Expansion bolts and expansion screws for changing operating forces and temperatures are the right choice for constructions

Expansion bolts & Expansion screws

maximum flexibility | for extreme loads

Expansion bolts & Expansion screws

maximum flexibility | for extreme loads

Expansion screws & expansion bolts

Expansion bolts and expansion studs (also known as screw connections with expansion shank according to e.g. DIN 2510) are unique fastening elements that have a unique property: They can expand under load. This property makes them an ideal solution for precise and secure connections in the industry. They are particularly suitable for constructions that are subject to changing operating forces and temperatures and where the durability of the screw connection needs to be ensured. The favorable behavior of expansion bolt connections is based on their elasticity, in particular the fact that they exhibit a greater elastic change in length with the same preload than so-called rigid bolt connections.

This behavior of expansion bolts leads to a number of advantages:

Expansion bolts have a high long-term durability, as the additional loads on the bolts due to changing operating forces, thermal expansion and bending moments are reduced.
The drop in preload, which contributes significantly to the loosening of the screw connections - during operation by creeping of the material, settling phenomena in the force-transmitting surfaces of the connection and the clamped parts, as well as by bending of the threads - is lower.
Under certain conditions, the amount of preload applied can be easily measured via the change in length of the screw.

The following aspects must be taken into account when designing expansion bolts and expansion studs:

The minimum length of the expansion shank should be at least twice, ideally four of the thread diameter to ensure sufficient elasticity.
The ratio of thread core diameter to expansion shank diameter should be around 1.1 in order to optimize the load-bearing capacity and elasticity of the screw.
The transition angle between the expansion shank and the thread should be kept relatively small. This leads to a favorable flow of force and better load distribution in the screwed thread.

Sources:

DIN 2510 Part 1
DIN 2510 Part 3
Wiegand / Illgner (1962) Calculation and design of screwed connections, Springer-Verlag, Berlin/Göttingen/Heidelberg

Difference between expansion bolts and expansion screws

Expansion bolts vs. expansion screws

Expansion bolts and expansion screws according to DIN 2510 are fasteners used to create a fixed connection between two components. The main difference between expansion bolts and expansion screws lies in their design and function.

Expansion bolts are special bolts that have a high strength and expand when tightened. They consist of an elongated body with a thread on one side and a conical end on the other. When the nut is tightened on the threaded end, the bolt expands, creating a firm connection between the components. Expansion bolts are often used in conjunction with a special expansion nut to create the required expansion and secure the connection.

Expansion screws, on the other hand, are screws that lengthen when tightened. They have a special thread profile that enables axial expansion. When the nut on the bolt is tightened, the bolt elongates, creating a firm connection between the components. Expansion bolts are often used in conjunction with a special expansion nut to create the required elongation and secure the connection.

Advantages of expansion bolts and expansion screws

The main advantage of expansion bolts and expansion screws is that they allow an even load distribution across the joint and have a high strength. They are often used in applications where a reliable and durable connection is required, such as in the construction industry, mechanical engineering and vehicle construction.

It is important to note that expansion bolts and expansion screws must be carefully sized and correctly tightened to ensure a secure and reliable connection. You can find more information about this in our expert guide.

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DIN 2510 Form L

DIN 2510 Form L is a special standard for expansion bolts defined by the German Industrial Standard (DIN). It defines the requirements for expansion bolts, in particular with regard to their dimensions, materials and mechanical properties. According to the standard, expansion bolts must have a certain geometry that allows them to expand under load. They must have an extended thread area, known as the expansion area. This expansion area allows the bolt to expand under load and thus create a uniform and controlled preload. DIN 2510 Form L also stipulates that expansion bolts must be made of high-strength materials in order to be able to withstand high loads. As a rule, they are made of alloy steel or stainless steel. The exact material requirements are specified in the standard. In addition, DIN 2510 Form L specifies the mechanical properties of expansion bolts, such as the minimum tensile strength, the minimum yield strength and the minimum elongation. These properties ensure that the expansion bolts meet the requirements for strength and reliability. DIN 2510 Form L is an internationally recognized standard for expansion bolts and is used by many manufacturers and users worldwide. It ensures that expansion bolts have a uniform quality and performance and can be used safely in various applications.
Thread (d1)	M12	M16	M20	M24	M27	M30	M33	M36	M39	M42	M45
d2	8,5	12	15	18	20,5	23	25,5	27,5	30,5	32,5	35,5
d3	8	12	14	14	18	18	25	25	28	28	32
b1	20	23	28	32	35	39	42	45	48	52	55
z1	1,75	2	2,5	3	3	3,5	3,5	4	4	4,5	4,5
z2	4	5	6	6	6	6	9	9	10	10	11
SW	7	10	11	11	13	13	22	22	24	24	27

