Screws · DIN 963
DIN 963 Slotted CSK Screw
Accurate Fastners manufactures DIN 963 slotted countersunk screws in stainless steel grades SS 202, SS 304 and SS 316, covering diameters M3 to M8 and lengths from 10 mm to 50 mm. These cold forged screws are produced to the DIN 963 standard and are available for domestic and international supply.
- Standard
- DIN 963
- Grades
- 304 / 316 / 202
- Size
- M3 – M8
- Length
- 10 mm – 50 mm
Overview
What is the DIN 963 Slotted CSK Screw?
DIN 963 is a metric standard specifying flat-head (countersunk) machine screws with a slotted drive. The countersunk head is designed to sit flush with or below the surface of the mating component when driven into a correspondingly chamfered hole, eliminating any protrusion. This profile is commonly used in assemblies where a smooth external surface is required and where head clearance is limited.
Accurate Fastners produces these screws by cold forging, a process that forms the head and shank from raw stainless steel rod under high compressive force without removing material. Cold forging generally improves grain structure and produces consistent head geometry, which is important for repeatable seating in countersunk holes. Metric machine thread is rolled along the shank, and the slotted recess is formed to accept a standard flat-blade screwdriver.
The DIN 963 designation defines the head angle, drive width and depth, and thread engagement proportions, giving designers a predictable fastener geometry across suppliers and assemblies. Accurate Fastners applies quality checks during both procurement of raw materials and at the point of delivery, in line with the company's stated quality control practice. The screws are available in three stainless steel grades to suit differing environmental and process requirements.
In Depth
Product description
Construction and Geometry
The DIN 963 screw features an 90-degree countersunk head with a flat bearing face and a slotted drive recess machined to the standard's prescribed width-to-depth ratio. The shank carries a metric machine thread compatible with standard metric nuts and tapped holes. Across the available range, diameters run from M3 to M8 and lengths from 10 mm to 50 mm, giving a reasonable selection for thin-section and moderate-thickness assemblies.
Cold forging produces a head that is integral with the shank rather than machined from a larger blank, which generally results in a compact and dimensionally consistent fastener. The slotted drive is simple in form, requiring only a flat-blade screwdriver and no special tooling, which can be advantageous in field assembly or where power tooling is unavailable. The stainless steel body contributes corrosion resistance relative to carbon steel equivalents.
Functional Behaviour in an Assembly
When installed into a correctly countersunk hole, the tapered underside of the head bears against the chamfered seat, drawing the joined parts together as the screw is tightened. The flush seating eliminates surface protrusion, which may reduce snagging, improve aesthetics, or allow close stacking of components. The slotted drive transmits torque from a screwdriver blade; drive engagement depth and recess condition are important for avoiding cam-out during installation.
Metric machine thread engages cleanly with standard ISO metric tapped holes or nuts. The thread form produced by cold rolling typically presents a consistent pitch and flank angle, which supports reliable thread engagement. Because the countersunk head self-centres in a properly formed seat, positional alignment of the fastener in the joint is partly guided by the chamfer geometry, which may assist assembly accuracy in repeated or volume production settings.
How It Differs from Similar Fasteners
The DIN 963 screw differs from a pan-head or hex-head screw in that its head is designed to sit recessed rather than proud of the surface. Compared with a Phillips or Pozidriv countersunk screw, the slotted drive is simpler but may be more susceptible to cam-out under high torque, making it better suited to lighter clamping loads. The DIN 963 standard itself differs from ISO 2009, which covers similar geometry but with marginally differing tolerances on head diameter and drive dimensions.
Within Accurate Fastners' range, a DIN 963 screw complements other screw types such as socket head or pan-head variants. Where flush fitting is not required, a raised countersunk (oval) head variant or a pan head may be more appropriate. Selection between slotted, Phillips or hexagon socket drive should consider the available installation tools, required torque, and how frequently the fastener may need to be removed and re-installed.
Material & Grade
Material and grade information
- SS 304
- SS 316
- SS 202
These screws are available in SS 202, SS 304 and SS 316. SS 304 is an austenitic grade that is widely used in general industrial and food-contact environments; it typically offers good resistance to oxidising conditions and is commonly specified where moderate corrosion resistance and hygiene are relevant. SS 316 contains molybdenum, which generally improves resistance to chloride-bearing environments and process chemicals; it is often selected for pharmaceutical machinery, coastal installations or fluid-handling assemblies.
SS 202 is a lower-nickel austenitic grade that may be suitable where cost considerations are relevant and the environment is less aggressive. It is generally considered less resistant to chloride attack than SS 304 or SS 316. The appropriate grade for a given application depends on the service environment, process media, cleaning regimes and relevant industry requirements. Customers are encouraged to confirm grade selection with their engineering team and with Accurate Fastners' sales team before ordering.
Grades shown are those documented for this product in the Accurate Fastners brochure. General material notes are guidance only; confirm grade selection for your environment.
