Carbonsteel304 DIN912 Allen Hex Socket Head Cap Knurled Screw Bolt

Product Description

PRODUCT PARAMETER

Hex Socket Head Cap Bolts

Hex socket head cap screws (Allen bolts) feature a cylindrical head with a hexagonal internal drive, enabling high torque transmission and flush/sunk installation. Their recessed design prevents surface protrusion, ideal for space-constrained or aesthetic applications. Made of carbon steel (8.8/12.9 grade, zinc-plated), stainless steel (304/316), or alloy steel, they meet standards like ISO 4762, DIN 912, with sizes M3–M30 and lengths 6–300mm.

Key uses include:

Mechanical Engineering: Securing motor mounts, gearboxes, and machine tool components (high tensile strength resists vibration).
Electronics/Aerospace: Fixing precision casings, panels, or avionics (flush heads prevent interference).
Automotive/Engine Systems: Bolting cylinder heads, turbochargers, or chassis parts (tightening via socket wrenches ensures uniform preload).
Medical/Industrial Equipment: Assembling devices requiring smooth surfaces (e.g., surgical tables, food processing machinery).
DIY/Modular Structures: Building furniture, robotics, or fixtures with hidden fasteners for sleek designs.

Hex Socket Head Cap Bolts

Thread size					M1.6	M2	M2.5	M3	M4
d
P		thread pitch			0.35	0.4	0.45	0.5	0.7
dk		Max	Smooth head		3	3.8	4.5	5.5	7
			Knurled head		3.14	3.98	4.68	5.68	7.22
		Min			2.86	3.62	4.32	5.32	6.78
ds		Max			1.6	2	2.5	3	4
		Min			1.46	1.86	2.36	2.86	3.82
k		Max			1.6	2	2.5	3	4
		Min			1.46	1.86	2.36	2.86	3.82
s		Nominal			1.5	1.5	2	2.5	3
		Max	Level 12.9		1.545	1.545	2.045	2.56	3.071
			Other performance levels		1.56	1.56	2.06	2.58	3.08
		Min			1.52	1.52	2.02	2.52	3.02
t		Min			0.7	1	1.1	1.3	2

Thread size					(M14)	M16	M20	M24	M30
d
P		thread pitch			2	2	2.5	3	3.5
dk		Max	Smooth head		21	24	30	36	45
			Knurled head		21.33	24.33	30.33	36.39	45.39
		Min			20.67	23.67	29.67	35.61	44.61
ds		Max			14	16	20	24	30
		Min			13.73	15.73	19.67	23.67	29.67
k		Max			14	16	20	24	30
		Min			13.57	15.57	19.48	23.48	29.48
s		Nominal			12	14	17	19	22
		Max	Level 12.9		12.142	14.142	17.23	19.275	22.275
			Other performance levels		12.212	14.212	17.23	19.275	22.275
		Min			12.032	14.032	17.05	19.065	22.065
t		Min			7	8	10	12	15.5

ABOUT US

LONGSHI FASTENERS MANUFACTURING CO.,LTD.,

Longshi Fastener Manufacturing Co., Ltd., founded in 2008, is located in Shahe City, Hebei Province, close to the country's largestLarge fastener industrial cluster - Yongnian standard parts Industrial Park. The company headquarters covers an area of 21 thousand square meters, the annual output value of 200 million yuan, with more than 200 employees, with domestic More than 100 sets of advanced production equipment. It is a "manufacturing + service" type enterprise integrating fastener production, intelligent warehousing and e-commerce sales. The company's construction of the sea screw e-commerce park is located in Yongnian District, Handan City, Hebei Province, covers an area of 45 acres, the park planning and construction of office area, production area, packaging area, storage area, etc., to provide fastener production, packaging, warehousing, e-commerce sales and other services. Longshi mainly produces high quality and high strength fasteners, and "Longshi" screws have become a well-known brand in the industry. Longshi always adhere to quality first, reputation first. From raw material procurement, design and development, production and processing to products strict quality control is implemented in every link of quality testing and sales to win the recognition of our customers. The company has established standardized product testing laboratories and quality testing processes and standards to ensure that products strictly comply with national standards.

FAQ

Q1: What is your minimum order quantity (MOQ)? Do you charge extra for small orders?
100 pieces MOQ (most peers require 1,000+), no price premium for small orders. First-time customers for cross-border e-commerce/trade get free samples.
Q2:Do you support custom orders? How long does the customization process take?
Longshi Advantage: 8-dimensional customization (material, specification, surface treatment, etc.), with 3D design drawings + process plans.
Q3: What if an item is out of stock?
Stockout rate <0.1% (peers: 10+%), with real-time inventory monitoring. For extreme stockouts, free upgraded alternatives are provided (peers often leave clients waiting indefinitely).
Q4: Do you provide technical support, such as installation guidance or drawing optimization?
Dedicated 1v1 engineer team offering free technical support.
Q5:Can I visit your factory or arrange a factory audit?
Support online factory tours (real-time video of production lines/laboratories) and offline visits (pick-up service available).