OEM metal fabrication is a broad spectrum description for an interlaced set of skills and a wide range of product types, sizes, complexities and refinements. No two fabrication factories are identical – from builders of roadbridge assemblies to custom fuel tanks, from street furniture to military equipment, the variety is beyond easy description. They use a common skillset in cutting, bending, fabricating, joining and finishing metals, to produce one-off custom, low volume and high volume products for all sectors of industry and commerce. More than any other sector, OEM metal fabrication factories use knowledge developed over thousands of years of industrial history to build products that are key to all areas of technical effort.
Overwhelmingly they work in steel, stainless steel and Aluminium – the materials at the core of most large constructions and systems and the bedrock of engineered materials for devices, products and components in most industries.
They take the cut and shaped products of raw materials and component supply processes and build these into larger and uniquely designed parts, sub-assemblies and constructs. OEM fabricators are likely to by adjunct to, partners with or include in-house many of the necessary raw material preparation processes, in order to optimise their flexibility and responsiveness.
OEM metal fabrication source material types
The wide range of products that can be successfully constructed by an OEM metal fabrication factory is best considered by raw materials types, rather than by skills or market classifications. Any given product is very likely to encompass a variety of material types, to solve diverse manufacturing and functional issues.
Devices and systems OEM metal fabricated from tube abound. Tubular materials can be stainless steels, alloy steels, mild steel, Aluminium plus Copper, brass and bronze – and even exotic materials such as Magnesium alloys, glass or Carbon fibre reinforced composites and titanium. Source materials in tube form may be extruded, roller welded, seamlessly rolled, laid-up resin bonded or moulded. The tube parts can serve as framing, fluid and gas ducting, pressure vessels, cable ducts and more. They can be built into vehicle chassis, architectural components, consumer products, cranes, furniture and much more.
Sheet metal construction
2D and 3D shapes cut from sheet material are very widely applied in the construction of OEM fabricated systems, components and devices. This involves the creation of high tolerance, intricate components and the synthesis of those fabricated materials into complex and precise assemblies in order to create the final product. The manufacture of sheet components may involve complex shaping stages to make a wide range of 3D forms, which can enhance strength and reduce part count and jointing requirements by better integrating parts. Design options in this regard are essentially unlimited, and design stage consulting with the OEM metal fabricator can enhance, cost control and simplify the product and its manufacture considerably.
The synthesis of parts into a whole involves a wide range of joining techniques and manual/automated equipment. With construction complete, many sheet metal constructions require surface finishes to be applied for cosmetic, corrosion or contamination issues.
Creating a precision fabricated assembly offers little room for error or inconsistencies, as such an assembly will almost always be built to fit into or to encompass other systems or devices, making the interfaces and position of every aspect critical. Use of state-of-the-art design, analysis and production tools to manufacture the most detailed and customer specific parts and products lies at the heart of metal fabrication service providers process.
Wire formed assemblies
Wire forming is a high level definition for the processes that shape wire (and light gauge bar) materials to deliver precise, repeatable shape/contour. It is usual for OEM metal fabrication services to offer this skill. Specific wire forming techniques may include piercing, bending, shearing, chamfering, swaging, and others depending on construction and configuration requirements. Application of wire forming across sectors such as food production, automotive production, shipping and handling, medical equipment, and many others – with products of this type used for framing/support, sifting, guarding, springing and more purposes.
Wire forming, of the full range of raw material sources, begins with coiled wire, which is generally straightened as the first step in processing. Various processes are employed for creating the required net-shapes of component parts, ranging from hand work to highly specialised computer numerical control (CNC) machines. Individual components are then joined together to form assemblies – which then usually require finishes to be applied.
Machined part assemblies
It is common for metal fabrications to include – or be manufactured largely from machined parts. Specifically, in this context machined parts refers to components that have resulted from manual or CNC machining from bar or plate stock. It is common for OEM metal fabrication shops to include CNC services in their range of offered skills, for completeness of response to customers needs.
Such assemblies of machined components may also include sheet, tube, rolled, pressed or forged parts within the construct – needs and variety that will be driven by the customers needs and the product/components specifications.
Assembly and jointing methods
Welding is the primary method employed for construction of tubular and sheet metal assemblies by OEM metal fabrication.
In the welding process, two or more (similar material) parts are heated and melted or forced together under extreme load and friction, causing the joined parts to fuse together and essentially function as one. Most commonly used welding methods introduce an alloy compatible filler material, to ease the joining process and allow for lower precision in the ‘dry’ fit. Welding encompasses various arc welding, resistance welding and oxyfuel gas welding methods such as Oxy-acetylene, TIG, MIG, arc welding, friction spin welding, thermite welding and (very commonly for sheet metal components), spot welding.
Brazing, which uses an unlike alloy to bond to both materials and act as a filler.
Brazing applies molten brass to two steel parts to be jointed. The brass is melted and the jointed parts heated (but not melted) using a air-gas or Oxy-acetylene torch, or a furnace and then the filler is distributed in between multiple solid metal components , using an oxide removing flux that allows the filler to fully ‘wet’ all surfaces. The filler metal melts at a high temperature, which is still below the melting point of the base metals.