DIN 2510 Form NF

DIN 2510 Form NF is a special version of expansion bolts manufactured in accordance with the German Industrial Standard (DIN) 2510. The designation "NF" stands for "non-flame-retardant" and refers to the specific requirements for expansion bolts used in potentially explosive atmospheres. DIN 2510 Form NF specifies special requirements for the design and material of expansion bolts to ensure that they comply with explosion protection requirements. This includes the use of materials that do not generate sparks and the prevention of potential ignition sources. DIN 2510 Form NF expansion bolts are often used in industries such as the chemical, oil and gas, petrochemical and other potentially explosive environments. They provide a safe and reliable connection that meets the high safety standards in these areas.
Thread (d1)	M12	M16	M20	M24	M27	M30	M33	M36	M39	M42	M45
d2	21	26	31	35	40	45	49	53,5	58,5	63,5	68,5
d3	14,5	18,5	22,5	26,5	30,5	33,5	36,5	39,5	42,5	45,5	49,5
m	12	16	20	24	27	30	33	36	39	42	45
s	22	27	32	36	41	46	50	55	60	65	70
t	2	2	2	3	3	3	3	3	3	3	3

DIN 2510 Form Z

DIN 2510 Form Z is a specific design of expansion bolts manufactured in accordance with the German Industrial Standard (DIN) 2510. It defines the requirements for expansion bolts, including their dimensions, materials and mechanical properties. The form Z characterizes a special variant of expansion bolts that have an extended shank and an extended thread. This design allows for greater elongation of the bolt under load, resulting in a more uniform and controlled preload. DIN 2510 Form Z is often used in areas where high accuracy and reliability are required. It is often used in the engineering, automotive and aerospace industries to join components that need to withstand heavy loads.
Thread (d1)	M12	M16	M20	M24	M27	M30	M33	M36	M39	M42	M45
d2	8,5	12	15	18	20,5	23	25,5	27,5	30,5	32,5	35,5
d3	8	12	14	14	18	18	25	25	28	28	32
b3	27	31	36	42	47	50	53	57	60	64	66
z1	1,75	2	2,5	3	3	3,5	3,5	4	4	4,5	4,5
SW	7	10	11	11	13	13	22	22	24	24	27

DIN 2510 Form K

DIN 2510 Form K specifies a particular type of expansion bolt that meets the requirements of the German Industrial Standard (DIN) 2510. This standard specifies the requirements for expansion bolts, including their dimensions, materials and mechanical properties. Form K refers to a special type of expansion bolt characterized by a specially designed head. This head is designed to provide a larger contact area, resulting in improved force distribution. This can help to reduce the load on the connected component and extend the service life of the connection. DIN 2510 Form K expansion bolts are often used in areas where high load-bearing capacity and durability are required. They are often used in the mechanical engineering, automotive and aerospace industries to securely connect components that have to withstand high loads.
Thread (d1)	M12	M16	M20	M24	M27	M30	M33	M36	M39	M42	M45
d2	8,5	12	15	18	20,5	23	25,5	27,5	30,5	32,5	35,5
d3	8	12	14	14	18	18	25	25	28	28	32
b2	13	16	20	24	27	30	33	36	39	42	45
z1	1,75	2	2,5	3	3	3,5	3,5	4	4	4,5	4,5
z2	4	5	6	6	6	6	9	9	10	10	11
SW	7	10	11	11	13	13	22	22	24	24	27

