GB819 Countersunk Cross Recessed Machine Screw

Wanluo supplier’s China GB819 Countersunk Cross Recessed Machine Screw are produced strictly according to national standard specifications, specializing in flat hidden precision assembly scenarios. Different from GB818 protruding pan head machine screws, this model adopts a standard 90-degree tapered countersunk head structure, which can be completely embedded into the workpiece after tightening to achieve zero-protrusion ultra-flat surface.

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Product Description

As a standard full-thread metric machine screw, GB819 Countersunk Cross Recessed Machine Screw by Wanluo requires matching pre-tapped threaded holes for assembly, featuring high-precision thread matching, no loose fitting and stable locking. It perfectly solves the problems of protruding screw interference, unflat workpiece surface and blocked moving parts in precision assembly, and is widely used in high-flatness equipment, precision molds and streamlined product assembly.

Product Build Characteristics & Mass Production Craftsmanship

GB819 cross countersunk head machine screws adopt integrated cold forging forming and high-precision secondary thread rolling process. The industrial standard 90° tapered head features accurate angle tolerance, which perfectly fits universal workpiece counterbore holes to realize seamless flush installation. The deepened standard cross recess fits tightly with manual and electric screwdrivers, effectively avoiding tool slipping and groove damage during high-speed batch assembly and repeated disassembly. The full and uniform metric thread has precise dimensional tolerance, smooth screwing and strong fitting tightness, without jamming or thread slipping. Made of high-quality stainless steel and galvanized carbon steel materials, the screw body has uniform hardness, excellent tensile resistance, anti-fatigue and anti-corrosion performance, maintaining long-term stable fastening accuracy in various light and medium load working environments.

Product Parameter

Parameter Item	Detailed Specification
Product Name	GB819 Countersunk Cross Recessed Machine Screw, Flat Head Metric Machine Bolt
Executive Standard	GB819, ISO Standard, Cross Reference DIN/ANSI Standard
Available Material	304, 316, 316L Stainless Steel, Carbon Steel Zinc-plated
Size Range	M1.6-M12 full standard metric sizes, custom non-standard length available
Head Type	90° standard tapered countersunk head, fully flush hidden installation
Drive Type	Standard cross recess, compatible with universal manual & electric tools
Thread Feature	Precise full metric thread, uniform tooth pitch, high matching accuracy
Surface Treatment	Pickling & passivation, burr-free smooth surface, anti-rust & anti-corrosion
Mechanical Properties	High tensile strength, stable locking force, anti-fatigue, reusable fastening
Packaging Method	Moisture-proof inner packaging + export carton, pallet packing for bulk orders
Supply Service	Spot bulk supply, non-standard customization, mixed fastener one-stop procurement

Gb819 Countersunk Cross Recessed Machine Screw

Screw Thread d			M1.6	M2	M2.5	M3	(M3.5)	M4	M5	M6	M8	M10
P	Pitch		0.35	0.4	0.45	0.5	0.6	0.7	0.8	1	1.25	1.5
a	max		0.7	0.8	0.9	1	1.2	1.4	1.6	2	2.5	3
d_k	theor.	max	3.6	4.4	5.5	6.3	8.2	9.4	10.4	12.6	17.3	20
	Actual	max=nominal size	3.0	3.8	4.7	5.5	7.30	8.40	9.30	11.30	15.80	18.30
	Actual	min	2.7	3.5	4.4	5.2	6.94	8.04	8.94	10.87	15.37	17.78
k	max=nominal size		1	1.2	1.5	1.65	2.35	2.7	2.7	3.3	4.65	5
r	max		0.4	0.5	0.6	0.8	0.9	1	1.3	1.5	2	2.5
x	max		0.9	1	1.1	1.25	1.5	1.75	2	2.5	3.2	3.8
Socket No.			0	0	1	1	2	2	2	3	4	4
M₁	Ref.		1.6	1.9	2.9	3.2	4.4	4.6	5.2	6.8	8.9	10
M₂	Ref.		1.6	1.9	2.8	3	4.1	4.4	4.9	6.6	8.8	9.8
Penetration depth	Type H	max	0.9	1.2	1.8	2.1	2.4	2.6	3.2	3.5	4.6	5.7
	Type H	min	0.6	0.9	1.4	1.7	1.9	2.1	2.7	3.0	4.0	5.1
	Type Z	max	0.95	1.2	1.73	2.01	2.2	2.51	3.05	3.45	4.6	5.64
	Type Z	min	0.7	0.95	1.48	1.76	1.75	2.06	2.6	3	4.15	5.19

Core Functional Benefits & System Engineering Application

1. Full countersunk flush installation design completely eliminates surface protrusions, effectively avoiding friction, collision and jamming of mechanical sliding parts, ensuring smooth operation and high flatness of assembled workpieces.

2. Standard 90° tapered head fits universal counterbore holes perfectly, realizing seamless fitting assembly, greatly improving the flatness and overall aesthetics of equipment surfaces, suitable for high-precision appearance assembly.

3. Precision rolled full metric thread features high tolerance accuracy, perfectly matching standard nuts, washers and threaded holes, with smooth screwing and no thread slipping, supporting long-term repeated disassembly and maintenance.

4. Optimized cross recess structure enhances tool fitting tightness, effectively preventing slipping and groove damage during high-torque locking and batch assembly, improving production efficiency and assembly yield.

5. Multiple material options adapt to different working environments. Stainless steel versions resist oxidation and corrosion, while galvanized carbon steel reduces procurement costs, covering indoor light assembly and outdoor mildly corrosive scene requirements.

Gb819 Countersunk Cross Recessed Machine Screw

FAQ

Q1: What is the difference between GB819 and GB818 machine screws?

A1: GB818 is a protruding pan head for conventional exposed installation, while GB819 is a countersunk flat head for fully flush hidden installation. Their thread specifications are consistent, only the head structure is different. GB819 is specially used for scenarios requiring zero protrusion and ultra-flat surface.

Q2: Does GB819 need pre-tapped holes for installation?

A2: Yes. As a standard machine screw, it must be matched with pre-tapped threaded holes or supporting nuts for fastening. It cannot be directly self-tapped like self-tapping screws, ensuring high-precision assembly tolerance.

Q3: Will the countersunk head affect fastening strength?

A3: No. The screw body thread and core diameter adopt standard industrial design, with consistent tensile strength and locking stability of ordinary machine screws. The countersunk head only changes the installation form without reducing fastening performance.

Q4: What scenarios are GB819 screws suitable for?

A4: Widely used in precision instruments, automation equipment sliding parts, mold accessories, electronic equipment casings, furniture flat assembly and all scenarios requiring flat surface and no structural interference.

Q5: Can you customize special specifications of GB819 screws?

A5: Yes. We support customizing non-standard screw length, special thread pitch and personalized surface treatment to meet special precision assembly and engineering customization needs.

Hot Tags: GB819 Countersunk Screw Manufacturer, Cross Recessed Machine Screw Supplier, Countersunk Machine Screw Wholesale

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