Stainless Steel Bowl Washers

Bowl-Shaped Metal Washers for Countersunk Screws, Surface Support & OEM Fastening

One-piece formed metal washers with a raised circular rim and smooth concave center. The bowl profile provides shaped support beneath compatible screw heads, a broader bearing footprint and a clean finished appearance.

Type

Bowl / Cup Shaped Washer

Construction

One-Piece Formed Metal

Profile

Concave Bowl / Raised Outer Rim

Materials

304 / A2, 316 / A4 Stainless Steel

Screw Compatibility

Countersunk / Raised Countersunk / OEM

Specification

Manufacturer / Customer Drawing

Key Dimensions

d1 / d2 / h / Thickness

Custom Options

Hole / OD / Depth / Profile / Material

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Product Overview

Bowl Washers are one-piece formed metal components with a round outer rim, central screw hole and smooth bowl-shaped seat. Also described as cup washers, countersunk cup washers, finishing washers or rosette washers, their defining feature is the formed bearing profile rather than a locking or sealing element.

With a compatible screw, the shaped seat can improve head support and centering, distribute localized fastening pressure and help protect the surrounding material. Countersunk, raised countersunk and oval-head screws may be suitable, but the actual head diameter, underside angle and washer depth must match. No universal flush appearance is assumed.

VALTOR supplies 304 / A2 and 316 / A4 stainless profiles to manufacturer specifications and customer drawings. For purchasing, specify center hole, outside diameter, overall height, bowl depth, material thickness, screw-head geometry, grade and quantity, ideally with a drawing or sample. Nominal screw size alone is not enough to define the washer.

Technical Specifications

Product

Stainless Steel Bowl Washers

Alternative Buyer Names

Cup Washers / Bowl Shaped Washers / Countersunk Cup Washers / Finishing Washers / Concave Washers / Fish Eye Washers / Rosette Washers

Product Type

One-piece formed metal bearing / finishing / support washer

Profile / Outer Edge

Smooth concave bowl or cup profile with raised circular outer rim

Center / Surface

Round screw-clearance hole; smooth metal without serrations, teeth or slots

Specification Basis

Manufacturer specification, customer drawing, customer sample or OEM requirement; no universal DIN/ISO designation is assumed

Primary Materials

304 / A2 Stainless Steel and 316 / A4 Stainless Steel

Other Materials

Carbon steel, brass or aluminum according to application and manufacturing feasibility

Commercial Screw Compatibility

Approximately M3, M4, M5, M6, M8 and M10; dimensional matching is required, not an artificial standard size range

Additional Sizes

Smaller or larger custom sizes according to drawing and feasibility; stock and lead time confirmed per enquiry

Compatible Head Families

Countersunk, raised countersunk, oval head and selected wood, machine or OEM screw heads

d1 / d2

Center-hole diameter / outside diameter

h / s

Overall formed height / material thickness

c / α

Bowl depth / internal seat or forming angle where specified

Manufacturing

Forming or press stamping, with blanking, punching, deburring and finishing where suitable for the geometry

Surface Condition

Natural stainless finish or another agreed finish; surface appearance and edge condition specified on order

Typical Applications

Machinery panels, equipment housings, furniture and timber hardware, marine fittings and OEM assemblies

Custom Supply

Special hole, OD, height, bowl depth, thickness, rim shape, profile and material

Inspection / Documentation

Material report or MTC, dimensional checks, material verification, sample approval and third-party inspection support as agreed

Order by d1 × d2 × h together with s, bowl depth, profile, material and quantity. There is no universal dimension table for every bowl-washer design. Where an industry or historical specification is requested, confirm the exact requirements before claiming compliance.

Bowl Profile, Screw Head Seating & Dimension Selection

Bowl Profile

A raised outer rim transitions smoothly into a concave seat and central hole. The part is a formed sheet-metal washer, not a solid cup or a flat washer.

Screw Head Seating

The inclined underside of a compatible countersunk or raised countersunk screw must correspond to the internal washer seat. The screw and washer remain separate components.

Center Hole d1

Select the required shank clearance or fit, allowing for the actual screw and application tolerances.

Outside Diameter d2

Defines the overall footprint and available bearing area; confirm surrounding space and the supporting surface.

Bowl Depth c

Influences head seating, finished appearance, washer height and contact geometry.

Material Thickness s

Affects rigidity, forming feasibility and bearing behavior; specify separately from overall height.