Technical Data
Technical specifications
| Product type | Screw – DIN 963 Slotted CSK Screw |
|---|---|
| Material | Stainless steel |
| Material grade | SS 304, SS 316, SS 202 |
| Applicable standard | DIN 963 |
| Nominal diameter / size | M3 – M8 |
| Length | 10 mm – 50 mm |
| Thread type | Metric machine thread |
| Head / form | Countersunk (flat) head |
| Drive / tightening | Slotted |
| Manufacturing process | Cold forged |
Sizes
Available sizes
Documented size range
M3 – M8
Documented length range
10 mm – 50 mm
Individual sizes within the documented range, thread pitches and lengths are confirmed at quotation stage.
Applications
Industrial applications
RO Water Purifier Assemblies
Countersunk screws in SS 304 or SS 316 may be used to fasten panels and frames in RO water purifier units where flush surfaces aid cleaning and where moisture exposure requires corrosion-resistant fasteners.
Solar Energy Mounting Structures
DIN 963 screws may secure covers or junction components in solar mounting systems where a flush external surface reduces wind load interference and stainless steel resists outdoor weathering over long service periods.
LED Lighting Enclosures
Flush-fitting slotted CSK screws are commonly used on LED luminaire housings and driver enclosures where protruding heads could obstruct fitment or aesthetics in finished lighting products.
Food and Beverage Processing Equipment
SS 316 countersunk screws may suit food machinery panels and guards where flush surfaces reduce harbourage points for residues and where regular wash-down with cleaning agents is standard practice.
Pharmaceutical Machinery
In pharmaceutical processing equipment, flush-head SS 316 screws may be specified for cladding panels or access covers where hygiene standards require smooth, cleanable surfaces and resistance to process chemicals.
Features & Selection
Features and selection considerations
Design features
Cold Forged Construction
The head and shank are formed by cold forging, which typically produces consistent head geometry and a sound grain structure throughout the fastener body without material removal.
Flush-Seating Countersunk Head
The 90-degree flat countersunk head sits recessed in a chamfered hole, providing a smooth assembly surface and eliminating the protrusion associated with pan or hex head screws.
Slotted Drive
The single slotted recess requires only a standard flat-blade screwdriver, making installation straightforward in locations where proprietary drive tools are unavailable.
Metric Machine Thread
Cold-rolled metric thread from M3 to M8 is compatible with standard ISO metric tapped holes and nuts, supporting interchangeability across assemblies.
Three Stainless Steel Grades
Availability in SS 202, SS 304 and SS 316 allows grade selection to be matched to the corrosion exposure, process media and budget requirements of a given assembly.
Before you order
Diameter and Length
Confirm the required metric diameter (M3–M8) and grip length (10–50 mm) based on the thickness of the parts being joined and the depth of thread engagement needed in the tapped hole or nut.
Grade Selection
Choose between SS 202, SS 304 and SS 316 based on the service environment. SS 316 is generally preferred where chlorides or aggressive process media are present; discuss requirements with Accurate Fastners' sales team.
Mating Parts and Countersink Preparation
Ensure that the receiving component is chamfered to the correct angle and diameter for DIN 963 geometry. Mismatched countersink angles may cause the head to sit proud or rock, reducing clamping effectiveness.
Quantity and Documentation
For project or bulk orders, specify required quantities, preferred packaging and any documentation needs such as material test certificates or dimensional inspection reports when submitting your enquiry.
FAQs
Frequently asked questions
What does DIN 963 specify for countersunk screws?
DIN 963 defines the head angle, drive slot dimensions and metric thread proportions for slotted flat-head machine screws. It establishes consistent geometry so that fasteners from compliant manufacturers are interchangeable in assemblies designed to the standard.
Which stainless steel grades are available for these screws?
Accurate Fastners supplies DIN 963 slotted CSK screws in SS 202, SS 304 and SS 316. Each grade offers differing levels of corrosion resistance; the appropriate choice depends on the service environment and process conditions of your specific assembly.
What size range is available?
The available diameter range is M3 to M8 and lengths run from 10 mm to 50 mm. If your application requires sizes outside this range, contact the Accurate Fastners sales team to discuss whether alternative options can be confirmed.
Can these screws be used with standard metric nuts and tapped holes?
Yes. The screws carry a standard metric machine thread, which is compatible with ISO metric nuts and tapped holes of the corresponding pitch. Always verify the thread pitch and engagement depth match your design requirements before ordering.
Are related fasteners such as nuts or washers also available from Accurate Fastners?
Accurate Fastners manufactures and supplies a broad range of fasteners including nuts, washers, thread bars and anchors. Complementary components for use with these screws can be discussed with the sales team at the time of enquiry.
How can I request a quotation for DIN 963 slotted CSK screws?
You may submit an enquiry through the website enquiry form, send details to export@accuratefastners.com, or contact the team via WhatsApp. Please include diameter, length, grade, quantity and any documentation requirements to receive an accurate quotation promptly.
Related Products
Complementary fasteners
- DIN 912304 · 316 · 202
DIN 912 Socket Head Cap Screw (Allen Cap Screw)
Size: M3 – M16
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