Bi-Metal Wafer Head Self-Drilling Screw Manufacturer

Overview

A low wafer head for clamping aluminium sections, flashing and window frames to steel without a raised head. The ceramic coating adds a barrier layer against galvanic contact with aluminium.

Standard 5.5 × 40 mm with other lengths to order.

Applications

Aluminium window and door frames
Facade sub-structures
Flashing

Used in these projects

Coastal facade and aluminium cladding

Key features

Low head for flush profiles
Coating reduces galvanic corrosion
A4 corrosion resistance
Custom lengths

Specifications

Typical values. Every dimension, hardness and coating is confirmed in writing with your quotation.

Bi-Metal Wafer Head Self-Drilling Screw specifications
Body	SS316
Tip	SS420
Head	Wafer, Phillips drive
Size	5.5 × 40 mm; other sizes to order
Finish	Ceramic coating, silver
Packing	Bags, boxes, cartons, buckets
Lead time	7–25 working days
MOQ	10,000 pcs
HS code	7318.14 / 7318.12 (by type)

Buying guide

Applies to all bi-metal screws.

304 or 316 body

A2 (304) suits inland exterior use. A4 (316) contains 2–3 % molybdenum and resists chloride pitting, so specify it within about 5 km of the sea, near pools or in chemical plants.

Tip material

SS410/SS420 tips keep some corrosion resistance; SCM435 and C1022 tips drill faster in thick steel. The tip should break through before the stainless threads engage.

Isolate dissimilar metals

On aluminium solar rails and cladding use a stainless EPDM washer or a coated screw to reduce galvanic corrosion between the fastener and the profile.

Ordering

Packing and delivery

Standard terms for this product. Tell us if your market needs something different.

PackingSmall boxes, buckets or 20–25 kg cartons on fumigated pallets; private label available.

Lead timeSamples in 7 days; production 25–35 days after deposit.

PaymentT/T 30 % deposit, 70 % against B/L copy, or L/C at sight.

ShippingFOB Shanghai or Ningbo, CFR or CIF to your port.

Questions about this product

How thick a steel section can a bi-metal screw drill?

Depending on point size, from 0.75 mm sheet up to about 6 mm structural steel. For thicker purlins we recommend a #5 point carbon screw or pre-drilling.

Are bi-metal screws magnetic?

The 304/316 body is mostly non-magnetic, while the hardened tip is magnetic. That is a quick way to confirm a bi-metal screw on site.

Do you supply mill certificates?

Yes. Each lot ships with a material test certificate covering chemistry, hardness, case depth and salt spray results.

Bi-Metal Screws