Soldering is essentially the same as brazing; the fundamental difference being that in soldering the filler metal is silver or lead-tin-antimony based and has a much lower melting point. No melting of the base base components occurs, but the filler metal wets and combines with the base metals to form a wetted and integrated bond.
In adhesive processes a polymer filler material, the adhesive, is used to hold multiple closely spaced parts together through surface attachment. The adhesive is a nonmetallic substance which hardens by evaporation of solvents or by cross linking between two materials in a catalytic process.
A very wide range of fastening methods are employed in OEM metal fabrications, to attach two or more parts together to form a strong joint. Fasteners are generally used, being added on during the assembly operation. However, tab and slot construction methods are also used for sheet metal parts, as these can be close integrated and lower cost. This involves the insertion and bending/locking of features of one of the components into or through features of a second component. Mechanical fastening can be divided into methods that allow for easy disassembly, threaded fasteners (both material tapped and PEMS insert based), and those that do not, rivets.
Surface preparation methods
OEM metal fabrication usually involves deburring, which smooths the process roughened edges of a metal component or assembly.
Cutting and joining processes create thermal burrs and slag. Any cutting process applied to a piece of metal creates small, sharp burrs that can be a potential hazard.
In the food, medical and pharmaceutical sectors, small flecks of metal that flake off can be an extreme health hazard. Components used in life critical assemblies such as in commercial aircraft can also pose a serious threat if components shed materials. Fabricators employ a range of tools to remove shards and burrs, rendering edges smooth.
Vibratory finishing or tumbling is often used for finishing smaller parts, but complex precision components, light gauge material and delicate alloys are not tumbled.
Deburring produces a high-quality finish and a smooth edge. No burrs or sharp edges makes for safe parts, a better surface for paint/plating, and products that give a better impression.
Graining is a technique to add uniform, parallel brush marks to Aluminium and stainless steel parts by OEM metal fabricators.
Wide-belt sanding and brushing the flat workpiece will both deburr and improve the appearance of flat parts – but it is a difficult and a skilled task to grain complex shapes such as hand rails and architectural components .
Brushed metal finishing is an effective method for removing surface imperfections resulting from welding.
Chemical etching is used to texture surfaces.
Photomask shielding of component surfaces, followed by mask development and etching allows a wide variety of textures, patterns and branding to be applied in a cannot-be-removed way that can greatly enhance the durable impression a product makes.
Applied surface finishes
Finishing involves adding a protective and/or cosmetic layer to the component/assembly surface, to achieve a better appearance or improve environmental resilience. A wide range of surface finishes are used in OEM metal fabrication.
Anodizing is an electrochemical process that increases the corrosion resistance of a metal part by forming a well integrated and resilient layer of oxide on its surface.
By immersing aluminium in an electrolyte bath and passing an electrical current through it, a tough and integrated aluminium oxide coat forms from the material itself. The result is a coating that improves resistance to corrosion and wear. The coating does not peel or chip, and lasts indefinitely – and is self healing to a limited degree.
Anodizing provides a better key for paint, while still maintaining the surface texture. Such treatment is essentially universal in the industrial and consumer use of Aluminium alloys – other than when they are cast, which chemical/crystalline structure lends itself poorly to the process..
Metal plating applies a secondary (other) metal as an outer coating on components.
Thin layers of a less corroding or higher cosmetic metal (such as nickel, copper, chromium) are applied in chemical deposition or galvanic circuits. Gold, silver and platinum are commonly used for decorative purposes. Metal plating improves durability, corrosion resistance, electrical contact resistance/wear and the cosmetics a metal product.
Galvanizing is a general term for the most widely used metal finishing on steel – most hardware parts are galvanised, which can be zinc electroplated but is more commonly liquid dip zinc plating. The zinc serves as a protective coating that shields the metal from water, moisture, and other exposure that may tarnish or rust the parts, acting as a sacrificial anode in the electrochemistry of corrosion.
Black oxide, blackening and gun bluing are all terms for the process of black iron oxide treatment of ferrous metals.
Oxidizing salts and catalysts and additives in the treatment process undergo a chemical reaction with the iron content of the part, when it is heated and immersed. The result is the formation of black iron oxide (magnetite) on the surface of the part.
The resulting black or blue finish ensures minimal changes to the dimensions, unlike paint or plated finishes. This provides modest corrosion resistance and an appealing appearance.
Powder-coating is commonly used for metals found in products from industrial machinery to household items and is widely offered by OEM metal fabricators.
Powder coating applies a decorative finish that is essentially paint, but with greater durability. Powder coated products are more resistant to scratches, corrosion, fading and weathering.
The coating is typically applied by electrostatic spray, and then hot cured to produce a textured, matte, or glossy coating. Powder coating does not use a liquid carrier or VOCs but is an all solids application, so it allows thick coating without runs.
For an extraordinary range of markets, product types and technologies, OEM metal fabrication is the preferred solution – allowing volumes from 1 to high volume mass production (through increasing automation) it can produce outstanding results, used in toys to oil platforms, airframes to window frames.
In particular, it is a powerful way to mix component technologies in integrated and cost effective solutions for diverse and complex problems.