 x 20

- Nominal diameter of the ISO metric thread (coarse): 6 mm
- Length of engagement (without the head): 20 mm


Figure 2. Hexagon head screw

1 nominal diameter, 2 length of engagement

Countersunk head screws

Used in industrial plant and equipment, where safety requires that no head projects the surface of any component. There are countersunk head screws of different sizes and lengths of thread according to ISO metric coarse thread, with different shapes of slots and tops of heads.

Typical designation:

Countersunk bolt with cross slot M6 x 20

- Nominal diameter of the ISO metric coarse thread: 6 mm
- Length of engagement (with the head): 20 mm


Figure 3. Countersunk-head screw

1 nominal diameter, 2 length of engagement

Cheese head screws

Used for light-weight structured and in general engineering. There are cheese head screws of different sizes and lengths of thread according to ISO metric coarse thread, with different shapes of head. Fillister socket-head screws can accept draw-in forces.

Typical designation:

Cheese head screw with cross slot M6 x 20

- Nominal diameter of the ISO metric coarse thread 6 mm
- Length of engagement (without the head) 20 mm


Figure 4. Cheese head screw

1 with cross slot, 2 with hexagonal socket head

Other ISO metric thread bolts and screws

Generally used in the field of engineering, restricted use in machines. There are different sizes and shapes of the head as well as various designs in bolts.


Figure 5. Other bolts and screws

1 threaded pin, 2 stud bolt, 3 knurled head screw, 4 eye-bolt, 5 thumb screw, 6 square bolt

Sheet metal screws

Generally used for car bodies, vessels and light-weight structures. The thread on the cylindrical portion of the screw (with the tip) cuts itself the thread in soft sheets. There are sheet metal screws of different sizes, lengths and shapes of the head. The threaded portion always extends over the entire length of the shank (with the tip), just up to the head.


Figure 6. Sheet metal screws

1 button-head sheet metal screw with cross slot, 2 oval head sheet metal screw with intersecting slots, 3 countersunk-head sheet metal screw with cross slot, 4 metric self-tapping screw

Wood screws

Wood screws are used in wood structures. The thread on the tapered portion of the shank (with the tip) cuts itself the thread in the wood. There are wood screws of different sizes, lengths and shapes of the head. Only the tapered portion of the shank is threaded, followed by a cylindrical neck.


Figure 7. Wood screws

1 hexagon head wood screw, 2 button-head wood screw, 3 countersunk wood screw

Where are countersunk head screws used?
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What is the difference in the lengths of engagement of a cheese head screw and a countersunk head screw?
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Where does the shape of a sheet metal screw differ from that of a wood screw?
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