DIN 2510 Form KU

DIN 2510 Form KU identifies a specific type of expansion bolt that meets the requirements of the German Industrial Standard (DIN) 2510. When installing a form KU bolt, which is characterized by a short thread and a spacer pin, the stress concentration in the first load-bearing threads on the shank side is reduced by an "overlapping" nut thread. This special shape is used exclusively in combination with double-sided capsule nuts up to M56 DIN 2510. Expansion bolts according to DIN 2510 form KU are used in particular for pressure vessel flange connections.
Thread (d1)	M12	M16	M20	M24	M27	M30	M33	M36	M39	M42	M45
d2	8,5	12	15	18	20,5	23	25,5	27,5	30,5	32,5	35,5
d3	8	12	14	14	18	18	25	25	28	28	32
d7	8	12	13	16	18	21	24	26	30	32	34
b2	13	16	20	24	27	30	33	36	39	42	45
z1	1,75	2	2,5	3	3	3,5	3,5	4	4	4,5	4,5
z2	4	5	6	6	6	6	9	9	10	10	11
z3	11	14	16	17	19	19	21	23	23	24	25
SW	7	10	11	11	13	13	22	22	24	24	27

DIN 2510 Form ZU

DIN 2510 Form ZU identifies a specific type of expansion bolt that meets the requirements of the German Industrial Standard (DIN) 2510. Expansion bolts according to DIN 2510 Form ZU are used for pressure vessel flange connections. Similar to the KU form, this standard also defines the requirements for the design, materials and testing of these connections. The "ZU" form refers to a specific type of connection used in specific applications.
Thread (d1)	M12	M16	M20	M24	M27	M30	M33	M36	M39	M42	M45
d2	8,5	12	15	18	20,5	23	25,5	27,5	30,5	32,5	35,5
d3	8	12	14	14	18	18	25	25	28	28	32
d7	8	12	13	16	18	21	24	26	30	32	34
b3	27	31	36	42	47	50	53	57	60	64	66
z1	1,75	2	2,5	3	3	3,5	3,5	4	4	4,5	4,5
z4	7	8	9	8	10	12	14	14	14	15	15
SW	7	10	11	11	13	13	22	22	24	24	27

Applications for expansion bolts in industry

There are many different applications for expansion bolts. They are frequently used in mechanical engineering, vehicle construction, shipbuilding, aircraft construction and many other branches of industry. They are used there to connect components that are subject to heavy loads.

Expansion bolts play an important role in mechanical engineering, where they are used to securely connect various machine parts such as gears, shafts and bearings. In the automotive and vehicle industry, expansion bolts are essential for the secure assembly of important components such as engines and gearboxes. Expansion bolts are also used in shipbuilding to connect different ship parts such as hull plates, decks and structures. In the aviation industry and in aircraft construction, expansion bolts are indispensable for securely fastening aircraft structures such as wings, landing gear and engines.

				
				Advantages of expansion bolts
						
				Flexibility
				Expansion bolts have the ability to expand and contract under load to adapt to different stresses. This ensures an optimal connection, even if the loads change during operation.
				
				Precision
				The elongation of the screw creates a uniform and controlled preload. This ensures a secure connection that remains stable even under high loads.
				
				Reliability
				Expansion bolts are characterized by their high load-bearing capacity and durability. They can absorb high forces and offer a reliable connection that can withstand extreme conditions.
				
				Simple assembly
				Expansion bolts are quick and easy to fit. They do not require any complex preparatory work such as fitting washers or adjusting the preload.
				
				Easy maintenance
				Expansion bolts allow for easy maintenance and inspection. If necessary, they can be easily replaced without having to remove other components.

Advantages of expansion bolts
Flexibility	Expansion bolts have the ability to expand and contract under load to adapt to different stresses. This ensures an optimal connection, even if the loads change during operation.
Precision	The elongation of the screw creates a uniform and controlled preload. This ensures a secure connection that remains stable even under high loads.
Reliability	Expansion bolts are characterized by their high load-bearing capacity and durability. They can absorb high forces and offer a reliable connection that can withstand extreme conditions.
Simple assembly	Expansion bolts are quick and easy to fit. They do not require any complex preparatory work such as fitting washers or adjusting the preload.
Easy maintenance	Expansion bolts allow for easy maintenance and inspection. If necessary, they can be easily replaced without having to remove other components.