Overall Height h

Controls the formed envelope where installation clearance or finished profile is limited.

Seat Angle α

Match the screw underside to the washer profile. Countersunk screws do not all use the same angle.

Finished Appearance

Depending on the combined geometry, the head may be recessed, approximately flush or slightly raised relative to the rim. No universal flush installation is promised.

Product Differences

DIN 6798 V has locking serrations; a bonded sealing washer includes elastomer; a Belleville washer is a designed disc spring; a wedge-lock washer is a cam pair. This product is a smooth one-piece formed bearing washer.

Function Limits

This all-metal bowl washer is not supplied as an anti-loosening, spring-locking, waterproof or vibration-proof device. It is not a roofing bowl washer with EPDM.

304 / 316 Stainless Steel & Size Options

304 / A2 is a common material choice for equipment, furniture, industrial hardware and suitable outdoor applications. 316 / A4 can be selected for marine, coastal, high-humidity and more corrosion-sensitive assemblies. Stainless steel is not corrosion-proof; the service environment and mating components matter.

Commercial screw-size examples include M3, M4, M5, M6, M8 and M10, but actual selection must use d1, d2, h, s, bowl depth and head profile. These examples do not establish a standard range or imply that every dimension combination is stocked.

Drawing-based options include smaller or larger holes, special OD, height, thickness and internal profile. Confirm availability, material, quantity and any surface-finish requirements at enquiry.

Custom Stamping & OEM Geometry

Custom Variables

Hole diameter, outside diameter, material thickness, overall height, bowl depth, seat angle, rim shape, edge radius and material.

Development Basis

Customer drawing, physical washer sample, screw sample or assembly requirement. An actual screw sample can help confirm head seating.

Manufacturing Route

Blanking, punching, press forming or stamping, deburring and surface finishing may be selected as appropriate to the material, size and profile.

RFQ Checklist

Drawing/sample; d1, d2, h, s and bowl depth; screw-head type and geometry; stainless grade; quantity and required delivery.

Production Approval

Agree profile and dimensional tolerances, finish, packaging and sample-approval requirements before production.

Forming Accuracy & Quality Inspection

Dimensions

Center hole, outside diameter, overall height, sheet thickness and bowl depth.

Form / Alignment

Seat geometry, concentricity, circularity and uniform rim height.

Forming Condition

Smooth bowl profile without cracking, severe wrinkling or sharp burrs; inspect edges and surface condition.

Screw Fit Checks

Use the actual or a representative screw to check head seating, hole clearance, bearing contact and finished assembly height.

Material Verification

Verify ordered grade and material documentation according to the purchase requirements.

Documentation

MTC or raw material report, dimensional inspection, material verification, sample approval and third-party inspection support may be arranged.

Applications

Separate Phillips screw seated in a concave-up stainless bowl washer on an equipment panel

Machinery Covers & Equipment Panels

Shaped screw-head seating and a broader bearing surface for suitable panels and housings.

Furniture & Timber Hardware

Compatible countersunk or raised countersunk screws where surface protection and a clean appearance are required.

Marine & Outdoor Hardware

316 stainless options for suitable marine, coastal and corrosion-sensitive assemblies.

Fixtures & Fabricated Components

Formed washer support beneath screw heads in metal fixtures, brackets and fabricated components.

OEM & Custom Fastening Assemblies

Drawing- or sample-based hole, OD, height and bowl geometry matched to the screw and assembly.

Frequently Asked Questions

What is a Bowl Washer?

A one-piece formed metal washer with a raised circular rim and concave bowl or cup-shaped center, commonly used for shaped support beneath compatible screw heads.

Is a Bowl Washer the same as a DIN 6798 V washer?

No. DIN 6798 V has serrated locking teeth. This Bowl Washer has a smooth formed surface and is primarily a bearing, finishing and support component.

What screws can be used with Bowl Washers?

Countersunk, raised countersunk, oval-head and other compatible screws may be used. Compatibility depends on head diameter, underside angle, bowl depth and opening diameter; one washer does not fit every screw.

Can VALTOR supply 304 and 316 Stainless Steel Bowl Washers?

Yes. 304 / A2 and 316 / A4 are the primary stainless options. Specify the grade with dimensional, finish and application requirements.

Can Bowl Washers be manufactured according to drawings?

Yes. Custom hole diameter, OD, height, thickness, bowl depth and profile can be produced according to drawing or sample, quantity and manufacturing feasibility.